山丘平原过渡区土壤重金属污染特征及评价——以四川省五通桥区为例

Investigation and Assessment on in the Mountain-hilly Transitive County, Soil Heavy Metal Contamination Zone： A Case from Wutongqiao Sichuan

采集和分析了五通桥区不同功能区和乡镇73个土壤样品，以了解山丘平原过渡区土壤重金属的含量和污染特征。结果表明，重金属的平均含量为Pb32．18mg／kg、Cd0．82mg／kg、Cu28．61mg／kg、Zn108．08mg／kg、Ni32．66mg／kg、Cr72．44mg／kg；与四川土壤背景值相比，Cu、Ni、Cr的含量与之持平，Pb增加了0．11倍，Zn增加了0．32倍，Cd的积累较为严重，比背景值增加了10倍。污染评价结果显示该过渡区存在一定程度的重金属污染问题，不同功能区的污染程度排序为工业区〉生活区〉农业区。Cd在六种元素的土壤污染分担率中占55．46％，是最主要的污染元素；土壤Cd含量与Pb和Zn存在较高的相关性（相关系数为0．525和0．500），表明存在Pb—Cd和Zn—Cd的复合污染。

The content of heavy metals of 73 soils sampled from different function zones and towns in Wutongqiao County were analyzed to understand the soil heavy metal contamination characteristics of the mountain-hilly transitive zone in Sichuan. The mean content was Pb 32.18 mg/kg, Cd 0.82 mg/kg, Cu 28.61 mg/kg, Zn 108.08 mg/ kg, Ni 32.66 mg/kg and Cr 72.44 mg/kg in the studied soils, respectively. Cu, Ni, and Cr in soil were close to the soil background value in Sichuan, and the contents of Pb and Zn increases 11.35% and 31.64% compared with the background value, respectively. Soil Cd pollution was very serious because the Cd content in soil increased 10 times in comparison with the background value. The results also revealed that the studied soils were contaminated to some extent, and the ranked order of contaminated degree was industrial zone 〉 residential zone 〉 agricultural zone. Cd was the major pollutant which contributed 55.46% of soil contamination. Soil Cd content was positively and significantly correlated with Pb and Zn content （ P 〈 0.01, n = 73 ）, implying that there have compound pollution between Pb -Cd and Zn -Cd.