Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Drake, Travis W., Wickland, Kimberly P., Spencer, Robert G. M., McKnight, Diane M., Striegl, Robert G.
• Format: Text
• Language: English
• Published: National Academy of Sciences 2015
• Subjects: Biological Sciences; Arctic; permafrost
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4653224/; http://www.ncbi.nlm.nih.gov/pubmed/26504243; https://doi.org/10.1073/pnas.1511705112

To our knowledge, this study is the first to directly link rapid microbial consumption of ancient permafrost-derived dissolved organic carbon (DOC) to CO2 production using a novel bioreactor. Rapid mineralization of the freshly thawed DOC was attributed to microbial decomposition of low–molecular-weight organic acids, which were completely consumed during the experiments. Our results indicate that substantial biodegradation of permafrost DOC occurs immediately after thaw and before downstream transport occurs. We estimate that, by 2100, between 5 to 10 Tg of DOC will be released from Yedoma soils every year given the most recent estimates for projected thaw. This represents 19–26% of annual DOC loads exported by Arctic rivers, yet it is so far undetectable likely due to rapid mineralization in soils and/or headwater streams.