胶州湾水生系统中Pb、Zn的分布特征及其在生物体中的浓缩

BIOGEOCHEMICAL CYCLES AND BIOACCUMULATION OF PB AND ZN IN JIAOZHOU BAY, CHINA

利用在胶州湾采集的47组同站位多介质样品,进行了痕量金属Pb、Zn及其它环境因子的化学成分测试,讨论了胶州湾水-沉积物-生物系统中Pb、Zn的生物地球化学总体特征及其在各介质平面上的分布,揭示了胶州湾水-沉积物-生物系统对陆源物质输入的响应。垂向上表层沉积物是Pb、Zn组分的富集带,该系统中的生物相对于其所处水环境具有显著的富集作用,生物体中Pb、Zn生物浓缩系数分别为36、935;横向上,Pb、Zn在底层水和沉积物介质中的分布主要受控于河口,即高值区分布于胶州湾的各个主要河口区,特别是在沉积物中金属组分浓度的高值区主要集中分布于胶州湾的东部。而孔隙水中Pb、Zn的高值主要分布于水交替较弱的海域,如红岛前缘。但生物体中的痕量金属组分化学场空间分布规律与上述各介质的化学场均不吻合,亦即是生物体中痕量金属组分的浓度与其所处环境中的同名金属组分浓度无关。作者认为,生物对痕量金属组分的富集并不简单地取决于它所处环境介质中同名金属组分的总量,而存在形态上的选择性。通过回归分析揭示了孔隙水对生物体中Pb、Zn的富集贡献较大。

Concentrations of Pb, Zn and other environmental elements were determined in bottom waters, pore waters, sediments, and clams collected from 47 stations in the Jiaozhou Bay, Qingdao City, China in summer 2003 and 2004. The trace metals contents were the highest in surficial sediment over those in bottom water, pore water, and organisms. Bioac- cumulation in clam was obvious for having factors at 36 for Pb, and 935 for Zn. Lately, the amounts of trace metals in both bottom water and sediments were mainly controlled by the proximity to the estuary, as high concentrations were generally found in estuaries. In this study, high value area of trace metals in sediment occurred mainly in the east of the Jiaozhou Bay; and high contents of the metals Pb, Zn in pore water was mainly limited in hydro-dynamically quiet area in the western front of Hongdao due to low exchange rate. However, distributions of Pb and Zn in clam are different from the above-mentioned scenario, indicating that trace metals in clams were irrelevant with metal concentrations in ambient sediment or seawater. Therefore, bioaccumulation of trace metals was not simply related with the ambient concentration, but with the chemical forms of metal in sediment or water. Regression analysis shows that pore water contributed more to the enrichment of Pb, Zn in the organism.