Porewater distribution and benthic flux measurements of mercury and methylmercury in the Gulf of Trieste (northern Adriatic Sea)
Porewater distribution and benthic flux measurements of mercury and methylmercury in the Gulf of Trieste (northern Adriatic Sea)
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DOI：
10.1006/ecss.1999.0466
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发表时间：
1999-04-01
影响因子：
2.8
通讯作者：
Brambati, A
中科院分区：
文献类型：
--
作者：
Covelli, S;Faganeli, J;Brambati, A
的里雅斯特湾是地中海汞污染最严重的地区之一。其特点是来自伊松佐河的高汞输入，伊德里卡河的支流排放斯洛文尼亚伊德里哈汞矿区的汞，那里的汞开采活动已经进行了近500年。因此，这似乎是研究影响海洋环境中汞循环的过程以及确定沉积物是否可能作为水柱中汞物种的二次来源的最合适地点之一。研究了孔隙水溶解态总汞（Hg（T））和甲基汞（MeHg）的季节分布特征。利用原位底栖箱，可以确定全年水-沉积物界面的汞和甲基汞的底栖通量。底栖通量进行了比较，从孔隙水剖面计算的扩散通量。结果表明，在夏季末的海底缺氧条件下，汞和甲基汞的底栖排放量和孔隙水浓度在秋季和冬季达到最高值。这可能是由于从夏末快速硫酸盐还原到较低温度的过渡，底层水层的氧化作用较高，微生物活动较低，非常适合汞的转化，积累和通量。根据底栖生物通量测量的初步估算表明，75%的汞（T）埋在沉积物中，而25%的汞（T）（约23%为甲基化形式）每年在水-沉积物界面循环和释放。(C)北京：科学出版社.
The Gulf of Trieste is one of the most mercury-contaminated areas in the Mediterranean Sea. It is characterized by high mercury inputs from the Isonzo River whose tributary, the Idrijca River, drains the mercury mining area of Idrija in Slovenia where extraction activity has taken place for nearly 500 years. This appears, therefore, to be one of the most suitable sites for studying processes that affect Hg cycling in the marine environment and for determining whether sediments might act as secondary sources of mercury species in the water column. Porewater seasonal distributions of total dissolved Hg (Hg(T)) and methylmercury (MeHg) were investigated. Using in situ benthic chambers it was possible to determine benthic fluxes of Hg, and MeHg at the water-sediment interface throughout the year. Benthic fluxes were also compared with diffusive fluxes calculated from porewater profiles. The results indicate that, following hypoxic conditions which occurred in late summer in the sea-bottom layer, highest benthic effluxes and porewater concentrations of Hg and MeHg appeared during autumn and winter. This was probably due to the transition from rapid sulphate reduction in late summer to cooler temperatures, higher oxygenation of the bottom water layer, and lower microbial activity which is well suited for Hg transformation, accumulation and flux. A tentative budget based on benthic flux measurements indicates that 75% of Hg(T) is buried in the sediment whereas 25% of Hg(T), approximately 23% in methylated form, is annually recycled and released at the water-sediment interface. (C) 1999 Academic Press.