长江(南京段)现代沉积物中重金属的分布特征及其形态研究

THE DISTRIBUTION AND PHASES OF HEAVY METALS IN PRESENT SEDIMENT FROM YANGTSE RIVER (NANJING SECTION)

本文通过对比取样和重金属形态实验研究,对长江现代沉积物中重金属含量在平面上和剖面上的分布特征以及存在的形态进行了分析讨论.结果表明,长江南京段现代沉积物中Cu,Pb,Co,Ni已形成轻—中等程度污染,并且重金属元素随沉积物由老到新正以增加的趋势叠加沉积,叠加速率Cu为0.083μg·g^(-1)·cm^(-1),Pb为0.067μg·g^(-1)·cm^(-1),Co为0.05μg·g^(-1)·cm^(-1),Cr为0.217μg·g^(-1)·cm^(-1),Ni为0.067μg·g^(-1)·cm^(-1).叠加量主要为有效态部分.重金属在其有效态中的聚集能力如下:可交换态中:Pb>Co>Cu>Ni,Cr;碳酸盐态中:Cu>Cr>Pb,Co,Ni;Fe-Mn氧化物态中:Co>Pb>Cu>Ni>Cr;有机态中:Cu>Cr>Pb,Co,Ni.

In this paper the research for heavy metals in present sediment from Yangtse river (Nanjing section) is studied by means of the experiments on heavy metal phases,the distribution of heavy metals on the depositing plane and in the vertical section. The study results have been obtained in the following: the sediment of Yangtse river (Nanjing section) has moderately been contaminated by Cu, Pb, Co and Ni. Moreover, Heavy metal elements are adding to depositing in the sediment. The rate of adding contamination is about at 0. 083μg·g-1·cm-1 for Cu, 0. 067μg·g-1·cm-1 for Pb, 0.06μg·g-1·cm-1 for Co, 0. 217μg·g-1·cm-1 for Cr, 0. 067μg·g-1·cm-1 for Ni. The adding heavy metals are mainly bound in their efficient phases (exchangeable, carbonates, Fe-Mn oxides and organic matter phases).Heavy metals accumulate in their efficient phases as order as the following: in exchangeable: Pb>Co>Cu>Ni, Cr, in carbonates: Cu>Cr>Pb, Co, Ni, in Fe-Mn oxides; Co>Pb>Cu>Ni>Cr, in organic matter; Cu>Cr>Pb, Co>Ni.