夏秋季长江口邻近海域水体中颗粒态汞及溶解态汞的研究

分别于2018年7月和10月随“科学三号”科学考察船对长江口邻近海域水体中颗粒态汞（PHg, particulate mercury）和溶解态汞（DHg, dissolved mercury）的时空分布及影响因素进行了研究。结果显示:两种形态Hg在不同站点表层海水中的浓度变化范围较大，且在不同季节间的差异明显，其中表层PHg在夏季呈现近岸高远海低的分布特点，而在秋季没有这种规律。该海域DHg占主体，不同水层DHg普遍表现为秋季高于夏季，且表层大于底层，表、底层的分配系数均从近岸到远海方向增加。表、底层PHg与总悬浮物（TSM, total suspended matter）呈显著正相关，PHg/TSM随盐度增加呈指数增加（R2=0.3365, p <0.01）。秋季冲淡水减少和较多大风天气是影响表层PHg时空分布变化的主要原因，颗粒物粒径变小和海源性有机颗粒物增加决定了DHg的分布特征，而在30° N处出现普遍较高浓度的DHg则反映了河流输送和周边污染排放的影响。

Study on particulate mercury and dissolved mercury in adjacent waters of the Yangtze River Estuary in summer and autumn

The distribution trend and influence of particulate mercury (PHg) and dissolved mercury (DHg) in adjacent waters of the Yangtze River Estuary were studied by the Science 3 scientific research vessel in July and October 2018, respectively. The results showed that PHg and DHg had a large variance in the surface seawater, and the difference was obvious in different seasons. In summer, PHg in surface water decreased from nearshore to the open seas. In the autumn period, this trend was not obvious. DHg accounted for a larger proportion in this sea area. DHg was higher in autumn than that in summer, and the surface water was higher than the bottom water. In summer, the particle-water partition coefficients in surface and the bottom water increased from nearshore to the open seas; PHg correlated with TSM significantly in the surface and bottom water and PHg/TSM increased exponentially with salinity (R2=0.3365, p<0.01). The main reason for the change in the temporal and spatial distribution of surface PHg was the decrease of Changjiang diluted water and more windy weather. The distribution characteristics of DHg were controlled by small particle diameter and more marine organic particles. While the higher concentration of DHg at 30°N reflected the effects of river transport and surrounding pollution discharge.