TY  - JOUR
A1  - Trauth, Nico
A1  - Schmidt, Christian
A1  - Vieweg, Michael
A1  - Oswald, Sascha Eric
A1  - Fleckenstein, Jan H.
T1  - Hydraulic controls of in-stream gravel bar hyporheic exchange and reactions
JF  - Water resources research
N2  - Hyporheic exchange transports solutes into the subsurface where they can undergo biogeochemical transformations, affecting fluvial water quality and ecology. A three-dimensional numerical model of a natural in-stream gravel bar (20 m x 6 m) is presented. Multiple steady state streamflow is simulated with a computational fluid dynamics code that is sequentially coupled to a reactive transport groundwater model via the hydraulic head distribution at the streambed. Ambient groundwater flow is considered by scenarios of neutral, gaining, and losing conditions. The transformation of oxygen, nitrate, and dissolved organic carbon by aerobic respiration and denitrification in the hyporheic zone are modeled, as is the denitrification of groundwater-borne nitrate when mixed with stream-sourced carbon. In contrast to fully submerged structures, hyporheic exchange flux decreases with increasing stream discharge, due to decreasing hydraulic head gradients across the partially submerged structure. Hyporheic residence time distributions are skewed in the log-space with medians of up to 8 h and shift to symmetric distributions with increasing level of submergence. Solute turnover is mainly controlled by residence times and the extent of the hyporheic exchange flow, which defines the potential reaction area. Although streamflow is the primary driver of hyporheic exchange, its impact on hyporheic exchange flux, residence times, and solute turnover is small, as these quantities exponentially decrease under losing and gaining conditions. Hence, highest reaction potential exists under neutral conditions, when the capacity for denitrification in the partially submerged structure can be orders of magnitude higher than in fully submerged structures.
KW  - in-stream gravel bar
KW  - groundwater-surface water interaction
KW  - aerobic respiration
KW  - denitrification
KW  - computational fluid dynamics
KW  - reactive transport model
Y1  - 2015
U6  - https://doi.org/10.1002/2014WR015857
SN  - 0043-1397
SN  - 1944-7973
VL  - 51
IS  - 4
SP  - 2243
EP  - 2263
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Carminati, Andrea
A1  - Schneider, Christoph L.
A1  - Moradi, Ahmad B.
A1  - Zarebanadkouki, Mohsen
A1  - Vetterlein, Doris
A1  - Vogel, Hans-Jörg
A1  - Hildebrandt, Anke
A1  - Weller, Ulrich
A1  - Schüler, Lennart
A1  - Oswald, Sascha Eric
T1  - How the rhizosphere may favor water availability to roots
JF  - Vadose zone journal
N2  - Recent studies have shown that rhizosphere hydraulic properties may differ from those of the bulk soil. Specifically, mucilage at the root-soil interface may increase the rhizosphere water holding capacity and hydraulic conductivity during drying. The goal of this study was to point out the implications of such altered rhizosphere hydraulic properties for soil-plant water relations. We addressed this problem through modeling based on a steady-rate approach. We calculated the water flow toward a single root assuming that the rhizosphere and bulk soil were two concentric cylinders having different hydraulic properties. Based on our previous experimental results, we assumed that the rhizosphere had higher water holding capacity and unsaturated conductivity than the bulk soil. The results showed that the water potential gradients in the rhizosphere were much smaller than in the bulk soil. The consequence is that the rhizosphere attenuated and delayed the drop in water potential in the vicinity of the root surface when the soil dried. This led to increased water availability to plants, as well as to higher effective conductivity under unsaturated conditions. The reasons were two: (i) thanks to the high unsaturated conductivity of the rhizosphere, the radius of water uptake was extended from the root to the rhizosphere surface; and (ii) thanks to the high soil water capacity of the rhizosphere, the water depletion in the bulk soil was compensated by water depletion in the rhizosphere. We conclude that under the assumed conditions, the rhizosphere works as an optimal hydraulic conductor and as a reservoir of water that can be taken up when water in the bulk soil becomes limiting.
Y1  - 2011
U6  - https://doi.org/10.2136/vzj2010.0113
SN  - 1539-1663
VL  - 10
IS  - 3
SP  - 988
EP  - 998
PB  - Soil Science Society of America
CY  - Madison
ER  - 
TY  - JOUR
A1  - Villarreyes, Carlos Andres Rivera
A1  - Baroni, Gabriele
A1  - Oswald, Sascha Eric
T1  - Inverse modelling of cosmic-ray soil moisture for field-scale soil hydraulic parameters
JF  - European journal of soil science
N2  - We used inverse modelling techniques and soil moisture measured by the cosmic-ray neutron sensing (CRS) to estimate root-zone soil hydraulic properties at the field scale. A HYDRUS-1D model was developed for inverse modelling and calibrated with parameter estimation software (PEST) using a global optimizer. Integral CRS measurements recorded from a sunflower farm in Germany comprised the model input. Data were transformed to soil water storage to enable direct model calibration with a HYDRUS soil-water balance. Effective properties at the CRS scale were compared against local measurements and other inversely estimated soil properties from independent soil moisture profiles. Moreover, CRS-scale soil properties were tested on the basis of how field soil moisture (vertical distribution) and soil water storage were reproduced. This framework provided good estimates of effective soil properties at the CRS scale. Simulated soil moisture at different depths at the CRS scale agreed with field observations. Moreover, simulated soil water storage at the CRS scale compared well with calculations from point-scale profiles, despite their different support volumes. The CRS-scale soil properties estimated with the inverse model were within the range of variation of properties identified from all inverse simulations at the local scale. This study demonstrates the potential of CRS for inverse estimation of soil hydraulic properties.
Y1  - 2014
U6  - https://doi.org/10.1111/ejss.12162
SN  - 1351-0754
SN  - 1365-2389
VL  - 65
IS  - 6
SP  - 876
EP  - 886
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Mitreiter, Ivonne
A1  - Oswald, Sascha Eric
A1  - Stallmach, Frank
T1  - Magnetic resonance measurements of iron turn-over in sands
T1  - Magnetresonanz-Messung von Eisenumsatzprozessen in Sanden
BT  - Nicht-invasive Charakterisierung von Reaktionsabläufen
BT  - non-invasive characterization of reaction processes
JF  - Grundwasser : Zeitschrift der Fachsektion Hydrogeologie in der Deutschen Gesellschaft für Geowissenschaften (FH-DGG)
N2  - In this study, Nuclear Magnetic Resonance (NMR), a non-destructive measurement technique, has been applied for investigation of iron turn-over processes. In non-invasive laboratory experiments, iron dissolution and precipitation reactions in saturated natural sands were observed spatially and temporally. These processes play an important role in groundwater with varying redox and pH conditions. Redox reactions turning Fe2+ into Fe3+ and Fe3+ into Fe2+ were detected in aqueous solution by the difference in magnetic relaxation times. Furthermore, the spatial distribution of the iron reduction reaction, the consumption and diffusive transfer to and from the reaction sites, was observed in a 1D set-up with natural sands. The achieved spatial resolution was less than one millimetre while repeating measurements every half an hour. It showed the system changing from diffusion-limited to reaction-limited.
KW  - Nuclear magnetic resonance
KW  - Ferric iron
KW  - Ferrous iron
KW  - Acidification
KW  - Redox reaction
KW  - Reactive transport modelling
Y1  - 2011
U6  - https://doi.org/10.1007/s00767-011-0177-6
SN  - 1430-483X
VL  - 16
IS  - 4
SP  - 269
EP  - 278
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Baroni, Gabriele
A1  - Oswald, Sascha Eric
T1  - A scaling approach for the assessment of biomass changes and rainfall interception using cosmic-ray neutron sensing
JF  - Journal of hydrology
N2  - Cosmic-Ray neutron sensing (CRS) is a unique approach to measure soil moisture at field scale filling the gap of current methodologies. However, CRS signal is affected by all the hydrogen pools on the land surface and understanding their relative importance plays an important role for the application of the method e.g., validation of remote sensing products and data assimilation. In this study, a soil moisture scaling approach is proposed to estimate directly the correct CRS soil moisture based on the soil moisture profile measured at least in one position within the field. The approach has the advantage to avoid the need to introduce one correction for each hydrogen contribution and to estimate indirectly all the related time-varying hydrogen pools. Based on the data collected in three crop seasons, the scaling approach shows its ability to identify and to quantify the seasonal biomass water equivalent. Additionally, the analysis conducted at sub-daily time resolution is able to quantify the daily vertical redistribution of the water biomass and the rainfall interception, showing promising applications of the CRS method also for these types of measurements. Overall, the study underlines how not only soil moisture but all the specific hydrological processes in the soil-plant-atmosphere continuum should be considered for a proper evaluation of the CRS signal. For this scope, the scaling approach reveals to be a simple and pragmatic analysis that can be easily extended to other experimental sites. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Cosmic-ray
KW  - Soil moisture
KW  - Scaling
KW  - Interception
KW  - Biomass water
KW  - Agricultural field
Y1  - 2015
U6  - https://doi.org/10.1016/j.jhydrol.2015.03.053
SN  - 0022-1694
SN  - 1879-2707
VL  - 525
SP  - 264
EP  - 276
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Moradi, Ahmad B.
A1  - Carminati, Andrea
A1  - Lamparter, Axel
A1  - Woche, Susanne K.
A1  - Bachmann, Jörg
A1  - Vetterlein, Doris
A1  - Vogel, Hans-Jörg
A1  - Oswald, Sascha Eric
T1  - Is the rhizosphere temporarily water repellent?
JF  - Vadose zone journal
N2  - The rhizosphere has a controlling role in the flow of water and nutrients from soil to plant roots; however, its hydraulic properties are not well understood. As roots grow, they change the pore size distribution of the surrounding soil. Roots release polymeric substances such as mucilage into their rhizosphere. Microorganisms living in the rhizosphere feed on these organic materials and release other polymeric substances into the rhizosphere. The presence of these organic materials might affect the water retention properties and the hydraulic conductivity of the rhizosphere soil during drying and rewetting. We used neutron radiography to monitor the dynamics of water distribution in the rhizosphere of lupin (Lupinus albus L.) plants during a period of drying and rewetting. The rhizosphere was shown to have a higher water content than the bulk soil during the drying period but a lower one during the subsequent rewetting. We evaluated the wettability of the bulk soil and the rhizosphere soil by measuring the contact angle of water in the soil. We found significantly higher contact angles for the rhizosphere soil than the bulk soil after drying, which indicates slight water repellency in the rhizosphere. This explains the lower soil water content in the rhizosphere than the bulk soil after rewetting. Our results suggest that the water holding capacity of the rhizosphere is dynamic and might shift toward higher or lower values than those of the surrounding bulk soil, not affected by roots, depending on the history of drying and rewetting cycles.
Y1  - 2012
U6  - https://doi.org/10.2136/vzj2011.0120
SN  - 1539-1663
VL  - 11
IS  - 3
PB  - Soil Science Society of America
CY  - Madison
ER  - 
TY  - JOUR
A1  - Rivera Villarreyes, C. A.
A1  - Baroni, Gabriele
A1  - Oswald, Sascha Eric
T1  - Integral quantification of seasonal soil moisture changes in farmland by cosmic-ray neutrons
JF  - Hydrology and earth system sciences : HESS
N2  - Soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only a few methods are on the way to close this gap between point measurements and remote sensing. One new measurement methodology that could determine integral soil moisture at this scale is the aboveground sensing of cosmic-ray neutrons, more precisely of ground albedo neutrons. The present study performed ground albedo neutron sensing (GANS) at an agricultural field in northern Germany. To test the method it was accompanied by other soil moisture measurements for a summer period with corn crops growing on the field and a later autumn-winter period without crops and a longer period of snow cover. Additionally, meteorological data and aboveground crop biomass were included in the evaluation. Hourly values of ground albedo neutron sensing showed a high statistical variability. Six-hourly values corresponded well with classical soil moisture measurements, after calibration based on one reference dry period and three wet periods of a few days each. Crop biomass seemed to influence the measurements only to minor degree, opposed to snow cover which has a more substantial impact on the measurements. The latter could be quantitatively related to a newly introduced field neutron ratio estimated from neutron counting rates of two energy ranges. Overall, our study outlines a procedure to apply the ground albedo neutron sensing method based on devices now commercially available, without the need for accompanying numerical simulations and suited for longer monitoring periods after initial calibration.
Y1  - 2011
U6  - https://doi.org/10.5194/hess-15-3843-2011
SN  - 1027-5606
VL  - 15
IS  - 12
SP  - 3843
EP  - 3859
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Moradi, Ahmad B.
A1  - Carminati, Andrea
A1  - Vetterlein, Doris
A1  - Vontobel, Peter
A1  - Lehmann, Eberhard
A1  - Weller, Ulrich
A1  - Hopmans, Jan W.
A1  - Vogel, Hans-Jörg
A1  - Oswald, Sascha Eric
T1  - Three-dimensional visualization and quantification of water content in the rhizosphere
JF  - New phytologist : international journal of plant science
N2  - Despite the importance of rhizosphere properties for water flow from soil to roots, there is limited quantitative information on the distribution of water in the rhizosphere of plants.
 Here, we used neutron tomography to quantify and visualize the water content in the rhizosphere of the plant species chickpea (Cicer arietinum), white lupin (Lupinus albus), and maize (Zea mays) 12 d after planting.
 We clearly observed increasing soil water contents (h) towards the root surface for all three plant species, as opposed to the usual assumption of decreasing water content. This was true for tap roots and lateral roots of both upper and lower parts of the root system. Furthermore, water gradients around the lower part of the roots were smaller and extended further into bulk soil compared with the upper part, where the gradients in water content were steeper.
 Incorporating the hydraulic conductivity and water retention parameters of the rhizosphere into our model, we could simulate the gradual changes of h towards the root surface, in agreement with the observations. The modelling result suggests that roots in their rhizosphere may modify the hydraulic properties of soil in a way that improves uptake under dry conditions.
KW  - extent of rhizosphere
KW  - modelling
KW  - neutron tomography
KW  - rhizosphere hydraulic properties
KW  - root water uptake
KW  - soil moisture profile
KW  - water distribution
Y1  - 2011
U6  - https://doi.org/10.1111/j.1469-8137.2011.03826.x
SN  - 0028-646X
VL  - 192
IS  - 3
SP  - 653
EP  - 663
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Balcke, Gerd U.
A1  - Hahn, M.
