First Pan-Arctic Assessment of Dissolved Organic Carbon in Permafrost-Region Lakes

Abstract

Abstract. Lakes in permafrost regions are dynamic landscape components and play an important role for climate change feedbacks. Lake processes such as mineralization and flocculation of dissolved organic carbon (DOC), one of the main carbon fractions in lakes, contribute to the greenhouse effect and are part of the global carbon cycle. These processes are in focus of climate research but studies so far are limited to specific study regions. In our synthesis, we analysed 2,167 water samples from 1,833 lakes across the Arctic in permafrost regions of Alaska, Canada, Greenland, and Siberia to provide first pan-Arctic insights for linkages between DOC concentrations and the environment. Using published data and unpublished datasets from the author team we report regional DOC differences linked to latitude, permafrost zones, ecoregions, geology, near-surface soil organic carbon contents, and ground ice classification of each lake region. The lake DOC concentrations in our dataset range from 0 mg L−1 to 1,130 mg L−1 (10.8 mg L−1 median DOC concentration). Regarding the permafrost regions of our synthesis, we found median lake DOC concentrations of 12.4 mg L−1 (Siberia), 12.3 mg L−1 (Alaska), 10.3 mg L−1 (Greenland), and 4.5 mg L−1 (Canada). Our synthesis shows a significant relationship of lake DOC concentration and ecoregion of the lake. We found higher lake DOC concentrations in boreal permafrost sites compared to tundra sites. About 22 % of the lakes in our extensive dataset are located in regions with ice-rich syngenetic permafrost deposits (yedoma). Yedoma contains large amounts of easily erodible organic carbon and we found significantly higher DOC concentrations in yedoma lakes compared to non-yedoma lakes. Compared to previous studies we found a weak significant relationship of soil organic carbon content and lake DOC concentration as well as between ground-ice content and lake DOC. Our pan-Arctic dataset shows that the DOC concentration of a lake strongly depends on its environmental properties, especially on permafrost extent and ecoregion, as well as vegetation, which is the most important driver of lake DOC in this study. This new dataset will be fundamental to quantify a pan-Arctic lake DOC pool for estimations of the impact of lake DOC on the global carbon cycle and climate change.

Hydrologic and Landscape Controls on Dissolved Organic Matter Composition Across Western North American Arctic Lakes

“…Most lakes regions, excluding Daring and the North Slope, had DOC concentrations comparable to those measured from the Yukon Flats (10–40 mg C L −1 ; Johnston et al., 2020), the Mackenzie Delta (5–16 mg C L −1 ; Tank et al., 2011), and across boreal forests (median = 15.3 mg C L −1 ; Stolpmann et al., 2021), but concentrations were typically higher than many northern high‐latitude and thawing permafrost‐fed fluvial sites (0.7–27 mg C L −1 ; Wologo et al., 2021; Johnston et al., 2021). SUVA 254 was also comparable to other lakes from the Yukon Flats (0.9–4.4 L mg C −1 m −1 ; Johnston et al., 2020), Mackenzie Delta (2–4 L mg C −1 m −1 ; Tank et al., 2011), and Alaskan rivers (2.0–4.5 L mg C −1 m −1 ; Spencer et al., 2008; Johnston et al., 2021); however, CDOM absorbance was greater than in Alaskan rivers (mean = 16.3 m −1 ; Johnston et al., 2021).…”

“…In contrast, studies of Arctic lakes from northern high‐latitude arid regions suggest that their DOM composition is mostly derived from autochthonous sources and that little allochthonous DOM is respired (Bogard et al., 2019; Johnston et al., 2019; Tank et al., 2009). Furthermore, as landcover spanning multiple regions has been increasingly recognized as an important factor in explaining northern high‐latitude organic carbon dynamics (Stolpmann et al., 2021) it is also likely to influence differences in lake DOM composition. However, upscaling to the inter‐regional level has been limited in its capacity to describe organic carbon cycling as many of these studies have only focused on lake sediments (e.g., Bell et al., 2020), or bulk DOC (e.g., Stackpoole et al., 2017; Stolpmann et al., 2021).…”

“…Furthermore, as landcover spanning multiple regions has been increasingly recognized as an important factor in explaining northern high‐latitude organic carbon dynamics (Stolpmann et al., 2021) it is also likely to influence differences in lake DOM composition. However, upscaling to the inter‐regional level has been limited in its capacity to describe organic carbon cycling as many of these studies have only focused on lake sediments (e.g., Bell et al., 2020), or bulk DOC (e.g., Stackpoole et al., 2017; Stolpmann et al., 2021).…”

Biogeochemical Distinctiveness of Peatland Ponds, Thermokarst Waterbodies, and Lakes

“…Because of the unique settings in which they develop, peatland ponds and thermokarst waterbodies are likely to show atypical combinations of morphometric and chemical properties among lentic systems. Recent studies have described the distribution and characteristics of peatland ponds and thermokarst waterbodies in specific regions of the world (e.g., Kuhn, Varner, et al., 2021; Stolpmann et al., 2021; Wik et al., 2016) or characterized the biogeochemistry of globally distributed freshwater systems without differentiating the matrix in which they develop (e.g., Abell et al., 2012; Sobek et al., 2010). However, currently, most freshwater models do not consider the heterogeneity in the biogeochemical processes among different types of lentic systems (Jones et al., 2018), limiting the robustness of regional estimates of C fluxes (Zwart et al., 2018) and their integration in earth system models.…”

Behavior of potentially toxic elements from stoker-boiler fly ash in Interior Alaska: paired batch leaching and solid-phase characterization

“…The interior Alaskan (sub-)Arctic environment is characterized by discontinuous permafrost, and typical surface water chemistry can have high dissolved organic carbon (DOC; > 10 mg L −1 ) (Ma et al 2019;Manasypov et al 2014;Stolpmann et al 2021). High DOC in Alaskan surface waters is especially intriguing when considering the fate of PTEs.…”