近百年来胶州湾沉积物中重金属元素的累积过程及其环境意义

Accumulation of heavy metals in the core sediments from the Jiaozhouwan Bay during last hundred years and its environmental significance

利用2003年9月中国科学院海洋研究所"金星二号"调查船采自胶州湾海域的6个沉积岩心样品,对其210Pb放射活度和重金属Zn、Cr、Cu、Pb、Cd、Co和Ni元素的含量进行了测定,计算了其不同分布模式下的沉积速率和沉积通量,并分析了相应的岩层中重金属元素累积过程,探讨了其沉积环境意义,结果表明,胶州湾中部、东部沿岸与胶州湾口门外海域沉积速率有较大的差异,平均沉积速率为(0.19～3.96)cm/a。根据聚集速率,近百年来胶州湾沉积物中重金属元素的累积过程基本上可分为3个阶段:第一阶段是聚积速率的背景水平阶段,这一阶段沉积物中的重金属元素含量可视为背景值;第二阶段为重金属聚积速率快速增加阶段,与胶州湾工业革命前沉积物重金属元素背景值相比,这一时期沉积物中的重金属元素的含量已达污染水平;第三阶段为重金属聚积速率降低阶段,这一时段主要在20世纪80年代后,沉积物中重金属元素的聚集速率有不同程度的下降趋势。近百年来,胶州湾沉积岩心中210Pb和重金属Zn、Cr、Cu、Pb、Cd、Co和Ni元素的垂直分布和累积过程受到沉积物粒度、污染源的排放和水动力条件等因素制约。

The ^210Pb activity and the heavy metals of Zn, Cr, Cu, Pb, Cd, Co and Ni in corresponding sediment layers in the cores of B3, C2, C4, B6, D4 and D6 from the Jiaozhouwan Bay were measured, and the sedimentation rate and sedimentation environment in different region for the Jiaozhouwan Bay have been discussed. The sedimentation rate had significant difference among the middle, the east coast and the mouth of the Jiaozhouwan Bay with the average between 0.19 cm/a and 3.96 cm/a. According to exactly strata age determined by ^210Pb, the background values of Zn, Cr, Cu, Pb, Cd, Co and Ni in every core sediment were determined. The accumulation rate of heavy metals in the Jiaozhouwan Bay during the last hundred years can be divided into three periods. The first period was characteristic of background value of heavy metals accumulation rate, which was before the time of the rapid development of industry and agriculture in Qingdao. And the main source of heavy metals was natural with relatively low sedimentation rate during that time. The second period was characteristic of quickly increasing accumulation rate of heavy metals, which was corresponded to the rapid development of industry and agriculture in Qingdao. During that time, Jiaozhouwan Bay had been subjected to various pollutants and led to the serious heavy metal pollution. Compared with the background value of heavy metal before industrial revolution in Jiaozhouwan Bay, the sediments had been polluted by heavy metal in that time. The third period was the time when the accumulation rate of heavy metals began to decrease due to the development of pollution control measures and continuous improvement of the environmental management system from 1980＇ s. And the Jiaozhouwan Bay sedimentation environment began to improve in this period. The vertical distributions and accumulation of ^210Pb, Zn, Cr, Cu, Pb, Cd, Co and Ni was controlled by sediment granularity, pollutant input and hydrodynamics in the Jiaozhouwan Bay. The distribution and accumulation rate of heavy metals in the core sediments can reflect clearly the change of sedimentation environment.