| Heavy metals are harmful to ecosystem with persistence in environemnt. Complex transformation and transport process of heavy metals occurring from rivers to the estuary area will affect the chemical speciation of metals in sea water and their bio-availability. The construction of large dam and the anthropogenic change of the hydrology for sand drainage on the upper reaches of the Yellow River might lead to the changes of the biogeochemical transformation of heavy metals in the estuary. Content of Cu, Pb, Zn, Cd, Hg, As and other environment factors were determined in the Yellow River estuary to study the distribution and pollution characteristics. The form and variance of metals was analyzed to research the behavior of heavy metals and the influences of heavy metals in the water caused by the Water-sediment regulation.. The results indicated that:1. In May 2009, most concentration values of heavy metals in the Yellow River Estuary Sea Area did not exceed those of the primary standard of Seawater Quality Standard of China. Zn contents exceeded the primary standard but lower than the secondary standard. The concentrations of soluble heavy metals decreased from littoral sea area and the Yellow River Estuary to the central sea area. Compared with other typical seas, the heavy metal concentration of the Yellow River Estuary was lower than that in the Jiaozhou Bay, while was higher than the North Yellow Sea, the South Yellow Sea and the South Sea.2. Before the Yellow River water-sediment regulation, except Cd, the average content of the remaining heavy metals in river water area was much higher than that in seawater area. Most heavy metal content decreased from river to sea. Particulate heavy metals accounted for the main part in the river area, but the dissolved heavy metals accounted for the main part in the sea area. 3. After the water-sediment regulation, in addition to Cd and As, the average content of the other four heavy metals were higher than that before the water-sediment regulation. From river to sea, most heavy metal content decreased and the ratio of dissolved to particulate heavy metal was increased significantly. As and Pb mainly existed in the dissolved and particulate form respectively, for the other elements, particulate was dominant in the river areas and dissolved heavy metals account for the main part in the sea areas. Most heavy metals have homology between before and after the Yellow River Water-sediment regulation. Compared with the Xiaoqing River in the same period, the average contents of dissolved and particulate heavy metals were all higher than that in the Xiaoqing River significantly. In the Xiaoqing River, Pb mainly existed in particulate form, the other heavy metals existed in dissolved form, and the content of particulate heavy metals decreased from river to sea.4. The salinity and suspended solids concentration were the main reason for the change of the heavy metal content in the Yellow River before and after the Water-sediment regulation. Most heavy metals showed a significant positive correlation with SS and pH value, and a significant negative correlation with DO and salinity. Heavy metal content in the water took on poor correlation with the dissolved organic carbon(DOC), it is less affected by organic carbon.5. The average content of the reactive mercury after the Yellow River Water-sediment regulation was 5.34ng/L, and had a significant positive correlation with the dissolved mercury concentration(p<0.1). The concentration of DGM was slightly higher than that in the Yellow River water before the Water-sediment regulation, and had no significant relationship with dissolved organic carbon content and mercury. The average content of the reactive mercury and DGM after the Yellow River Water-sediment regulation were higher than that in the Xiaoqing River. |
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