Diverging pond dissolved organic matter characteristics yield similar CO2 flux potentials in a disturbed High Arctic landscape

• Published in: Environmental Research Letters
• Main Authors: J K Heslop, J K Y Hung, H Tong, M J Simpson, F M Chapman, N Roulet, M J Lafrenière, S F Lamoureux
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2021
• Subjects: carbon; permafrost; High Arctic; dissolved CO2; ponds; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999; Arctic
• Online Access: https://doi.org/10.1088/1748-9326/abc913; https://doaj.org/article/c550a4a7150a4c4f9a6b971c46256fc1

Climate warming and permafrost thaw have the potential to shift Arctic carbon (C) cycling dynamics so ponds, which represent over a quarter of northern circumpolar surface water area, may play a larger role in the mineralization of terrestrial C and emission of greenhouse gases (GHG). Here, we constrain how active layer detachments (ALDs) affect C cycling dynamics in High Arctic ponds ( n = 19) through the examination of geochemistry, dissolved organic matter (DOM) characteristics, and dissolved GHG concentrations. Summer rainfall events were identified as the primary source of pond water over a 5 week period during the monitored thaw season. We observed two distinct geochemical and DOM composition groups in ponds surrounded by undisturbed, vegetated areas compared to ponds located within the geomorphologically-disturbed ALDs. DOM in undisturbed areas had characteristics suggesting allochthonous origin from modern vegetation. Ponds in the ALDs had lower mean dissolved organic carbon (DOC) concentrations than ponds within undisturbed landscapes, with DOM characterization suggesting greater proportions of autochthonous DOM. Observed differences in DOC concentrations and DOM composition between ponds located within the disturbed and undisturbed landscapes did not translate into significant differences in dissolved CO _2 concentrations among pond types. We conclude that our observed changes in DOM composition and characteristics in High Arctic ponds may not result in substantial increases in GHG flux as a result of continued Arctic warming.