Preprints
https://doi.org/10.5194/egusphere-2023-64
https://doi.org/10.5194/egusphere-2023-64
 
19 Jan 2023
19 Jan 2023
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

Changing sources and burial of organic carbon in the Chukchi Sea sediments with retreating sea ice over recent centuries

Liang Su1,2, Jian Ren2, Marie-Alexandrine Sicre3, Youcheng Bai2, Ruoshi Zhao1,2, Xibing Han4, Zhongqiao Li2, Haiyan Jin2,5, Anatolii S. Astakhov6, Xuefa Shi7, and Jianfang Chen2,5 Liang Su et al.
  • 1Ocean College, Zhejiang University, Zhoushan 316021, China
  • 2Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China
  • 3Sorbonne Université, Pierre et Marie Curie, CNRS, LOCEAN, Case 100, 4 place Jussieu, F-75005 Paris, France
  • 4Key Laboratory of Submarine Geosciences, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China
  • 5State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China
  • 6V.I. Il'ichev Pacific Oceanological Institute, Far Eastern Branch of Russian Academy of Sciences, Vladivostok 690041, Russia
  • 7Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China

Abstract. Decreasing sea ice extent in summer caused by climate change is affecting the carbon cycle of the Arctic Ocean. In this study, surface sediments across the western Arctic Ocean are investigated to characterize sources of sedimentary organic carbon (OC). Bulk organic parameters (total organic carbon, total nitrogen, δ13Corg and δ15N) combined with molecular organic biomarkers (e.g., sterols and highly branched isoprenoids (HBIs)) are applied to distinguish between sympagic, pelagic, and terrestrial OC. Furthermore, downcore profiles of these parameters were also generated from the Chukchi Sea R1 core (74° N) to evaluate changes in the relative contribution of these three components of sedimentary OC over the last 200 years with decreasing sea ice. Our data evidence that from 1820s to 1930s, prevailing high and variable sea ice cover inhibited in situ primary production resulting in prominent land-derived material stored in sediments. From 1930s to 1980s, with the gradual decline of sea ice, primary production increased progressively. The ratio of sympagic and pelagic OC began to rise to account for a larger portion of sedimentary OC. Since 1980s, accelerated sea ice loss led to enhanced primary production, stabilizing over the last decades due to freshwater induced surface ocean stratification in summer.

Liang Su et al.

Status: open (until 16 Mar 2023)

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Liang Su et al.

Liang Su et al.

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Short summary
We reconstructed sea ice and organic carbon composition variabilities based on biomarkers and carbon stable isotopes in the northern Chukchi Sea, western Arctic Ocean, over the past 200 years. Under permanent ice cover, organic carbon was dominated by land sources transported by sea ice and ocean currents, while local primary productivity was suppressed by light limitation. Since ice retreated in 20th century, organic carbon from primary production gradually overtook the terrestrial component.