保定市城市绿地土壤重金属分布及其风险评价

The distributions and risk assessment of heavy metals in the soils from different urban greenland region of Baoding city

为给保定市城市绿地土壤重金属污染的预防和修复工作提供科学依据,采用调查分析方法,对保定市不同绿地土壤重金属(Cu、Zn、Ni、Cr、Pb和Cd)分布状况进行了调查,并采用单项、综合污染评价法和潜在生态风险指数法对土壤中重金属的污染程度进行了评价。结果表明:保定市城市绿地土壤主要的重金属污染因子为Gd,其次是Cu、Zn和Ni,Cr和Pb污染较小。不同绿地类型重金属污染由重到轻的顺序为:道路绿地>防护绿地>公园绿地>附属绿地>生产绿地。道路绿地和防护绿地土壤重金属潜在生态风险指数分别高达212.63和191.12,已经达到中等生态风险;公园绿地、附属绿地和生产绿地潜在生态风险指数分别为91.36、80.19和66.00,属于轻微生态风险。

The present distribution of heavy metals in the soils from Baoding urban greenlands were investigated and assessed using the contamination index of single item and comprehensive item, and the potential ecological risks of heavy metals were evaluated by the potential ecological risk index developed by Hakanson. The results indicated that the contamination of Cd was most serious in Baod- ing urban greenlands, the next in order being Cu, Zn and Ni, and that of Cr and Pb was the least. The ranking order of the heavy metal contamination in different types of greenland was the road greenland〉 the shelter greenland 〉 the park greenland 〉 the accessory greenland 〉 the production greenland. The potential ecological risk index of heavy metals in road greenland（RI = 212.63）and shelter greenland（RI = 191.12） have both reached a medium level, and that in park greenland（RI = 91.36）, accessory greenland （ RI = 80.19 ） and production greenland （ RI = 66.00 ） presented a slight ecological risk.