基于主成分分析法的泉州湾表层沉积物中重金属污染可能来源分析

Analysis of the source of heavy metal contamination in surface sediments of Quanzhou Bay based on principal component analysis(PCA)

通过测定泉州湾潮间带表层沉积物中重金属含量,并用地质累积指数(Igeo)对各重金属元素的污染状况进行了评价,发现泉州湾表层沉积物中各重金属元素污染状况可分为4类:无污染(Igeo<0)的元素为Co(Igeo=-0.67);轻-中度污染(0<Igeo<1)的元素为Cr(Igeo=0.65)、As(Igeo=0.52)、Zn(Igeo=0.75)、Pb(Igeo=0.11);中度污染(1<Igeo<2)的元素为Cu(Igeo=1.58)、Ni(Igeo=1.32)、Mn(Igeo=1.08);极严重污染(Igeo>5)的元素为Cd(Igeo=8.70).通过主成分分析法(PCA)进一步研究了沉积物中重金属的来源,发现前3个主成分的贡献率分别为32.884%、31.676%、21.988%.这表明重金属污染主要有3个来源:即工业点源排污;矿物开采及农业化肥农药使用的非点源污染;岩石的自然风化侵蚀过程和有机质降解产生的内源释放.同时聚类分析结果表明,调查的9个站位根据其在重金属污染程度上的差异,可分为3个大类:2～7号站位为第1类;1号站位为第2类;8、9号站位为第3类.这反映了泉州湾潮间带表层沉积物中的重金属污染物空间分布特点即重金属污染物含量由湾内向湾外逐渐降低,同时也支持了晋江和洛阳江的工业点源排污、矿物开采和化肥农药残留的非点源污染是沉积物中重金属主要污染源的分析.

Concentrations of heavy metals in the surface sediments from the intertidal zone of Quanzhou Bay were determined and the geo-accumulation Index（Igeo） was employed to evaluate the extent of heavy metal contamination.The results show that heavy metal contamination in the bay could be divided into four groups： no contamination（Igeo〈0）,as in the case of Co（Igeo=-0.67）;light-moderate contamination（0〈Igeo〈1）,as in the case of Cr（Igeo=0.65）,As（Igeo=0.52）,Zn（Igeo=0.75） and Pb（Igeo=0.11）;moderate contamination（1〈Igeo〈2）,as in the case of Cu（Igeo=1.58）,Ni（Igeo=1.32） and Mn（Igeo=1.08）;severe contamination（Igeo〉5）,as in the case of Cd（Igeo=8.70）.Heavy metal contamination source analysis though principal component analysis（PCA） revealed that the contribution rates of the top three principal components were 32.884%,31.676% and 21.988%,respectively,indicating that the three main sources of heavy metals were as follows： industrial wastewater;chemical fertilizers and pesticides of agriculture and mining;degradation of organic matter and erosion of rocks.The clustering indicated that the nine stations could be divided into three groups： 2～7 for Class 1;1 for Class 2;8 and 9 for Class 3.These findings not only reflected the heavy metals contamination characteristic of surface sediments in space,but also provided fundamental evidence that industrial wastewater,chemical fertilizers and pesticides from agriculture and mining present in the Jinjiang River and Luoyang River were the principal sources of heavy metal contamination in surface sediments of Quanzhou Bay.