Organic Carbon and Nitrogen Stocks Along a Thermokarst Lake Sequence in Arctic Alaska

Fuchs, Matthias; Lenz, Josefine; Jock, Suzanne; Nitze, Ingmar; Jones, Benjamin M.; Strauß, Jens; Günther, Frank; Grosse, Guido

doi:10.1029/2018jg004591

Cited by 22 publications

(14 citation statements)

References 79 publications

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“…Other commonly studied topics are the dynamics in groundwater storage volume (e.g., [209,433]), assessment of ice wedge volumes (e.g., [139,193,439]) and soil carbon or nitrogen stocks (e.g., [445,446]).…”

Section: Environmental Research Focus: Subsurface Features and Processesmentioning

confidence: 99%

Trends in Satellite Earth Observation for Permafrost Related Analyses—A Review

Philipp

Dietz

Buchelt³

et al. 2021

Remote Sensing

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Climate change and associated Arctic amplification cause a degradation of permafrost which in turn has major implications for the environment. The potential turnover of frozen ground from a carbon sink to a carbon source, eroding coastlines, landslides, amplified surface deformation and endangerment of human infrastructure are some of the consequences connected with thawing permafrost. Satellite remote sensing is hereby a powerful tool to identify and monitor these features and processes on a spatially explicit, cheap, operational, long-term basis and up to circum-Arctic scale. By filtering after a selection of relevant keywords, a total of 325 articles from 30 international journals published during the last two decades were analyzed based on study location, spatio-temporal resolution of applied remote sensing data, platform, sensor combination and studied environmental focus for a comprehensive overview of past achievements, current efforts, together with future challenges and opportunities. The temporal development of publication frequency, utilized platforms/sensors and the addressed environmental topic is thereby highlighted. The total number of publications more than doubled since 2015. Distinct geographical study hot spots were revealed, while at the same time large portions of the continuous permafrost zone are still only sparsely covered by satellite remote sensing investigations. Moreover, studies related to Arctic greenhouse gas emissions in the context of permafrost degradation appear heavily underrepresented. New tools (e.g., Google Earth Engine (GEE)), methodologies (e.g., deep learning or data fusion etc.) and satellite data (e.g., the Methane Remote Sensing LiDAR Mission (Merlin) and the Sentinel-fleet) will thereby enable future studies to further investigate the distribution of permafrost, its thermal state and its implications on the environment such as thermokarst features and greenhouse gas emission rates on increasingly larger spatial and temporal scales.

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Section: Environmental Research Focus: Subsurface Features and Processesmentioning

confidence: 99%

Trends in Satellite Earth Observation for Permafrost Related Analyses—A Review

Philipp

Dietz

Buchelt³

et al. 2021

Remote Sensing

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“…It remains however unclear how mineral-OC interactions and nutrient supply will evolve upon permafrost thaw (Opfergelt, 2020), especially in ice-rich permafrost regions. This is mainly due to a lack of knowledge about the mineral element content in permafrost regions, relative to the well-known OC stocks in permafrost soils (Harden et al, 2012;Hugelius et al, 2014;Strauss et al, 2017;Hugelius et al, 2020;Kuhry et al, 2020) and the increasing knowledge on N stocks (Fuchs et al, 2018;Fuchs et al, 2019;Fouché et al, 2020;Hugelius et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Mineral Element Stocks in the Yedoma Domain: A Novel Method Applied to Ice-Rich Permafrost Regions

et al. 2021

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With permafrost thaw, significant amounts of organic carbon (OC) previously stored in frozen deposits are unlocked and become potentially available for microbial mineralization. This is particularly the case in ice-rich regions such as the Yedoma domain. Excess ground ice degradation exposes deep sediments and their OC stocks, but also mineral elements, to biogeochemical processes. Interactions of mineral elements and OC play a crucial role for OC stabilization and the fate of OC upon thaw, and thus regulate carbon dioxide and methane emissions. In addition, some mineral elements are limiting nutrients for plant growth or microbial metabolic activity. A large ongoing effort is to quantify OC stocks and their lability in permafrost regions, but the influence of mineral elements on the fate of OC or on biogeochemical nutrient cycles has received less attention and there is an overall lack of mineral element content analyses for permafrost sediments. Here, we combine portable X-ray fluorescence (pXRF) with a bootstrapping technique to provide i) the first large-scale Yedoma domain Mineral Concentrations Assessment (YMCA) dataset, and ii) estimates of mineral element stocks in never thawed (since deposition) ice-rich Yedoma permafrost and previously thawed and partly refrozen Alas deposits. The pXRF method for mineral element quantification is non-destructive and offers a complement to the classical dissolution and measurement by optical emission spectrometry (ICP-OES) in solution. Using this method, mineral element concentrations (Si, Al, Fe, Ca, K, Ti, Mn, Zn, Sr and Zr) were assessed on 1,292 sediment samples from the Yedoma domain with lower analytical effort and lower costs relative to the ICP-OES method. The pXRF measured concentrations were calibrated using alkaline fusion and ICP-OES measurements on a subset of 144 samples (R2 from 0.725 to 0.996). The results highlight that i) the mineral element stock in sediments of the Yedoma domain (1,387,000 km2) is higher for Si, followed by Al, Fe, K, Ca, Ti, Mn, Zr, Sr, and Zn, and that ii) the stock in Al and Fe (598 ± 213 and 288 ± 104 Gt) is in the same order of magnitude as the OC stock (327–466 Gt).

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“…Soils in northern Alaska contain ∼40-150 kg total organic carbon (TOC) m −2 in the top 3 m (Strauss et al, 2013;Hugelius et al, 2014;Schuur et al, 2015;Fuchs et al, 2019). Most of this TOC is sequestered in permafrost; however, coastal erosion can rapidly liberate large quantities of this frozen organic matter into the coastal ocean (Vonk et al, 2012;Vonk and Gustafsson, 2013;Fritz et al, 2017;Stein and MacDonald, 2004).…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska

Bristol¹,

Connolly²,

Lorenson

et al. 2021

Front. Earth Sci.

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Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year−1. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ13C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m−2 year−1 during the Holocene and 0.5 ± 0.1 g TOC m−2 year−1 during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m−1 year−1 during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year−1 from this 9 km coastline (12,318 metric tons C year−1) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km2 area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and nitrogen trapped in permafrost to enter modern biogeochemical cycles, where it may fuel food webs and greenhouse gas emissions in the marine environment.

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Organic Carbon and Nitrogen Stocks Along a Thermokarst Lake Sequence in Arctic Alaska

Cited by 22 publications

References 79 publications

Trends in Satellite Earth Observation for Permafrost Related Analyses—A Review

Trends in Satellite Earth Observation for Permafrost Related Analyses—A Review

Mineral Element Stocks in the Yedoma Domain: A Novel Method Applied to Ice-Rich Permafrost Regions

Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska

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