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

• Published in: Climate of the Past
• Main Authors: Su, Liang, Ren, Jian, Sicre, Marie-Alexandrine, Bai, Youcheng, Zhao, Ruoshi, Han, Xibing, Li, Zhongqiao, Jin, Haiyan, Astakhov, Anatolii S., Shi, Xuefa, Chen, Jianfang
• Other Authors: Ocean College, Zhejiang University, Key Laboratory of Marine Ecosystem Dynamics, Variabilité de l'Océan et de la Glace de mer (VOG), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Second Institute of Oceanography, State Oceanic Administration (SOA), State Key Laboratory of Satellite Ocean Environment Dynamics (SOED), V.I. Il'ichev Pacific Oceanological Institute, Il'ichev Pacific Oceanological Institute, First Institute of Oceanography Qingdao (FIO), Ministry of Natural Resources of China
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDU]Sciences of the Universe [physics]; Arctic; Arctic Ocean; Chukchi; Chukchi Sea; Climate change; Sea ice
• Online Access: https://insu.hal.science/insu-04188266; https://insu.hal.science/insu-04188266/document; https://insu.hal.science/insu-04188266/file/cp-19-1305-2023.pdf; https://doi.org/10.5194/cp-19-1305-2023

International audience Decreasing sea ice extent 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, δ 13 C org , and δ 15 N) and molecular organic biomarkers (e.g., sterols and highly branched isoprenoids - HBIs) are combined to distinguish between sympagic, pelagic, and terrestrial OC sources. Their downcore profiles generated at the Chukchi Sea R1 core site (74 ∘ N) are then used to evaluate changes in the relative contribution of these components of sedimentary OC over the last 200 years with decreasing sea ice. Our data evidence that, from the 1820s to the 1930s, prevailing high sea ice cover inhibited in situ primary production, resulting in prominent land-derived material in sediments. Then, from the 1930s to the 1980s, primary production started increasing with the gradual decline of summer sea ice. The ratio of sympagic and pelagic OC began to rise to account for the larger portion of sedimentary OC. Since the 1980s, accelerated sea ice loss led to enhanced primary production, stabilizing over the last decades due to freshwater-induced surface ocean stratification in summer.