THE DEPOSITIONAL MECHANISM OF TRACE METALS IN OFFSHORE SEDIMENTS AND AQUATIC SYSTEM
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摘要: 痕量金属和有毒金属通过面源(如大气沉降)和点源(如河流、地下水和倾废)污染过程参与近海水生系统的生物地球化学循环。根据近年来主持的多项沿海生态地球化学调查与评价项目的理论与实践,概括了痕量金属在水生系统中迁移、转化的生物地球化学模式,并对模式意义作了概要的解释。近海水生系统中痕量(有毒)金属形成取决于系统内发生的生物、氧化-还原、溶解与沉淀、配位与螯合等一系列化学反应竞争的结果以及这些金属被海洋生物浓缩与放大的程度。痕量(有毒)金属在进入海底沉积物后的生物有效性问题涉及到这些金属与酸可释放硫AVS和黄铁矿的相关性以及与黄铁矿发生共沉淀的机理。Abstract: Trace metals and toxic metals are brought into offshore sediments and aquatic systems through various point and none-point pollutant sources, and eventually join in biogeochemical cycles. This paper made a review on the processes affecting the mobility and bioavailability of trace and toxic metals based on the research practice and current achievements made by the authors in this field. A model revealing trace and toxic metal behaviors in the offshore sediments and related aquatic system was proposed in this paper. It is suggested that the deposition of trace metals and toxic metals in offshore aquatic environment depends upon the organisms, oxidation-reduction, dissolution and precipitation, and chemical interaction in sea water, or the bioaccumulation by marine organisms. With respect to the bioavailability of these metals once they moved into marine sediments, it depends upon their relationship with pyrite and acid volatile sufide (AVS) and the mechanisms of their coprecipitation with pyrite.
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Key words:
- offshore sediments /
- aquatic system /
- trace metals /
- activation /
- pyrite /
- decomposition of organic carbon
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