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  • 2020-2022  (13)
  • 2005-2009  (15)
  • 2021  (13)
  • 2009  (15)
  • 1
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    Methane dynamics in three different Siberian water bodies under winter and summer conditions (2021)
    Copernicus
    Details
    Publication Date: 2021-03-22
    Description: Arctic regions and their water bodies are affected by a rapidly warming climate. Arctic lakes and small ponds are known to act as an important source of atmospheric methane. However, not much is known about other types of water bodies in permafrost regions, which include major rivers and coastal bays as a transition type between freshwater and marine environments. We monitored dissolved methane concentrations in three different water bodies (Lena River, Tiksi Bay, and Lake Golzovoye, Siberia, Russia) over a period of 2 years. Sampling was carried out under ice cover (April) and in open water (July–August). The methane oxidation (MOX) rate and the fractional turnover rate (k′) in water and melted ice samples from the late winter of 2017 was determined with the radiotracer method. In the Lena River winter methane concentrations were a quarter of the summer concentrations (8 nmol L−1 vs. 31 nmol L−1), and mean winter MOX rate was low (0.023 nmol L−1 d−1). In contrast, Tiksi Bay winter methane concentrations were 10 times higher than in summer (103 nmol L−1 vs. 13 nmol L−1). Winter MOX rates showed a median of 0.305 nmol L−1 d−1. In Lake Golzovoye, median methane concentrations in winter were 40 times higher than in summer (1957 nmol L−1 vs. 49 nmol L−1). However, MOX was much higher in the lake (2.95 nmol L−1 d−1) than in either the river or bay. The temperature had a strong influence on the MOX (Q10=2.72±0.69). In summer water temperatures ranged from 7–14 ∘C and in winter from −0.7 to 1.3 ∘C. In the ice cores a median methane concentration of 9 nM was observed, with no gradient between the ice surface and the bottom layer at the ice–water interface. MOX in the (melted) ice cores was mostly below the detection limit. Comparing methane concentrations in the ice with the underlaying water column revealed methane concentration in the water column 100–1000 times higher. The winter situation seemed to favor a methane accumulation under ice, especially in the lake with a stagnant water body. While on the other hand, in the Lena River with its flowing water, no methane accumulation under ice was observed. In a changing, warming Arctic, a shorter ice cover period is predicted. With respect to our study this would imply a shortened time for methane to accumulate below the ice and a shorter time for the less efficient winter MOX. Especially for lakes, an extended time of ice-free conditions could reduce the methane flux from the Arctic water bodies.
    Print ISSN: 1726-4170
    Electronic ISSN: 1726-4189
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 2
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    Methane pathways in winter ice of a thermokarst lake–lagoon–coastal water transect in north Siberia (2021)
    Copernicus
    Details
    Publication Date: 2021-03-31
    Description: The thermokarst lakes of permafrost regions play a major role in the global carbon cycle. These lakes are sources of methane to the atmosphere although the methane flux is restricted by an ice cover for most of the year. How methane concentrations and fluxes in these waters are affected by the presence of an ice cover is poorly understood. To relate water body morphology, ice formation and methane to each other, we studied the ice of three different water bodies in locations typical of the transition of permafrost from land to ocean in a continuous permafrost coastal region in Siberia. In total, 11 ice cores were analyzed as records of the freezing process and methane composition during the winter season. The three water bodies differed in terms of connectivity to the sea, which affected fall freezing. The first was a bay underlain by submarine permafrost (Tiksi Bay, BY), the second a shallow thermokarst lagoon cut off from the sea in winter (Polar Fox Lagoon, LG) and the third a land-locked freshwater thermokarst lake (Goltsovoye Lake, LK). Ice on all water bodies was mostly methane-supersaturated with respect to atmospheric equilibrium concentration, except for three cores from the isolated lake. In the isolated thermokarst lake, ebullition from actively thawing basin slopes resulted in the localized integration of methane into winter ice. Stable δ13CCH4 isotope signatures indicated that methane in the lagoon ice was oxidized to concentrations close to or below the calculated atmospheric equilibrium concentration. Increasing salinity during winter freezing led to a micro-environment on the lower ice surface where methane oxidation occurred and the lagoon ice functioned as a methane sink. In contrast, the ice of the coastal marine environment was slightly supersaturated with methane, consistent with the brackish water below. Our interdisciplinary process study shows how water body morphology affects ice formation which mitigates methane fluxes to the atmosphere.
