TY - JOUR A1 - Kaiser, Knut A1 - Oldorff, Silke A1 - Breitbach, Carsten A1 - Kappler, Christoph A1 - Theuerkauf, Martin A1 - Scharnweber, Tobias A1 - Schult, Manuela A1 - Kuester, Mathias A1 - Engelhardt, Christof A1 - Heinrich, Ingo A1 - Hupfer, Michael A1 - Schwalbe, Grit A1 - Kirschey, Tom A1 - Bens, Oliver T1 - A submerged pine forest from the early Holocene in the Mecklenburg Lake District, northern Germany JF - Boreas N2 - For the first time, evidence of a submerged pine forest from the early Holocene can be documented in a central European lake. Subaquatic tree stumps were discovered in Lake Giesenschlagsee at a depth of between 2 and 5m using scuba divers, side-scan sonar and a remotely operated vehicle. Several erect stumps, anchored to the ground by roots, represent an insitu record of this former forest. Botanical determination revealed the stumps to be Scots pine (Pinus sylvestris) with an individual tree age of about 80years. The trees could not be dated by means of dendrochronology, as they are older than the regional reference chronology for pine. Radiocarbon ages from the wood range from 10880 +/- 210 to 10370 +/- 130cal. a BP, which is equivalent to the mid-Preboreal to early Boreal biozones. The trees are rooted in sedge peat, which can be dated to this period as well, using pollen stratigraphical analysis. Tilting of the peat bed by 4m indicates subsidence of the ground due to local dead ice melting, causing the trees to become submerged and preserved for millennia. Together with recently detected Lateglacial insitu tree occurrences in nearby lakes, the submerged pine forest at Giesenschlagsee represents a new and highly promising type of geo-bio-archive for the wider region. Comparable insitu pine remnants occur at some terrestrial (buried setting) and marine (submerged setting) sites in northern central Europe and beyond, but they partly differ in age. In general, the insitu pine finds document shifts of the zonal boreal forest ecosystem during the late Quaternary. Y1 - 2018 U6 - https://doi.org/10.1111/bor.12314 SN - 0300-9483 SN - 1502-3885 VL - 47 IS - 3 SP - 910 EP - 925 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Rolf, Werner A1 - Pauleit, Stephan A1 - Wiggering, Hubert T1 - A stakeholder approach, door opener for farmland and multifunctionality in urban green infrastructure JF - Urban forestry & urban greening N2 - During the last years Urban Green Infrastructure (UGI) has evolved as a research focus across Europe. UGI can be understood as a multifunctional network of different urban green spaces and elements contributing to urban benefits. Urban agriculture has gained increasing research interest in this context. While a strong focus has been made on functions and benefits of small scale activities, the question is still open, whether these findings can be up-scaled and transferred to the farmland scale. Furthermore, multifunctionality of urban and peri-urban agriculture is rarely being considered in the landscape context. This research aims to address these gaps and harnesses the question if agricultural landscapes – which in many European metropolitan regions provide significant spatial potential – can contribute to UGI as multifunctional green spaces. This work considers multifunctionality qualitatively based on stakeholder opinion, using a participatory research approach. This study provides new insights in peri-urban farmland potentials for UGI development, resulting into a strategy framework. Furthermore, it reflects on the role of the stakeholder involvement for `multifunctionality planning´. It suggests that it helps to define meaningful bundles of intertwined functions that interact on different scales, helping to deal with non-linearity of multiple functions and to better manage them simultaneously. KW - Benefits KW - Functions KW - Green surge KW - Multifunctionality KW - Participation KW - Peri-urban agriculture KW - Stakeholder KW - Urban learning lab Y1 - 2018 U6 - https://doi.org/10.1016/j.ufug.2018.07.012 SN - 1618-8667 VL - 40 SP - 73 EP - 83 PB - Urban & Fischer CY - Jena ER - TY - JOUR A1 - Gao, Yongbo A1 - Merz, Christoph A1 - Lischeid, Gunnar A1 - Schneider, Michael T1 - A review on missing hydrological data processing JF - Environmental earth sciences N2 - Like almost all fields of science, hydrology has benefited to a large extent from the tremendous improvements in scientific instruments that are able to collect long-time data series and an increase in available computational power and storage capabilities over the last decades. Many model applications and statistical analyses (e.g., extreme value analysis) are based on these time series. Consequently, the quality and the completeness of these time series are essential. Preprocessing of raw data sets by filling data gaps is thus a necessary procedure. Several interpolation techniques with different complexity are available ranging from rather simple to extremely challenging approaches. In this paper, various imputation methods available to the hydrological researchers are reviewed with regard to their suitability for filling gaps in the context of solving