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  - Obu, Jaroslav
A1  - Lantuit, Hugues
A1  - Fritz, Michael
A1  - Pollard, Wayne H.
A1  - Sachs, Torsten
A1  - Guenther, Frank
T1  - Relation between planimetric and volumetric measurements of permafrost coast erosion: a case study from Herschel Island, western Canadian Arctic
JF  - Polar research : a Norwegian journal of Polar research
N2  - Ice-rich permafrost coasts often undergo rapid erosion, which results in land loss and release of considerable amounts of sediment, organic carbon and nutrients, impacting the near-shore ecosystems. Because of the lack of volumetric erosion data, Arctic coastal erosion studies typically report on planimetric erosion. Our aim is to explore the relationship between planimetric and volumetric coastal erosion measurements and to update the coastal erosion rates on Herschel Island in the Canadian Arctic. We used high-resolution digital elevation models to compute sediment release and compare volumetric data to planimetric estimations of coastline movements digitized from satellite imagery. Our results show that volumetric erosion is locally less variable and likely corresponds better with environmental forcing than planimetric erosion. Average sediment release volumes are in the same range as sediment release volumes calculated from coastline movements combined with cliff height. However, the differences between these estimates are significant for small coastal sections. We attribute the differences between planimetric and volumetric coastal erosion measurements to mass wasting, which is abundant along the coasts of Herschel Island. The average recorded coastline retreat on Herschel Island was 0.68m a(-1) for the period 2000-2011. Erosion rates increased by more than 50% in comparison with the period 1970-2000, which is in accordance with a recently observed increase along the Alaskan Beaufort Sea. The estimated annual sediment release was 28.2 m(3) m(-1) with resulting fluxes of 590 kg C m(-1) and 104 kg N m(-1).
KW  - Coastal erosion
KW  - LiDAR
KW  - carbon fluxes
KW  - mass wasting
KW  - landslides
KW  - digital elevation model
Y1  - 2016
U6  - https://doi.org/10.3402/polar.v35.30313
SN  - 0800-0395
SN  - 1751-8369
VL  - 35
SP  - 57
EP  - 99
PB  - Co-Action Publ.
CY  - Jarfalla
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  - GEN
A1  - Radosavljevic, Boris
A1  - Lantuit, Hugues
A1  - Pollard, Wayne
A1  - Overduin, Pier Paul
A1  - Couture, Nicole
A1  - Sachs, Torsten
A1  - Helm, Veit
A1  - Fritz, Michael
T1  - Erosion and flooding-threats to coastal Infrastructure in the Arctic
BT  - a case study from Herschel Island, Yukon Territory, Canada
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Arctic coastal infrastructure and cultural and archeological sites are increasingly vulnerable to erosion and flooding due to amplified warming of the Arctic, sea level rise, lengthening of open water periods, and a predicted increase in frequency of major storms. Mitigating these hazards necessitates decision-making tools at an appropriate scale. The objectives of this paper are to provide such a tool by assessing potential erosion and flood hazards at Herschel Island, a UNESCO World Heritage candidate site. This study focused on Simpson Point and the adjacent coastal sections because of their archeological, historical, and cultural significance. Shoreline movement was analyzed using the Digital Shoreline Analysis System (DSAS) after digitizing shorelines from 1952, 1970, 2000, and 2011. For purposes of this analysis, the coast was divided in seven coastal reaches (CRs) reflecting different morphologies and/or exposures. Using linear regression rates obtained from these data, projections of shoreline position were made for 20 and 50 years into the future. Flood hazard was assessed using a least cost path analysis based on a high-resolution light detection and ranging (LiDAR) dataset and current Intergovernmental Panel on Climate Change sea level estimates. Widespread erosion characterizes the study area. The rate of shoreline movement in different periods of the study ranges from −5.5 to 2.7 m·a⁻¹ (mean −0.6 m·a⁻¹). Mean coastal retreat decreased from −0.6 m·a⁻¹ to −0.5 m·a⁻¹, for 1952–1970 and 1970–2000, respectively, and increased to −1.3 m·a⁻¹ in the period 2000–2011. Ice-rich coastal sections most exposed to wave attack exhibited the highest rates of coastal retreat. The geohazard map combines shoreline projections and flood hazard analyses to show that most of the spit area has extreme or very high flood hazard potential, and some buildings are vulnerable to coastal erosion. This study demonstrates that transgressive forcing may provide ample sediment for the expansion of depositional landforms, while growing more susceptible to overwash and flooding.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 996 
KW  - Arctic
KW  - coastal erosion
KW  - UNESCO
KW  - vulnerability mapping;
KW  - permafrost coasts
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-432279
