广州主城区土壤砷元素污染及健康风险评价

Arsenic Contamination in Soil and Health Risk Assessment in Guangzhou Downtown Areas

[目的]了解广州主城区土壤砷（As）含量、空间变异性及其影响因素,评价土壤As污染程度和人体健康风险。[方法]采用网格布点法选择广州主城区土壤为研究对象,采用原子荧光光谱法测定土壤As含量;基于ArcGIS地统计模块研究土壤As空间变异性;采用单因子污染指数评价As污染程度以及美国环保署（EPA）风险评价模型评价人体健康风险。[结果]广州主城区土壤As平均含量（23.40mg/kg）高于广州市、广东省和中国土壤背景值（P〈0.05）,不同城区土壤As分布差异无统计学意义（P〉0.05）;土壤As呈中等空间相关关系,主要受结构性因素和随机性因素的影响;土壤As含量与土壤有机质、pH不呈相关关系（P〉0.05）;土壤As污染程度从无污染到中度污染范围变化,66.13%土壤样遭受污染,平均污染程度为轻度污染;广州主城区土壤As的儿童平均非致癌风险值大于风险限值1,成人平均非致癌风险值小于风险限值1;儿童和成人土壤As致癌风险指数在1×10-5~1×10-6范围,均在致癌风险阈值1×10-6～1×10-4范围。[结论]广州主城区土壤As遭受不同程度污染;广州主城区土壤As对儿童非致癌风险存在潜在健康风险;对儿童和成人致癌风险均在致癌风险阈值范围内,对人体健康不会造成明显危害。

[ Objective ] To explore the distribution, spatial variability, and its influencing factors of arsenic in surface soil of Guangzhou downtown areas, and to assess the pollution level and human health risks of arsenic contaminated soil. [ Methods ] Soil samples were collected from the downtown areas of Guangzhou by lattice technique. Arsenic contamination was determined by atomic fluorescence spectroscopy. The spatial variability of arsenic was analyzed by the geostatistics module of ArcGIS. The pollution level of arsenic was assessed with single pollution index. Human health risk of arsenic was assessed by U.S. Environmental Protection Agency＇s risk assessment model. [ Results ~ The mean concentration of arsenic in Guangzhou downtown areas （23.40 mg/kg） exceeded the background value in Guangzhou, Guangdong Province, and China, respectively （P 〈 0.05）; and no statistical differences in the arsenic contaminations were found among the districts （P 〉 0.05）. The results of geostatistical analysis showed medium spatial correlations of arsenic, indicating that the concentrations of arsenic in soil were affected by random factors and structural factors. There was no significant correlation among arsenic content, pH, and organic matter content （P 〉 0.05）. The selected soil samples ranged from none to medium arsenic pollution, 66.13% soil samples were contaminated, and averaged at slight pollution. The non-cancer risk index of arsenic exceeded the risk limit of 1 for children and were lower than the risk limit of 1 for adults. The cancer risk index of arsenic in surface soil was in the range of 1 ×0-5-1 × 10-6 for both children and adults, within the risk threshold of 1 × 10-4-1 × 10-6. [ Conclusion ] The soil in Guangzhou downtown areas is polluted by arsenic in varying degrees. The cancer risk index level in the exposed population is acceptable, but the non-cancer risk index level for children is higher than the limit value and may pose potential health risks to local children.