TY  - JOUR
A1  - Coch, Caroline
A1  - Juhls, Bennet
A1  - Lamoureux, Scott F.
A1  - Lafreniere, Melissa J.
A1  - Fritz, Michael
A1  - Heim, Birgit
A1  - Lantuit, Hugues
T1  - Comparisons of dissolved organic matter and its optical characteristics in small low and high Arctic catchments
JF  - Biogeosciences
N2  - Climate change is affecting the rate of carbon cycling, particularly in the Arctic. Permafrost degradation through deeper thaw and physical disturbances results in the release of carbon dioxide and methane to the atmosphere and to an increase in lateral dissolved organic matter (DOM) fluxes. Whereas riverine DOM fluxes of the large Arctic rivers are well assessed, knowledge is limited with regard to small catchments that cover more than 40% of the Arctic drainage basin. Here, we use absorption measurements to characterize changes in DOM quantity and quality in a low Arctic (Herschel Island, Yukon, Canada) and a high Arctic (Cape Bounty, Melville Island, Nunavut, Canada) setting with regard to geographical differences, impacts of permafrost degradation, and rainfall events. We find that DOM quantity and quality is controlled by differences in vegetation cover and soil organic carbon content (SOCC). The low Arctic site has higher SOCC and greater abundance of plant material resulting in higher chromophoric dissolved organic matter (cDOM) and dissolved organic carbon (DOC) than in the high Arctic. DOC concentration and cDOM in surface waters at both sites show strong linear relationships similar to the one for the great Arctic rivers. We used the optical characteristics of DOM such as cDOM absorption, specific ultraviolet absorbance (SUVA), ultraviolet (UV) spectral slopes (S275-295), and slope ratio (SR) for assessing quality changes downstream, at base flow and storm flow conditions, and in relation to permafrost disturbance. DOM in streams at both sites demonstrated optical signatures indicative of photodegradation downstream processes, even over short distances of 2000 m. Flow pathways and the connected hydrological residence time control DOM quality. Deeper flow pathways allow the export of permafrost-derived DOM (i.e. from deeper in the active layer), whereas shallow pathways with shorter residence times lead to the export of fresh surface- and near-surface-derived DOM. Compared to the large Arctic rivers, DOM quality exported from the small catchments studied here is much fresher and therefore prone to degradation. Assessing optical properties of DOM and linking them to catchment properties will be a useful tool for understanding changing DOM fluxes and quality at a pan-Arctic scale.
Y1  - 2019
U6  - https://doi.org/10.5194/bg-16-4535-2019
SN  - 1726-4170
SN  - 1726-4189
VL  - 16
IS  - 23
SP  - 4535
EP  - 4553
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Coch, Caroline
A1  - Lamoureux, Scott F.
A1  - Knoblauch, Christian
A1  - Eischeid, Isabell
A1  - Fritz, Michael
A1  - Obu, Jaroslav
A1  - Lantuit, Hugues
T1  - Summer rainfall dissolved organic carbon, solute, and sediment fluxes in a small Arctic coastal catchment on Herschel Island (Yukon Territory, Canada)
JF  - Artic science
N2  - Coastal ecosystems in the Arctic are affected by climate change. As summer rainfall frequency and intensity are projected to increase in the future, more organic matter, nutrients and sediment could bemobilized and transported into the coastal nearshore zones. However, knowledge of current processes and future changes is limited. We investigated streamflow dynamics and the impacts of summer rainfall on lateral fluxes in a small coastal catchment on Herschel Island in the western Canadian Arctic. For the summer monitoring periods of 2014-2016, mean dissolved organic matter flux over 17 days amounted to 82.7 +/- 30.7 kg km(-2) and mean total dissolved solids flux to 5252 +/- 1224 kg km(-2). Flux of suspended sediment was 7245 kg km(-2) in 2015, and 369 kg km(-2) in 2016. We found that 2.0% of suspended sediment was composed of particulate organic carbon. Data and hysteresis analysis suggest a limited supply of sediments; their interannual variability is most likely caused by short-lived localized disturbances. In contrast, our results imply that dissolved organic carbon is widely available throughout the catchment and exhibits positive linear relationship with runoff. We hypothesize that increased projected rainfall in the future will result in a similar increase of dissolved organic carbon fluxes.