A1  - Oswald, Sascha Eric
T1  - Nitrogen as an indicator of mass transfer during in-situ gas sparging
JF  - Journal of contaminant hydrology
N2  - Aiming at the stimulation of intrinsic microbial activity, pulses of pure oxygen or pressurized air were recurrently injected into groundwater polluted with chlorobenzene. To achieve well-controlled conditions and intensive sampling, a large, vertical underground tank was filled with the local unconfined sandy aquifer material. In the course of two individual gas injections, one using pure oxygen and one using pressurized air, the mass transfer of individual gas species between trapped gas phase and groundwater was studied. Field data on the dissolved gas composition in the groundwater were combined with a kinetic model on gas dissolution and transport in porous media. Phase mass transfer of individual gas components caused a temporary enrichment of nitrogen, and to a lower degree of methane, in trapped gas leading to the formation of excess dissolved nitrogen levels downgradient from the dissolving gas phase. By applying a novel gas sampling method for dissolved gases in groundwater it was shown that dissolved nitrogen can be used as a partitioning tracer to indicate complete gas dissolution in porous media.
KW  - Inter-phase mass transfer
KW  - Groundwater
KW  - Remediation
KW  - Gas sparging
KW  - Nitrogen
KW  - Methane
KW  - Kinetics
KW  - Bitterfeld
Y1  - 2011
U6  - https://doi.org/10.1016/j.jconhyd.2011.05.005
SN  - 0169-7722
VL  - 126
IS  - 1-2
SP  - 8
EP  - 18
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Al-Mashaikhi, K.
A1  - Oswald, Sascha Eric
A1  - Attinger, Sabine
A1  - Büchel, G.
A1  - Knöller, K.
A1  - Strauch, G.
T1  - Evaluation of groundwater dynamics and quality in the Najd aquifers located in the Sultanate of Oman
JF  - Environmental earth sciences
N2  - The Najd, Oman, is located in one of the most arid environments in the world. The groundwater in this region is occurring in four different aquifers A to D of the Hadhramaut Group consisting mainly of different types of limestone and dolomite. The quality of the groundwater is dominated by the major ions sodium, calcium, magnesium, sulphate, and chloride, but the hydrochemical character is varying among the four aquifers. Mineralization within the separate aquifers increases along the groundwater flow direction from south to north-northeast up to high saline sodium-chloride water in aquifer D in the northeast area of the Najd. Environmental isotope analyses of hydrogen and oxygen were conducted to monitor the groundwater dynamics and to evaluate the recharge conditions of groundwater into the Najd aquifers. Results suggest an earlier recharge into these aquifers as well as ongoing recharge takes place in the region down to present day. Mixing of modern and submodern waters was detected by water isotopes in aquifer D in the mountain chain (Jabal) area and along the northern side of the mountain range. In addition, delta H-2 and delta O-18 variations suggest that aquifers A, B, and C are assumed to be connected by faults and fractures, and interaction between the aquifers may occur. Low tritium concentrations support the mixing assumption in the recharge area. The knowledge about the groundwater development is an important factor for the sustainable use of water resources in the Dhofar region.
KW  - Environmental isotopes
KW  - Groundwater
KW  - Najd aquifer
KW  - Oman
KW  - Recharge
KW  - Water quality
Y1  - 2012
U6  - https://doi.org/10.1007/s12665-011-1331-2
SN  - 1866-6280
VL  - 66
IS  - 4
SP  - 1195
EP  - 1211
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Busch, Jan Philip
A1  - Meissner, Tobias
A1  - Potthoff, Annegret
A1  - Oswald, Sascha Eric
T1  - Transport of carbon colloid supported nanoscale zero-valent iron in saturated porous media
JF  - Journal of contaminant hydrology
N2  - Injection of nanoscale zero-valent iron (nZVI) has recently gained great interest as emerging technology for in-situ remediation of chlorinated organic compounds from groundwater systems. Zero-valent iron (ZVI) is able to reduce organic compounds and to render it to less harmful substances. The use of nanoscale particles instead of granular or microscale particles can increase dechlorination rates by-orders of magnitude due to its high surface area. However, classical nZVI appears to be hampered in its environmental application by its limited mobility. One approach is colloid supported transport of nZVI, where the nZVI gets transported by a Mobile colloid. In this study transport properties of activated carbon colloid supported nZVI (c-nZVI; d(50) = 2.4 mu m) are investigated in column tests using columns of 40 cm length, which were filled with porous media. A suspension was pumped through the column under different physicochemical conditions (addition of a polyanionic stabilizer and changes in pH and ionic strength). Highest observed breakthrough was 62% of the injected concentration in glass beads with addition of stabilizer. Addition of mono- and bivalent salt, e.g. more than 0.5 mM/L CaCl2, can decrease mobility and changes in pH to values below six can inhibit mobility at all. Measurements of colloid sizes and zeta potentials show changes in the mean particle size by a factor of ten and an increase of zeta potential from -62 mV to -80 mV during the transport experiment. However, results suggest potential applicability of c-nZVI under field conditions. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Nanoscale zero-valent iron (nZVI)
KW  - Nanomaterial
KW  - Carbo-Iron (R)
KW  - Colloid transport
KW  - Mobility
KW  - In-situ remediation
Y1  - 2014
U6  - https://doi.org/10.1016/j.jconhyd.2014.05.006
SN  - 0169-7722
SN  - 1873-6009
VL  - 164
SP  - 25
EP  - 34
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha Eric
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 385 
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-402237
ER  - 
TY  - JOUR
A1  - Rudolph, Nicole
A1  - Esser, Hanna G.
A1  - Carminati, Andrea
A1  - Moradi, Ahmad B.
A1  - Hilger, Andre
A1  - Kardjilov, Nikolay
A1  - Nagl, Stefan
A1  - Oswald, Sascha Eric
T1  - Dynamic oxygen mapping in the root zone by fluorescence dye imaging combined with neutron radiography
JF  - Journal of soils and sediments : protection, risk assessment and remediation
N2  - The rooted zone of a soil, more precisely the rhizosphere, is a very dynamic system. Some of the key processes are water uptake and root respiration. We have developed a novel method for measuring the real-time distribution of water and oxygen concentration in the rhizosphere as a biogeochemical interface in soil. This enables understanding where and when roots are active in respect to root respiration and water uptake and how the soil responds to it.
 We used glass containers (15 x 15 x 1 cm), which were filled with a quartz sand mixture. Sensor foils for fluorescence dye imaging of O-2 were installed on the inner side of the containers. A lupine plant was grown in each container for 2 weeks under controlled conditions. Then we took time series of fluorescence images for time-lapsed visualization of oxygen depletion caused by root respiration. Changing water content was mapped in parallel by non-invasive neutron radiography, which yields water content distributions in high spatial resolution. Also it can detect the root system of the lupine plants. By this combined imaging of the samples, a range of water contents and different oxygen concentration levels, both induced by root activities, could be assessed.
 We monitored the dynamics of these vital parameters induced by roots during a period of several hours. We observed that for high water saturation, the oxygen concentration decreased in parts of the container. The accompanying neutron radiographies gave us the information that these locations are spatially correlated to roots. Therefore, it can be concluded that the observed oxygen deficits close to the roots result from root respiration and show up while re-aeration from atmosphere by gas phase transport is restricted by the high water saturation.
 Our coupled imaging setup was able to monitor the spatial distribution and temporal dynamics of oxygen and water content in a night and day cycle. This reflects complex plant activities such as photosynthesis, transpiration, and metabolic activities impacting the root-soil interface. Our experimental setup provides the possibility to non-invasively visualize these parameters with high resolution. The particular oxygen imaging method as well as the combination with simultaneously mapping the water content by neutron radiography is a novelty.
KW  - Fluorescence imaging
KW  - Neutron radiography
KW  - Oxygen mapping
KW  - Rhizosphere
KW  - Root respiration
KW  - Water distribution
Y1  - 2012
U6  - https://doi.org/10.1007/s11368-011-0407-7
SN  - 1439-0108
VL  - 12
IS  - 1
SP  - 63
EP  - 74
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - GEN
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Hilger, André
A1  - Rudolph-Mohr, Nicole
A1  - Manke, Ingo
A1  - Oswald, Sascha Eric
T1  - Three-dimensional in vivo analysis of water uptake and translocation in maize roots by fast neutron tomography
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Root water uptake is an essential process for terrestrial plants that strongly affects the spatiotemporal distribution of water in vegetated soil. Fast neutron tomography is a recently established non-invasive imaging technique capable to capture the 3D architecture of root systems in situ and even allows for tracking of three-dimensional water flow in soil and roots. We present an in vivo analysis of local water uptake and transport by roots of soil-grown maize plants—for the first time measured in a three-dimensional time-resolved manner. Using deuterated water as tracer in infiltration experiments, we visualized soil imbibition, local root uptake, and tracked the transport of deuterated water throughout the fibrous root system for a day and night situation. This revealed significant differences in water transport between different root types. The primary root was the preferred water transport path in the 13-days-old plants while seminal roots of comparable size and length contributed little to plant water supply. The results underline the unique potential of fast neutron tomography to provide time-resolved 3D in vivo information on the water uptake and transport dynamics of plant root systems, thus contributing to a better understanding of the complex interactions of plant, soil and water.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1217 
KW  - Environmental sciences
KW  - Optics and photonics
KW  - Plant sciences
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-529915
SN  - 1866-8372
ER  - 
TY  - JOUR
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Hilger, André
A1  - Rudolph-Mohr, Nicole
A1  - Manke, Ingo
A1  - Oswald, Sascha Eric
T1  - Three-dimensional in vivo analysis of water uptake and translocation in maize roots by fast neutron tomography
JF  - Scientific Reports
N2  - Root water uptake is an essential process for terrestrial plants that strongly affects the spatiotemporal distribution of water in vegetated soil. Fast neutron tomography is a recently established non-invasive imaging technique capable to capture the 3D architecture of root systems in situ and even allows for tracking of three-dimensional water flow in soil and roots. We present an in vivo analysis of local water uptake and transport by roots of soil-grown maize plants—for the first time measured in a three-dimensional time-resolved manner. Using deuterated water as tracer in infiltration experiments, we visualized soil imbibition, local root uptake, and tracked the transport of deuterated water throughout the fibrous root system for a day and night situation. This revealed significant differences in water transport between different root types. The primary root was the preferred water transport path in the 13-days-old plants while seminal roots of comparable size and length contributed little to plant water supply. The results underline the unique potential of fast neutron tomography to provide time-resolved 3D in vivo information on the water uptake and transport dynamics of plant root systems, thus contributing to a better understanding of the complex interactions of plant, soil and water.
KW  - Environmental sciences
KW  - Optics and photonics
KW  - Plant sciences
Y1  - 2021
U6  - https://doi.org/10.1038/s41598-021-90062-4
SN  - 2045-2322
VL  - 11
PB  - Macmillan Publishers Limited
CY  - London
ER  - 
TY  - JOUR
A1  - Rudolph-Mohr, Nicole
A1  - Vontobel, Peter
A1  - Oswald, Sascha Eric
T1  - A multi-imaging approach to study the root-soil interface
JF  - Annals of botany
N2  - Background and Aims Dynamic processes occurring at the soil-root interface crucially influence soil physical, chemical and biological properties at a local scale around the roots, and are technically challenging to capture in situ. This study presents a novel multi-imaging approach combining fluorescence and neutron radiography that is able to simultaneously monitor root growth, water content distribution, root respiration and root exudation.
 Methods Germinated seeds of white lupins (Lupinus albus) were planted in boron-free glass rhizotrons. After 11 d, the rhizotrons were wetted from the bottom and time series of fluorescence and neutron images were taken during the subsequent day and night cycles for 13 d. The following day (i.e. 25 d after planting) the rhizotrons were again wetted from the bottom and the measurements were repeated. Fluorescence sensor foils were attached to the inner sides of the glass and measurements of oxygen and pH were made on the basis of fluorescence intensity. The experimental set-up allowed for simultaneous fluorescence imaging and neutron radiography.
 Key Results The interrelated patterns of root growth and distribution in the soil, root respiration, exudation and water uptake could all be studied non-destructively and at high temporal and spatial resolution. The older parts of the root system with greater root-length density were associated with fast decreases of water content and rapid changes in oxygen concentration. pH values around the roots located in areas with low soil water content were significantly lower than the rest of the root system.
 Conclusions The results suggest that the combined imaging set-up developed here, incorporating fluorescence intensity measurements, is able to map important biogeochemical parameters in the soil around living plants with a spatial resolution that is sufficiently high enough to relate the patterns observed to the root system.
KW  - Roots
KW  - soil-root interaction
KW  - root distribution
KW  - Lupinus albus
KW  - lupin
KW  - pH dynamics
KW  - oxygen dynamics
KW  - soil water distribution
KW  - rhizosphere
KW  - fluorescence imaging
KW  - neutron radiography
Y1  - 2014
U6  - https://doi.org/10.1093/aob/mcu200
SN  - 0305-7364
SN  - 1095-8290
VL  - 114
IS  - 8
SP  - 1779
EP  - 1787
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Rudolph-Mohr, Nicole
A1  - Gottfried, Sebastian
A1  - Lamshöft, Marc
A1  - Zühlke, Sebastian
A1  - Oswald, Sascha Eric
A1  - Spiteller, Michael
T1  - Non-invasive imaging techniques to study O-2 micro-patterns around pesticide treated lupine roots
JF  - Geoderma : an international journal of soil science
N2  - The soil root interface is a highly heterogeneous system, e.g. in terms of O-2 and pH distribution. The destructive character of conventional methods disturbs the natural conditions of those biogeochemical gradients. Therefore, experiments aiming to control these influences and study pesticide kinetics under given O-2 and pH conditions suffer from a large uncertainty of the "real" O-2/pH at a certain position. Our approach with two different imaging techniques will examine the soil-root interface as well as the dissipation of the applied pesticide at a high spatial resolution.
 The obtained outcomes show directly that the pH has an influence on enantioselective dissipation of the acetanilide fungicide metalaxyl. In areas with high pH from an applied racemic mixture, the R-enantiomer dissipates faster than the S-enantiomer. Moreover, we found significantly reduced oxygen values in the bulk soil and vicinity of metalaxyl treated roots compared to control plant roots. The combination of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) and fluorescence imaging indicated the oxygen-dependent behavior of metalaxyl at the root surface.
 The results presented here underline the great potential of combining different imaging methods to examine the soil-root interfaces as well as the dissipation of organic pollutants in small soil compartments. (C) 2014 Elsevier B.V. All rights reserved.
