A centennial record of fluvial organic matter input from the discontinuous permafrost catchment of Lake Tornetrsk

• Published in: Journal of Geophysical Research: Biogeosciences
• Main Authors: Vonk, Jorien E., Alling, Vanja, Rahm, Lars, Mrth, Carl Magnus, Humborg, Christoph, Gustafsson, Örjan
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2012
• Subjects: Arctic; Climate change; permafrost
• Online Access: https://research.vu.nl/en/publications/ff8c7dcb-b68e-45ba-ae26-7a1d98a089f8; https://doi.org/10.1029/2011JG001887; http://hdl.handle.net/1871.1/ff8c7dcb-b68e-45ba-ae26-7a1d98a089f8; http://www.scopus.com/inward/record.url?scp=84865379567&partnerID=8YFLogxK; http://www.scopus.com/inward/citedby.url?scp=84865379567&partnerID=8YFLogxK

High-latitude regions are underlain by the most organic carbon (OC)-rich soils on earth and currently subject to intense climate warming, potentially increasing remobilization and mineralization of soil OC. Sub-Arctic Scandinavia is located on the 0C mean annual isotherm and is therefore particularly vulnerable to climate change. This study aimed to establish a baseline for soil OC release over the past century into Lake Tornetrsk, the largest lake in sub-Arctic Scandinavia, through bulk geochemical and molecular radiocarbon analyses in chronologically constrained sediment cores. Our results suggest a dominance of peat-derived terrestrial OC inflow. We show that the annual terrestrial OC inflow to the lake is ∼12 times higher than the in-lake produced particulate OC, and consists for a large part (ca. 60%) of old OC from deep reservoirs in the catchment. The sedimentary record shows signs of increasing inflow of more degraded terrestrial matter since ∼1975, as indicated by increasing %TOC concentrations, a lower δ 13 C value and lower TOC:TN ratios. Based on simultaneous changes in local climate and reported signs of permafrost degradation (e.g., active layer deepening, mire/peat erosion), the observed changes in the sedimentary record of Scandinavia's largest mountain lake likely reflect a climate warming-induced change in terrestrial OC inflow.