Articles | Volume 19, issue 17
https://doi.org/10.5194/bg-19-3959-2022
https://doi.org/10.5194/bg-19-3959-2022
Research article
 | 
31 Aug 2022
Research article |  | 31 Aug 2022

The dominant role of sunlight in degrading winter dissolved organic matter from a thermokarst lake in a subarctic peatland

Flora Mazoyer, Isabelle Laurion, and Milla Rautio

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Cited articles

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Arlen-Pouliot, Y. and Bhiry, N.: Palaeoecology of a palsa and a filled thermokarst pond in a permafrost peatland, subarctic Québec, Canada, The Holocene, 15, 408–419, https://doi.org/10.1191/0959683605hl818rp, 2005. 
Bégin, P. N. and Vincent, W. F.: Permafrost thaw lakes and ponds as habitats for abundant rotifer populations, Arct. Sci., 3, 354–377, https://doi.org/10.1139/as-2016-0017, 2017. 
Berggren, M., Laudon, H., and Jansson, M.: Landscape regulation of bacterial growth efficiency in boreal freshwaters, Global Biogeochem. Cy., 21, GB4002, https://doi.org/10.1029/2006GB002844, 2007. 
Berggren, M., Gudasz, C., Guillemette, F., Hensgens, G., Ye, L., and Karlsson, J.: Systematic microbial production of optically active dissolved organic matter in subarctic lake water, Limnol. Oceanogr., 65, 951–961, https://doi.org/10.1002/lno.11362, 2020. 
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Short summary
Dissolved organic matter collected at the end of winter from a peatland thermokarst lake was highly transformed and degraded by sunlight, leading to bacterial stimulation and CO2 production, but a fraction was also potentially lost by photoflocculation. Over 18 days, 18 % of the incubated dissolved organic matter was lost under sunlight, while dark bacterial degradation was negligible. Sunlight could have a marked effect on carbon cycling in organic-rich thermokarst lakes after ice-off.
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