KW  - MALDI imaging
KW  - Fluorescence imaging
KW  - pH
KW  - O-2
KW  - Rhizosphere
KW  - Rac-metalaxyl
Y1  - 2015
U6  - https://doi.org/10.1016/j.geoderma.2014.10.022
SN  - 0016-7061
SN  - 1872-6259
VL  - 239
SP  - 257
EP  - 264
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Rudolph-Mohr, Nicole
A1  - Toetzke, Christian
A1  - Kardjilov, Nikolay
A1  - Oswald, Sascha Eric
T1  - Mapping water, oxygen, and pH dynamics in the rhizosphere of young maize roots
JF  - Journal of plant nutrition and soil science = Zeitschrift für Pflanzenernährung und Bodenkunde
N2  - Rhizosphere processes are highly dynamic in time and space and strongly depend on each other. Key factors influencing pH changes in the rhizosphere are root exudation, respiration, and nutrient supply, which are influenced by soil water content levels. In this study, we measured the real-time distribution of soil water, pH changes, and oxygen distribution in the rhizosphere of young maize plants using a recently developed imaging approach. Neutron radiography was used to capture the root system and soil water distribution, while fluorescence imaging was employed to map soil pH and soil oxygen changes. Germinated seeds of maize (Zea mays L.) were planted in glass rhizotrons equipped with pH and oxygen-sensitive sensor foils. After 20 d, the rhizotrons were wetted from the bottom and time-lapsed images via fluorescence and neutron imaging were taken during the subsequent day and night cycles for 5 d. We found higher water content and stronger acidification in the first 0.5 mm from the root surface compared to the bulk soil, which could be a consequence of root exudation. While lateral roots only slightly acidified their rhizosphere, crown roots induced stronger acidification of up to 1 pH unit. We observed changing oxygen patterns at different soil moisture conditions and increasing towards lateral as well as crown roots while extending laterally with ongoing water logging. Our work indicates that plants alter the rhizosphere pH and oxygen also depending on root type, which may indirectly arise also from differences in age and water content changes. The results presented here were possible only by combining different imaging techniques to examine profiles at the root-soil interface in a comprehensive way during wetting and drying.
KW  - crown roots
KW  - imaging
KW  - optical sensors
KW  - root exudation
KW  - root respiration
Y1  - 2017
U6  - https://doi.org/10.1002/jpln.201600120
SN  - 1436-8730
SN  - 1522-2624
VL  - 180
SP  - 336
EP  - 346
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schrön, Martin
A1  - Zacharias, Steffen
A1  - Womack, Gary
A1  - Köhli, Markus
A1  - Desilets, Darin
A1  - Oswald, Sascha Eric
A1  - Bumberger, Jan
A1  - Mollenhauer, Hannes
A1  - Kögler, Simon
A1  - Remmler, Paul
A1  - Kasner, Mandy
A1  - Denk, Astrid
A1  - Dietrich, Peter
T1  - Intercomparison of cosmic-ray neutron sensors and water balance monitoring in an urban environment
JF  - Geoscientific instrumentation, methods and data systems
N2  - Sensor-to-sensor variability is a source of error common to all geoscientific instruments that needs to be assessed before comparative and applied research can be performed with multiple sensors. Consistency among sensor systems is especially critical when subtle features of the surrounding terrain are to be identified. Cosmic-ray neutron sensors (CRNSs) are a recent technology used to monitor hectometre-scale environmental water storages, for which a rigorous comparison study of numerous co-located sensors has not yet been performed. In this work, nine stationary CRNS probes of type "CRS1000" were installed in relative proximity on a grass patch surrounded by trees, buildings, and sealed areas. While the dynamics of the neutron count rates were found to be similar, offsets of a few percent from the absolute average neutron count rates were found. Technical adjustments of the individual detection parameters brought all instruments into good agreement. Furthermore, we found a critical integration time of 6 h above which all sensors showed consistent dynamics in the data and their RMSE fell below 1% of gravimetric water content. The residual differences between the nine signals indicated local effects of the complex urban terrain on the scale of several metres. Mobile CRNS measurements and spatial simulations with the URANOS neutron transport code in the surrounding area (25 ha) have revealed substantial sub-footprint heterogeneity to which CRNS detectors are sensitive despite their large averaging volume. The sealed and constantly dry structures in the footprint furthermore damped the dynamics of the CRNS-derived soil moisture. We developed strategies to correct for the sealed-area effect based on theoretical insights about the spatial sensitivity of the sensor. This procedure not only led to reliable soil moisture estimation during dry-out periods, it further revealed a strong signal of intercepted water that emerged over the sealed surfaces during rain events. The presented arrangement offered a unique opportunity to demonstrate the CRNS performance in complex terrain, and the results indicated great potential for further applications in urban climate research.
Y1  - 2018
U6  - https://doi.org/10.5194/gi-7-83-2018
SN  - 2193-0856
SN  - 2193-0864
VL  - 7
IS  - 1
SP  - 83
EP  - 99
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Busch, Jan Philip
A1  - Meißner, Tobias
A1  - Potthoff, Annegret
A1  - Bleyl, Steffen
A1  - Georgi, Anett
A1  - Mackenzie, Katrin
A1  - Trabitzsch, Ralf
A1  - Werban, Ulrike
A1  - Oswald, Sascha Eric
T1  - A field investigation on transport of carbon-supported nanoscale zero-valent iron (nZVI) in groundwater
JF  - Journal of contaminant hydrology
N2  - The application of nanoscale zero-valent iron (nZVI) for subsurface remediation of groundwater contaminants is a promising new technology, which can be understood as alternative to the permeable reactive barrier technique using granular iron. Dechlorination of organic contaminants by zero-valent iron seems promising. Currently, one limitation to widespread deployment is the fast agglomeration and sedimentation of nZVI in colloidal suspensions, even more so when in soils and sediments, which limits the applicability for the treatment of sources and plumes of contamination. Colloid-supported nZVI shows promising characteristics to overcome these limitations. Mobility of Carbo-Iron Colloids (CIC) - a newly developed composite material based on finely ground activated carbon as a carrier for nZVI - was tested in a field application: In this study, a horizontal dipole flow field was established between two wells separated by 53 m in a confined, natural aquifer. The injection/extraction rate was 500 L/h. Approximately 12 kg of CIC was suspended with the polyanionic stabilizer carboxymethyl cellulose. The suspension was introduced into the aquifer at the injection well. Breakthrough of CIC was observed visually and based on total particle and iron concentrations detected in samples from the extraction well. Filtration of water samples revealed a particle breakthrough of about 12% of the amount introduced. This demonstrates high mobility of CIC particles and we suggest that nZVI carried on CIC can be used for contaminant plume remediation by in-situ formation of reactive barriers. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Nanoscale zero-valent iron (nZVI)
KW  - Fe-C composite
KW  - Carbon colloid
KW  - Field aquifer
KW  - Remediation
KW  - Particle mobility
Y1  - 2015
U6  - https://doi.org/10.1016/j.jconhyd.2015.03.009
SN  - 0169-7722
SN  - 1873-6009
VL  - 181
SP  - 59
EP  - 68
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Hund, Silja V.
A1  - Brown, Sandra
A1  - Lavkulich, Les M.
A1  - Oswald, Sascha Eric
T1  - Relating P Lability in Stream Sediments to Watershed Land Use via an Effective Sequential Extraction Scheme
JF  - Water, air & soil pollution : an international journal of environmental pollution
N2  - High applications of P fertilizers and manure are general practice in intensive agriculture and may cause eutrophication in adjacent streams. Bioavailability of P can be estimated by sequential extractions commonly used for soil or sediment. A single combined method may facilitate more effective comparisons of topsoils and adjoining stream sediments, and enhance management decisions. In this study, the suitability of an established soil P sequential extraction was tested on stream bed sediments. The study was conducted in the Sumas River watershed in the agricultural Lower Fraser Valley, Canada. Sediment samples with differing land use (forest, low and high intensity agriculture) from 1993, 1994, 2008, and 2009 from 14 sites along the Sumas River and tributaries were used. Total sequential extraction concentrations were in agreement with aqua regia digestion (Rs=0.96) and showed consistency over the study time sequence. P fractions released by 0.5 M NaHCO3 (median 14 %), 0.1 M NaOH (33 %), and 1.0 M HCl (38 %) were significantly (alpha=0.05) higher than P released by other extractants. These three extraction steps provide a practical and time-effective assessment of P lability in stream sediments and may be used as a combined scheme for sediment and soil. Analytical results further revealed that land use has a major and characteristic impact on P lability. With a land use change from forest to intensive agriculture, results showed an increase in total P concentrations (30 to 4,000 ppm) and in P lability, in particular for the moderately labile NaOH-P fraction (20 to 50 %).
KW  - Phosphorus
KW  - Eutrophication
KW  - Availability
KW  - Sequential extraction
KW  - Agriculture
KW  - River bed sediment
Y1  - 2013
U6  - https://doi.org/10.1007/s11270-013-1643-9
SN  - 0049-6979
SN  - 1573-2932
VL  - 224
IS  - 9
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha Eric
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
JF  - Scientific reports
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06046-w
SN  - 2045-2322
VL  - 7
PB  - Macmillan Publishers Limited
CY  - London
ER  - 
TY  - JOUR
A1  - Munz, Matthias
A1  - Oswald, Sascha Eric
A1  - Schmidt, C.
T1  - Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation
JF  - Hydrology and earth system sciences : HESS
N2  - Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of +/- 1.3 md(-1). Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical water flux.
Y1  - 2011
U6  - https://doi.org/10.5194/hess-15-3495-2011
SN  - 1027-5606
VL  - 15
IS  - 11
SP  - 3495
EP  - 3510
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Busch, Jan Philip
A1  - Meissner, Tobias
A1  - Potthoff, Annegret
A1  - Oswald, Sascha Eric
T1  - Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) in a column experiment and a laboratory 2D-aquifer test system
JF  - Environmental science and pollution research : official organ of the EuCheMS Division for Chemistry and the Environment, EuCheMS DCE
N2  - Nanoscale zero-valent iron (nZVI) has recently gained great interest in the scientific community as in situ reagent for installation of permeable reactive barriers in aquifer systems, since nZVI is highly reactive with chlorinated compounds and may render them to harmless substances. However, nZVI has a high tendency to agglomerate and sediment; therefore it shows very limited transport ranges. One new approach to overcome the limited transport of nZVI in porous media is using a suited carrier colloid. In this study we tested mobility of a carbon colloid supported nZVI particle "Carbo-Iron Colloids" (CIC) with a mean size of 0.63 mu m in a column experiment of 40 cm length and an experiment in a two-dimensional (2D) aquifer test system with dimensions of 110x40x5 cm. Results show a breakthrough maximum of 82 % of the input concentration in the column experiment and 58 % in the 2D-aquifer test system. Detected residuals in porous media suggest a strong particle deposition in the first centimeters and few depositions in the porous media in the further travel path. Overall, this suggests a high mobility in porous media which might be a significant enhancement compared to bare or polyanionic stabilized nZVI.
KW  - Carbon colloid
KW  - Nanoscale zero-valent iron (nZVI)
KW  - Aquifer systems
Y1  - 2014
U6  - https://doi.org/10.1007/s11356-014-3049-7
SN  - 0944-1344
SN  - 1614-7499
VL  - 21
IS  - 18
SP  - 10908
EP  - 10916
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Rudolph, Nicole
A1  - Voss, Sebastian
A1  - Moradi, Ahmad B.
A1  - Nagl, Stefan
A1  - Oswald, Sascha Eric
T1  - Spatio-temporal mapping of local soil pH changes induced by roots of lupin and soft-rush
JF  - Plant and soil
N2  - The rhizosphere is a dynamic system strongly influenced by root activity. Roots modify the pH of their surrounding soil causing the soil pH to vary as a function of distance from root surface, location along root axes, and root maturity. Non-invasive imaging techniques provide the possibility to capture pH patterns around the roots as they develop.
 We developed a novel fluorescence imaging set up and applied to the root system of two lupin (Lupinus albus L., Lupinus angustifolius L.) and one soft-rush (Juncus effusus L.) species. We grew plants in glass containers filled with soil and equipped with fluorescence sensor foils on the container side walls. We gained highly-resolved data on the spatial distribution of H+ around the roots by taking time-lapse images of the samples over the course of several days.
 We showed how the soil pH in the vicinity of roots developed over time to different values from that of the original bulk soil. The soil pH in the immediate vicinity of the root surface varied greatly along the root length, with the most acidic point being at 0.56-3.36 mm behind the root tip. Indications were also found for temporal soil pH changes due to root maturity.
 In conclusion, this study shows that this novel optical fluorescence imaging set up is a powerful tool for studying pH developments around roots in situ.
KW  - Acidification
KW  - Alkalization
KW  - Exudates
KW  - Fluorescence imaging
KW  - Optical sensors
KW  - pH mapping
KW  - Rhizosphere
Y1  - 2013
U6  - https://doi.org/10.1007/s11104-013-1775-0
SN  - 0032-079X
VL  - 369
IS  - 1-2
SP  - 669
EP  - 680
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Barkow, Isolde S.
A1  - Oswald, Sascha Eric
A1  - Lensing, Hermann Josef
A1  - Munz, Matthias
T1  - Seasonal dynamics modifies fate of oxygen, nitrate, and organic micropollutants during bank filtration
BT  - temperature-dependent reactive transport modeling of field data
JF  - Environmental science and pollution research : official organ of the EuCheMS Division for Chemistry and the Environment, EuCheMS DCE
N2  - Bank filtration is considered to improve water quality through microbially mediated degradation of pollutants and is suitable for waterworks to increase their production. In particular, aquifer temperatures and oxygen supply have a great impact on many microbial processes. To investigate the temporal and spatial behavior of selected organic micropollutants during bank filtration in dependence of relevant biogeochemical conditions, we have set up a 2D reactive transport model using MODFLOW and PHT3D under the user interface ORTI3D. The considered 160-m-long transect ranges from the surface water to a groundwater extraction well of the adjacent waterworks. For this purpose, water levels, temperatures, and chemical parameters were regularly measured in the surface water and groundwater observation wells over one and a half years. To simulate the effect of seasonal temperature variations on microbial mediated degradation, we applied an empirical temperature factor, which yields a strong reduction of the degradation rate at groundwater temperatures below 11 degrees C. Except for acesulfame, the considered organic micropollutants are substantially degraded along their subsurface flow paths with maximum degradation rates in the range of 10(-6) mol L-1 s(-1). Preferential biodegradation of phenazone, diclofenac, and valsartan was found under oxic conditions, whereas carbamazepine and sulfamethoxazole were degraded under anoxic conditions. This study highlights the influence of seasonal variations in oxygen supply and temperature on the fate of organic micropollutants in surface water infiltrating into an aquifer.
