广州市不同功能区土壤重金属污染特征及评价

Characteristic and Evaluation of Soil Pollution by Heavy Metal in Different Functional Zones of Guangzhou

目的分析广州市不同功能区土壤重金属的含量水平。方法于2008年4月选择广州居民区、商业区、汽车站、文教区、医疗区和公园为研究对象,共采集55份土样。采用原子吸收光谱法测定Mn、Cu、Zn、Pb、Cd、Ni,采用原子荧光光谱法测定As、Hg;采用相关性分析探讨土壤重金属相互关系,采用单因子污染指数、内梅罗综合污染指数评价重金属污染程度。结果广州市不同功能区8种土壤重金属平均含量均超过广东省土壤背景值,其中Hg、Cd重金属含量分别高达背景值的16.28、14.64倍;Cu、Zn、Pb、Cd、Ni和As含量以商业区最高,Mn以汽车站最高,Hg以公园最高。Cu、Zn、Pb、Hg在不同功能区的分布差异存在统计学意义(P<0.05);Mn-Cu-Zn-Pb-Ni之间、Cu-Zn-Pb-Cd-Ni之间、Cu-Pb-Hg之间均存在相关性(P<0.05);各功能区中土壤重金属的污染程度表现为Zn、Cd、Hg呈重度污染,Cu、Pb、As呈中度污染(除商业区Cu、Pb和汽车站Cu为重度污染外),Mn、Ni呈无污染或轻度污染(除商业区Ni为中度污染外);不同功能区的土壤重金属内梅罗综合污染指数为:公园(18.13)>商业区(15.85)>居民区(13.34)>汽车站(10.75)>医疗区(9.61)>文教区(8.98),均达到重度污染。结论广州市不同功能区土壤重金属不同程度受到污染。

Objective To investigate and analyze the heavy metal pollution in soil in different functional zones of Guangzhou. Methods The commercial areas, bus stations, residential areas, cultural and educational areas, medical service areas and parks in Guangzhou were taken as the research objects, the soil samples were randomly collected by triple subsampling technique in each functional zone. The contents of Pb, Zn, Cu, Ni, Mn were determined by AAS, and the contents of As, Hg were determined by AFS. The relationship of heavy metal was analyzed with Pearson correlation analysis. The pollution of heavy metal was assessed with Nemerow comprehensive pollution index. Results The mean contents of heavy metals in soil samples from different city zones of Guangzhou exceeded the related background values in Guangdong province. The mean contents of Hg and As were 16.28 and 14.64 times respectively as high as those background values in soil in Guangdong. The contents of Cu, Zn, Pb, Cd, Ni and As were dominant in commercial areas, Mn was dominant in residential areas, Hg was dominant in urban parks. There was a significant difference in the level of Cu, Zn, Pb and Hg among different city zones （P〈0.05）. There were positive correlations among Mn, Cu, Zn, Pb and Ni, among Cu, Zn, Pb, Cd and Ni, and among Cu,Pb and. Hg （P〈0.05）, respectively. The Zn, Cd, Hg pollution was the severest among different functional zones. The Nemerow comprehensive pollution indexes ranked as follows： urban park （18.13） 〉 commercial area（15.85）〉residential area （13.34） 〉bus station（10.75） 〉 education area （8.98） 〉 hospital area （9.61）. Conclusion The urban soil in Guangzhou has been polluted by heavy metals.