防城港近岸海域及河口溶解态重金属污染特征

Pollution characteristics of dissolved heavy metals in nearshore and estuary of Fangchenggang

为了解近岸海域及河口重金属的分布特征和污染状况,测定了采自防城港近岸海域及河口的25个表层水样的溶解态重金属(Zn、Cu、Pb、Cd、As、Hg)含量,并分析了其含量特征及空间分布特点,探讨了重金属与主要环境因子之间的相关性,并按单项污染指数法及综合指数WQI法对其进行评价。结果表明,研究区域溶解态重金属含量从高到低的顺序依次是Zn>Cu>Pb>As>Cd>Hg,除Zn、Pb元素外,Cu、Cd、As、Hg元素平均含量均低于国家一类海水水质标准。重金属与环境因子相关性分析表明,p H对Zn含量的影响比较显著,盐度对As、Zn、Pb含量的影响比较显著,温度对Cu、As、Hg含量的影响比较显著,而溶解氧对Cu、Pb含量的影响比较显著。从单项污染指数来看,研究区Zn、Pb均受到一定程度的污染,而西湾和东湾在一定程度受到Hg的污染;从综合污染指数来看,除防城江上游区域外,防城港近岸水域溶解态重金属综合污染指数均小于1,属无污染。

In order to grasp the distribution and pollution characteristics of heavy metals in coastal waters and estuaries,the content characteristic and distribution characteristics of dissolved Zn,Cu,Pb,Cd,As and Hg in surface water samples of the near shore and estuary in Fangchenggang were determined and analyzed,the correlation of main water body environmental factors and heavy metal contents was discussed,and six heavy metals were assessed by the single pollution index and water quality index(WQI).The results showed that the average contents of dissolved heavy metals in the surface waters of Fangchenggang offshore waters were Zn>Cu>Pb>As>Cd>Hg,in addition to the contents of Zn and Pb,the average contents of Cu,Cd,As and Hg were below the national seawater quality standards.Different heavy metals had different correlations with pH,salinity,temperature,and dissolved oxygen(DO),which showed that the effect of pH on the content of Zn and salinity on the content of As,Zn and Pb was significant,and the influence of temperature on Cu,As and Hg content was significant,while the influence of DO on Cu and Pb content was significant.The single pollution index showed that Zn and Pb in the study area are polluted to a certain extent,while the west bay and east bay were polluted by a certain degree of Hg.According to WQI,in addition to the upstream area of Fangchenggang River,the water quality index of dissolved heavy metals in the surface offshore waters was less than 1,which was pollution-free.