成都市不同功能区表层土壤中重金属元素分布特征及风险评价

Distribution Characteristics and Risk Assessment of Heavy Metal Elements in Topsoil of Different Functional Areas in Chengdu

为探究成都市不同功能区环境质量,对成都市区交通区、商业区、居住区、文娱区的表层土中重金属含量进行分析,运用富集因子法、潜在生态风险指数法和EPA(Environmental Protection Agency,美国环保署)健康风险评价法对环境和人体风险进行评价。结果表明,表层土中重金属元素含量整体表现为交通区>商业区>居住区>文娱区,Zn含量普遍最高,Cd均相对较低;各重金属元素受人为源影响较大,Cr、Ni、Pb、Cu均存在不同程度地富集;Ni、Cd存在明显的潜在生态风险,而综合潜在生态风险指数RI在交通区和商业区为很强,其余二者为较强;人体健康方面,重金属暴露风险途径为手-口摄入>皮肤接触>呼吸吸入,且儿童风险暴露量均高于成人,各金属元素的非致癌风险可忽略,而致癌重金属元素Cd、Ni、Cr均不存在致癌风险。总的来说,成都市各功能区表层土中重金属元素对生态环境风险较大,对人体危害较小,但相关部门仍应对其进行密切关注,采取针对性措施,防止其生态风险进一步加强,并持续将其健康风险控制在合理范围,使各功能区土壤环境质量持续改善。

In order to explore the environmental quality of diferent functional areas in Chengdu,heavy metal contents in topsoil of transportation areas,commercial areas,residential areas and entertainment areas were analyzed.The enrichment factor method,potential ecological risk index method,and EPA(Environmental Protection Agency)health risk assessment method were used to evaluate the risks of heavy metals to environmental and human.The results showed that the overall contents of heavy metal elements in topsoil was in the order of transportation areas>commercial areas>residential areas>cultural and entertainment areas,and the content of Zn was generally the highest,while that of Cd was relatively low.The heavy metal elements were greatly influenced by human activites,Cr,Ni,Pb and Cu were all enriched to varying degrees in the topsoil of each functional areas.Potential ecological risks of Ni and Cd were significant,and the comprehensive potential ecological risk index RI in traffic and commercial areas were very strong,while the remaining two areas were relatively strong.In terms of human health,the risk routes of heavy metal exposure was hand-mouth intake>skin contact>respiratory inhalation,and the risk exposure of children was higher than that of adults.The non-carcinogenic risk of all metal element could be ignored,while the carcinogenicheavy metal elements Cd,Ni and Cr have no carcinogenic risk.Generally speaking,the heavy metal elements in the topsoil of each functional areas in Chengdu have a greater risk to the ecological environment,but less harm to the human health.However,the relevant departments should still pay close attention to them,and take targeted measures to prevent their ecological risks from further strengthening,and continue to control the health risks within a reasonable range,so that the soil environmental quality of each functional area could continue to improve.