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& #215;10-5-1& #215;10-6 for both children and adults, within the risk threshold of 1& #215;10-4-1& #215;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.
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