长江河口主要重金属元素的分布和迁移

The Distribution and Shift of Heavy Metal Elements in Changjiang Estuary

根据近10多年来长江河口水域历次调查资料，阐述了长江河口水域各相重金属元素的分布和迁移规律，结果表明，除水相和悬浮相中Cd的含量为河口段低于口外海滨外，其余均为河口段高于口外海滨，并在南、北槽口-122°25′E之间形成高含量区，这主要与陆源重金属元素受河口锋的作用有关。长江河口重金属元素的迁移有4种形式；相间迁移、屏障迁移载体迁移和动力迁移，其中相间迁移存在于整个河口过程，屏障迁移使重金属元素残留河口，载体迁移将重金属元素输往海洋，动力迁移可使残留沉积相的重金属元素再次以参与载体迁移，长江河口主要重金属元素Zn、Cu、Pb、Cd的入海通量的量级分别为10^5、10^4、10^4和10t/a。

Based on the investigation of many years, the distribution of various phases of heavy metal elements (HME) is presented. Except that the concentration of Cd element in water and suspended sediments is lower in Changjiang estuary than marine area, all HME show higher concentration in the estuary. High concentration area was formed from the mouth of Changjiang's north and south channel to 122°25′ E due to the terrestrial source of HME and he action of estuarine front. Results suggest that there are four shifting patterns for HME: shift among phases, barrier shift, carrier shift and dynamic shift. The shift among phases occurs in the whole estuarine process, the barrier shift induces HME to remain in estuarine area, the carrier shift causes HME to transport toward the sea, and the dynamic shift makes HME remained in sediments to involve carrier shift again. HME flux to the sea is estimated, the magnitude of Zn, Cu, Pb and Cd are 10~5, 10~4, 10~4and 10 t/a respectively.