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Circulation, biogeochemistry and carbon cycling in ocean margins
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Lateral transport of particulate organic carbon constrained by radionuclides (210Po, 210Pb and 234Th) in the northeastern South China Sea
P-M1-22-S
Xiufeng Zhao* , College of Ocean and Earth Sciences, Xiamen University
Weifeng Yang, State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University
Haoyang Ma, College of Ocean and Earth Sciences, Xiamen University
Yusheng Qiu, College of Ocean and Earth Sciences, Xiamen University
Minfang Zheng, College of Ocean and Earth Sciences, Xiamen University
Presenter Email: zhaoxf@stu.xmu.edu.cn |
| Abstract Sediment transport across shelf-slope is important for the redistribution of sedimentary chemicals. Here, particles fluxes, based upon radionuclides (210Po, 210Pb and 234Th) at two time-series stations, were examined over the shelf and slope of the northeastern South China Sea (SCS) to study sediment transport. Suspended particulate matter contents were much higher in bottom water than overlying water column on the shelf, indicating resuspension. At the slope station, increased black carbon contents below 50 m proved the lateral transport of re-suspended sediment. 210Po-derived lateral particulate organic carbon (POC) fluxes accounted for 5.6±2.4% and 74.1±9.5% of the total POC fluxes at 150m and 800m. 234Th-derived POC accounted for 6.4±2.6% and 73.5±11.0% respectively. These results indicated that lateral transport seems to less influence the POC flux out of the euphotic zone. Instead, its influence on POC flux in the mesopelagic zone could not be neglected. Thus, quantifying the biological pump efficiency within the mesopelagic water of the SCS needs a well constraint on the lateral POC transport from shelf sediment resuspension. Acknowledgements This work was supported by the National Key Research and Development Program of China (2016YFA0601201) and NSFC (41476061). |
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