Bounding cross-shelf transport time and degradation in Siberian-Arctic land-ocean carbon transfer

• Published in: Nature Communications
• Main Authors: Bröder, Lisa, Tesi, Tommaso, Andersson, August, Semiletov, Igor, Gustafsson, Örjan
• Format: Text
• Language: English
• Published: Nature Publishing Group UK 2018
• Subjects: Article; Arctic; Laptev Sea; Global warming; laptev; lena river; permafrost
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824890/; http://www.ncbi.nlm.nih.gov/pubmed/29476050; https://doi.org/10.1038/s41467-018-03192-1

The burial of terrestrial organic carbon (terrOC) in marine sediments contributes to the regulation of atmospheric CO2 on geological timescales and may mitigate positive feedback to present-day climate warming. However, the fate of terrOC in marine settings is debated, with uncertainties regarding its degradation during transport. Here, we employ compound-specific radiocarbon analyses of terrestrial biomarkers to determine cross-shelf transport times. For the World’s largest marginal sea, the East Siberian Arctic shelf, transport requires 3600 ± 300 years for the 600 km from the Lena River to the Laptev Sea shelf edge. TerrOC was reduced by ~85% during transit resulting in a degradation rate constant of 2.4 ± 0.6 kyr−1. Hence, terrOC degradation during cross-shelf transport constitutes a carbon source to the atmosphere over millennial time. For the contemporary carbon cycle on the other hand, slow terrOC degradation brings considerable attenuation of the decadal-centennial permafrost carbon-climate feedback caused by global warming.