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Special Session 3: Size matters or not, particles export in marine environments |
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210Po and 210Pb in the northern South China Sea: Implications for export and resuspension of particulate matter
SS3-01-S
Haoyang Ma* , State Key Laboratory of Marine Environmental Science and 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
Lihao Zhang, Guangxi Key Laboratory of Environmental Pollution Control Theory Technology, Guilin University of Technology
Ziming Fang, State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University
Min Chen, State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University
Yusheng Qiu, State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University
Minfang Zheng, State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University
Presenter Email: mahy@stu.xmu.edu.cn
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| Abstract Biogeochemical cycling of 210Po and 210Pb in seawater is the important contents of GEOTRACES Program in order to extend their applications in oceanic environments. Here, 210Po and 210Pb were examined in the water columns over the shelf and slope of the northern South China Sea. Elevated concentrations of suspended particulate matter (SPM) in bottom water indicated resuspension of sediments on the shelf. Meanwhile, the 210Po/210Pb ratios in bottom water were higher than those observed at the similar depths on the slope, further supporting the resuspension of sediments. Based on the traditional model of 210Po-210Pb disequilibrium, the average POC export fluxes on the shelf and slope were 3.56¡À0.54 and 3.10¡À0.39 mmol m-2 d-1, illustrating an underestimate of POC flux on the northern continental shelf due to sediment resuspension. Combining 210Po and 210Pb in sediments, a resuspension model of 210Po-210Pb was proposed to quantify the flux of sediment resuspension. The resuspension flux of POC ranged from 2.61¡À0.89 to 4.30¡À1.70 mmol m-2 d-1. Thus, the actual POC export flux, without the influence of resuspension, was estimated to range from 6.17¡À1.04 to 7.86¡À1.79 mmolm-2 d-1. These results indicated that the disequilibria between 210Po and 210Pb could be used to quantify the resuspension dynamics in bottom water.
This work was supported by State Oceanic Administration program (201505034-1), the National Key Research and Development Program (2016YFA0601201) and NSFC (41476061).
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