九龙江河口表层沉积物中重金属污染评价及来源

采用电感耦合等离子体质谱(ICP-MS)法测定了九龙江河口表层沉积物中24种重金属的质量分数,并采用地累积指数法和潜在生态风险指数法对该水域表层沉积物重金属的污染程度和潜在生态风险进行评价和分析. 结果表明,沉积物中重金属质量分数为w(Fe)>w(Ti)>w(Mn)>w(Ba)>w(Zn)>w(Sc)>w(Co)>w(Rb)>w(Y)>w(Ni)>w(Cr)>w(Pb)>w(Cu)>w(Th)>w(Sr)>w(V)>w(Li)>w(U)>w(Cs)>w(Bi)>w(Cd)>w(Sb)>w(Mo)>w(Hg),其中w(Cd)、w(Sc)、w(Bi)、w(Co)、w(Ni)、w(Zn)、w(Hg)和w(Cu)远高于背景值,说明九龙江河口表层沉积物中上述元素已存在一定程度的富集. 九龙江河口表层沉积物中Cd的I_geo(地累积指数)最高,属于偏重度污染；重金属的潜在生态危害顺序为Cd>Hg>Co>Ni>Cu>Zn>Pb>Cr>Mn>V,其中Cd的潜在生态危害属极强水平,Hg属较强水平. 多元统计分析(因子分析和聚类分析)结果表明,该河口沉积物中重金属污染来源主要有农业生产活动与自然源的复合污染、燃煤污染和采矿污染,其贡献率分别为48.81%、21.51%和13.72%. 

Pollution Assessment and Source Analysis of Heavy Metals in Surface Sediments from Jiulong River Estuary

Contents of 24 heavy metals in the surface sediments of Jiulong River Estuary were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Pollution degree and sources of the heavy metals were assessed and discussed. The results showed that the contents of heavy metals in the sediments followed the decreasing order of w(Fe)>w(Ti)>w(Mn)>w(Ba)>w(Zn)>w(Sc)>w(Co)>w(Rb)>w(Y)>w(Ni)>w(Cr)>w(Pb)>w(Cu)>w(Th)>w(Sr)>w(V)>w(Li)>w(U)>w(Cs)>w(Bi)>w(Cd)>w(Sb)>w(Mo)>w(Hg). Contents of Cd, Sc, Bi, Co, Ni, Zn, Hg and Cu were much higher than the background values, indicating these elements were rich in the sediments. Geo-accumulation index (I_geo) and potential ecological risk index were applied to evaluate the pollution degree and potential ecological risk of heavy metals in the area. The results of pollution assessment by geo-accumulation index revealed that the pollution degree of Cd was the highest and at a severely polluted level. The assessment results of potential ecological risk indicated that the potential ecological risk of heavy metals showed the order of Cd>Hg>Co>Ni>Cu>Zn>Pb>Cr>Mn>V. Cadmium had a high potential ecological risk, followed by Hg, which presented considerably high potential ecological risk. Multivariate statistical analysis (factor analysis and cluster analysis) was applied to investigate the possible sources of heavy metal pollution in the sediments. The results suggested that a combination of pollution of agricultural activities and natural processes, coal combustion pollution and mining pollution were the three major sources, accounting for 48.81%, 21.51% and 13.72%, respectively.