摘要:
对深圳市中心区城市绿地表层土壤(0—20cm)中Cu,Zn,Pb和Cd的含量、化学形态分布和迁移性进行研究.结果表明,土壤中Cu,Zn,Pb和Cd的含量分别为6.4—188.2(26.3)mg·kg-1,34.9—284.8(69.1)mg·kg-1,15.2—245.5(47.2)mg·kg-1和0.01—3.48(0.47)mg·kg-1.道路绿化带土壤中Cu,Zn和Pb的平均含量最高,在公园绿地土壤中Cd的平均含量最高.分别有75.6%,87.0%,98.8%和98.8%的土壤中Cu,Zn,Pb和Cd的含量超过广东省赤红壤的背景值,重金属在土壤中呈现明显的富集特征.土壤中Cu,Zn和Cd以残渣态所占比例最高,Pb以铁锰氧化物结合态最高.随着土壤中Cu,Zn,Pb和Cd含量的增加其残渣态所占比例降低,铁锰氧化物结合态或交换态所占比例增加,重金属活性增大.土壤中Cd迁移能力最强,迁移能力依次为CdZnPb和Cu.
关键词:
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重金属
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化学形态
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土壤
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深圳市
Abstract:
Soil samples with 0—20cm depth for urban green space were collected at central districts in Shenzhen city,and the concentration,chemical fractionation and mobility of Cu,Zn,Pb and Cd in soils were studied.The results indicated that the concentrations of Cu,Zn,Pb and Cd were 6.4—188.2(26.3)mg·kg-1,34.9—284.8(69.1)mg·kg-1,15.2—245.5(47.2)mg·kg-1 and 0.01—3.48(0.47)mg·kg-1respectively.The mean concentrations of Cu,Zn and Pb in soils for road green belt,and Cd for park green space were the highest.75.6%,87.0%,98.8% and 98.8% of studied soils for Cu,Zn,Pb and Cd concentrations were higher than background values in Latosolic red earth of Guangdong province respectively,which reflected significant enrichment of heavy metals in soils.The Cu,Zn and Cd in soils were predominately located in residual fraction,Pb in Fe-Mn oxide fraction.With the increase of soil Cu,Zn,Pb and Cd concentrations,the precentage of their residual fraction decreased,Fe-Mn oxide or exchangeable fraction increased,and their activities increased.Cadmium was identified as the most mobile element,and the order of mobility was Cd Zn Pb,Cu.
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