大连湾近100年来重金属污染度的演变

THE EVOLUTION OF HEAVY METAL POLLUTION DURING LAST HUNDRED YEARS IN THE DALIAN BAY

随着工业化进程的发展 ,重金属污染已给人类生活带来越来越大的危害。文中基于大连湾水下 11m深 6 1cm沉积柱状样品的地球化学元素测定 ,探讨大连湾近 10 0年来Cd ,Hg,Pb ,As ,Zn ,Cu重金属含量的逐年变化。分析底栖有孔虫多样性的时间分布 ,探讨底栖微体生物对环境污染的效应。分析结果表明 ,上述 6个重金属元素的污染度在近百年间 ,经历了从无污染或轻微污染到中度污染到重度污染的过程。至 1999年 11月 ,污染度增加的幅度分别为Cd 85 .5倍 ,Hg 6倍 ,Pb 7.5 4倍 ,As 3.82倍 ,Zn 7.82倍 ,Cu 3.4 6倍。有孔虫物种数量的年代分布 ,表现出与环境污染度变化的一致性。有孔虫的物种数在 195 0年达到高峰 (2 6个种 ) ,以后物种数和个体数不断减少 ,直至 1997年有孔虫消失。文章讨论了重金属污染对生命健康的影响 ,重金属污染已威胁到人群身体健康 。

With the development of industrialization, heavy metal pollution has become more risky for daily life. Based on the Earth chemical analysis of sediment core taken from 11 meters below the sea surface in the Dalian Bay, we have discussed the variations of six heavy metal elements in sediment deposits during the last hundred odd years. The results show us that the contents of these heavy metals are getting higher and higher. Early last century there was no any heavy metal pollution except Pb in the Dalian Bay. The content of Pb was about 33×10 -6 , being light pollution. It is more distinct that since the middle of the century the contents of mentioned heavy metals have gotten higher and higher. The degree of pollution in the Dalian Bay has increased from light to heavy. In November 1997, the pollution degree has increased 85.5 times for Cd, 6 times for Hg, 7.54 times for Pb, 3.82 times for As, 7.82 times for Zn and 3.46 times for Cu compared respectively with the lowest content of these elements during last hundred years. It is obvious that at the end of last century the heavy metal pollution in the Dalian Bay become much more serious. 120 species of benthic Foraminifera are identified from 121 sediment samples. With years passing by, the number of foraminifera species was getting less. In 1997 no foraminifera was found in the samples. The response of benthic foraminifera to polluted environment is sensitive. It is concluded that benthic foraminifera can be used as pollution indicators. The risks of above mentioned heavy metals for the life and the health of human beings are discussed in the paper.