    Print ISSN: 1994-0416
    Electronic ISSN: 1994-0424
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
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    Seasonal Variations in Bottom Water Temperatures and their Influence on Subaquatic Permafrost Thermal Regimes (2021)
    In:  EPIC3EGU General Assembly 2021, onlilne, 2021-04-19-2021-04-30
    Details
    Publication Date: 2021-05-30
    Description: The thermal regime in sediment below the ocean or lakes is mostly governed by the sea or lake bed temperature and by the geothermal heat flow. This thermal regime will determine whether permafrost beneath water bodies is preserved or how rapidly it thaws. Thermal modelling uses mean annual bottom water temperatures to calculate permafrost presence or absence, while predictions of shallow sediment thermal regimes must be forced with time series of changing bottom water temperatures that also account for freezeback of the water column to the bottom, forming bottom-fast ice. However, continuous, annual measurements of bottom water temperatures in Arctic lakes and coastal marine settings are hard to obtain and therefore scarce. Waves and sea ice movement make deployment and recovery of instruments difficult. We provide a parameterization of the bottom water temperature function that relies on easier to obtain variables, such as the mean, minimum and maximum air temperature and the water depth, by comparing measured and modelled shallow sediment thermal regimes from the Arctic. We use a parameterization based on a simple cosine for the water temperature with mean temperature, amplitude and time shift and add the minimum water temperature to obtain a 4 parameter function. For shallow regions with bottom-fast ice, additionally the duration of the ice-growth and -melting period as well as the minimum air temperature are needed. We test our parameterizations with a globally unique data set of 4 years of ground temperature data collected from the seabed to a depth of 10 m from the near shore zone of the Mackenzie Delta. At the instrumented sites, permafrost is present beneath mostly freshwater bottom-fast and floating ice. Forward modeling of sediment temperatures is performed using the 1D heat transfer model CryoGrid with depth dependent thermal properties. We neglect advective processes and long-term temperature trends in the bottom water temperatures. Rough parameterization of the annual variation of water bottom temperatures reproduce measured water temperatures with a RMSE of 20-40 %. The resulting modeled sediment temperature field based on 10 years of repeated parameterized bottom water temperatures matches the modeled sediment temperature field based on measured water temperatures in terms of permafrost characteristics, including the depth of the active layer defined by the 0°C isotherm over the year. However, both modelled temperature fields yield significantly higher sediment temperatures than the measured sediment temperature field. This may be the result of choice of sediment thermal properties in the thermal model or shifts in the duration of bottom-fast ice contact or on-ice snow Since modelled temperature fields from both repeated measured and parameterized bottom water temperatures show the same deviation, it suggests that the bottom water temperatures were warmer during the measurement period than the average over the previous 10 years.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 4
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    Seasonal methane and carbon dioxide emissions upon the coastal region of the Kolyma river (2021)
    In:  EPIC3International Symposium 'Focus Siberian Permafrost – Terrestrial Cryosphere and Climate Change', 2021-03-24-2021-03-25
    Details
    Publication Date: 2021-03-30
    Description: Massive Arctic rivers are feeding ≈11% of the global river discharge into the Arctic Ocean, while the ocean stores only ≈1% of the global ocean volume. The ongoing rapid climate warming has led to pronounced changes in precipitation, active layer thickening, increased air and soil temperatures, increased riverbank and coastal erosion rates, extensive permafrost thaw and increasing freshwater discharge to the Arctic Ocean. Since most studies have focused on rivers or oceans itself and mainly during the late summer, near-shore coastal regions are understudied and crucial in determining the amount of carbon transported and/or released into the Arctic Ocean. Here, we investigated river-derived carbon dioxide (CO2) and methane (CH4) emissions from seven repeated transects of the Kolyma River and nearshore (120 km between Cherskiy and Ambarchik) over the entire open water season between June and September 2019. We estimated the cumulative gross delivery of river-derived CH4 and CO2 to the coastal ocean to be around 0.0008 Tg CH4 (800 000 kg) and 0.2 Tg CO2 (200 000 000 kg). Measurements reveal that more than 50% of the cumulative gross delivery is happening during the fresh period, making the season dynamics extremely important.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 5
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    The impact of sea state: from coastal erosion to sailing (2021)