hydrological questions. The methodological approaches include arithmetic mean imputation, principal component analysis, regression-based methods and multiple imputation methods. In particular, autoregressive conditional heteroscedasticity (ARCH) models which originate from finance and econometrics will be discussed regarding their applicability to data series characterized by non-constant volatility and heteroscedasticity in hydrological contexts. The review shows that methodological advances driven by other fields of research bear relevance for a more intensive use of these methods in hydrology. Up to now, the hydrological community has paid little attention to the imputation ability of time series models in general and ARCH models in particular. KW - Missing data KW - Imputation KW - Hydrological time series analysis KW - ARCH KW - ARIMA KW - Heteroscedasticity Y1 - 2018 U6 - https://doi.org/10.1007/s12665-018-7228-6 SN - 1866-6280 SN - 1866-6299 VL - 77 IS - 2 PB - Springer CY - New York ER - TY - JOUR A1 - Aiken, John M. A1 - Aiken, Chastity A1 - Cotton, Fabrice T1 - A python library for teaching computation to seismology students JF - Seismological research letters N2 - Python is at the forefront of scientific computation for seismologists and therefore should be introduced to students interested in becoming seismologists. On its own, Python is open source and well designed with extensive libraries. However, Python code can also be executed, visualized, and communicated to others with "Jupyter Notebooks". Thus, Jupyter Notebooks are ideal for teaching students Python and scientific computation. In this article, we designed an openly available Python library and collection of Jupyter Notebooks based on defined scientific computation learning goals for seismology students. The Notebooks cover topics from an introduction to Python to organizing data, earthquake catalog statistics, linear regression, and making maps. Our Python library and collection of Jupyter Notebooks are meant to be used as course materials for an upper-division data analysis course in an Earth Science Department, and the materials were tested in a Probabilistic Seismic Hazard course. However, seismologists or anyone else who is interested in Python for data analysis and map making can use these materials. Y1 - 2018 U6 - https://doi.org/10.1785/0220170246 SN - 0895-0695 SN - 1938-2057 VL - 89 IS - 3 SP - 1165 EP - 1171 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Woutersen, Amber A1 - Jardine, Phillip E. A1 - Giovanni Bogota-Angel, Raul A1 - Zhang, Hong-Xiang A1 - Silvestro, Daniele A1 - Antonelli, Alexandre A1 - Gogna, Elena A1 - Erkens, Roy H. J. A1 - Gosling, William D. A1 - Dupont-Nivet, Guillaume A1 - Hoorn, Carina T1 - A novel approach to study the morphology and chemistry of pollen in a phylogenetic context, applied to the halophytic taxon Nitraria L.(Nitrariaceae) JF - PeerJ N2 - Nitraria is a halophytic taxon (i.e., adapted to saline environments) that belongs to the plant family Nitrariaceae and is distributed from the Mediterranean, across Asia into the south-eastern tip of Australia. This taxon is thought to have originated in Asia during the Paleogene (66-23 Ma), alongside the proto-Paratethys epicontinental sea. The evolutionary history of Nitraria might hold important clues on the links between climatic and biotic evolution but limited taxonomic documentation of this taxon has thus far hindered this line of research. Here we investigate if the pollen morphology and the chemical composition of the pollen wall are informative of the evolutionary history of Nitraria and could explain if origination along the proto-Paratethys and dispersal to the Tibetan Plateau was simultaneous or a secondary process. To answer these questions, we applied a novel approach consisting of a combination of Fourier Transform Infrared spectroscopy (FTIR), to determine the chemical composition of the pollen wall, and pollen morphological analyses using Light Microscopy (LM) and Scanning Electron Microscopy (SEM). We analysed our data using ordinations (principal components analysis and non-metric multidimensional scaling), and directly mapped it on the Nitrariaceae phylogeny to produce a phylomorphospace and a phylochemospace. Our LM, SEM and FTIR analyses show clear morphological and chemical differences between the sister groups Peganum and Nitraria. Differences in the morphological and chemical characteristics of highland species (Nitraria schoberi, N. sphaerocarpa, N. sibirica and N. tangutorum) and lowland species (Nitraria billardierei and N. retusa) are very subtle, with phylogenetic history appearing to be a more important control on Nitraria pollen than local environmental conditions. Our approach shows a compelling consistency between the chemical and morphological characteristics of the eight studied Nitrariaceae species, and these traits are in agreement with the phylogenetic tree. Taken together, this demonstrates how novel methods for studying fossil pollen can facilitate the evolutionary investigation of living and extinct taxa, and the environments they represent. KW - FTIR KW - LM KW - SEM KW - Paratethys KW - Tibet KW - Sporopollenin KW - Mediterranean KW - Steppe-desert KW - Australia KW - Palynology Y1 - 2018 U6 - https://doi.org/10.7717/peerj.5055 SN - 2167-8359 VL - 6 PB - PeerJ Inc. CY - London ER - TY - JOUR A1 - Dietrich, Marcel A1 - Behrens, Harald A1 - Wilke, Max T1 - A new optical cell for in situ Raman spectroscopy, and its application to study sulfur-bearing fluids at elevated pressures and temperatures JF - American mineralogist : an international journal of earth and planetary materials N2 - Sulfur is an important component in volcanic gases at the Earth surface but also present in the deep Earth in hydrothermal or magmatic fluids. Little is known about the evolution of such fluids during ascent in the crust. A new optical cell was developed for in situ Raman spectroscopic investigations on fluids allowing abrupt or continuous changes of pressure up to 200 MPa at temperatures up to 750 degrees C. The concept is based on a flexible gold bellow, which separates the sample fluid from the pressure medium water. To avoid reactions between aggressive fluids and the pressure cell, steel components in contact with the fluid are shielded by gold foil. The cell was tested to study redox reactions in fluids using aqueous ammonium sulfate solutions as a model system. During heating at constant pressure of 130 MPa, sulfate ions transform first to HSO4- ions and then to molecular units such as H2SO4. Variation of pressure shows that the stability of sulfate species relies on fluid density, i.e., highly charged species are stable only in high-density fluids. Partial decomposition of ammonium was evident above 550 degrees C by the occurrence of a nitrogen peak in the Raman spectra. Reduced sulfur species were observed above 700 degrees C by Raman signals near 2590 cm(-1) assigned to HS- and H2S. No clear evidence for the formation of sulfur dioxide was found in contrary to previous studies on aqueous H2SO4, suggesting very reducing conditions in our experiments. Fluid-mineral interaction was studied by inserting into the cell a small, semi-open capsule filled with a mixture of pyrite and pyrrhotite. Oxidation of the sample assembly was evident by transformation of pyrite to pyrrhotite. As a consequence, sulfide species were observed in the fluid already at temperatures of similar to 600 degrees C. KW - In situ Raman spectroscopy KW - fluids KW - decompression KW - optical cell KW - sulfur speciation KW - redox reactions Y1 - 2018 U6 - https://doi.org/10.2138/am-2018-6244 SN - 0003-004X SN - 1945-3027 VL - 103 IS - 3 SP - 418 EP - 429 PB - Mineralogical Society of America CY - Chantilly ER - TY - JOUR A1 - Öztürk, Ugur A1 - Marwan, Norbert A1 - von Specht, Sebastian A1 - Korup, Oliver A1 - Jensen, J. T1 - A new centennial sea-level record for Antalya, Eastern Mediterranean JF - Journal of geophysical research-oceans N2 - Quantitative estimates of sea-level rise in the Mediterranean Basin become increasingly accurate thanks to detailed satellite monitoring. However, such measuring campaigns cover several years to decades, while longer-term sea-level records are rare for the Mediterranean. We used a data archeological approach to reanalyze monthly mean sea-level data of the Antalya-I (1935–1977) tide gauge to fill this gap. We checked the accuracy and reliability of these data before merging them with the more recent records of the Antalya-II (1985–2009) tide gauge, accounting for an eight-year hiatus. We obtain a composite time series of monthly and annual mean sea levels spanning some 75 years, providing the longest record for the eastern Mediterranean Basin, and thus an essential tool for studying the region's recent sea-level trends. We estimate a relative mean sea-level rise of 2.2 ± 0.5 mm/year between 1935 and 2008, with an annual variability (expressed here as the standard deviation of the residuals, σresiduals = 41.4 mm) above that at the closest tide gauges (e.g., Thessaloniki, Greece, σresiduals = 29.0 mm). Relative sea-level rise accelerated to 6.0 ± 1.5 mm/year at Antalya-II; we attribute roughly half of this rate (~3.6 mm/year) to tectonic crustal motion and anthropogenic land subsidence. Our study highlights the value of data archeology for recovering and integrating historic tide gauge data for long-term sea-level and climate studies. KW - sea level KW - tide gauge KW - data archeology KW - Mediterranean Sea Y1 - 2018 U6 - https://doi.org/10.1029/2018JC013906 SN - 2169-9275 SN - 2169-9291 VL - 123 IS - 7 SP - 4503 EP - 4517 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Kotha, Sreeram Reddy A1 - Cotton, Fabrice A1 - Bindi, Dino T1 - A new approach to site classification BT - Mixed-effects Ground Motion Prediction Equation with spectral clustering of site amplification functions JF - Soil Dynamics and Earthquake Engineering N2 - With increasing amount of strong motion data, Ground Motion Prediction Equation (GMPE) developers are able to quantify empirical site amplification functions (delta S2S(s)) from GMPE residuals, for use in site-specific Probabilistic Seismic Hazard Assessment. In this study, we first derive a GMPE for 5% damped