重庆城口地区黑色页岩风化土壤重金属元素的富集特征和健康风险评价  

Enrichment characteristic and health risk assessment of heavy metals in soils derived from black shale in Chengkou area,Chongqing

作　　者：魏巍 凌斯祥 李晓宁 巫锡勇 WEI Wei;LING Sixiang;LI Xiaoning;WU Xiyong(Faulty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu,611756,China;School of Emergency Management,Xihua University,Chengdu,610039,China)

机构地区：[1]西南交通大学地球科学与环境工程学院,成都611756 [2]西华大学应急管理学院,成都610039

出　　处：《环境化学》2024年第7期2303-2312,共10页Environmental Chemistry

基　　金：国家自然科学基金(42077271,42377198,41877215);四川省科技厅项目(2023YFS0364);成都市科技支撑计划(2022-YF05-00340-SN)资助.

摘　　要：通过对重庆城口地区黑色页岩风化土壤进行系统采样,分析风化土壤重金属元素的含量组成和化学形态,探讨风化土壤重金属元素的富集特征,基于元素含量和化学形态开展人类健康风险评价.结果表明,研究区黑色页岩风化土壤中多种重金属元素的平均含量都超过中国土壤背景值,甚至超过农用地的风险管控值,表现出不同程度的重金属元素富集特征,尤其是Mo、Cd、As和Tl.致癌风险评价模型结果表明,As对于儿童和成人的大部分TCR值都超过风险安全限,Cr对于儿童和成人的绝大部分TCR值介于风险筛选值和风险安全限之间,少部分TCR值超过风险安全限,Pb对于儿童和成人的TCR值都小于风险筛选值.致癌元素地球化学形态萃取结果显示,土壤中As(92.53%—99.51%)、Cr(89.22%—97.87%)和Pb(62.59%—89.74%)主要以残余态的形式存在,具有很低的生物利用度和可给性,表明土壤中As、Cr和Pb对人类产生的致癌风险可以忽略不计.但是,土壤中Cd主要以可交换态(13.04%—36.82%)、碳酸盐结合态(18.69%—30.11%)和铁锰氧化物结合态(17.79%—31.07%)的形式存在,表现出较高的生物可获得性.由于Cd的TCR值均超过风险筛选值,且部分TCR值接近甚至超过风险安全限值.因此,研究区黑色页岩风化土壤中Cd可能对人类产生潜在的致癌风险,需要引起关注和重视.Soils derived from black shale weathering in Chengkou area,Chongqing were sampled and analyzed for concentration and geochemical speciation of heavy metals to investigate enrichment characteristic and human health risk assessment.The results indicate that elevated concentrations of most heavy metals in the soils underlain by black shale exceed the national soil background values,even the risk screening values,especially for Mo,Cd,As and Tl.The results of carcinogenic risk assessment model show that most of the TCR values of As for children and adults exceed the risk safety limit;most of the TCR values of Cr for children and adults fall into the range of the risk screening value and the risk safety limit,with a few TCR values exceeding the risk safety limit;all the TCR values of Pb for children and adults are less than the risk screening value.Sequential extraction of carcinogenic elements shows that As(92.53%—99.51%),Cr(89.22%—97.87%)and Pb(62.59%—89.74%)in soils mainly exist in residual faction that is difficult to be directly available by organisms,indicating that the carcinogenic risks from As,Cr and Pb in soils are negligible.However,Cd mainly exists in exchangeable fraction(13.04%—36.82%),carbonate fraction(18.69%—30.11%)and Fe-Mn oxide fraction(17.79%—31.07%)in soils,showing high bio-availability.Because the total carcinogenic risk TCR values of Cd exceed the risk screening value,and some of the TCR values are close to or even exceed the risk safety limit.Therefore,Cd in our studied soils may pose potential carcinogenic risks to local humans.

关 键 词：黑色页岩土壤 重金属 富集特征 地球化学形态 致癌风险 

分 类 号：X-1[环境科学与工程] O6[理学—化学]