KW  - permafrost
KW  - hydrology
KW  - lateral fluxes
KW  - hysteresis
KW  - climate change
Y1  - 2018
U6  - https://doi.org/10.1139/as-2018-0010
SN  - 2368-7460
VL  - 4
IS  - 4
SP  - 750
EP  - 780
PB  - Canadian science publishing
CY  - Ottawa
ER  - 
TY  - JOUR
A1  - Couture, Nicole J.
A1  - Irrgang, Anna Maria
A1  - Pollard, Wayne
A1  - Lantuit, Hugues
A1  - Fritz, Michael
T1  - Coastal erosion of permafrost soils along the yukon coastal plain and fluxes of organic carbon to the canadian beaufort sea
JF  - Journal of geophysical research : Biogeosciences
N2  - Reducing uncertainties about carbon cycling is important in the Arctic where rapid environmental changes contribute to enhanced mobilization of carbon. Here we quantify soil organic carbon (SOC) contents of permafrost soils along the Yukon Coastal Plain and determine the annual fluxes from coastal erosion. Different terrain units were assessed based on surficial geology, morphology, and ground ice conditions. To account for the volume of wedge ice and massive ice in a unit, SOC contents were reduced by 19% and sediment contents by 16%. The SOC content in a 1m(2) column of soil varied according to the height of the bluff, ranging from 30 to 662kg, with a mean value of 183kg. Forty-four per cent of the SOC was within the top 1m of soil and values varied based on surficial materials, ranging from 30 to 53kg C/m(3), with a mean of 41kg. Eighty per cent of the shoreline was erosive with a mean annual rate of change of -0.7m/yr. This resulted in a SOC flux per meter of shoreline of 132kg C/m/yr, and a total flux for the entire 282km of the Yukon coast of 35.5 x 10(6) kg C/yr (0.036 Tg C/yr). The mean flux of sediment per meter of shoreline was 5.3 x 10(3) kg/m/yr, with a total flux of 1,832 x 10(6)kg/yr (1.832 Tg/yr). Sedimentation rates indicate that approximately 13% of the eroded carbon was sequestered in nearshore sediments, where the overwhelming majority of organic carbon was of terrestrial origin. Plain Language Summary The oceans help slow the buildup of carbon dioxide (CO2) because they absorb much of this greenhouse gas. However, if carbon from other sources is added to the oceans, it can affect their ability to absorb atmospheric CO2. Our study examines the organic carbon added to the Canadian Beaufort Sea from eroding permafrost along the Yukon coast, a region quite vulnerable to erosion. Understanding carbon cycling in this area is important because environmental changes in the Arctic such as longer open water seasons, rising sea levels, and warmer air, water and soil temperatures are likely to increase coastal erosion and, thus, carbon fluxes to the sea. We measured the carbon in different types of permafrost soils and applied corrections to account for the volume taken up by various types of ground ice. By determining how quickly the shoreline is eroding, we assessed how much organic carbon is being transferred to the ocean each year. Our results show that 36 x 10(6) kg of carbon is added annually from this section of the coast. If we extrapolate these results to other coastal areas along the Canadian Beaufort Sea, the flux of organic carbon is nearly 3 times what was previously thought.
KW  - coastal erosion
KW  - organic carbon
KW  - ground ice
KW  - Yukon
KW  - Canadian Beaufort Sea
Y1  - 2018
U6  - https://doi.org/10.1002/2017JG004166
SN  - 2169-8953
SN  - 2169-8961
VL  - 123
IS  - 2
SP  - 406
EP  - 422
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - THES
A1  - Fritz, Michael
T1  - Late quaternary environmental dynamics of the western canadian artic : permafrost and lake sediment archives at the easter beringian edge
Y1  - 2011
CY  - Potsdam
ER  - 
TY  - GEN
A1  - Fritz, Michael
A1  - Deshpande, B. N.
