Diatom responses and geochemical feedbacks to environmental changes at Lake Rauchuagytgyn (Far East Russian Arctic)

Biskaborn, Boris K.; Forster, Amy; Pfalz, Gregor; Pestryakova, Luidmila; Stoof‐Leichsenring, Kathleen R.; Strauß, Jens; Kröger, Tim; Herzschuh, Ulrike

doi:10.5194/egusphere-2022-985

Cited by 2 publications

(2 citation statements)

References 59 publications

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“…Temperature is one of the key control variable for the mineralization and burial of carbon in lakes, regardless of the origin of carbon (i.e., autochthonous or allochthonous) (Gudasz et al, 2010;Gudasz et al, 2015). Not only is an increase in temperature associated with higher carbon mineralization and burial, but also favors higher turnover of carbon through more in-lake primary production by macrophytes/aquatic plants (Li et al, 2017;Velthuis et al, 2018) and algae (Biskaborn et al, 2022). As a consequence, lake systems can shift from being a net carbon sink to net carbon source and vice versa (Sobek et al, 2014;Heathcote et al, 2015;Denfeld et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature on carbon accumulation in northern lake systems over the past 21,000 years

Pfalz,

Diekmann,

Freytag

et al. 2023

Front. Earth Sci.

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Introduction: Rising industrial emissions of carbon dioxide and methane highlight the important role of carbon sinks and sources in fast-changing northern landscapes. Northern lake systems play a key role in regulating organic carbon input by accumulating carbon in their sediment. Here we look at the lake history of 28 lakes (between 50°N and 80°N) over the past 21,000 years to explore the relationship between carbon accumulation in lakes and temperature changes.Method: For this study, we calculated organic carbon accumulation rates (OCAR) using measured and newly generated organic carbon and dry bulk density data. To estimate new data, we used and evaluated seven different regression techniques in addition to a log-linear model as our base model. We also used combined age-depth modeling to derive sedimentation rates and the TraCE-21ka climate reanalysis dataset to understand temperature development since the Last Glacial Maximum. We determined correlation between temperature and OCAR by using four different correlation coefficients.Results: In our data collection, we found a slightly positive association between OCAR and temperature. OCAR values peaked during warm periods Bølling Allerød (38.07 g·m−2·yr−1) and the Early Holocene (40.68 g·m−2·yr−1), while lowest values occurred during the cold phases of Last Glacial Maximum (9.47 g·m−2·yr−1) and Last Deglaciation (10.53 g·m−2·yr−1). However, high temperatures did not directly lead to high OCAR values.Discussion: We assume that rapid warming events lead to high carbon accumulation in lakes, but as warming progresses, this effect appears to change as increased microbial activity triggers greater outgassing. Despite the complexity of environmental forcing mechanisms affecting individual lake systems, our study showed statistical significance between measured OCAR and modelled paleotemperature for 11 out of 28 lakes. We concluded that air temperature alone appears to drive the carbon accumulation in lakes. We expected that other factors (catchment vegetation, permafrost, and lake characteristics) would influence accumulation rates, but could not discover a conclusive factor that had a statistical significant impact. More data available on long-term records from northern lake systems could lead to more confidence and accuracy on the matter.

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Section: Introductionmentioning

confidence: 99%

Effect of temperature on carbon accumulation in northern lake systems over the past 21,000 years

Pfalz,

Diekmann,

Freytag

et al. 2023

Front. Earth Sci.

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“…c. mercury, https://doi.org/10.1594/PANGAEA.953130(Biskaborn et al, 2023c); d. dating and accumulation rates, https://doi.org/10.1594/ PANGAEA.953132(Biskaborn et al, 2023d); and e…”

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confidence: 99%

Diatom responses and geochemical feedbacks to environmental changes at Lake Rauchuagytgyn (Far East Russian Arctic)

et al. 2023

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Abstract. This study is based on multiproxy data gained from a 14C-dated 6.5 m long sediment core and a 210Pb-dated 23 cm short core retrieved from Lake Rauchuagytgyn in Chukotka, Arctic Russia. Our main objectives are to reconstruct the environmental history and ecological development of the lake during the last 29 kyr and to investigate the main drivers behind bioproduction shifts. The methods comprise age-modeling, accumulation rate estimation, and light microscope diatom species analysis of 74 samples, as well as organic carbon, nitrogen, and mercury analysis. Diatoms have appeared in the lake since 21.8 ka cal BP and are dominated by planktonic Lindavia ocellata and L. cyclopuncta. Around the Pleistocene–Holocene boundary, other taxa including planktonic Aulacoseira, benthic fragilarioid (Staurosira), and achnanthoid species increase in their abundance. There is strong correlation between variations of diatom valve accumulation rates (DARs; mean 176.1×109 valves m2 a1), organic carbon accumulation rates (OCARs; mean 4.6 g m−2 a−1), and mercury accumulation rates (HgARs; mean 63.4 µg m−2 a−1). We discuss the environmental forcings behind shifts in diatom species and find moderate responses of key taxa to the cold glacial period, postglacial warming, the Younger Dryas, and the Holocene Thermal Maximum. The short-core data likely suggest recent change of the diatom community at the beginning of the 20th century related to human-induced warming but only little evidence of atmospheric deposition of contaminants. Significant correlation between DAR and OCAR in the Holocene interglacial indicates within-lake bioproduction represents bulk organic carbon deposited in the lake sediment. During both glacial and interglacial episodes HgAR is mainly bound to organic matter in the lake associated with biochemical substrate conditions. There were only ambiguous signs of increased HgAR during the industrialization period. We conclude that if increased short-term emissions are neglected, pristine Arctic lake systems can potentially serve as long-term CO2 and Hg sinks during warm climate episodes driven by insolation-enhanced within-lake primary productivity. Maintaining intact natural lake ecosystems should therefore be of interest to future environmental policy.

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Diatom responses and geochemical feedbacks to environmental changes at Lake Rauchuagytgyn (Far East Russian Arctic)

Cited by 2 publications

References 59 publications

Effect of temperature on carbon accumulation in northern lake systems over the past 21,000 years

Effect of temperature on carbon accumulation in northern lake systems over the past 21,000 years

Diatom responses and geochemical feedbacks to environmental changes at Lake Rauchuagytgyn (Far East Russian Arctic)

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