KW  - bank filtration
KW  - aerobic and anaerobic conditions
KW  - pharmaceuticals and
KW  - personal care products
KW  - reactive transport modeling
KW  - degradation
Y1  - 2020
U6  - https://doi.org/10.1007/s11356-020-11002-9
SN  - 0944-1344
SN  - 1614-7499
VL  - 28
IS  - 8
SP  - 9682
EP  - 9700
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Wang, Wei-shi
A1  - Oswald, Sascha Eric
A1  - Gräff, Thomas
A1  - Lensing, Hermann Josef
A1  - Liu, Tie
A1  - Strasser, Daniel
A1  - Munz, Matthias
T1  - Impact of river reconstruction on groundwater flow during bank filtration assessed by transient three-dimensional modelling of flow and heat transport
JF  - Hydrogeology journal : official journal of the International Association of Hydrogeologists
N2  - Bank filtration (BF) is an established indirect water-treatment technology. The quality of water gained via BF depends on the subsurface capture zone, the mixing ratio (river water versus ambient groundwater), spatial and temporal distribution of subsurface travel times, and subsurface temperature patterns. Surface-water infiltration into the adjacent aquifer is determined by the local hydraulic gradient and riverbed permeability, which could be altered by natural clogging, scouring and artificial decolmation processes. The seasonal behaviour of a BF system in Germany, and its development during and about 6 months after decolmation (canal reconstruction), was observed with a long-term monitoring programme. To quantify the spatial and temporal variation in the BF system, a transient flow and heat transport model was implemented and two model scenarios, 'with' and 'without' canal reconstruction, were generated. Overall, the simulated water heads and temperatures matched those observed. Increased hydraulic connection between the canal and aquifer caused by the canal reconstruction led to an increase of similar to 23% in the already high share of BF water abstracted by the nearby waterworks. Subsurface travel-time distribution substantially shifted towards shorter travel times. Flow paths with travel times <200 days increased by similar to 10% and those with <300 days by 15%. Generally, the periodic temperature signal, and the summer and winter temperature extrema, increased and penetrated deeper into the aquifer. The joint hydrological and thermal effects caused by the canal reconstruction might increase the potential of biodegradable compounds to further penetrate into the aquifer, also by potentially affecting the redox zonation in the aquifer.
KW  - bank filtration
KW  - groundwater
KW  - surface-water relations
KW  - groundwater modelling
Y1  - 2019
U6  - https://doi.org/10.1007/s10040-019-02063-3
SN  - 1431-2174
SN  - 1435-0157
VL  - 28
IS  - 2
SP  - 723
EP  - 743
PB  - Springer
CY  - Berlin ; Heidelberg [u.a.]
ER  - 
TY  - GEN
A1  - Busch, Jan Philip
A1  - Meißner, Tobias
A1  - Potthoff, Annegret
A1  - Oswald, Sascha Eric
T1  - Plating of nano zero-valent iron (nZVI) on activated carbon : a fast delivery method of iron for source remediation?
N2  - The use of nano zerovalent iron (nZVI) for environmental remediation is a promising new technique for in situ remediation. Due to its high surface area and high reactivity, nZVI is able to dechlorinate organic contaminants and render them harmless. Limited mobility, due to fast aggregation and sedimentation of nZVI, limits the capability for source and plume remediation. Carbo-Iron is a newly developed material consisting of activated carbon particles (d50 = 0,8 µm) that are plated with nZVI particles. These particles combine the mobility of activated carbon and the reactivity of nZVI. This paper presents the first results of the transport experiments.
N2  - Der Einsatz von elementarem Nanoeisen ist eine vielversprechende Technik zur Sanierung von Altlastenschadensfällen. Aufgrund der hohen Oberfläche und der hohen Reaktivität kannn ZVI chlororganische Schadstoffe dechlorieren und zu harmlosen Substanzen umwandeln. Der Einsatz von Nanoeisen zur Quellen- und Fahnensanierung wird jedoch durch mangelnde Mobilität im Boden im eingeschränkt. Carbo-Iron ist ein neu entwickeltes Material, das aus Aktivkohlepartikeln (d50 = 0,8 µm) und nZVI besteht. Diese Partikel kombinieren die Mobilit ät von Aktivkohle mit der Reaktivität von nZVI. Dieser Artikel beschreibt erste Ergebnisse von Transportuntersuchungen.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 165 
KW  - Carbo-Iron
KW  - Nanoeisen
KW  - nZVI
KW  - Grundwassersanierung
KW  - Carbo-Iron
KW  - nano zero-valent iron
KW  - nZVI
KW  - remediation
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-53792
ER  - 
TY  - JOUR
A1  - Schattan, Paul
A1  - Köhli, Markus
A1  - Schrön, Martin
A1  - Baroni, Gabriele
A1  - Oswald, Sascha Eric
T1  - Sensing area-average snow water equivalent with cosmic-ray neutrons: the influence of fractional snow cover
JF  - Water resources research
N2  - Cosmic-ray neutron sensing (CRNS) is a promising non-invasive technique to estimate snow water equivalent (SWE) over large areas. In contrast to preliminary studies focusing on shallow snow conditions (SWE <130 mm), more recently the method was shown experimentally to be sensitive also to deeper snowpacks providing the basis for its use at mountain experimental sites. However, hysteretic neutron response has been observed for complex snow cover including patchy snow-free areas. In the present study we aimed to understand and support the experimental findings using a comprehensive neutron modeling approach. Several simulations have been set up in order to disentangle the effect on the signal of different land surface characteristics and to reproduce multiple observations during periods of snow melt and accumulation. To represent the actual land surface heterogeneity and the complex snow cover, the model used data from terrestrial laser scanning. The results show that the model was able to accurately reproduce the CRNS signal and particularly the hysteresis effect during accumulation and melting periods. Moreover, the sensor footprint was found to be anisotropic and affected by the spatial distribution of liquid water and snow as well as by the topography of the nearby mountains. Under fully snow-covered conditions the CRNS is able to accurately estimate SWE without prior knowledge about snow density profiles or other spatial anomalies. These results provide new insights into the characteristics of the detected neutron signal in complex terrain and support the use of CRNS for long-term snow monitoring in high elevated mountain environments.
KW  - area-average snow monitoring
KW  - cosmic-ray neutron sensing
KW  - neutron simulations
KW  - spatial heterogeneity
KW  - fractional snow cover
Y1  - 2019
U6  - https://doi.org/10.1029/2019WR025647
SN  - 0043-1397
SN  - 1944-7973
VL  - 55
IS  - 12
SP  - 10796
EP  - 10812
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Munz, Matthias
A1  - Oswald, Sascha Eric
A1  - Schaefferling, Robin
A1  - Lensing, Hermann Josef
T1  - Temperature-dependent redox zonation, nitrate removal and attenuation of organic micropollutants during bank filtration
JF  - Water research
N2  - River bank filtration (RBF) is considered to efficiently remove nitrate and trace organic micropollutants (OMP) from polluted surface waters. This is essential for maintaining good groundwater quality and providing high quality drinking water. Predicting the fate of OMP during RBF is difficult as the biogeochemical factors controlling the removal efficiency are not fully understood. To determine in-situ removal efficiency and degradation rates of nitrate and OMP indicator substances we conducted a field study in a RBF system during a period of one and a half years incorporating temporally and spatially varying redox conditions and temperature changes typically occurring in temperate climates. RBF was analyzed by means of mixing ratios between infiltrated river water and groundwater as well as average residence times of surface water towards the individual groundwater observation wells. These results were used to calculate temperature dependent first order degradation rates of redox sensitive species and several OMP. Five out of ten investigated OMP were completely removed along RBF pathways. We demonstrate that degradation rates of several OMP during bank filtration were controlled by redox conditions and temperature whereby temperature itself also had a significant influence on the extent of the most reactive oxic zone. The seasonal variations in temperature alone could explain a considerable percentage of the variance in dissolved oxygen (34%), nitrate (81%) as well as the OMPs diclofenac (44%) and sulfamethoxazole (76%). Estimated in-situ degradation rates roughly varied within one order of magnitude for temperature changes between 5 degrees C and 20 degrees C. This study highlights that temporal variability in temperature and redox zonation is a significant factor for migration and degradation of nitrate and several OMPs. (C) 2019 Elsevier Ltd. All rights reserved.
KW  - Pharmaceuticals
KW  - In-situ degradation rates
KW  - Denitrification
KW  - River-groundwater-interaction
KW  - Urban water cycle
Y1  - 2019
U6  - https://doi.org/10.1016/j.watres.2019.06.041
SN  - 0043-1354
VL  - 162
SP  - 225
EP  - 235
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Baroni, Gabriele
A1  - Scheiffele, Lena M.
A1  - Schrön, Martin
A1  - Ingwersen, Joachim
A1  - Oswald, Sascha Eric
T1  - Uncertainty, sensitivity and improvements in soil moisture estimation with cosmic-ray neutron sensing
JF  - Journal of hydrology
N2  - Cosmic-ray neutron sensing (CRNS) is a promising proximal soil sensing technique to estimate soil moisture at intermediate scale and high temporal resolution. However, the signal shows complex and non-unique response to all hydrogen pools near the land surface, providing some challenges for soil moisture estimation in practical applications. Aims of the study were 1) to assess the uncertainty of CRNS as a stand-alone approach to estimate volumetric soil moisture in cropped field 2) to identify the causes of this uncertainty 3) and possible improvements. Two experimental sites in Germany were equipped with a CRNS probe and point-scale soil moisture network. Additional monitoring activities were conducted during the crop growing season to characterize the soil-plant systems. This data is used to identify and quantify the different sources of uncertainty (factors). An uncertainty analysis, based on Monte Carlo approach, is applied to propagate these uncertainties to CRNS soil moisture estimations. In addition, a sensitivity analysis based on the Sobol’ method is performed to identify the most important factors explaining this uncertainty. Results show that CRNS soil moisture compares well to the soil moisture network when these point-scale values are weighted to account for the spatial sensitivity of the signal and other sources of hydrogen (lattice water and organic carbon) are added to the water content. However, the performance decreases when CRNS is considered as a stand-alone method to retrieve the actual (non-weighted) volumetric soil moisture. The support volume (penetration depth and radius) shows also a considerable uncertainty, especially in relatively dry soil moisture conditions. Four of the seven factors analyzed (the vertical soil moisture profile, bulk density, incoming neutron correction and the calibrated parameter N0) were found to play an important role. Among the possible improvements identified, a simple correction factor based on vertical point-scale soil moisture profiles shows to be a promising approach to account for the sensitivity of the CRNS signal to the upper soil layers.
KW  - Soil moisture
KW  - Cosmic-ray neutrons
KW  - Uncertainty analysis
KW  - Sensitivity analysis
Y1  - 2018
U6  - https://doi.org/10.1016/j.jhydrol.2018.07.053
SN  - 0022-1694
SN  - 1879-2707
VL  - 564
SP  - 873
EP  - 887
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Haber-Pohlmeier, Sabina
A1  - Tötzke, Christian
A1  - Oswald, Sascha Eric
A1  - Lehmann, Eberhard
A1  - Blümich, Bernhard
A1  - Pohlmeier, Andreas
T1  - Imaging of root zone processes using MRI T-1 mapping
JF  - Microporous and mesoporous materials : zeolites, clays, carbons and related materials
N2  - Noninvasive imaging in the root soil compartment is mandatory for improving knowledge about root soil interactions and uptake processes which eventually control crop growth and productivity. Here we propose a method of MRI T-1 relaxation mapping to investigate water uptake patterns, and as second example, in combination with neutron tomography (NT), property changes in the rhizosphere. The first part demonstrates quantification of solute enrichment by advective transport to the roots due to water uptake. This accumulation is counterbalanced by net downward flow and dispersive spreading. One can furthermore discriminate between zones of high accumulation patterns and zones with much less enrichment. This behavior persists over days. The second part presents the novel combination of MRI with neutron tomography to couple static, proton density information of roots and their interface to the surrounding soil with information about the local water dynamics, reflected by NMR relaxation times. The root soil interface of a broad bean plant is characterized by slightly increasing MRI and NT signal intensity but decreasing T-1 relaxation time indicating locally changed soil properties.
KW  - Low field MRI
KW  - Neutron tomography
KW  - Root zone processes
KW  - Solute transport
KW  - Quantification of contrast agent
KW  - T1 mapping
Y1  - 2017
U6  - https://doi.org/10.1016/j.micromeso.2017.10.046
SN  - 1387-1811
SN  - 1873-3093
VL  - 269
SP  - 43
EP  - 46
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Selle, Benny
A1  - Graeff, Thomas
A1  - Salzmann, Thomas
A1  - Oswald, Sascha Eric
A1  - Walther, Marc
A1  - Miegel, Konrad
T1  - Investigation of a renatured fen catchment on the Baltic Sea coast of Mecklenburg - Part II: Salt dynamics and water balance
JF  - Hydrologie und Wasserbewirtschaftung
N2  - Coastal fens like the nature reserve "Hutelmoor und Heiligensee" (north-eastern Germany) are important landscape elements along the southern Baltic coast, which exchange fresh water and brackish water with the Baltic Sea. These exchange processes can be understood as experiments with a natural tracer, which may be used to investigate the hydrologic behaviour of these fen systems. With the establishment of coastal protection measures such as dunes and dikes, the installation of surface drainage and, more recently, also nature conservation measures, the hydrologic regime of these coastal wetlands has constantly altered over the last centuries.The rehabilitated wetland "Hutelnnoor und Heiligensee" is suitable for an analysis of hydrologic change as it has been monitored over the time period since nature conservation measures started in the 1990s. Collected data sets included observation of groundwater levels and electrical conductivities, weather data as well as discharge at the outlet of the drainage catchment. In this article, as a second part of the dual publication, processes and quantified process magnitudes have been identified that govern the salt balance of the study area including its variability in space and time. It was detected that - over the period of rehabilitation - salt water entered the catchment with an episodic storm surge by wave overtopping of dunes in 1995. The intruded brackish water was then diluted, which was a slow process extending over decades. It was governed by local groundwater recharge from precipitation and the inflow of relatively fresh groundwater from the hinterland. It is concluded that salt inputs from the Baltic Sea provide a natural tracer of hydrological processes, which can be readily monitored via electrical conductivity measurements.
