奎屯河表层不同粒径沉积物中重金属空间分布及污染评价

在对新疆奎屯河表层沉积物粒径组成分析的基础上,采用原子吸收光谱仪测试了不同粒径沉积物中Co、Cr、Cu、Mn、Ni、Pb、Zn 7种重金属的质量比,研究了奎屯河表层沉积物不同粒径中各种重金属的空间分布特征,并运用单因子污染指数法与内梅罗综合污染指数法评价了各采样点重金属的污染状况。结果表明,奎屯河表层沉积物粒径主要分布在250μm的范围内,其中粉砂所占比例最大,平均质量分数达到63.66%;黏土次之,平均占16.77%。从上游到下游地区,各重金属污染物没有形成一定规律的分布特征。单因子污染指数评价表明除了Co,各采样点不同粒径沉积物中6种重金属存在着不同等级的污染,在粒径4μm、4~63μm、63~125μm、125~250μm的沉积物中,各重金属污染样品所占比例由大到小为Cu、Zn、Cr、Pb、Ni、Mn,Zn、Cu、Ni、Cr、Pb、Mn,Cu、Zn、Pb、Cr、Mn、Ni,Cu、Pb、Zn、Cr、Mn、Ni。内梅罗综合污染评价表明,各采样点均受到不同程度的重金属污染。

Spatial distribution and contamination evaluation of heavy metals in the surface sediment of different particle-size of Kuitun River

The paper is engaged in a study on contamination evaluation and spatial distribution of heavy metal in the surface sediment of different particle-size of Kuitun River in Xingjiang.For the said purpose,we have collected and measured the contents of 7 heavy metals including Co,Cr,Cu,Mn,Ni,Pb and Zn in the sediments by using the atomic absorption spectrograph based on the analysis of the size composition.Our evaluation has also been done by choosing the two indexes:the single factor pollution index and Nemerow integrated pollution index in hoping to determine the heavy metal pollution grade.The results of our evaluation and testing measurements can be illustrated in the following ways:(1)The surface sediments of Kuitun River have been found dominated by the particles sized smaller than 250 μm,in which the biggest part is the silt (4-63 μm),which takes about 63.66％ among these four sorts of particles.And,the secondary sort of particles is referred to as the clay fraction (＜ 4 μm),which stands for about 16.77％.(2) The spatial distributions of such heavy metal contaminants in the sediments fail to reveal any definite regulations in their size variety.(3) The distributive concentrations of Co along the entire reach of the river prove to be lower than the average background value of heavy metal contaminants in Xinjiang.However,the single factor pollution index indicates that all kinds of heavy metal contaminants tend to be different in their pollution grades almost in every sampling point except Co.Therefore,all the rest 6 heavy metal contaminants can be illustrated in the following descending order:Cu ＞ Zn ＞ Cr ＞Pb＞Ni＞Mn,Zn＞Cu＞Ni＞Cr＞Pb＞Mn,Cu＞Zn＞Pb＞Cr ＞ Mn ＞ Ni,Cu ＞ Pb ＞ Zn ＞ Cr ＞ Mn ＞ Ni,with their respective particle sizes being ＜4 μm,4-63 μm,63-125 μm and 125-250 μm.On the other hand,the evaluation results done by using Nemerow integrated pollution index indicate that all the sampling points tend to reveal different pollution grades.For example,the more sampling points where either moderate pollution or heavy pollution have been found with the particles of the sizes smaller than ＜ 4 μm in the sediment.Furthermore,qualitative analysis shows that heavy metal contamination has mainly resulted from the coal mining area,the urban sewage discharge and/or chemical fertilizer application.