Pseudo Spectral Acceleration (g) of Active Shallow Crustal earthquakes in Japan with 3.4 <= M-w <= 7.3 and 0 <= R-JB <= 600km. Using k-mean spectral clustering technique, we then classify our estimated delta S2S(s)(T = 0.01 - 2s) of 588 wellcharacterized sites, into 8 site clusters with distinct mean site amplification functions, and within-cluster site-tosite variability similar to 50% smaller than the overall dataset variability (phi(S2S)). Following an evaluation of existing schemes, we propose a revised data-driven site classification characterized by kernel density distributions of V-s30, V-s10, H-800, and predominant period (T-G) of the site clusters. KW - Mixed-effects regression KW - Ground Motion Prediction Equation KW - Site classification KW - Spectral clustering analysis KW - Empirical site amplification functions Y1 - 2018 U6 - https://doi.org/10.1016/j.soildyn.2018.01.051 SN - 0267-7261 SN - 1879-341X VL - 110 SP - 318 EP - 329 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Hartman, Jan F. A1 - Gentz, Torben A1 - Schiller, Amanda A1 - Greule, Markus A1 - Grossart, Hans-Peter A1 - Ionescu, Danny A1 - Keppler, Frank A1 - Martinez-Cruz, Karla A1 - Sepulveda-Jauregui, Armando A1 - Isenbeck-Schroeter, Margot T1 - A f ast and sensitive method for the continuous in situ determination of dissolved methane and its delta C-13-isotope ratio in surface waters JF - Limnology and Oceanography-methods N2 - A fast and sensitive method for the continuous determination of methane (CH4) and its stable carbon isotopic values (delta C-13-CH4) in surface waters was developed by applying a vacuum to a gas/liquid exchange membrane and measuring the extracted gases by a portable cavity ring-down spectroscopy analyser (M-CRDS). The M-CRDS was calibrated and characterized for CH4 concentration and delta C-13-CH4 with synthetic water standards. The detection limit of the M-CRDS for the simultaneous determination of CH4 and delta C-13-CH4 is 3.6 nmol L-1 CH4. A measurement precision of CH4 concentrations and delta C-13-CH4 in the range of 1.1%, respectively, 1.7 parts per thousand (1 sigma) and accuracy (1.3%, respectively, 0.8 parts per thousand [1 sigma]) was achieved for single measurements and averaging times of 10 min. The response time tau of 57 +/- 5 s allow determination of delta C-13-CH4 values more than twice as fast than other methods. The demonstrated M-CRDS method was applied and tested for Lake Stechlin (Germany) and compared with the headspace-gas chromatography and fast membrane CH4 concentration methods. Maximum CH4 concentrations (577 nmol L-1) and lightest delta C-13-CH4 (-35.2 parts per thousand) were found around the thermocline in depth profile measurements. The M-CRDS-method was in good agreement with other methods. Temporal variations in CH4 concentration and delta C-13-CH4 obtained in 24 h measurements indicate either local methane production/oxidation or physical variations in the thermocline. Therefore, these results illustrate the need of fast and sensitive analyses to achieve a better understanding of different mechanisms and pathways of CH4 formation in aquatic environments. Y1 - 2018 U6 - https://doi.org/10.1002/lom3.10244 SN - 1541-5856 VL - 16 IS - 5 SP - 273 EP - 285 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Kriegerowski, Marius A1 - Petersen, Gesa Maria A1 - Vasyura-Bathke, Hannes A1 - Ohrnberger, Matthias T1 - A Deep Convolutional Neural Network for Localization of Clustered Earthquakes Based on Multistation Full Waveforms JF - Seismological research letters N2 - Earthquake localization is both a necessity within the field of seismology, and a prerequisite for further analysis such as source studies and hazard assessment. Traditional localization methods often rely on manually picked phases. We present an alternative approach using deep learning that once trained can predict hypocenter locations efficiently. In seismology, neural networks have typically been trained with either single-station records or based on features that have been extracted previously from the waveforms. We use three-component full-waveform records of multiple stations directly. This means no information is lost during preprocessing and preparation of the data does not require expert knowledge. The first convolutional layer of our deep convolutional neural network (CNN) becomes sensitive to features that characterize the waveforms it is trained on. We show that this layer can therefore additionally be used as an event detector. As a test case, we trained our CNN using more than 2000 earthquake swarm events from West Bohemia, recorded by nine local three-component stations. The CNN successfully located 908 validation events with standard deviations of 56.4 m in east-west, 123.8 m in north-south, and 136.3 m in vertical direction compared to a double-difference relocated reference catalog. The detector is sensitive to events with magnitudes down to M-L = -0.8 with 3.5% false positive detections. Y1 - 2018 U6 - https://doi.org/10.1785/0220180320 SN - 0895-0695 SN - 1938-2057 VL - 90 IS - 2 SP - 510 EP - 516 PB - Seismological Society of America CY - Albany ER -