桑沟湾溶解态汞的生物地球化学行为

作为一种毒性极强的重金属元素,汞在海洋中可以通过海洋生物的呼吸、摄食和吸附等过程被利用,并在沿食物链传递的过程中不断富集,最终危害人类的健康。利用冷原子荧光光度法(CV-AFS)对2011年4月、8月、10月和2012年1月桑沟湾溶解态无机汞(DIHg)和溶解态有机汞(DOHg)的含量进行了测定。结果表明,桑沟湾四个季节DIHg的浓度范围分别为52~865、131~359、31~134和22~119 pmol·L-1,DOHg的浓度范围分别为37~214、52~635、21~98和未检出~51 pmol·L-1。桑沟湾DIHg和DOHg具有相似的分布特征,均呈现出从近岸向外海逐渐降低的趋势,有明显的季节变化。桑沟湾DIHg和DOHg的周日变化与潮汐呈现出较好的负相关关系,且存在明显的昼夜差异。影响桑沟湾DIHg和DOHg分布的主要因素包括河流和地下水的输入、大气的干湿沉降、与黄海的交换、活性气态汞(Hg0)在海-气界面的交换、表层水体发生的光化学还原反应以及养殖生物的清除等。通过初步计算,桑沟湾溶解态汞(TDHg)的存留时间约为(1.27±0.53)年,远远低于大洋。根据美国国家环境保护局汞的质量标准和我国地表水环境质量标准,桑沟湾没有明显的汞污染。但海产品体内富集的汞可能会带来潜在的生态危机和食品安全问题,需要相关部门加以重视,确保桑沟湾养殖产业的平衡发展。

Biogeochemical Behavior of Dissolved Mercury in the Sanggou Bay

Mercury, atoxic heavy metal can be strongly bioaccumulated by the phytoplankton and passed up the food web in the sea, and finally be harmful to human beings. Four cruises were carried out in April, August, October 2011 and January 2012 in the Sanggou Bay. The concentrations of dissolved inorganic mercury (DIHg) and dissolved organic mercury (DOHg) were measured by Cold Vapor-Atomic Fluorescence Spectrophotometry (CV-AFS). The concentrations of DIHgwere 52-865 pmol·L^-1 in April, 131-359 pmol·L^-1 in August, 31-134 pmol·L^-1in October and 22-119 pmol·L^-1 in January. The concentrations of DOHg ranged from 37 to 214pmol·L^-1, 52 to 635 pmol·L^-1, 21 to 98 pmol·L^-1and less than 51 pmol·L^-1 during four cruises, respectively. The concentrations of DIHg and DOHg both decreased seaward, and had significant seasonal variations. The negative relationship between the daily concentrations of DIHg or DOHg and tide could be observed at anchor stations, and showed obvious changes between day and night. Riverine input, groundwater input, wet and dry atmospheric deposition, incursion of Yellow Sea, exchange of active gaseous mercury (Hg⁰) at air-sea interface, photochemical reduction in surface waters and bioaccumulation were the main factors affecting the distributions of DIHg and DOHg in the Sanggou Bay. The residence time of TDHg was estimated to be (1.27±0.53)a in the Sanggou Bay, which was much shorter than that in the open ocean. According to the National Primary Drinking in Water Standards from USEnvironmental Protection Agency and Environmental Quality Standards for Surface Water of China, there is no obvious anthropogenic mercury pollution in the Sanggou Bay. However, the enrichment of mercury by cultivated species may lead to potential ecological crisis and food safety problems, and need to be paid more attentions to ensure the sustainable development of aquaculture in the Sanggou Bay.