    In:  EPIC3ESA Sea State CCI: User Consultation Meeting #2, Online, 2021-03-23-2021-03-25
    Details
    Publication Date: 2021-04-26
    Description: Wind and wave conditions are a primary concern for many people living along the coastline, but when considering the partially frozen coastline in the Arctic, this concern is highlighted by the cascading detrimental thawing effects on indigenous cultural sites and subsistence practices. Media coverage has extensively shown cemeteries being washed away into the sea, ice cellars being inundated with floodwaters, and entire villages planning to relocate without having the funds to do so. If we take a look further offshore, sea state directly impacts the safety of subsistence hunters travelling by boat, leading to the fact that a lengthening open water season does not necessarily mean the same increase in the number of safely boat-able days. Beyond the scope of native communities, but still well within the lens of the media, professional sailors are constantly looking for products that improve their knowledge and forecasts of sea state to better inform which routes and actions they will take during months-long competitions. This talk will contain a broad overview of the specific uses of wave and wind information, citing specific examples from the authors’ own experience on coastal erosion model development and interaction with Arctic native coastal communities. A main goal of this talk is also to illuminate the incentives for the scientific community to be actively engaged in improving operational sea state products, from Arctic indigenous coastal communities to professional sailors, particularly in light of the increasing media attention to the general public.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
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    Assessing the dynamic interface between land and ocean in the Arctic: results from the joint BMBF-NERC project Changing Arctic organic Carbon cycle in the cOastal Ocean Near-shore (CACOON) (2021)
    In:  EPIC3International Symposium 'Focus Siberian Permafrost – Terrestrial Cryosphere and Climate Change', 2021-03-24-2021-03-25
    Details
    Publication Date: 2021-04-02
    Description: No other region has warmed as rapidly in the past decades as the Arctic. Funded by the British Natural Environment Research Council (NERC) and the German Federal Ministry of Education and Research (BMBF), the Changing Arctic Carbon cycle in the Coastal Ocean Near-shore (CACOON) project investigates how this warming influences Arctic coastal-marine ecosystems. Arctic rivers annually carry around 13% of the globally transported dissolved organic carbon (despite the Arctic Ocean making up only approx. 1% of the Earth's ocean volume). Arctic shelf waters are therefore dominated by terrestrial organic carbon pools, so that shelf ecosystems are intimately linked to freshwater supplies. Arctic ecosystems also contain permafrost organic carbon that may be released with warming. Climate change already thaws permafrost, reduces sea ice and increases riverine discharge, triggering important feedbacks. The importance of the near-shore region, consisting of several tightly connected ecosystems that include rivers, deltas, and the shelf, is however often overlooked. Year-round studies are scarce but needed to predict the impact of shifting seasonality, fresher water, changing nutrient supply and greater proportions of permafrost-derived organic carbon on coastal waters. The aims of the CACOON project are to quantify the effect of changing freshwater export and permafrost thaw on the type and fate of river-borne organic matter (OM) delivered to the Arctic shore and resulting changes on ecosystem functioning in the coastal Arctic Ocean. We are achieving this through a combined observational, experimental, and modelling approach. We conduct laboratory experiments to parameterise the susceptibility of terrigenous organic carbon to abiotic and biotic transformation and losses, then use the results from these to deliver a marine ecosystem model capable of representing major biogeochemical cycles. We apply this model to assess how future changes to freshwater runoff and carbon fluxes alter the ecosystems. To reach these aims, we conducted 4 field campaigns in 2019 in the Lena (see https://epic.awi.de/id/eprint/53575/) and Kolyma Delta region. In the Lena Delta, during spring we were using a mobile camp on sledges to collect water samples, ice cores, surface sediments, gas samples as well as CTD profiles. A permafrost cliff (Sobo-Sise) was sampled to analyse terrestrial endmembers of organic matter entering the deltaic and eventually marine system following erosion and transport. During the summer campaign we retrieved samples along a 200 km transect from the centre of the Delta to the Laptev Sea covering the fresh-salt water transition. The aim of Kolyma field sampling was to capture the open water season from the ice breakup to re-freezing and sample the Kolyma River and the near shore area. The lab work on these samples is currently ongoing with first papers lead by CACOON or with project contributions being published already (available here: https://www.researchgate.net/project/CACOON-Changing-Arctic-Carbon-cycle-in-the-coastal-ocean-near-shore).
