海南小海海水富营养化和重金属特征分析与评价

Analysis and Evaluation of Eutrophication of Seawater and Characteristics of Heavy Metal in Xiaohai,Hainan

通过对万宁小海水体环境调查与数据分析,并采用单因子指数、综合污染指数、有机污染指数、富营养化指数对水质状况进行评价。结果显示,整个小海海域水质状况处于四类海水水质标准,呈贫营养状态,湾内中部出现了轻度或中度富营养,属于氮限制潜在性富营养;重金属单因子指数污染为:Cu>Pb>Zn>Hg>Cd;有机污染指数均值为0.6,有机物污染等级较低,水质状况较好;小海重金属的污染程度轻微(WQI远小于1),属于清洁海域。相关性分析表明小海海域盐度、pH、DO、石油类和Hg主要受南海的潮汐输送影响,DIN、DIP、CODMn、Zn、Cd、Pb和Cu则受河流径流影响较大。Zn、Cd、Pb和Cu来源于相似或同一污染源。变异系数结果表明海水中重金属空间离散性较小,重金属污染物同源性高。

According to survey and analysis of the seawater environment in Xiaohai lagoon in Wanning,the status of marine environment was assessed using the single factor index,water quality index(WQI),eutrophication index,and organic pollution index.The results showed that the seawater quality of the entire Xiaohai lagoon conformed to the GradeⅣstandard,which was in the oligotrophic level.There was a mild or moderate eutrophication in the central of the lagoon,which belonged to the potential eutrophication of nitrogen limitation.The single factor index values of heavy metals were in the following order:Cu>Pb>Zn>Hg>Cd.The degree of organic pollution was low,the water quality was at good level and the average value of the organic pollution index was 0.6.The WQI was less than 1and the pollution level of heavy metal in seawater was low and clean.The correlation analysis showed that salinity,pH,DO,petroleum and Hg were mainly affected by the tidal runoff from the South China Sea,and DIN,DIP,CODMn,Zn,Cd,Pb and Cu were greatly influenced by river input.Zn,Cd,Pb and Cu showed a similar distribution pattern.The results of coefficient of variation(Cv)showed that the spatial dispersion of heavy metal was small,and the sources of heavy metal pollutants were same.