运用主成分分析(PCA)评价海洋沉积物中重金属污染来源

测定了胶州湾表层沉积物中重金属和有机质的含量,并用平均富集因子(Average Enrichment Factors,AEF)进行污染状况评价,发现胶州湾表层沉积物重金属污染可分为3类:轻度污染(AEFs<2),其中有Zn(AEF=1.11)、Pb(AEF=1.15)、Cr(AEF=1.52)、Mn(AEF=0.80)、Fe(AEF=0.45);中度污染(AEFs=2～3),包括Cu(AEF=2.79)和Cd(AEF=2.52);严重污染(AEFs>3),主要有As(AEF=3.03)和Hg(AEF=8.08).进一步通过主成分分析(Principal Component Analysis,PCA)研究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52.61%、17.37%和15.60%,表明重金属主要有3个来源:工业排污、有机质降解、岩石的自然风化与侵蚀过程.PCA的聚类分析指出,本次研究中所调查的14个站位在污染程度上可分为5大类,此结果既反映了胶州湾表层沉积物近河口污染程度重远河口污染程度轻的特点,同时也支持了工业排污是沉积物中重金属污染主要来源的分析.

Application of Principal Component Analysis(PCA) for the Estimation of Source of Heavy Metal Contamination in Marine Sediments

Concentrations of heavy metals and organic matter in the bottom sediments of Jiaozhou Bay were determined and the average enrichment factors (AEFs) were used simultaneously to evaluate the extent of metal enrichment-contamination. Results show that heavy metal contamination in this bay could be divided into three groups: negligible to low contamination (AEFs < 2), which is the case of Zn (AEF = 1.11), Pb (AEF = 1.15), Cr (AEF = 1.52), Mn (AEF = 0.80) and Fe (AEF = 0.45); moderate contamination (AEFs = 2 - 3), which is the case of Cu (AEF = 2.79) and Cd (AEF = 2.52); certain to severe contamination (AEFs > 3), As (AEF = 3.03) and Hg (AEF = 8.08) being included in this group. Principal component analysis (PCA) was applied to estimate the sources of heavy metal contamination. Results that the first three components accounted for 52.61%, 17.37% and 15.60% of the total variance respectively exhibited that industrial wastewater, degradation of organic matter and erosion of rocks were the main sources of heavy metal contamination. The Q-analysis of PCA indicated that 14 stations could be divided into five groups. This result not only reflected the pollution characteristic of surface sediments, but also provided fundamental evidences for the putative analysis that industrial discharge is the main source of heavy metal contamination in Jiaozhou Bay.