TY - JOUR
T1 - Increased petrogenic and biospheric organic carbon burial in sub-Antarctic fjord sediments in response to recent glacier retreat
AU - Berg, Sonja
AU - Jivcov, Sandra
AU - Kusch, Stephanie
AU - Kuhn, Gerhard
AU - White, Duanne
AU - Bohrmann, Gerhard
AU - Melles, Martin
AU - Rethemeyer, Janet
N1 - Funding Information:
This study was funded by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the priority program “SPP1158 Antarctic Research with comparative investigations in Arctic ice areas,” grant BE 4764/3‐1. The fieldwork was carried out within the scope of the Polarstern cruise PS81; we are grateful to the captain and the crew for their support. We also like to thank the Government of South Georgia and the South Sandwich Islands for providing helpful advice and the permission for fieldwork. Data will be made available via PANGAEA geoscientific database. Open access funding enabled and organized by Projekt DEAL. RV
Publisher Copyright:
© 2021 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.
PY - 2021/12
Y1 - 2021/12
N2 - Fjords are recognized as hotspots of organic carbon (OC) burial in the coastal ocean. In fjords with glaciated catchments, glacier discharge carries large amounts of suspended matter. This sedimentary load includes OC from bedrock and terrigenous sources (modern vegetation, peat, soil deposits), which is either buried in the fjord or remineralized during export, acting as a potential source of CO2 to the atmosphere. In sub-Antarctic South Georgia, fjord-terminating glaciers have been retreating during the past decades, likely as a response to changing climate conditions. We determine sources of OC in surface sediments of Cumberland Bay, South Georgia, using lipid biomarkers and the bulk 14C isotopic composition, and quantify OC burial at present and for the time period of documented glacier retreat (between 1958 and 2017). Petrogenic OC is the dominant type of OC in proximity to the present-day calving fronts (60.4 ± 1.4% to 73.8 ± 2.6%) and decreases to 14.0 ± 2.7% outside the fjord, indicating that petrogenic OC is effectively buried in the fjord. Beside of marine OC, terrigenous OC comprises 2.7 ± 0.5% to 7.9 ± 5.9% and is mostly derived from modern plants and Holocene peat and soil deposits that are eroded along the flanks of the fjord, rather than released by the retreating fjord glaciers. We estimate that the retreat of tidewater glaciers between 1958 and 2017 led to an increase in petrogenic carbon accumulation of 22% in Cumberland West Bay and 6.5% in Cumberland East Bay, suggesting that successive glacier retreat does not only release petrogenic OC into the fjord, but also increases the capacity of OC burial.
AB - Fjords are recognized as hotspots of organic carbon (OC) burial in the coastal ocean. In fjords with glaciated catchments, glacier discharge carries large amounts of suspended matter. This sedimentary load includes OC from bedrock and terrigenous sources (modern vegetation, peat, soil deposits), which is either buried in the fjord or remineralized during export, acting as a potential source of CO2 to the atmosphere. In sub-Antarctic South Georgia, fjord-terminating glaciers have been retreating during the past decades, likely as a response to changing climate conditions. We determine sources of OC in surface sediments of Cumberland Bay, South Georgia, using lipid biomarkers and the bulk 14C isotopic composition, and quantify OC burial at present and for the time period of documented glacier retreat (between 1958 and 2017). Petrogenic OC is the dominant type of OC in proximity to the present-day calving fronts (60.4 ± 1.4% to 73.8 ± 2.6%) and decreases to 14.0 ± 2.7% outside the fjord, indicating that petrogenic OC is effectively buried in the fjord. Beside of marine OC, terrigenous OC comprises 2.7 ± 0.5% to 7.9 ± 5.9% and is mostly derived from modern plants and Holocene peat and soil deposits that are eroded along the flanks of the fjord, rather than released by the retreating fjord glaciers. We estimate that the retreat of tidewater glaciers between 1958 and 2017 led to an increase in petrogenic carbon accumulation of 22% in Cumberland West Bay and 6.5% in Cumberland East Bay, suggesting that successive glacier retreat does not only release petrogenic OC into the fjord, but also increases the capacity of OC burial.
UR - http://www.scopus.com/inward/record.url?scp=85117907440&partnerID=8YFLogxK
U2 - 10.1002/lno.11965
DO - 10.1002/lno.11965
M3 - Article
AN - SCOPUS:85117907440
SN - 0024-3590
VL - 66
SP - 4347
EP - 4362
JO - Limnology and Oceanography
JF - Limnology and Oceanography
IS - 12
ER -