Program
 
Special Session 2: Changing ocean environment: from the sedimentary perspective -- processes and records
 
 
 
Poster
Provenance and lithogenic controls on the preservation of organic matter in recent sediments from the continental shelf of the East China Sea
SS2-15-S
Can Yang* , State Key Laboratory of Marine Environmental Science and Department of Geological Oceanography, Xiamen University, Xiamen, China
Huawei Wang, State Key Laboratory of Marine Environmental Science and Department of Geological Oceanography, Xiamen University, Xiamen, China
Baozhi Lin, State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
Jiann-Yuh Lou, Department of Marine Science, Chinese Naval Academy, Kaohsiung, Taiwan, ROC
Zhifei Liu, State Key Laboratory of Marine Geology, Tongji University, Shanghai, China
Presenter Email: 1157520145@qq.com
The elemental and isotopic compositions of organic matter preserved in sediments of the shallow shelf sea provide information on the provenance and environmental condition of the depositional setting. In this study, we investigate a suite of organic and inorganic parameters along with grain size in two sediment cores collected from the mud belt (DH6-1) and nearby sand-silt substratum (DH7-3) across the shelf of East China Sea to understand the variation of sedimentary environment in recent years in the southern coast of the East China Sea. Based on the source indicators of organic matter (C/N ratios and ¦Ä13C, ¦Ä15N values), we find that both cores contain higher marine-derived organics due to their proximal locations to nutrient-rich waters by coastal rivers. Although there is no much difference between ¦Ä13C and ¦Ä15N values between these two cores, core DH6-1 contains lower mean size, higher contents of mud, Al, K and Ti compared to core DH7-3. On the other hand, core DH7-3 contains higher contents of silica and CaCO3 than that of core DH6-1, suggesting a weak dispersal of riverine fine sediment across the outer shelf of the East China Sea. Insignificant relationships between grain size parameters and organic and inorganic parameters in these cores may indicate a weak control of grain size on the variation of these parameters in sediments of recent years. In addition, decreasing silica content, but increasing TOC and Al contents in core DH6-1 in the top 10 cm likely attributed to either decreased Yangtze-derived sediment input in recent years or the intensity of resuspension in the estuarine region of Yangtze by China coastal current has increased and that supplied fine sediments to the distal end of the mud belt in the East China Sea. Even though preservation of organic matter in bottom sediments and penetration of particulate organic carbon to the sea floor are largely governed by the input of lithogenic material, results of our study reveal an insignificant control of lithogenic material on organic matter preservation in recent sediments of the East China Sea.