KW  - Baltic Sea
KW  - coastal wetland
KW  - drainage of the catchment area
KW  - groundwater flow
KW  - management effects
KW  - system analysis
KW  - water balance
Y1  - 2016
U6  - https://doi.org/10.5675/HyWa_2016.4_2
SN  - 1439-1783
VL  - 60
SP  - 259
EP  - 268
PB  - Bundesanst. für Gewässerkunde
CY  - Koblenz
ER  - 
TY  - JOUR
A1  - Munz, Matthias
A1  - Oswald, Sascha Eric
A1  - Schmidt, Christian
T1  - Analysis of riverbed temperatures to determine the geometry of subsurface water flow around in-stream geomorphological structures
JF  - Journal of hydrology
N2  - The analytical evaluation of diurnal temperature variation in riverbed sediments provides detailed information on exchange fluxes between rivers and groundwater. The underlying assumption of the stationary, one-dimensional vertical flow field is frequently violated in natural systems where subsurface water flow often has a significant horizontal component. In this paper, we present a new methodology for identifying the geometry of the subsurface flow field using vertical temperature profiles. The statistical analyses are based on model optimisation and selection and are used to evaluate the shape of vertical amplitude ratio profiles. The method was applied to multiple profiles measured around in-stream geomorphological structures in a losing reach of a gravel bed river. The predominant subsurface flow field was systematically categorised in purely vertical and horizontal (hyporheic, parafluvial) components. The results highlight that river groundwater exchange flux at the head, crest and tail of geomorphological structures significantly deviated from the one-dimensional vertical flow, due to a significant horizontal component. The geometry of the subsurface water flow depended on the position around the geomorphological structures and on the river level. The methodology presented in this paper features great potential for characterising the spatial patterns and temporal dynamics of complex subsurface flow geometries by using measured temperature time series in vertical profiles. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Temperature time series
KW  - Amplitude ratio
KW  - River-groundwater exchange
KW  - Hyporheic zone
KW  - In-stream geomorphological structures
KW  - River restoration
Y1  - 2016
U6  - https://doi.org/10.1016/j.jhydrol.2016.05.012
SN  - 0022-1694
SN  - 1879-2707
VL  - 539
SP  - 74
EP  - 87
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Schroen, Martin
A1  - Koehli, Markus
A1  - Scheiffele, Lena
A1  - Iwema, Joost
A1  - Bogena, Heye R.
A1  - Lv, Ling
A1  - Martini, Edoardo
A1  - Baroni, Gabriele
A1  - Rosolem, Rafael
A1  - Weimar, Jannis
A1  - Mai, Juliane
A1  - Cuntz, Matthias
A1  - Rebmann, Corinna
A1  - Oswald, Sascha Eric
A1  - Dietrich, Peter
A1  - Schmidt, Ulrich
A1  - Zacharias, Steffen
T1  - Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity
JF  - Hydrology and earth system sciences : HESS
N2  - In the last few years the method of cosmic-ray neutron sensing (CRNS) has gained popularity among hydrologists, physicists, and land-surface modelers. The sensor provides continuous soil moisture data, averaged over several hectares and tens of decimeters in depth. However, the signal still may contain unidentified features of hydrological processes, and many calibration datasets are often required in order to find reliable relations between neutron intensity and water dynamics. Recent insights into environmental neutrons accurately described the spatial sensitivity of the sensor and thus allowed one to quantify the contribution of individual sample locations to the CRNS signal. Consequently, data points of calibration and validation datasets are suggested to be averaged using a more physically based weighting approach. In this work, a revised sensitivity function is used to calculate weighted averages of point data. The function is different from the simple exponential convention by the extraordinary sensitivity to the first few meters around the probe, and by dependencies on air pressure, air humidity, soil moisture, and vegetation. The approach is extensively tested at six distinct monitoring sites: two sites with multiple calibration datasets and four sites with continuous time series datasets. In all cases, the revised averaging method improved the performance of the CRNS products. The revised approach further helped to reveal hidden hydrological processes which otherwise remained unexplained in the data or were lost in the process of overcalibration. The presented weighting approach increases the overall accuracy of CRNS products and will have an impact on all their applications in agriculture, hydrology, and modeling.
Y1  - 2017
U6  - https://doi.org/10.5194/hess-21-5009-2017
SN  - 1027-5606
SN  - 1607-7938
VL  - 21
SP  - 5009
EP  - 5030
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Schattan, Paul
A1  - Baroni, Gabriele
A1  - Oswald, Sascha Eric
A1  - Schoeber, Johannes
A1  - Fey, Christine
A1  - Kormann, Christoph
A1  - Huttenlau, Matthias
A1  - Achleitner, Stefan
T1  - Continuous monitoring of snowpack dynamics in alpine terrain by aboveground neutron sensing
JF  - Water resources research
N2  - The characteristics of an aboveground cosmic-ray neutron sensor (CRNS) are evaluated for monitoring a mountain snowpack in the Austrian Alps from March 2014 to June 2016. Neutron counts were compared to continuous point-scale snow depth (SD) and snow-water-equivalent (SWE) measurements from an automatic weather station with a maximum SWE of 600 mm (April 2014). Several spatially distributed Terrestrial Laser Scanning (TLS)-based SD and SWE maps were additionally used. A strong nonlinear correlation is found for both SD and SWE. The representative footprint of the CRNS is in the range of 230-270 m. In contrast to previous studies suggesting signal saturation at around 100 mm of SWE, no complete signal saturation was observed. These results imply that CRNS could be transferred into an unprecedented method for continuous detection of spatially averaged SD and SWE for alpine snowpacks, though with sensitivity decreasing with increasing SWE. While initially different functions were found for accumulation and melting season conditions, this could be resolved by accounting for a limited measurement depth. This depth limit is in the range of 200 mm of SWE for dense snowpacks with high liquid water contents and associated snow density values around 450 kg m(-3) and above. In contrast to prior studies with shallow snowpacks, interannual transferability of the results is very high regardless of presnowfall soil moisture conditions. This underlines the unexpectedly high potential of CRNS to close the gap between point-scale measurements, hydrological models, and remote sensing of the cryosphere in alpine terrain.
KW  - cosmic-ray neutron sensing
KW  - snow hydrology
KW  - continuous snowpack monitoring
KW  - alpine environment
Y1  - 2017
U6  - https://doi.org/10.1002/2016WR020234
SN  - 0043-1397
SN  - 1944-7973
VL  - 53
SP  - 3615
EP  - 3634
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Munz, Matthias
A1  - Oswald, Sascha Eric
A1  - Schmidt, Christian
T1  - Coupled Long-Term Simulation of Reach-Scale Water and Heat Fluxes Across the River-Groundwater Interface for Retrieving Hyporheic Residence Times and Temperature Dynamics
JF  - Water resources research
N2  - Flow patterns in conjunction with seasonal and diurnal temperature variations control ecological and biogeochemical conditions in hyporheic sediments. In particular, hyporheic temperatures have a great impact on many temperature-sensitive microbial processes. In this study, we used 3-D coupled water flow and heat transport simulations applying the HydroGeoSphere code in combination with high-resolution observations of hydraulic heads and temperatures to quantify reach-scale water and heat flux across the river-groundwater interface and hyporheic temperature dynamics of a lowland gravel bed river. The model was calibrated in order to constrain estimates of the most sensitive model parameters. The magnitude and variations of the simulated temperatures matched the observed ones, with an average mean absolute error of 0.7 degrees C and an average Nash Sutcliffe efficiency of 0.87. Our results indicate that nonsubmerged streambed structures such as gravel bars cause substantial thermal heterogeneity within the saturated sediment at the reach scale. Individual hyporheic flow path temperatures strongly depend on the flow path residence time, flow path depth, river, and groundwater temperature. Variations in individual hyporheic flow path temperatures were up to 7.9 degrees C, significantly higher than the daily average (2.8 degrees C), but still lower than the average seasonal hyporheic temperature difference (19.2 degrees C). The distribution between flow path temperatures and residence times follows a power law relationship with exponent of about 0.37. Based on this empirical relation, we further estimated the influence of hyporheic flow path residence time and temperature on oxygen consumption which was found to partly increase by up to 29% in simulations.
Y1  - 2017
U6  - https://doi.org/10.1002/2017WR020667
SN  - 0043-1397
SN  - 1944-7973
VL  - 53
SP  - 8900
EP  - 8924
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Toetzke, Christian
A1  - Kardjilov, Nikolay
A1  - Manke, Ingo
A1  - Oswald, Sascha Eric
T1  - Capturing 3D Water Flow in Rooted Soil by Ultra-fast Neutron Tomography
JF  - Scientific reports
N2  - Water infiltration in soil is not only affected by the inherent heterogeneities of soil, but even more by the interaction with plant roots and their water uptake. Neutron tomography is a unique non-invasive 3D tool to visualize plant root systems together with the soil water distribution in situ. So far, acquisition times in the range of hours have been the major limitation for imaging 3D water dynamics. Implementing an alternative acquisition procedure we boosted the speed of acquisition capturing an entire tomogram within 10 s. This allows, for the first time, tracking of a water front ascending in a rooted soil column upon infiltration of deuterated water time-resolved in 3D. Image quality and resolution could be sustained to a level allowing for capturing the root system in high detail. Good signal-to-noise ratio and contrast were the key to visualize dynamic changes in water content and to localize the root uptake. We demonstrated the ability of ultra-fast tomography to quantitatively image quick changes of water content in the rhizosphere and outlined the value of such imaging data for 3D water uptake modelling. The presented method paves the way for time-resolved studies of various 3D flow and transport phenomena in porous systems.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06046-w
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Haber-Pohlmeier, Sabina
A1  - Tötzke, Christian
A1  - Lehmann, E.
A1  - Kardjilov, Nikolay
A1  - Pohlmeier, A.
A1  - Oswald, Sascha Eric
T1  - Combination of magnetic resonance imaging and neutron computed tomography for three-dimensional rhizosphere imaging
JF  - Vadose zone journal
N2  - Core Ideas

    3D MRI relaxation time maps reflect water mobility in root, rhizosphere, and soil.
    3D NCT water content maps of the same plant complement relaxation time maps.
    The relaxation time T1 decreases from soil to root, whereas water content increases.
    Parameters together indicate modification of rhizosphere pore space by gel phase.
    The zone of reduced T1 corresponds to the zone remaining dry after rewetting.

In situ investigations of the rhizosphere require high‐resolution imaging techniques, which allow a look into the optically opaque soil compartment. We present the novel combination of magnetic resonance imaging (MRI) and neutron computed tomography (NCT) to achieve synergistic information such as water mobility in terms of three‐dimensional (3D) relaxation time maps and total water content maps. Besides a stationary MRI scanner for relaxation time mapping, we used a transportable MRI system on site in the NCT facility to capture rhizosphere properties before desiccation and after subsequent rewetting. First, we addressed two questions using water‐filled test capillaries between 0.1 and 5 mm: which root diameters can still be detected by both methods, and to what extent are defined interfaces blurred by these imaging techniques? Going to real root system architecture, we demonstrated the sensitivity of the transportable MRI device by co‐registration with NCT and additional validation using X‐ray computed tomography. Under saturated conditions, we observed for the rhizosphere in situ a zone with shorter T1 relaxation time across a distance of about 1 mm that was not caused by reduced water content, as proven by successive NCT measurements. We conclude that the effective pore size in the pore network had changed, induced by a gel phase. After rewetting, NCT images showed a dry zone persisting while the MRI intensity inside the root increased considerably, indicating water uptake from the surrounding bulk soil through the still hydrophobic rhizosphere. Overall, combining NCT and MRI allows a more detailed analysis of the rhizosphere's functioning.
Y1  - 2019
U6  - https://doi.org/10.2136/vzj2018.09.0166
SN  - 1539-1663
VL  - 18
IS  - 1
PB  - Soil Science Society of America
CY  - Madison
ER  - 
TY  - JOUR
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Lenoir, Nicolas
A1  - Manke, Ingo
A1  - Oswald, Sascha Eric
A1  - Tengattini, Alessandro
T1  - What comes NeXT?
BT  - High-Speed Neutron Tomography at ILL
JF  - Optics express : the international electronic journal of optics
N2  - Here, we report on a new record in the acquisition time for fast neutron tomography. With an optimized imaging setup, it was possible to acquire single radiographic projection images with 10 ms and full tomographies with 155 projections images and a physical spatial resolution of 200 mu m within 1.5 s. This is about 6.7 times faster than the current record. We used the technique to investigate the water infiltration in the soil with a living lupine root system. The fast imaging setup will be part of the future NeXT instrument at ILL in Grenoble with a great field of possible future applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Y1  - 2019
U6  - https://doi.org/10.1364/OE.27.028640
SN  - 1094-4087
VL  - 27
IS  - 20
SP  - 28640
EP  - 28648
PB  - Optical Society of America
CY  - Washington
ER  - 
TY  - JOUR
A1  - Miegel, Konrad
A1  - Gräff, Thomas
A1  - Franck, Christian
A1  - Salzmann, Thomas
A1  - Bronstert, Axel
A1  - Walther, Marc
A1  - Oswald, Sascha Eric
T1  - Auswirkungen des Sturmhochwassers der Ostsee
am 4./5. Januar 2017 auf das renaturierte Nieder-
moor „Hütelmoor und Heiligensee“ an der deut-
schen Ostseeküste
BT  - Effects of the January 4/5 2017 storm surge on a restored fen at the German Baltic Sea coast
JF  - Hydrologie und Wasserbewirtschaftung
N2  - Entlang der Küstenniederung des Naturschutzgebietes „Hütelmoor und Heiligensee“, ca. 6 km nordöstlich von Rostock-Warnemünde gelegen, wird seit dem Jahr 2000 die Küstendüne nicht mehr instand gehalten. Im Rahmen der Renaturierung des Gebietes werden so grundsätzlich wieder Überflutungen bei Ostseehochwassern zugelassen, was bisher jedoch noch nicht eingetreten ist. Am 4./5. Januar 2017 ereignete sich ein Sturmhochwasser der Ostsee, mit einem Scheitelwasserstand in Warnemünde, der sich zwischen dem 10- und 20-jährlichen Hochwasserstand einordnet. Dennoch kam es bei diesem Ereignis nicht zum Dünendurchbruch und zur seeseitigen Überflutung, wohl aber zum binnenseitigen Einstrom von Salz- bzw. Brackwasser. Dieser erfolgte über den Graben, durch den das Gebiet normalerweise über die Warnow in die Ostsee entwässert. Durch das Einströmen über die Sohlschwelle, sonst Auslass des Gebietes, stiegen die Wasserstände und Salzkonzentrationen in der südwestlichen Hälfte der Niederung an. Mit zunehmender Entfernung zur Sohlschwelle waren diese Auswirkungen jedoch geringer spürbar. Dies gilt wegen der Retentionswirkung der Niederung mehr für den Wasserstand als für die Salzkonzentration. Während der Wasserstand durch den Einstau der Niederung und Überschwemmungen flächenhaft anstieg, breitete sich die Salzfront präferentiell in den ehemaligen Entwässerungsgräben, die trotz des Einstaus nach wie vor hydraulisch aktiv sind, eher linienhaft aus. Diese Interpretation beruht auf Messergebnissen von Wasserstand, elektrischer Leitfähigkeit und Wassertemperatur.
