湛江湾表层沉积物微量元素特征及生态风险评价

利用ICP-MS和XRF方法,对湛江湾表层沉积物样品进行稀土元素和重金属元素丰度测试,并利用5种不同的评价方法进行重金属污染评价,对湛江湾临港产业布局提供参考。结果表明,沉积物中稀土元素总量高于大洋玄武岩,LREE和HREE存在一定程度的分异,Eu和Ce表现均为负异常特征,其来源可能主要来源于陆源物质。单因子指数评价法和地质积累指数法表明,沉积物Cu与Zn少量超标,具有中等程度污染,而Cd超标严重,达到严重污染程度。沉积物质量基准法分析表明,污染物质对水生生物的毒性发生概率在21%左右,其中以Cu,Zn和Cd为主。潜在生态风险评估结果表明,生态风险等级为Cd>Cu>Zn>Pb>Cr,其中Cr具极强的潜在生态风险,并且存在增大的趋势,须采取有效措施加以改善。

Analysis of Trace Element Characteristics and Ecological Risk Assessment in the Surface of Sediments in the Zhanjiang Bay

In this study,ICP-MS and XRF methods were used to test the abundance of rare earth elements(REE)and heavy metal elements in the surface sediments in the Zhanjiang Bay,and five different evaluation methods were used to conduct the pollution assessment of heavy metals,which can provide a reference for the industrial layout in the Zhanjiang Bay.The total REE content is lower than those from the oceanic basalt.There are a certain degree of differentiation between light rare earth elements(LREE)and high rare earth elements(HREE)in sediment as well as negative anomalies of Eu and Ce.The REE in sediments of the Zhanjiang Bay probably generated from terrestrial input.In this study,the single factor index evaluation method and the index of geological accumulation method showed that a small amount of Cu and Zn in sediments exceeded the standard and had a moderate degree of pollution,while Cd exceeded the standard and reached a severe degree of pollution.The sediment quality guideline showed that the probability of Cu,Zn and Cd poisoning in aquatic organisms of Zhanjiang Bay was approximately 21%.The assessment results of potential ecological risk indicate that the ecological risk grade was as follows:Cd>Cu>Zn>Pb>Cr.Among them,Cr has a strong potential ecological risk with an increasing trend,which must be taken by effective measures to improve it.