A1  - Bouchard, F.
A1  - Högström, E.
A1  - Malenfant-Lepage, J.
A1  - Morgenstern, Anne
A1  - Nieuwendam, A.
A1  - Oliva, M.
A1  - Paquette, M.
A1  - Rudy, A. C. A.
A1  - Siewert, M. B.
A1  - Sjöberg, Y.
A1  - Weege, Stefanie
T1  - Brief communication
BT  - Future avenues for permafrost science from the perspective of early career researchers
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - Accelerating climate change and increased economic and environmental interests in permafrost-affected regions have resulted in an acute need for more directed permafrost research. In June 2014, 88 early career researchers convened to identify future priorities for permafrost research. This multidisciplinary forum concluded that five research topics deserve greatest attention: permafrost landscape dynamics, permafrost thermal modeling, integration of traditional knowledge, spatial distribution of ground ice, and engineering issues. These topics underline the need for integrated research across a spectrum of permafrost-related domains and constitute a contribution to the Third International Conference on Arctic Research Planning (ICARP III).
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 490 
KW  - association
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-408096
SN  - 1866-8372
IS  - 490
ER  - 
TY  - JOUR
A1  - Fritz, Michael
A1  - Herzschuh, Ulrike
A1  - Wetterich, Sebastian
A1  - Lantuit, Hugues
A1  - De Pascale, Gregory P.
A1  - Pollard, Wayne H.
A1  - Schirrmeister, Lutz
T1  - Late glacial and holocene sedimentation, vegetation, and climate history from easternmost Beringia (northern Yukon Territory, Canada)
JF  - Quaternary research : an interdisciplinary journal
N2  - Beringian climate and environmental history are poorly characterized at its easternmost edge. Lake sediments from the northern Yukon Territory have recorded sedimentation, vegetation, summer temperature and precipitation changes since similar to 16 cal ka BP. Herb-dominated tundra persisted until similar to 14.7 cal ka BP with mean July air temperatures <= 5 degrees C colder and annual precipitation 50 to 120 mm lower than today. Temperatures rapidly increased during the Bolling/Allerod interstadial towards modern conditions, favoring establishment of Betula-Salix shrub tundra. Pollen-inferred temperature reconstructions recorded a pronounced Younger Dryas stadial in east Beringia with a temperature drop of similar to 1.5 degrees C (similar to 2.5 to 3.0 degrees C below modern conditions) and low net precipitation (90 to 170 mm) but show little evidence of an early Holocene thermal maximum in the pollen record. Sustained low net precipitation and increased evaporation during early Holocene warming suggest a moisture-limited spread of vegetation and an obscured summer temperature maximum. Northern Yukon Holocene moisture availability increased in response to a retreating Laurentide Ice Sheet, postglacial sea level rise, and decreasing summer insolation that in turn led to establishment of Alnus-Berula shrub tundra from similar to 5 cal ka BP until present, and conversion of a continental climate into a coastal-maritime climate near the Beaufort Sea.
KW  - Trout Lake
KW  - Laurentide Ice Sheet
KW  - Younger Dryas
KW  - Holocene thermal maximum
KW  - Lake sediments
KW  - Pollen
KW  - Temperature reconstruction
KW  - Precipitation reconstruction
KW  - WAPLS
KW  - Modern analogue technique
Y1  - 2012
U6  - https://doi.org/10.1016/j.yqres.2012.07.007
SN  - 0033-5894
VL  - 78
IS  - 3
SP  - 549
EP  - 560
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Fritz, Michael
A1  - Opel, Thomas
A1  - Tanski, George
A1  - Herzschuh, Ulrike
A1  - Meyer, H.
A1  - Eulenburg, A.