N2  - Maintenance and repair of the coastal dunes of the conservation area, Hutelmoor und Heiligensee" have been ceased for renaturation purposes since the year 2000 to aid flooding of the area during high water levels of the Baltic Sea. On January 4th and 5th 2017, the Baltic Sea experienced a storm surge resulting in a water level in Warnemunde with a 10-to 20-year reoccurrence rate. Nevertheless, the event caused neither a dune failure nor a sea-sided flooding, but did result in an upstream inflow of salt and brackwater through the trench which normally drains the area into the Baltic Sea via the Warnow. Water levels and salinity concentrations rose in the south-western part of the area due to the influx via a ground sill, which normally acts as the outlet of the lowland. The effects within the lowland were less pronounced with increasing distance to the ground sill, which proved to be even more significant for the water levels than for salinities due to the retention capabilities of the area. While water levels increased extensively as a result of the flooding, the salinity front is presumed to have spread primarily along the former draining channels. This interpretation is based on monitoring data of the water level as well as the environmental tracers electrical conductivity and water temperature.
KW  - Baltic Sea
KW  - storm surge
KW  - coastal lowland
KW  - flooding
KW  - salinization
KW  - environmental tracer
KW  - process analysis
KW  - Ostsee
KW  - Sturmhochwasser
KW  - Küstenniederung
KW  - Überflutung
KW  - Versalzung
KW  - Umwelttracer
KW  - Prozessgeschehen
Y1  - 2017
U6  - https://doi.org/10.5675/HyWa_2017,4_2
SN  - 1439-1783
VL  - 61
IS  - 4
SP  - 232
EP  - 243
PB  - Bundesanst. für Gewässerkunde
CY  - Koblenz
ER  - 
TY  - GEN
A1  - Wagner, Kathrin
A1  - Oswald, Sascha Eric
A1  - Frick, Annett
T1  - Multitemporal soil moisture monitoring by use of optical remote sensing data in a dike relocation area
T2  - Remote Sensing for Agriculture, Ecosystems, and Hydrology XX
N2  - The nature restoration project ‘Lenzener Elbtalaue’, realised from 2002 to 2011 at the river Elbe, included the first large scale dike relocation in Germany (420 ha). Its aim was to initiate the development of endangered natural wetland habitats and processes, accompanied by greater biodiversity in the former grassland dominated area. The monitoring of spatial and temporal variations of soil moisture in this dike relocation area is therefore particularly important for estimating the restoration success. The topsoil moisture monitoring from 1990 to 2017 is based on the Soil Moisture Index (SMI)1 derived with the triangle method2 by use of optical remotely sensed data: land surface temperature and Normalized Differnce Vegetation Index are calculated from Landsat 4/5/7/8 data and atmospheric corrected by use of MODIS data. Spatial and temporal soil moisture variations in the restored area of the dike relocation are compared to the agricultural and pasture area behind the new dike. Ground truth data in the dike relocation area was obtained from field measurements in October 2017 with a FDR device. Additionally, data from a TERENO soil moisture sensor network (SoilNet) and mobile cosmic ray neutron sensing (CRNS) rover measurements are compared to the results of the triangle method for a region in the Harz Mountains (Germany). The SMI time series illustrates, that the dike relocation area has become significantly wetter between 1990 and 2017, due to restructuring measurements. Whereas the SMI of the dike hinterland reflects constant and drier conditions. An influence of climate is unlikely. However, validation of the dimensionless index with ground truth measurements is very difficult, mostly due to large differences in scale.
KW  - soil moisture
KW  - time series
KW  - SMI
KW  - triangle method
KW  - Landsat
KW  - restoration
Y1  - 2018
SN  - 978-1-5106-2150-3
U6  - https://doi.org/10.1117/12.2325319
SN  - 0277-786X
SN  - 1996-756X
VL  - 10783
PB  - SPIE-INT Soc Optical Engineering
CY  - Bellingham
ER  - 
TY  - JOUR
A1  - Günther, Oliver
A1  - Schüle, Manja
A1  - Zurell, Damaris
A1  - Jeltsch, Florian
A1  - Roeleke, Manuel
A1  - Kampe, Heike
A1  - Zimmermann, Matthias
A1  - Scholz, Jana
A1  - Mikulla, Stefanie
A1  - Engbert, Ralf
A1  - Elsner, Birgit
A1  - Schlangen, David
A1  - Agrofylax, Luisa
A1  - Georgi, Doreen
A1  - Weymar, Mathias
A1  - Wagener, Thorsten
A1  - Bookhagen, Bodo
A1  - Eibl, Eva P. S.
A1  - Korup, Oliver
A1  - Oswald, Sascha Eric
A1  - Thieken, Annegret Henriette
A1  - van der Beek, Peter
T1  - Portal Wissen = Excellence
JF  - Portal Wissen: The research magazine of the University of Potsdam
N2  - When something is not just good or very good, we often call it excellent. But what does that really mean? Coming from the Latin word “excellere,” it describes things, persons, or actions that are outstanding or superior and distinguish themselves from others. It cannot get any better. Excellence is the top choice for being the first or the best. Research is no exception.
At the university, you will find numerous exceptional researchers, outstanding projects, and, time and again, sensational findings, publications, and results. But is the University of Potsdam also excellent? A question that will certainly create a different stir in 2023 than it did perhaps 20 years ago. Since the launch of the Excellence Initiative in 2005, universities that succeed in winning the most comprehensive funding program for research in Germany have been considered – literally – excellent. Whether in the form of graduate schools, research clusters, or – since the program was continued in 2019 under the title “Excellence Strategy” – entire universities of excellence: Anyone who wants to be among the best research universities needs the seal of excellence.
The University of Potsdam is applying for funding with three cluster proposals in the recently launched new round of the “Excellence Strategy of the German Federal and State Governments.” One proposal comes from ecology and biodiversity research. The aim is to paint a comprehensive picture of ecological processes by examining the role of single individuals as well as the interactions among many species in an ecosystem to precisely determine the function of biodiversity. A second proposal has been submitted by the cognitive sciences. Here, the complex coexistence of language and cognition, development and learning, as well as motivation and behavior will be researched as a dynamic interrelation. The projects will include cooperation with the educational sciences to constantly consider linked learning and educational processes. The third proposal from the geo and environmental sciences concentrates on extreme and particularly devastating natural hazards and processes such as floods and droughts. The researchers examine these extreme events, focusing on their interaction with society, to be able to better assess the risks and damages they might involve and to initiate timely measures in the future.
“All three proposals highlight the excellence of our performance,” emphasizes University President Prof. Oliver Günther, Ph.D. “The outlines impressively document our commitment, existing research excellence, and the potential of the University of Potsdam as a whole. The fact that three powerful consortia have come together in different subject areas shows that we have taken a good step forward on our way to becoming one of the top German universities.”
In this issue, we are looking at what is in and behind these proposals: We talked to the researchers who wrote them. We asked them about their plans in case their proposals are successful and they bring a cluster of excellence to the university. But we also looked at the research that has led to the proposals, has long shaped the university’s profile, and earned it national and international recognition. We present a small selection of projects, methods, and researchers to illustrate why there really is excellent research in these proposals!
By the way, “excellence” is also not the end of the flagpole. After all, the adjective “excellent” even has a comparative and a superlative. With this in mind, I wish you the most excellent pleasure reading this issue!
T3  - Portal Wissen: The research magazine of the University of Potsdam [Englische Ausgabe] - 02/2023 
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-611456
SN  - 2198-9974
IS  - 02/2023
ER  - 
TY  - JOUR
A1  - Schrön, Martin
A1  - Rosolem, Rafael
A1  - Köhli, Markus
A1  - Piussi, L.
A1  - Schröter, I.
A1  - Iwema, J.
A1  - Kögler, S.
A1  - Oswald, Sascha Eric
A1  - Wollschläger, U.
A1  - Samaniego, Luis
A1  - Dietrich, Peter
A1  - Zacharias, Steffen
T1  - Cosmic-ray Neutron Rover Surveys of Field Soil Moisture and the Influence of Roads
JF  - Water resources research
N2  - Measurements of root-zone soil moisture across spatial scales of tens to thousands of meters have been a challenge for many decades. The mobile application of Cosmic Ray Neutron Sensing (CRNS) is a promising approach to measure field soil moisture noninvasively by surveying large regions with a ground-based vehicle. Recently, concerns have been raised about a potentially biasing influence of local structures and roads. We employed neutron transport simulations and dedicated experiments to quantify the influence of different road types on the CRNS measurement. We found that roads introduce a substantial bias in the CRNS estimation of field soil moisture compared to off-road scenarios. However, this effect becomes insignificant at distances beyond a few meters from the road. Neutron measurements on the road could overestimate the field value by up to 40 % depending on road material, width, and the surrounding field water content. The bias could be largely removed with an analytical correction function that accounts for these parameters. Additionally, an empirical approach is proposed that can be used without prior knowledge of field soil moisture. Tests at different study sites demonstrated good agreement between road-effect corrected measurements and field soil moisture observations. However, if knowledge about the road characteristics is missing, measurements on the road could substantially reduce the accuracy of this method. Our results constitute a practical advancement of the mobile CRNS methodology, which is important for providing unbiased estimates of field-scale soil moisture to support applications in hydrology, remote sensing, and agriculture. Plain Language Summary Measurements of root-zone soil moisture across spatial scales of tens to thousands of meters have been a challenge for many decades. The mobile application of Cosmic Ray Neutron Sensing (CRNS) is a promising approach to measure field soil moisture noninvasively by surveying large regions with a ground-based vehicle. Recently, concerns have been raised about a potentially biasing influence of roads. We employed physics simulations and dedicated experiments to quantify the influence of different road types on the CRNS measurement. We found that the presence of roads biased the CRNS estimation of field soil moisture compared to nonroad scenarios. Neutron measurements could overestimate the field value by up to 40 % depending on road material, width, surrounding field water content, and distance from the road. We proposed a correction function that successfully removed this bias and works even without prior knowledge of field soil moisture. Tests at different study sites demonstrated good agreement between corrected measurements and other field soil moisture observations. Our results constitute a practical advancement of the mobile CRNS methodology, which is important for providing unbiased estimates of field-scale soil moisture to support applications in hydrology, remote sensing, and agriculture.
KW  - road effect
KW  - field-scale
KW  - soil moisture
KW  - cosmic ray neutrons
KW  - mobile survey
KW  - COSMOS rover
Y1  - 2018
U6  - https://doi.org/10.1029/2017WR021719
SN  - 0043-1397
SN  - 1944-7973
VL  - 54
IS  - 9
SP  - 6441
EP  - 6459
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Schmidt, Lena Katharina
A1  - Bochow, Mathias
A1  - Imhof, Hannes K.
A1  - Oswald, Sascha Eric
T1  - Multi-temporal surveys for microplastic particles enabled by a novel and fast application of SWIR imaging spectroscopy
BT  - Study of an urban watercourse traversing the city of Berlin, Germany
JF  - Environmental pollution
N2  - Following the widespread assumption that a majority of ubiquitous marine microplastic particles originate from land-based sources, recent studies identify rivers as important pathways for microplastic particles (MPP) to the oceans. Yet a detailed understanding of the underlying processes and dominant sources is difficult to obtain with the existing accurate but extremely time-consuming methods available for the identification of MPP. Thus in the presented study, a novel approach applying short-wave infrared imaging spectroscopy for the quick and semi-automated identification of MPP is applied in combination with a multitemporal survey concept. Volume-reduced surface water samples were taken from transects at ten points along a major watercourse running through the South of Berlin, Germany, on six dates. After laboratory treatment, the samples were filtered onto glass fiber filters, scanned with an imaging spectrometer and analyzed by image processing. The presented method allows to count MPP, classify the plastic types and determine particle sizes. At the present stage of development particles larger than 450 m in diameter can be identified and a visual validation showed that the results are reliable after a subsequent visual final check of certain typical error types. Therefore, the method has the potential to accelerate microplastic identification by complementing FTIR and Raman microspectroscopy. Technical advancements (e.g. new lens) will allow lower detection limits and a higher grade of automatization in the near future. The resulting microplastic concentrations in the water samples are discussed in a spatio-temporal context with respect to the influence (i) of urban areas, (ii) of effluents of three major Berlin wastewater treatment plants discharging into the canal and (iii) of precipitation events. Microplastic concentrations were higher downstream of the urban area and after precipitation. An increase in microplastic concentrations was discernible for the wastewater treatment plant located furthest upstream though not for the other two. (C) 2018 Elsevier Ltd. All rights reserved.
Y1  - 2018
U6  - https://doi.org/10.1016/j.envpol.2018.03.097
SN  - 0269-7491
SN  - 1873-6424
VL  - 239
SP  - 579
EP  - 589
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - GEN
A1  - Schrön, Martin
A1  - Köhli, Markus
A1  - Scheiffele, Lena
A1  - Iwema, Joost
A1  - Bogena, Heye R.