SN  - 1866-8372
IS  - 996
ER  - 
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  - Tanski, George
A1  - Couture, Nicole
A1  - Lantuit, Hugues
A1  - Eulenburg, Antje
A1  - Fritz, Michael
T1  - Eroding permafrost coasts release low amounts of dissolved organic carbon (DOC) from ground ice into the nearshore zone of the Arctic Ocean
JF  - Global biogeochemical cycles
N2  - Ice-rich permafrost coasts in the Arctic are highly sensitive to climate warming and erode at a pace that exceeds the global average. Permafrost coasts deliver vast amounts of organic carbon into the nearshore zone of the Arctic Ocean. Numbers on flux exist for particulate organic carbon (POC) and total or soil organic carbon (TOC, SOC). However, they do not exist for dissolved organic carbon (DOC), which is known to be highly bioavailable. This study aims to estimate DOC stocks in coastal permafrost as well as the annual flux into the ocean. DOC concentrations in ground ice were analyzed along the ice-rich Yukon coast (YC) in the western Canadian Arctic. The annual DOC flux was estimated using available numbers for coast length, cliff height, annual erosion rate, and volumetric ice content in different stratigraphic horizons. Our results showed that DOC concentrations in ground ice range between 0.3 and 347.0mgL(-1) with an estimated stock of 13.63.0gm(-3) along the YC. An annual DOC flux of 54.90.9Mgyr(-1) was computed. These DOC fluxes are low compared to POC and SOC fluxes from coastal erosion or POC and DOC fluxes from Arctic rivers. We conclude that DOC fluxes from permafrost coasts play a secondary role in the Arctic carbon budget. However, this DOC is assumed to be highly bioavailable. We hypothesize that DOC from coastal erosion is important for ecosystems in the Arctic nearshore zones, particularly in summer when river discharge is low, and in areas where rivers are absent.
KW  - Arctic
KW  - permafrost
KW  - coastal erosion
KW  - biogeochemistry
KW  - carbon cycle
Y1  - 2016
U6  - https://doi.org/10.1002/2015GB005337
SN  - 0886-6236
SN  - 1944-9224
VL  - 30
SP  - 1054
EP  - 1068
PB  - American Geophysical Union
CY  - Cambridge
ER  - 
TY  - GEN
A1  - Radosavljevic, Boris
A1  - Lantuit, Hugues
A1  - Pollard, Wayne
A1  - Overduin, Pier Paul
A1  - Couture, Nicole
A1  - Sachs, Torsten
A1  - Helm, Veit
A1  - Fritz, Michael
T1  - Erosion and Flooding - Threats to Coastal Infrastructure in the Arctic: A Case Study from Herschel Island, Yukon Territory, Canada (vol 39, pg 900, 2016)
T2  - Estuaries and coasts : journal of the Estuarine Research Federation
Y1  - 2016
U6  - https://doi.org/10.1007/s12237-016-0115-z
SN  - 1559-2723
SN  - 1559-2731
VL  - 39
SP  - 1294
EP  - 1295
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Tanski, George
A1  - Lantuit, Hugues
A1  - Ruttor, Saskia
A1  - Knoblauch, Christian
A1  - Radosavljevic, Boris
A1  - Strauß, Jens
A1  - Wolter, Juliane
A1  - Irrgang, Anna Maria
A1  - Ramage, Justine Lucille
A1  - Fritz, Michael
T1  - Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - The changing climate in the Arctic has a profound impact on permafrost coasts, which are subject to intensified thermokarst formation and erosion. Consequently, terrestrial organic matter (OM) is mobilized and transported into the nearshore zone. Yet, little is known about the fate of mobilized OM before and after entering the ocean. In this study we investigated a retrogressive thaw slump (RTS) on Qikiqtaruk - Herschel Island (Yukon coast, Canada). The RTS was classified into an undisturbed, a disturbed (thermokarst-affected) and a nearshore zone and sampled systematically along transects. Samples were analyzed for total and dissolved organic carbon and nitrogen (TOC, DOC, TN, DN), stable carbon isotopes (delta C-13-TOC, delta C-13-DOC), and dissolved inorganic nitrogen (DIN), which were compared between the zones. C/N-ratios, delta C-13 signatures, and ammonium (NH4-N) concentrations were used as indicators for OM degradation along with biomarkers (n-alkanes, n-fatty adds, n-alcohols). Our results show that OM significantly decreases after disturbance with a TOC and DOC loss of 77 and 55% and a TN and DN loss of 53 and 48%, respectively. C/N-ratios decrease significantly, whereas NH4-N concentrations slightly increase in freshly thawed material. In the nearshore zone, OM contents are comparable to the disturbed zone. We suggest that the strong decrease in OM is caused by initial dilution with melted massive ice and immediate offshore transport via the thaw stream. In the mudpool and thaw stream, OM is subject to degradation, whereas in the slump floor the nitrogen decrease is caused by recolonizing vegetation. Within the nearshore zone of the ocean, heavier portions of OM are directly buried in marine sediments close to shore. We conclude that RTS have profound impacts on coastal environments in the Arctic. They mobilize nutrients from permafrost, substantially decrease OM contents and provide fresh water and nutrients at a point source.
