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Special Session 2: Changing ocean environment: from the sedimentary perspective -- processes and records |
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Decoupled organic carbon burial and productivity in the subtropical north Pacific
Wednesday 11th @ 1145-1200
Room 4
Dawei Li* , State Key Laboratory of Marine Environmental Science, Xiamen University
Shuh-Ji Kao, State Key Laboratory of Marine Environmental Science, Xiamen University
Qian Li, State Key Laboratory of Marine Environmental Science, Xiamen University
Xiaodong Ding, State Key Laboratory of Marine Environmental Science, Xiamen University
Liwei Zheng, State Key Laboratory of Marine Environmental Science, Xiamen University
Presenter Email: ldw647@xmu.edu.cn
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| The burial of marine sourced organic carbon into sediment contributed to the atmosphere carbon dioxide change on geological time scale. However, our understanding about factors that controlling marine organic carbon burial is still ambiguous, especially in marginal seas. In this study, we compared organic carbon burial with the export productivity, inferred from reactive phosphorus, from a sediment core on the slope in the middle Okinawa Trough (OT) spanning over the past 30 kyr. We found decoupling between organic burial and productivity. Organic carbon burial efficiency, inferred from the ratio of marine source organic carbon to reactive phosphorus, experienced higher values during the last glacial-deglacial state but low values during the Holocene. Accordingly, redox sensitive metals and total sulfur content indicate that glacial-deglacial OT deep water oxygen was reduced. Based on this, we suggested that lower water column oxygenation favored the organic carbon burial efficiency resulting in the decoupling relation between productivity and organic carbon burial during the glacial-deglacial stage. |
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