Spatiotemporal variations and health risks of arsenic in soils of the Pearl River Basin, China.

The Pearl River Basin (PRB), the second-largest river basin in China, is the most economically developed at its lower reaches and rich in arsenic-bearing mineral resources at its upper reaches. Arsenic (As) is emerging as a serious environmental and health-related concern, becoming a focal point of public attention. The objective of this study was to explore the spatiotemporal variations of As concentration and distribution in the topsoils of the PRB using monitoring data 3 times from the 1990s, the 2000s, and the 2010s, based on geochemical baselines project. Results indicate that the As content in soils displayed an increasing pattern from the 1990s (median 11.40 mg/kg) to the 2000s (14.46 mg/kg), followed by a decrease from the 2000s to the 2010s (12.25 mg/kg). The largest changes occurred in mining areas. The proportion of samples with As concentrations exceeding the risk screening value decreased from 19.51 % (1990s), 10.78 % (2000s), to 4.69 % (2010s). The hazard quotient (HQ) of pollutant into non-carcinogenic risk for adults increased from 0.12 in the 1990s to 0.19 in the 2000s, and then decreased to 0.08 in the 2010s. Meanwhile, the HQ for children increased from 0.96 in the 1990s to 1.54 in the 2000s, and decreased to 0.67 in the 2010s. These characteristics suggest that certain areas still exhibited localized As pollution and associated health risks. The high values and changes of As in soils are attributed to geologic background and anthropogenic activities. Comprehensive management, particularly the implementation of soil pollution prevention and control policies by the Chinese government since 2008, has constituted a pivotal tool in reducing the As content in the alluvial surface soils newly formed by river water picking up pollutants that decreased from the 2000s to the 2010s into watercourses and deposited in the overbank or plain region.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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