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
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    Thermo‐erosional valleys in Siberian ice‐rich permafrost (2021)
    Details
    Publication Date: 2021-07-04
    Description: Thermal erosion is a major mechanism of permafrost degradation, resulting in characteristic landforms. We inventory thermo‐erosional valleys in ice‐rich coastal lowlands adjacent to the Siberian Laptev Sea based on remote sensing, Geographic Information System (GIS), and field investigations for a first regional assessment of their spatial distribution and characteristics. Three study areas with similar geological (Yedoma Ice Complex) but diverse geomorphological conditions vary in valley areal extent, incision depth, and branching geometry. The most extensive valley networks are incised deeply (up to 35 m) into the broad inclined lowland around Mamontov Klyk. The flat, low‐lying plain forming the Buor Khaya Peninsula is more degraded by thermokarst and characterized by long valleys of lower depth with short tributaries. Small, isolated Yedoma Ice Complex remnants in the Lena River Delta predominantly exhibit shorter but deep valleys. Based on these hydrographical network and topography assessments, we discuss geomorphological and hydrological connections to erosion processes. Relative catchment size along with regional slope interact with other Holocene relief‐forming processes such as thermokarst and neotectonics. Our findings suggest that thermo‐erosional valleys are prominent, hitherto overlooked permafrost degradation landforms that add to impacts on biogeochemical cycling, sediment transport, and hydrology in the degrading Siberian Yedoma Ice Complex.
    Description: Christiane Nüsslein‐Volhard Foundation
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: German Academic Exchange Service DAAD P.R.I.M.E.
    Description: Helmholtz‐Gemeinschaft http://dx.doi.org/10.13039/501100001656
    Description: Polar Geospatial Center, NSF‐OPP awards
    Description: RapidEye Science Archive (RESA)
    Description: Russian Foundation for Basic Research http://dx.doi.org/10.13039/501100002261
    Description: Studienstiftung des Deutschen Volkes http://dx.doi.org/10.13039/501100004350
    Description: Universität Potsdam http://dx.doi.org/10.13039/501100004238
    Description: BMBF KoPf
    Keywords: 551.3 ; geomorphology ; periglacial landscapes ; permafrost degradation ; thermal erosion ; valley distribution ; Yedoma Ice Complex
    Type: article
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  • 8
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    New statistics on Arctic circumpolar coastal erosion (2009)
    In:  EPIC3ArcticNet Annual Science Meeting, 8-12 December 2009, Victoria, BC, Canada.
    Details
    Publication Date: 2019-07-17
    Description: Permafrost coasts represent 34 % of the global coastline and are likely to become one of the most impacted environments of the Earth under changing climate conditions. The lengthening of the open-water season and the increasing open-water area, due to the decline of sea ice extent, will induce changes to the length of the fetch and allow storms to hit the coasts further in the fall season. These storms are thought to bear staggering threats to the coasts in the form of destruction of community and industry infrastructure as well as dramatic changes in sediment and nutrient pathways in the nearshore zone. Alas, Arctic coasts remain largely unknown and unexplored, which puts current adaptation and mitigation strategies in northern communities into jeopardy. A thorough systematic investigation of the coast at the circum-Arctic scale is needed to better understand the processes that act upon it. This presentation shows the end product stemming from the ten-year (1999-2009) Arctic Coastal Dynamics project in the form of a coastal classification segmenting the arctic coast in more than 1300 stretches of coast.The presentation will highlight the similarities and differences between the different seas in the Arctic and the contribution of coastal erosion to nearshore sediment budget. It will also depict the geographical distribution of a wide range of parameters related to geomorphology, cryolithology (Ground ice) and geochemistry. Finally, it will put this assessment in perspective with the location of coastal settlements in the Arctic.
    Repository Name: EPIC Alfred Wegener Institut
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  • 9
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    OCoc- from Ocean Colour to Organic Carbon (2009)
    In:  EPIC3American Geophysical Union Fall Meeting, December 14-18, 2009, San Francisco, CA, USA.
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    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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  • 10
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    Land-Ocean Interface (2009)
    In:  EPIC3Arctic in Rapid Transition Initiation Workshop, International Arctic Research Center, Fairbanks, AlaskaNovember, 7, 2009 p.
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    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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