浙江省近岸海域表层沉积物重金属分布特征及地球化学分区

THE HEAVY METALS DISTRIBUTION PATTERN AND GEOCHEMICAL PROVINCES OF THE SURFICIAL SEDIMENTS OFFSHORE ZHEJIANG

对浙江省近岸海域305个表层沉积物中7种重金属的地球化学特征及主要影响因素进行了分析研究,并进行了地球化学分区。结果表明,研究区表层沉积物中7种重金属(As、Cd、Hg、Pb、Cr、Cu、Zn)基本上具有相同或相似的分布规律,高值区主要分布在椒江口、乐清湾、温州湾及瑞安—苍南沿海;杭州湾为低值集中分布区;象山港,璇门湾出现部分低值。其中,As、Cd、Hg和Pb在所有站位均未超标;Cr有218个站位超国家一类标准,占全区的71.5%,2个站位超国家二类标准,占全区的0.7%;Cu有90个站位超国家一类标准,占全区的29.5%;Zn有2个站位超国家一类标准;水动力条件、沉积物物质来源和沉积物类型是影响沉积物重金属含量分布的主要因素;通过R型因子分析法,将整个研究区划分为3个地球化学子区,Ⅰ区为As、Cr、Cu、Pb、Zn元素组合类,Ⅱ区为Hg类,Ⅲ区为Cd类。

The geochemical features and geochemical provinces based upon As, Cr, Cu, Pb, Zn, Hg, Cd in the surficial sediments offshore Zhejiang are discussed in this paper. The results show that the distribution patterns of the seven heavy metals are similar. The heavy metals are high around the Jiao- jiang estuary, Leqing Bay, Wenzhou Bay and Rui an-Cangnan offshore, but low in the Hangzhou Bay. In the study area, the content of As, Cd, Hg and Pb never exceeds the national standard, except Cr, of which the content exceeds the band 1 national standard at 218 stations, and the area with excess Cr accounts to 71.5% of the total, with 2 stations exceeding band 2 national standard. The content of Cu exceeds band 1 national standard at 90 stations and the area with excess Cu accounts to 29.5% of the total. The content of Zn exceeds band 1 national standard only at 2 stations. Facts demonstrate that hydrodynamic conditions, the source and type of sediments have important effects on the distribution of heavy metals. The authors adopted the method of R mode factor analysis as a mean and divided the whole area into three geochemical provinces： the first province rich in As, Cr, Cu, Pb, Zn, the sec ond rich in Hg and the third rich in Cd.