A1  - Lv, Ling
A1  - Martini, Edoardo
A1  - Baroni, Gabriele
A1  - Rosolem, Rafael
A1  - Weimar, Jannis
A1  - Mai, Juliane
A1  - Cuntz, Matthias
A1  - Rebmann, Corinna
A1  - Oswald, Sascha Eric
A1  - Dietrich, Peter
A1  - Schmidt, Ulrich
A1  - Zacharias, Steffen
T1  - Improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - In the last few years the method of cosmic-ray neutron sensing (CRNS) has gained popularity among hydrologists, physicists, and land-surface modelers. The sensor provides continuous soil moisture data, averaged over several hectares and tens of decimeters in depth. However, the signal still may contain unidentified features of hydrological processes, and many calibration datasets are often required in order to find reliable relations between neutron intensity and water dynamics. Recent insights into environmental neutrons accurately described the spatial sensitivity of the sensor and thus allowed one to quantify the contribution of individual sample locations to the CRNS signal. Consequently, data points of calibration and validation datasets are suggested to be averaged using a more physically based weighting approach. In this work, a revised sensitivity function is used to calculate weighted averages of point data. The function is different from the simple exponential convention by the extraordinary sensitivity to the first few meters around the probe, and by dependencies on air pressure, air humidity, soil moisture, and vegetation. The approach is extensively tested at six distinct monitoring sites: two sites with multiple calibration datasets and four sites with continuous time series datasets. In all cases, the revised averaging method improved the performance of the CRNS products. The revised approach further helped to reveal hidden hydrological processes which otherwise remained unexplained in the data or were lost in the process of overcalibration. The presented weighting approach increases the overall accuracy of CRNS products and will have an impact on all their applications in agriculture, hydrology, and modeling.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 636 
KW  - forested headwater catchment
KW  - moisture observing system
KW  - soil-water content
KW  - parameterization methods
KW  - scale
KW  - field
KW  - dynamics
KW  - observatories
KW  - networks
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-419134
IS  - 636
SP  - 5009
EP  - 5030
ER  - 
TY  - GEN
A1  - Heistermann, Maik
A1  - Francke, Till
A1  - Schrön, Martin
A1  - Oswald, Sascha Eric
T1  - Spatio-temporal soil moisture retrieval at the catchment scale using a dense network of cosmic-ray neutron sensors
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Cosmic-ray neutron sensing (CRNS) is a powerful technique for retrieving representative estimates of soil water content at a horizontal scale of hectometres (the “field scale”) and depths of tens of centimetres (“the root zone”). This study demonstrates the potential of the CRNS technique to obtain spatio-temporal patterns of soil moisture beyond the integrated volume from isolated CRNS footprints. We use data from an observational campaign carried out between May and July 2019 that featured a dense network of more than 20 neutron detectors with partly overlapping footprints in an area that exhibits pronounced soil moisture gradients within one square kilometre. The present study is the first to combine these observations in order to represent the heterogeneity of soil water content at the sub-footprint scale as well as between the CRNS stations. First, we apply a state-of-the-art procedure to correct the observed neutron count rates for static effects (heterogeneity in space, e.g. soil organic matter) and dynamic effects (heterogeneity in time, e.g. barometric pressure). Based on the homogenized neutron data, we investigate the robustness of a calibration approach that uses a single calibration parameter across all CRNS stations. Finally, we benchmark two different interpolation techniques for obtaining spatio-temporal representations of soil moisture: first, ordinary Kriging with a fixed range; second, spatial interpolation complemented by geophysical inversion (“constrained interpolation”). To that end, we optimize the parameters of a geostatistical interpolation model so that the error in the forward-simulated neutron count rates is minimized, and suggest a heuristic forward operator to make the optimization problem computationally feasible. Comparison with independent measurements from a cluster of soil moisture sensors (SoilNet) shows that the constrained interpolation approach is superior for representing horizontal soil moisture gradients at the hectometre scale. The study demonstrates how a CRNS network can be used to generate coherent, consistent, and continuous soil moisture patterns that could be used to validate hydrological models or remote sensing products.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1162 
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-522131
SN  - 1866-8372
ER  - 
TY  - JOUR
A1  - Heistermann, Maik
A1  - Francke, Till
A1  - Schrön, Martin
A1  - Oswald, Sascha Eric
T1  - Spatio-temporal soil moisture retrieval at the catchment scale using a dense network of cosmic-ray neutron sensors
JF  - Hydrology and Earth System Sciences (HESS)
N2  - Cosmic-ray neutron sensing (CRNS) is a powerful technique for retrieving representative estimates of soil water content at a horizontal scale of hectometres (the “field scale”) and depths of tens of centimetres (“the root zone”). This study demonstrates the potential of the CRNS technique to obtain spatio-temporal patterns of soil moisture beyond the integrated volume from isolated CRNS footprints. We use data from an observational campaign carried out between May and July 2019 that featured a dense network of more than 20 neutron detectors with partly overlapping footprints in an area that exhibits pronounced soil moisture gradients within one square kilometre. The present study is the first to combine these observations in order to represent the heterogeneity of soil water content at the sub-footprint scale as well as between the CRNS stations. First, we apply a state-of-the-art procedure to correct the observed neutron count rates for static effects (heterogeneity in space, e.g. soil organic matter) and dynamic effects (heterogeneity in time, e.g. barometric pressure). Based on the homogenized neutron data, we investigate the robustness of a calibration approach that uses a single calibration parameter across all CRNS stations. Finally, we benchmark two different interpolation techniques for obtaining spatio-temporal representations of soil moisture: first, ordinary Kriging with a fixed range; second, spatial interpolation complemented by geophysical inversion (“constrained interpolation”). To that end, we optimize the parameters of a geostatistical interpolation model so that the error in the forward-simulated neutron count rates is minimized, and suggest a heuristic forward operator to make the optimization problem computationally feasible. Comparison with independent measurements from a cluster of soil moisture sensors (SoilNet) shows that the constrained interpolation approach is superior for representing horizontal soil moisture gradients at the hectometre scale. The study demonstrates how a CRNS network can be used to generate coherent, consistent, and continuous soil moisture patterns that could be used to validate hydrological models or remote sensing products.
Y1  - 2021
U6  - https://doi.org/10.5194/hess-25-4807-2021
SN  - 1607-7938
VL  - 25
PB  - Copernicus Publications
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Francke, Till
A1  - Heistermann, Maik
A1  - Köhli, Markus
A1  - Budach, Christian
A1  - Schrön, Martin
A1  - Oswald, Sascha Eric
T1  - Assessing the feasibility of a directional cosmic-ray neutron sensing sensor for estimating soil moisture
JF  - Geoscientific Instrumentation, Methods and Data Systems
N2  - Cosmic-ray neutron sensing (CRNS) is a non-invasive tool for measuring hydrogen pools such as soil moisture, snow or vegetation. The intrinsic integration over a radial hectare-scale footprint is a clear advantage for averaging out small-scale heterogeneity, but on the other hand the data may become hard to interpret in complex terrain with patchy land use.

This study presents a directional shielding approach to prevent neutrons from certain angles from being counted while counting neutrons entering the detector from other angles and explores its potential to gain a sharper horizontal view on the surrounding soil moisture distribution.

Using the Monte Carlo code URANOS (Ultra Rapid Neutron-Only Simulation), we modelled the effect of additional polyethylene shields on the horizontal field of view and assessed its impact on the epithermal count rate, propagated uncertainties and aggregation time.

The results demonstrate that directional CRNS measurements are strongly dominated by isotropic neutron transport, which dilutes the signal of the targeted direction especially from the far field. For typical count rates of customary CRNS stations, directional shielding of half-spaces could not lead to acceptable precision at a daily time resolution. However, the mere statistical distinction of two rates should be feasible.
KW  - water-balance
KW  - quantification
KW  - calibration
KW  - validation
Y1  - 2021
U6  - https://doi.org/10.5194/gi-11-75-2022
SN  - 2193-0864
SN  - 2193-0856
VL  - 11
SP  - 75
EP  - 92
PB  - Copernicus Publ.
CY  - Göttingen
ER  - 
TY  - GEN
A1  - Heistermann, Maik
A1  - Bogena, Heye
A1  - Francke, Till
A1  - Güntner, Andreas
A1  - Jakobi, Jannis
A1  - Rasche, Daniel
A1  - Schrön, Martin
A1  - Döpper, Veronika
A1  - Fersch, Benjamin
A1  - Groh, Jannis
A1  - Patil, Amol
A1  - Pütz, Thomas
A1  - Reich, Marvin
A1  - Zacharias, Steffen
A1  - Zengerle, Carmen
A1  - Oswald, Sascha Eric
T1  - Soil moisture observation in a forested headwater catchment: combining a dense cosmic-ray neutron sensor network with roving and hydrogravimetry at the TERENO site Wüstebach
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Cosmic-ray neutron sensing (CRNS) has become an effective method to measure soil moisture at a horizontal scale of hundreds of metres and a depth of decimetres. Recent studies proposed operating CRNS in a network with overlapping footprints in order to cover root-zone water dynamics at the small catchment scale and, at the same time, to represent spatial heterogeneity. In a joint field campaign from September to November 2020 (JFC-2020), five German research institutions deployed 15 CRNS sensors in the 0.4 km2 Wüstebach catchment (Eifel mountains, Germany). The catchment is dominantly forested (but includes a substantial fraction of open vegetation) and features a topographically distinct catchment boundary. In addition to the dense CRNS coverage, the campaign featured a unique combination of additional instruments and techniques: hydro-gravimetry (to detect water storage dynamics also below the root zone); ground-based and, for the first time, airborne CRNS roving; an extensive wireless soil sensor network, supplemented by manual measurements; and six weighable lysimeters. Together with comprehensive data from the long-term local research infrastructure, the published data set (available at https://doi.org/10.23728/b2share.756ca0485800474e9dc7f5949c63b872; Heistermann et al., 2022) will be a valuable asset in various research contexts: to advance the retrieval of landscape water storage from CRNS, wireless soil sensor networks, or hydrogravimetry; to identify scale-specific combinations of sensors and methods to represent soil moisture variability; to improve the understanding and simulation of land–atmosphere exchange as well as hydrological and hydrogeological processes at the hillslope and the catchment scale; and to support the retrieval of soil water content from airborne and spaceborne remote sensing platforms.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1272 
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-567756
SN  - 1866-8372
IS  - 1272
SP  - 2501
EP  - 2519
ER  - 
TY  - GEN
A1  - Francke, Till
A1  - Heistermann, Maik
A1  - Köhli, Markus
A1  - Budach, Christian
A1  - Schrön, Martin
A1  - Oswald, Sascha Eric
T1  - Assessing the feasibility of a directional cosmic-ray neutron sensing sensor for estimating soil moisture
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Cosmic-ray neutron sensing (CRNS) is a non-invasive tool for measuring hydrogen pools such as soil moisture, snow or vegetation. The intrinsic integration over a radial hectare-scale footprint is a clear advantage for averaging out small-scale heterogeneity, but on the other hand the data may become hard to interpret in complex terrain with patchy land use.

This study presents a directional shielding approach to prevent neutrons from certain angles from being counted while counting neutrons entering the detector from other angles and explores its potential to gain a sharper horizontal view on the surrounding soil moisture distribution.

Using the Monte Carlo code URANOS (Ultra Rapid Neutron-Only Simulation), we modelled the effect of additional polyethylene shields on the horizontal field of view and assessed its impact on the epithermal count rate, propagated uncertainties and aggregation time.

The results demonstrate that directional CRNS measurements are strongly dominated by isotropic neutron transport, which dilutes the signal of the targeted direction especially from the far field. For typical count rates of customary CRNS stations, directional shielding of half-spaces could not lead to acceptable precision at a daily time resolution. However, the mere statistical distinction of two rates should be feasible.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1228 
KW  - water-balance
KW  - quantification
KW  - calibration
KW  - validation
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-544229
SN  - 1866-8372
SP  - 75
EP  - 92
ER  - 
TY  - JOUR
A1  - Heistermann, Maik
A1  - Bogena, Heye
A1  - Francke, Till
A1  - Güntner, Andreas
A1  - Jakobi, Jannis
A1  - Rasche, Daniel
A1  - Schrön, Martin
A1  - Döpper, Veronika
A1  - Fersch, Benjamin
A1  - Groh, Jannis
A1  - Patil, Amol
A1  - Pütz, Thomas
A1  - Reich, Marvin
A1  - Zacharias, Steffen
A1  - Zengerle, Carmen
A1  - Oswald, Sascha Eric
T1  - Soil moisture observation in a forested headwater catchment: combining a dense cosmic-ray neutron sensor network with roving and hydrogravimetry at the TERENO site Wüstebach
JF  - Earth System Science Data (ESSD)
N2  - Cosmic-ray neutron sensing (CRNS) has become an effective method to measure soil moisture at a horizontal scale of hundreds of metres and a depth of decimetres. Recent studies proposed operating CRNS in a network with overlapping footprints in order to cover root-zone water dynamics at the small catchment scale and, at the same time, to represent spatial heterogeneity. In a joint field campaign from September to November 2020 (JFC-2020), five German research institutions deployed 15 CRNS sensors in the 0.4 km2 Wüstebach catchment (Eifel mountains, Germany). The catchment is dominantly forested (but includes a substantial fraction of open vegetation) and features a topographically distinct catchment boundary. In addition to the dense CRNS coverage, the campaign featured a unique combination of additional instruments and techniques: hydro-gravimetry (to detect water storage dynamics also below the root zone); ground-based and, for the first time, airborne CRNS roving; an extensive wireless soil sensor network, supplemented by manual measurements; and six weighable lysimeters. Together with comprehensive data from the long-term local research infrastructure, the published data set (available at https://doi.org/10.23728/b2share.756ca0485800474e9dc7f5949c63b872; Heistermann et al., 2022) will be a valuable asset in various research contexts: to advance the retrieval of landscape water storage from CRNS, wireless soil sensor networks, or hydrogravimetry; to identify scale-specific combinations of sensors and methods to represent soil moisture variability; to improve the understanding and simulation of land–atmosphere exchange as well as hydrological and hydrogeological processes at the hillslope and the catchment scale; and to support the retrieval of soil water content from airborne and spaceborne remote sensing platforms.
Y1  - 2022
U6  - https://doi.org/10.5194/essd-14-2501-2022
SN  - 1866-3516
VL  - 14
SP  - 2501
EP  - 2519
PB  - Copernicus
CY  - Katlenburg-Lindau
ER  - 
TY  - JOUR
A1  - Günther, Oliver
A1  - Schüle, Manja
A1  - Zurell, Damaris
A1  - Jeltsch, Florian
A1  - Roeleke, Manuel
A1  - Kampe, Heike
A1  - Zimmermann, Matthias
A1  - Scholz, Jana
A1  - Engbert, Ralf
A1  - Elsner, Birgit
A1  - Schlangen, David
A1  - Agrofylax, Luisa
A1  - Georgi, Doreen
A1  - Weymar, Mathias
A1  - Wagener, Thorsten
A1  - Bookhagen, Bodo
A1  - Eibl, Eva P. S.