KW  - Canadian Arctic
KW  - Coastal erosion
KW  - Retrogressive thaw slump
KW  - Biogeochemistry
KW  - Carbon degradation
Y1  - 2017
U6  - https://doi.org/10.1016/j.scitotenv.2016.12.152
SN  - 0048-9697
SN  - 1879-1026
VL  - 581
SP  - 434
EP  - 447
PB  - Elsevier Science
CY  - Amsterdam
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  - 
TY  - JOUR
A1  - Radosavljevic, Boris
A1  - Lantuit, Hugues
A1  - Pollard, Wayne
A1  - Overduin, Pier Paul
A1  - Couture, Nicole
A1  - Sachs, Torsten
A1  - Helm, Veit
A1  - Fritz, Michael
T1  - Erosion and Flooding-Threats to Coastal Infrastructure in the Arctic: A Case Study from Herschel Island, Yukon Territory, Canada
JF  - Estuaries and coasts : journal of the Estuarine Research Federation
N2  - Arctic coastal infrastructure and cultural and archeological sites are increasingly vulnerable to erosion and flooding due to amplified warming of the Arctic, sea level rise, lengthening of open water periods, and a predicted increase in frequency of major storms. Mitigating these hazards necessitates decision-making tools at an appropriate scale. The objectives of this paper are to provide such a tool by assessing potential erosion and flood hazards at Herschel Island, a UNESCO World Heritage candidate site. This study focused on Simpson Point and the adjacent coastal sections because of their archeological, historical, and cultural significance. Shoreline movement was analyzed using the Digital Shoreline Analysis System (DSAS) after digitizing shorelines from 1952, 1970, 2000, and 2011. For purposes of this analysis, the coast was divided in seven coastal reaches (CRs) reflecting different morphologies and/or exposures. Using linear regression rates obtained from these data, projections of shoreline position were made for 20 and 50 years into the future. Flood hazard was assessed using a least cost path analysis based on a high-resolution light detection and ranging (LiDAR) dataset and current Intergovernmental Panel on Climate Change sea level estimates. Widespread erosion characterizes the study area. The rate of shoreline movement in different periods of the study ranges from -5.5 to 2.7 mI double dagger a(-1) (mean -0.6 mI double dagger a(-1)). Mean coastal retreat decreased from -0.6 mI double dagger a(-1) to -0.5 mI double dagger a(-1), for 1952-1970 and 1970-2000, respectively, and increased to -1.3 mI double dagger a(-1) in the period 2000-2011. Ice-rich coastal sections most exposed to wave attack exhibited the highest rates of coastal retreat. The geohazard map combines shoreline projections and flood hazard analyses to show that most of the spit area has extreme or very high flood hazard potential, and some buildings are vulnerable to coastal erosion. This study demonstrates that transgressive forcing may provide ample sediment for the expansion of depositional landforms, while growing more susceptible to overwash and flooding.
KW  - Arctic
KW  - Coastal erosion
KW  - UNESCO
KW  - Vulnerability mapping
KW  - Permafrost coasts
Y1  - 2016
U6  - https://doi.org/10.1007/s12237-015-0046-0
SN  - 1559-2723
SN  - 1559-2731
VL  - 39
SP  - 900
EP  - 915
PB  - Springer
CY  - New York
ER  -