A1  - Lantuit, Hugues
T1  - Dissolved organic carbon (DOC) in Arctic ground ice
JF  - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2  - Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC) and nutrients which have accumulated in late Pleistocene and Holocene unconsolidated deposits. Permafrost vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change are largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and other elements which are important for ecosystems and carbon cycling. Here we show, using biogeochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage, with a maximum of 28.6 mg L-1 (mean: 9.6 mg L-1). Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly frozen and stored in ground ice, especially in ice wedges, even before further degradation. We found that ice wedges in the Yedoma region represent a significant DOC (45.2 Tg) and DIC (33.6 Tg) pool in permafrost areas and a freshwater reservoir of 4200 km(2). This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost car-bon pool for ecosystems and climate feedback upon mobilization.
Y1  - 2015
U6  - https://doi.org/10.5194/tc-9-737-2015
SN  - 1994-0416
SN  - 1994-0424
VL  - 9
IS  - 2
SP  - 737
EP  - 752
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - GEN
A1  - Fritz, Michael
A1  - Opel, Thomas
A1  - Tanski, George
A1  - Herzschuh, Ulrike
A1  - Meyer, Hanno
A1  - Eulenburg, A.
A1  - Lantuit, Hugues
T1  - Dissolved organic carbon (DOC) in Arctic ground ice
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC) and nutrients which have accumulated in late Pleistocene and Holocene unconsolidated deposits. Permafrost vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change are largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and other elements which are important for ecosystems and carbon cycling. Here we show, using biogeochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage, with a maximum of 28.6 mg L-1 (mean: 9.6 mg L-1). Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly frozen and stored in ground ice, especially in ice wedges, even before further degradation. We found that ice wedges in the Yedoma region represent a significant DOC (45.2 Tg) and DIC (33.6 Tg) pool in permafrost areas and a freshwater reservoir of 4200 km(2). This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost car-bon pool for ecosystems and climate feedback upon mobilization.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 493 
KW  - last glacial maximum
KW  - Beaufort Sea coast
KW  - Cape Mamontov Klyk
KW  - permafrost carbon
KW  - Laptev Sea
KW  - Lyakhovsky Island
KW  - climate-change
KW  - old carbon
KW  - hologene
KW  - Siberia
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-408155
SN  - 1866-8372
IS  - 493
ER  - 
TY  - JOUR
A1  - Fritz, Michael
A1  - Unkel, Ingmar
A1  - Lenz, Josefine
A1  - Gajewski, Konrad
A1  - Frenzel, Peter
A1  - Paquette, Nathalie
A1  - Lantuit, Hugues
A1  - Körte, Lisa
A1  - Wetterich, Sebastian
T1  - Regional environmental change versus local signal preservation in Holocene thermokarst lake sediments
BT  - a case study from Herschel Island, Yukon (Canada)
JF  - Journal of paleolimnolog
N2  - Thermokarst lakes cover nearly one fourth of ice-rich permafrost lowlands in the Arctic. Sediments from an athalassic subsaline thermokarst lake on Herschel Island (69°36′N; 139°04′W, Canadian Arctic) were used to understand regional changes in climate and in sediment transport, hydrology, nutrient availability and permafrost disturbance. The sediment record spans the last ~ 11,700 years and the basal date is in good agreement with the Holocene onset of thermokarst initiation in the region. Electrical conductivity in pore water continuously decreases, thus indicating desalinization and continuous increase of lake size and water level. The inc/coh ratio of XRF scans provides a high-resolution organic-carbon proxy which correlates with TOC measurements. XRF-derived Mn/Fe ratios indicate aerobic versus anaerobic conditions which moderate the preservation potential of organic matter in lake sediments. The coexistence of marine, brackish and freshwater ostracods and foraminifera is explained by (1) oligohaline to mesohaline water chemistry of the past lake and (2) redeposition of Pleistocene specimens found within upthrusted marine sediments around the lake. Episodes of catchment disturbance are identified when calcareous fossils and allochthonous material were transported into the lake by thermokarst processes such as active-layer detachments, slumping and erosion of ice-rich shores. The pollen record does not show major variations and the pollen-based climate record does not match well with other summer air temperature reconstructions from this region. Local vegetation patterns in small catchments are strongly linked to morphology and sub-surface permafrost conditions rather than to climate. Multidisciplinary studies can identify the onset and life cycle of thermokarst lakes as they play a crucial role in Arctic freshwater ecosystems and in the global carbon cycle of the past, present and future.