A1  - Korup, Oliver
A1  - Oswald, Sascha Eric
A1  - Thieken, Annegret Henriette
A1  - van der Beek, Peter
T1  - Portal Wissen = Exzellenz
JF  - Portal Wissen: Das Forschungsmagazin der Universität Potsdam
N2  - Was nicht nur gut oder sehr gut ist, nennen wir gern exzellent. Aber was meint das eigentlich? Vom lateinischen „excellere“ kommend, beschreibt es Dinge, Personen oder Handlungen, die „hervor-“ oder „herausragen“ aus der Menge, sich „auszeichnen“ gegenüber anderen. Mehr geht nicht. Exzellenz ist das Mittel der Wahl, wenn es darum geht, der Erste oder Beste zu sein. Und das macht auch vor der Forschung nicht halt. Wer auf die Universität Potsdam schaut, findet zahlreiche ausgezeichnete Forschende, hervorragende Projekte und immer wieder auch aufsehenerregende Erkenntnisse, Veröffentlichungen und Ergebnisse.
Aber ist die UP auch exzellent? Eine Frage, die 2023 ganz sicher andere Wellen schlägt als vielleicht vor 20 Jahren. Denn seit dem Start der Exzellenzinitiative 2005 gelten als – wörtlich – exzellent jene Hochschulen, denen es gelingt, in dem umfangreichsten Förderprogramm für Wissenschaft in Deutschland einen Zuschlag zu erhalten. Egal ob in Form von Graduiertenschulen, Forschungsclustern oder – seit Fortsetzung des Programms ab 2019 unter dem Titel „Exzellenzstrategie“ – ganzen Exzellenzuniversitäten: Wer im Kreis der Forschungsuniversitäten zu den Besten gehören will, braucht das Siegel der Exzellenz. In der gerade eingeläuteten neuen Wettbewerbsrunde der „Exzellenzstrategie des Bundes und der Länder“ bewirbt sich die Universität Potsdam mit drei Clusterskizzen um Förderung.
Ein Antrag kommt aus der Ökologie- und Biodiversitätsforschung. Ziel ist es, ein komplexes Bild ökologischer Prozesse zu zeichnen – und dabei die Rolle von einzelnen Individuen ebenso zu betrachten wie das Zusammenwirken vieler Arten in einem Ökosystem, um die Funktion der Artenvielfalt genauer zu bestimmen. Eine zweite Skizze haben die Kognitionswissenschaften eingereicht. Hier soll das komplexe Nebeneinander von Sprache und Kognition, Entwicklung und Lernen sowie Motivation und Verhalten als dynamisches Miteinander erforscht werden – wobei auch mit den Erziehungswissenschaften kooperiert wird, um verknüpfte Lernund Bildungsprozesse stets mitzudenken. Der dritte Antrag aus den Geo- und Umweltwissenschaften nimmt extreme und besonders folgenschwere Naturgefahren und -prozesse wie Überschwemmungen und Dürren in den Blick. Die Forschenden untersuchen die Extremereignisse mit besonderem Fokus auf deren Wechselwirkung mit der Gesellschaft, um mit ihnen einhergehende Risiken und Schäden besser einschätzen sowie künftig rechtzeitig Maßnahmen einleiten zu können.
„Alle drei Anträge zeichnen ein hervorragendes Bild unserer Leistungsfähigkeit“, betont der Präsident der Universität, Prof. Oliver Günther, Ph.D. „Die Skizzen dokumentieren eindrucksvoll unser Engagement, vorhandene Forschungsexzellenz sowie die Potenziale der Universität Potsdam insgesamt. Allein die Tatsache, dass sich drei schlagkräftige Konsortien in ganz unterschiedlichen Themenbereichen zusammengefunden haben, zeigt, dass wir auf unserem Weg in die Spitzengruppe der deutschen Universitäten einen guten Schritt vorangekommen sind.“
In diesem Heft schauen wir, was sich in und hinter diesen Anträgen verbirgt: Wir haben mit den Wissenschaftlerinnen und Wissenschaftlern gesprochen, die sie geschrieben haben, und sie gefragt, was sie sich vornehmen, sollten sie den Zuschlag erhalten und ein Cluster an die Universität holen. Wir haben aber auch auf die Forschung geschaut, die zu den Anträgen geführt hat und die schon länger das Profil der Universität prägt und ihr national wie international Anerkennung eingebracht hat. Wir stellen eine kleine Auswahl an Projekten, Methoden und Forschenden vor, um zu zeigen, warum in diesen Anträgen tatsächlich exzellente Forschung steckt! Übrigens: Auch „Exzellenz“ ist nicht das Ende der Fahnenstange. Immerhin lässt sich das Adjektiv exzellent sogar steigern. In diesem Sinne wünschen wir exzellentestes Vergnügen beim Lesen!
T3  - Portal Wissen: Das Forschungsmagazin der Universität Potsdam [Deutsche Ausgabe] - 02/2023 
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-611440
SN  - 2194-4245
IS  - 02/2023
ER  - 
TY  - JOUR
A1  - van Afferden, Manfred
A1  - Rahman, Khaja Z.
A1  - Mosig, Peter
A1  - De Biase, Cecilia
A1  - Thullner, Martin
A1  - Oswald, Sascha Eric
A1  - Müller, Roland A.
T1  - Remediation of groundwater contaminated with MTBE and benzene the potential of vertical-flow soil filter systems
JF  - Water research
N2  - Field investigations on the treatment of MTBE and benzene from contaminated groundwater in pilot or full-scale constructed wetlands are lacking hugely. The aim of this study was to develop a biological treatment technology that can be operated in an economic, reliable and robust mode over a long period of time. Two pilot-scale vertical-flow soil filter eco-technologies, a roughing filter (RF) and a polishing filter (PF) with plants (willows), were operated independently in a single-stage configuration and coupled together in a multi-stage (RF + PF) configuration to investigate the MTBE and benzene removal performances. Both filters were loaded with groundwater from a refinery site contaminated with MTBE and benzene as the main contaminants, with a mean concentration of 2970 +/- 816 and 13,966 +/- 1998 mu g L(-1), respectively. Four different hydraulic loading rates (HLRs) with a stepwise increment of 60, 120, 240 and 480 L m(-2) d(-1) were applied over a period of 388 days in the single-stage operation. At the highest HLR of 480 L m(-2)d(-1), the mean concentrations of MTBE and benzene were found to be 550 +/- 133 and 65 +/- 123 mu g L(-1) in the effluent of the RF. In the effluent of the PP system, respective mean MTBE and benzene concentrations of 49 +/- 77 and 0.5 +/- 0.2 mu g L(-1) were obtained, which were well below the relevant MTBE and benzene limit values of 200 and 1 mu g L-1 for drinking water quality. But a dynamic fluctuation in the effluent MTBE concentration showed a lack of stability in regards to the increase in the measured values by nearly 10%, which were higher than the limit value. Therefore, both (RF + PF) filters were combined in a multi-stage configuration and the combined system proved to be more stable and effective with a highly efficient reduction of the MTBE and benzene concentrations in the effluent. Nearly 70% of MTBE and 98% of benzene were eliminated from the influent groundwater by the first vertical filter (RF) and the remaining amount was almost completely diminished (similar to 100% reduction) after passing through the second filter (PF), with a mean MTBE and benzene concentration of 5 +/- 10 and 0.6 +/- 0.2 mu g L(-1) in the final effluent. The emission rate of volatile organic compounds mass into the air from the systems was less than 1% of the inflow mass loading rate. The results obtained in this study not only demonstrate the feasibility of vertical-flow soil filter systems for treating groundwater contaminated with MTBE and benzene, but can also be considered a major step forward towards their application under full-scale conditions for commercial purposes in the oil and gas industries.
KW  - Benzene
KW  - Groundwater remediation
KW  - Hydraulic loading rate
KW  - MTBE
KW  - Pilot-scale constructed wetland
KW  - Vertical-flow soil filter
KW  - Willow tree
Y1  - 2011
U6  - https://doi.org/10.1016/j.watres.2011.07.010
SN  - 0043-1354
VL  - 45
IS  - 16
SP  - 5063
EP  - 5074
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - De Biase, Cecilia
A1  - Carminati, Andrea
A1  - Oswald, Sascha Eric
A1  - Thullner, Martin
T1  - Numerical modeling analysis of VOC removal processes in different aerobic vertical flow systems for groundwater remediation
JF  - Journal of contaminant hydrology
N2  - Vertical flow systems filled with porous medium have been shown to efficiently remove volatile organic contaminants (VOCs) from contaminated groundwater. To apply this semi-natural remediation strategy it is however necessary to distinguish between removal due to biodegradation and due to volatile losses to the atmosphere. Especially for (potentially) toxic VOCs, the latter needs to be minimized to limit atmospheric emissions. In this study, numerical simulation was used to investigate quantitatively the removal of volatile organic compounds in two pilot-scale water treatment systems: an unplanted vertical flow filter and a planted one, which could also be called a vertical flow constructed wetland, both used for the treatment of contaminated groundwater. These systems were intermittently loaded with contaminated water containing benzene and MTBE as main VOCs. The highly dynamic but permanently unsaturated conditions in the porous medium facilitated aerobic biodegradation but could lead to volatile emissions of the contaminants. Experimental data from porous material analyses, flow rate measurements, solute tracer and gas tracer test, as well as contaminant concentration measurements at the boundaries of the systems were used to constrain a numerical reactive transport modeling approach. Numerical simulations considered unsaturated water flow, transport of species in the aqueous and the gas phase as well as aerobic degradation processes, which made it possible to quantify the rates of biodegradation and volatile emissions and calculating their contribution to total contaminant removal. A range of degradation rates was determined using experimental results of both systems under two operation modes and validated by field data obtained at different operation modes applied to the filters. For both filters, simulations and experimental data point to high biodegradation rates, if the flow filters have had time to build up their removal capacity. For this case volatile emissions are negligible and total removal can be attributed to biodegradation, only. The simulation study thus supports the use of both of these vertical flow systems for the treatment of groundwater contaminated with VOCs and the use of reactive transport modeling for the assessment of VOCs removal and operation modes in these high performance treatment systems.
KW  - Benzene
KW  - Biodegradation
KW  - MTBE
KW  - Unsaturated zone
KW  - Vertical flow filters
KW  - Volatilization
Y1  - 2013
U6  - https://doi.org/10.1016/j.jconhyd.2013.07.007
SN  - 0169-7722
SN  - 1873-6009
VL  - 154
IS  - 11
SP  - 53
EP  - 69
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - De Biase, Cecilia
A1  - Maier, Uli
A1  - Baeder-Bederski, Oliver
A1  - Bayer, Peter
A1  - Oswald, Sascha Eric
A1  - Thullner, Martin
T1  - Removal of volatile organic compounds in vertical flow filters -  predictions from reactive transport modeling
JF  - Ground water monitoring & remediation
N2  - Vertical flow filters are containers filled with porous medium that are recharged from top and drained at the bottom, and are operated at partly saturated conditions. They have recently been suggested as treatment technology for groundwater containing volatile organic compounds (VOCs). Numerical reactive transport simulations were performed to investigate the relevance of different filter operation modes on biodegradation and/or volatilization of the contaminants and to evaluate the potential limitation of such remediation mean due to volatile emissions. On the basis of the data from a pilot-scale vertical flow filter intermittently fed with domestic waste water, model predictions on the systems performance for the treatment of contaminated groundwater were derived. These simulations considered the transport and aerobic degradation of ammonium and two VOCs, benzene and methyl tertiary butyl ether (MTBE). In addition, the advective-diffusive gas-phase transport of volatile compounds as well as oxygen was simulated. Model predictions addressed the influence of depth and frequency of the intermittent groundwater injection, degradation rate kinetics, and the composition of the filter material. Simulation results show that for unfavorable operation conditions significant VOC emissions have to be considered and that operation modes limiting VOC emissions may limit aerobic biodegradation. However, a suitable combination of injection depth and composition of the filter material does facilitate high biodegradation rates while only little VOC emissions take place. Using such optimized operation modes would allow using vertical flow filter systems as remediation technology suitable for groundwater contaminated with volatile compounds.
Y1  - 2012
U6  - https://doi.org/10.1111/j.1745-6592.2011.01374.x
SN  - 1069-3629
VL  - 32
IS  - 2
SP  - 106
EP  - 121
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - De Biase, Cecilia
A1  - Reger, Daniel
A1  - Schmidt, Axel
A1  - Jechalke, Sven
A1  - Reiche, Nils
A1  - Martinez-Lavanchy, Paula M.
A1  - Rosell, Monica
A1  - Van Afferden, Manfred
A1  - Maier, Uli
A1  - Oswald, Sascha Eric
A1  - Thullner, Martin
T1  - Treatment of volatile organic contaminants in a vertical flow filter -  relevance of different removal processes
JF  - Ecological engineering : the journal of ecotechnology
N2  - Vertical flow filters and vertical flow constructed wetlands are established wastewater treatment systems and have also been proposed for the treatment of contaminated groundwater. This study investigates the removal processes of volatile organic compounds in a pilot-scale vertical flow filter. The filter is intermittently irrigated with contaminated groundwater containing benzene, MTBE and ammonium as the main contaminants. The system is characterized by unsaturated conditions and high contaminant removal efficiency. The aim of the present study is to evaluate the contribution of biodegradation and volatilization to the overall removal of benzene and MTBE. Tracer tests and flow rate measurements showed a highly transient flow and heterogeneous transport regime. Radon-222, naturally occurring in the treated groundwater, was used as a gas tracer and indicated a high volatilization potential. Radon-222 behavior was reproduced by numerical simulations and extrapolated for benzene and MTBE, and indicated these compounds also have a high volatilization potential. In contrast, passive sampler measurements on top of the filter detected only low benzene and MTBE concentrations. Biodegradation potential was evaluated by the analysis of catabolic genes involved in organic compound degradation and a quantitative estimation of biodegradation was derived from stable isotope fractionation analysis. Results suggest that despite the high volatilization potential, biodegradation is the predominant mass removal process in the filter system, which indicates that the volatilized fraction of the contaminants is still subject to subsequent biodegradation. In particular, the upper filter layer located between the injection tubes and the surface of the system might also contribute to biodegradation, and might play a crucial role in avoiding the emission of volatilized contaminants into the atmosphere.
KW  - Benzene
KW  - Biodegradation
KW  - Catabolic genes
KW  - MTBE
KW  - Numerical modeling
KW  - Radon
KW  - SAFIRA II
KW  - Stable isotope fractionation analysis
KW  - Tracers
KW  - VOCs
KW  - Volatilization
Y1  - 2011
U6  - https://doi.org/10.1016/j.ecoleng.2011.03.023
SN  - 0925-8574
VL  - 37
IS  - 9
SP  - 1292
EP  - 1303
PB  - Elsevier
CY  - Amsterdam
ER  -