广利河口北潮滩重金属分布特征及评价

DISTRIBUTION PATTERN AND ASSESSMENT OF HEAVY METALS IN THE SEDIMENTS OF NORTH GUANG-LI RIVER ESTUARY

基于广利河口北潮滩45个表层沉物和2个岩心柱样重金属、粒度、TOC数据,分析了广利河口北潮滩沉积物重金属分布规律及其来源,采用内梅罗综合指数法进行质量评价。结果表明:Cu、Pb、Zn、Cr、Cd、Hg、As 7种元素含量低于国家一类标准;在空间分布特征上,距岸一定范围内数值相对较高,主要受沿岸余流作用的影响;就来源而言,Cr元素明显为广利河注入,表层、Z1和Z2沉积物粒度对重金属的控制作用有明显差异;研究区内Cr和As污染指数最高,Cu污染指数变化最大,综合污染指数呈"哑铃状"分布,靠近现代黄河口和广利河口各高值相对较高。目前广利河口北潮滩重金属含量没有到达污染的程度,但有向轻度污染发展的趋势。

Based on the data of heavy metals,grain sizes and TOC for 45 surface sediments and 2 core columns taken from the north tidal flat of the Guang-li River estuary,we studied the distribution patterns and sources of heavy metals in the sediments of the estuary.Environmental quality evaluation is made with the Nemerow comprehensive index.The results show that the 7 elements of Cu,Pb,Zn,Cr,Cd,Hg and As,are all lower than the national standard of heavy metal pollution.In the spatial distribution,a high value anomaly of heavy metals is discovered in a place to certain distance from the shore,under the influence of coastal residual current.In terms of the source,however,the Cr element is clearly injected by the Guang-li River.In the sediments taken from the surface and the Z1 and Z2 sinks,grain size has obvious controlling effect over heavy metal distribution.The pollution indices of Cr and As remain the highest in the study area,while the pollution index of Cu changes greatly.The distribution of comprehensive pollution index is in a ＂ dumbbell-like＂ pattern,with a high value region near the modern Yellow River estuary and another in the Guang-li River estuary.To conclude,the heavy metal content in the north tidal flat of the Guang-li River estuary has so far not reached the level of pollution,but the trend of development towards slight pollution is observed.