广西廉州湾贝类养殖区重金属的含量变化及潜在生态风险评价

Variation of heavy metals in shellfish culture area of Lianzhou Bay,Guangxi and potential ecological risk assessment

根据2012—2017年每年8月廉州湾贝类养殖区现场监测资料,探讨了重金属(Hg、Cu、Pb、Cd)在其海水和表层沉积物中的含量变化,评价了2种介质中重金属的污染状况和沉积物重金属的潜在危害状况.结果表明:海水中重金属平均含量为Cu> Pb> Cd> Hg,除Cu外,Hg、Pb、Cd的年际变化均呈明显上升趋势,其污染程度顺序为Cu> Hg> Pb> Cd,整体水质状况基本属于本底水平;表层沉积物中重金属平均含量为Pb> Cu> Cd> Hg,除Hg外,Cu、Pb、Cd的年际变化趋势和水相中的变化基本一致,其污染程度排序为Cu> Pb> Hg> Cd,整体处于中等污染水平;表层沉积物中重金属的潜在生态风险程度顺序依次为Hg> Cd> Cu> Pb,6次调查结果的综合潜在生态风险指数RI值均低于140,平均值为76. 98,表明该海域属于低潜在生态风险水平.

According to the on-site monitoring data of shellfish culture area in Lianzhou Bay in August from 2012 to 2017,the contents of heavy metals(Hg,Cu,Pb and Cd)in seawater and surface sediments were discussed,and the pollution status of heavy metals in two media and potential hazards of heavy metals in sediments were evaluated.The results showed that the average contents of heavy metals in seawater were Cu>Pb>Cd>Hg.The inter-annual variations of Hg,Pb and Cd all showed an obvious upward trend except for Cu.The pollution level was Cu>Hg>Pb>Cd while the overall water quality of heavy metals was basically at the background level.The average contents of heavy metals in surface sediments were Pb>Cu>Cd>Hg.The inter-annual variations of Cu,Pb and Cd were basically the same as those in the aqueous phase except for Hg.The pollution level was Cu>Pb>Hg>Cd while the overall pollution level was medium.The potential ecological risk level of heavy metals in surface sediments was Hg>Cd>Cu>Pb and the synthetical potential ecological risk index RI was less than 140 with an average 76.98 from the results of 6 surveys.It indicates that the area was in the state of low potential ecological risk level.