Program     Modern and past processes of ocean-atmosphere-climate interactions in the low-latitude western Pacific and Indian Ocean       Poster Carbon and Nitrogen Isotopic Records of Sedimentary Organic Matter from the Min-Zhe Mud Deposit on the East China Sea Continental Shelf: Implications for Paleoenvironmental Changes from the Late Glacial P-G2-05-S Huawei Wang* , Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen China Can Yang, Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen China Qianqian Liu, Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen China Shengfa Liu, Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao, China Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China Xuefa Shi, Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao, China Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China Huaiyan Lei, Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen China Selvaraj Kandasamy, Department of Geological Oceanography, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen China Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China Presenter Email: hwwang@stu.xmu.edu.cn Millennial scale carbon cycling and glacial-interglacial environmental changes are profoundly dependent on organic carbon (OC) burial in the marine realm, wherein the continental margins alone account for approximately 85% of total OC burial. Mud deposits formed in the inner shelf of the marginal seas during the Holocene contain both land-derived and marine-sourced organic matter (OM), but the proportion of these sources and key mechanisms controlling their burial are less constrained. In this study, a 35.3 m-long core (MZ02) recovered from the Min-Zhe mud deposit in the East China Sea was measured for the contents of organic carbon (OC), total nitrogen (TN) and their stable isotopes (δ13C, δ15N), as well as grain size, to investigate the provenance of OM and reconstruct paleoenvironmental evolution for the last around 13000 yr BP. Results show relatively higher molar C/N ratios (7.3-10.5, mean: 8.7) and lower δ13C values (-24.0‰ to -22.2‰ mean: -23.0‰ indicating higher contribution of land-derived OM due to low sea level between 13000 and ~10000 yr BP. Very low OC and TN accumulated in sand dominated sediments with low δ15N values during Early Holocene (10000-8900 yr BP), reflecting a strong sea level control in OM preservation in the mud deposit. Based on δ13C and molar N/C three end-member (Changjiang, Taiwan river and Marine) mixing model, we noted an increased OM contribution from Taiwan Island, especially during 4600-2400 yr BP, corresponding to the strengthened East Asian Summer Monsoon (EASM) and intensified Taiwan Warm Current (TWC) during this interval. The mixing model calculation indicated that the marine-sourced OC was dominated (~55%) in most periods from the Late Glacial, followed by Changjiang (29%) and Taiwan (16%) river-derived OC. In addition, the Changjiang-derived OC slightly increased from 2400 yr BP to present, though the Changjiang freshwater discharge declined due to insolation-driven reduced EASM, suggesting increased OC production in the Changjiang drainage basin perhaps related to human activities.

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