海南岛典型港湾沉积物化学特征及重金属污染评价

为探讨海南岛海湾污染物来源及其沉积物环境质量, 对海南岛洋浦湾、铺前湾、清澜湾和小海湾等4个港湾的表层沉积物化学要素含量进行了测定, 分析其分布特征及相关性, 并利用潜在生态危害指数法对重金属的生态危害程度进行评价。结果表明, 74站表层沉积物化学要素TOC、Cu和Cr含量分别为0.156 % ~3.142 % 、2.0×10-6~45.1×10-6和10.9×10-6~515.0×10-6, 大部分站位含量低于一类海洋沉积物质量标准, 超一类标准的站位比例分别为8.1 % 、4.1 % 和12.2 % ; Hg、Pb、Zn、Cd和As的含量范围分别为0.013×10-6~0.150×10-6、7.2×10-6~48.7×10-6、18.6×10-6~125.7×10-6、未检出~0.211×10-6和1.8×10-6~17.2×10-6, 均未超过一类海洋沉积物质量标准。统计学分析显示, 径流输入是控制海南岛上述4个港湾污染物质来源的主要因子, 海水养殖或工业废水排放是重要点状污染源。 重金属的评价结果表明, 轻微生态危害的站位比例为58.1 %, 中等生态危害的站位比例为40.5 %, 强生态危害的站位比例为1.4 % ; 港湾生态危害的排序为清澜湾>小海湾>铺前湾>洋浦湾, 这一排序主要反映了汇入海湾的河流流域的污染状况。

THE CHARACTERISTICS OF CHEMICAL PARAMETERS AND THE POLLUTION EVALUATION OF HEAVY METALS IN SURFICIAL SEDIMENTS OF FOUR TYPICAL BAYS,HAINAN PROVINCE

Heavy metals are important indicators of marine sediment quality.In order to study the sources of pollutants and sediment quality of bays in Hainan Province, southern China, 74 surface sediments were collected from the Yangpu Bay(10 samples), Puqian Bay(20 samples), Qinglan Bay(14 samples)and Xiaohai Bay(30 samples)in June 2008.Sediment type of the samples was mainly sandy silt.The contents of heavy metals(Hg, Cu, Pb, Zn, Cr, Cd and As), Total Nitrogen, Total Phosphorus, Total Organic Carbon were measured in laboratory.Based on these data, correlation analysis and principal component analysis were used to find the main factors controlling the pollution sources.The ecological risks of heavy metals were evaluated by potential ecological risk index method to assess the pollution of heavy metals in bays.The measured results of 74 samples showed that:(1)TOC (0.156 % ~3.142 % ), Cu (2.0×10-6~45.1×10-6)and Cr (10.9×10-6~515.0×10-6)in most of the stations were lower than the first class of the sediment quality standards, while the percentage of stations excessing standards were 8.1 %, 4.1 % and 12.2 % for TOC, Cu and Cr respectively; (2)Hg (0.013×10-6~0.150×10-6), Pb (7.2×10-6~48.7×10-6), Zn (18.6×10-6~125.7×10-6), Cd (undetected~0.211×10-6)and As (1.8×10-6~17.2×10-6)in all samples were lower than the first class of the sediment quality standards.Based on the results of statistical analyses, three main factors were identified to control the sources of pollutants at a level of 86.12 % total variance:(1)runoff inputs, which explained 58.86 % of variance; (2)marine culture or sewage outfall, which explained 13.98 % and (3)primary productivity, which explained 13.28 %.Further analysis of individual bay suggested that runoff inputs was the dominate factor controlling the pollution level of bays.The results of potential ecological risk index showed that the percentage of stations were 58.1 %, 40.5 % and 1.4 % for the slight ecological risk, the medium ecological risk and strong ecological risk respectively.A descending order of the potential ecological risk of the four bays was Qinglan Bay, Xiaohai Bay, Puqian Bay, and Yangpu Bay, which represented the pollution status of the drainage basin of rivers into bays.