海南岛东部陆架表层沉积物重金属污染评价

对海南岛东部陆架29个站位的表层沉积物重金属元素(Cu、Cr、As、Pb、Zn和Cd)进行了含量测试及分布特征分析,采用地累积指数(I_geo)、富集因子(EF)和潜在生态危害指数对其进行了评价.研究结果表明:重金属含量空间分布趋势较为相似,呈现出由陆向海略微减小的趋势.6种重金属元素可能有相同或相似的来源,但Pb和As受到了人类活动影响.以上地壳和海南岛近岸未受污染沉积物为背景值的I_geo和EF值排序有所不同.研究区单项潜在生态危害系数平均值排序为Cd> As> Cu> Pb> Cr> Zn,Cu、Cr、Pb和Zn等4种重金属为轻微潜在生态危害,As和Cd在个别站位达到了中等潜在生态危害水平.综合潜在生态危害指数评价结果显示,研究区绝大多数站位处于轻微潜在生态危害水平.潜在生态危害水平相对较高的区域邻近万泉河、陵水河和三亚河河口.

Evaluation of heavy metal pollution in surface sediments in the continental shelf to the east of Hainan Island

The distribution and concentrations of six heavy metals (Cu, Cr, As, Pb, Zn, and Cd) in 29 surface sediment samples collected from the eastern continental shelf of Hainan Island were determined in this study. The geo-accumulation index (I_geo), the enrichment factor (EF), and the potential ecological risk index (PERI) were analyzed to assess the potential contamination and the environmental risks associated with heavy metals. Generally, the concentrations of 6 heavy metals showed a similar distribution pattern, and were slightly decreased from the coast toward offshore. It was possible that these heavy metals shared similar sources, whereas the levels of Pb and As were influenced by anthropogenic activities. There were differences in the I_geo and EF values obtained from upper continental crust and the unpolluted sediment in offshore of Hainan Island. The average individual potential risk index of heavy metals showed the order Cd> As> Cu> Pb> Cr> Zn, suggesting “low potential ecological risks” of Cu, Cr, Pb and Zn. There were only a few sites possessing “considerable potential ecological risks” of As and Cd. PERI indicated that most of the sites could be categorized as “low potential ecological risks” in the studied area. The areas with higher potential ecological risks were near Wanquanhe, Lingshuihe and Sanyahe.