沉积物重金属污染评价标准比较研究

Sediment Heavy Metals Pollution Assessment:A Comparison Study between Two Criteria

沉积物重金属污染中广泛应用指数法,评价标准的不同会导致评价结果的显著差异。依据区域地球化学基准值和国家标准值,采用内梅罗综合污染指数法、反距离加权插值法,对舟山港海域35个表层沉积物中的重金属污染特征进行比较研究。结果表明:(1)两种标准所揭示的污染水平基本一致,舟山港表层沉积物重金属的污染水平仍处于较低水平,污染最严重的区域靠近码头和船厂;(2)依据区域地球化学基准值的评价结果更为严格,污染空间分异更大,能够更加精确的分辨可能的污染源位置;(3)国家标准值具有更好的获取优势,特别是缺乏基准值的区域。此外,应用国家标准便于开展区域之间的比较研究。

Various indexes were widely used in heavy metal pollution assessment. Evaluation standards may lead to significant difference in results and play a crucial role in these studies. In our study, Zhoushan Harbor was chosen as the study area and thirty five surface sediment samples were collected to understand the characteristics of heavy metal pollution. The concentrations of seven heavy metals including Cu, Pb, Zn, Cd,Hg, As and Cr were measured. Nemerow Synthetical Pollution Indexes were calculated, Inverse Distance Weighted interpolation was used, as well as two evaluation criteria（regional geochemical reference value and national standard value） were used to carry out comparative studies. The results showed that：（1） the general trends of pollution level in two comparative studies were similar; the heavy metal pollution in surface sediment of Zhoushan harbor is still at a low level. The most seriously polluted areas were near docks and shipyards, and more attention should be paid to these areas.（2） Regional geochemical reference value gave a more strict result and a better spatial resolution in pollution analysis, reveal more precise locations of possible pollution source.（3） National standard values have advantage of availability, especially in areas lack of natural background value. Besides, national standard make the studies more comparable between areas.