KW  - Arctic
KW  - Permafrost
KW  - Athalassic subsaline lake
KW  - XRF scanning
KW  - Pore-water hydrochemistry
KW  - Ostracoda
Y1  - 2018
U6  - https://doi.org/10.1007/s10933-018-0025-0
SN  - 0921-2728
SN  - 1573-0417
VL  - 60
IS  - 1
SP  - 77
EP  - 96
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Fritz, Michael
A1  - Wolter, Juliane
A1  - Rudaya, Natalia
A1  - Palagushkina, Olga
A1  - Nazarova, Larisa B.
A1  - Obu, Jaroslav
A1  - Rethemeyer, Janet
A1  - Lantuit, Hugues
A1  - Wetterich, Sebastian
T1  - Holocene ice-wedge polygon development in northern Yukon permafrost peatlands (Canada)
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - Ice-wedge polygon (IWP) peatlands in the Arctic and Subarctic are extremely vulnerable to climatic and environmental change. We present the results of a multidisciplinary paleoenvironmental study on IWPs in the northern Yukon, Canada. High-resolution laboratory analyses were carried out on a permafrost core and the overlying seasonally thawed (active) layer, from an IWP located in a drained lake basin on Herschel Island. In relation to 14 Accelerator Mass Spectrometry (AMS) radiocarbon dates spanning the last 5000 years, we report sedimentary data including grain size distribution and biogeochemical parameters (organic carbon, nitrogen, C/N ratio, delta C-13), stable water isotopes (delta O-18, delta D), as well as fossil pollen, plant macrofossil and diatom assemblages. Three sediment units (SUS) correspond to the main stages of deposition (1) in a thermokarst lake (SW : 4950 to 3950 cal yrs BP), (2) during transition from lacustrine to palustrine conditions after lake drainage (SU2: 3950 to 3120 cal yrs BP), and (3) in palustrine conditions of the IWP field that developed after drainage (SU3: 3120 cal yrs BP to 2012 CE). The lacustrine phase (pre 3950 cal yrs BP) is characterized by planktonic-benthic and pioneer diatom species indicating circumneutral waters, and very few plant macrofossils. The pollen record has captured a regional signal of relatively stable vegetation composition and climate for the lacustrine stage of the record until 3950 cal yrs BP. Palustrine conditions with benthic and acidophilic diatom species characterize the peaty shallow-water environments of the low-centered IWP. The transition from lacustrine to palustrine conditions was accompanied by acidification and rapid revegetation of the lake bottom within about 100 years. Since the palustrine phase we consider the pollen record as a local vegetation proxy dominated by the plant communities growing in the IWP. Ice-wedge cracking in water-saturated sediments started immediately after lake drainage at about 3950 cal yrs BP and led to the formation of an IWP mire. Permafrost aggradation through downward closed-system freezing of the lake talik is indicated by the stable water isotope record. The originally submerged IWP center underwent gradual drying during the past 2000 years. This study highlights the sensitivity of permafrost landscapes to climate and environmental change throughout the Holocene. (C) 2016 Elsevier Ltd. All rights reserved.
KW  - Permafrost peatlands
KW  - Arctic
KW  - Thermokarst
KW  - Talik
KW  - Ice-wedge polygon
KW  - Pollen
KW  - Diatoms
KW  - Plant macrofossils
KW  - Stable water isotopes
KW  - Deuterium excess
Y1  - 2016
U6  - https://doi.org/10.1016/j.quascirev.2016.02.008
SN  - 0277-3791
VL  - 147
SP  - 279
EP  - 297
PB  - Elsevier
CY  - Oxford
ER  -