Source-oriented health risk assessment of heavy metals in soil and dust at coal resource-based urban parks in northern China based on bioaccessibilities

Abstract

The mining and utilisation of coal release numerous heavy metals (HMs) into the urban environment, but there are few studies expanding on source-oriented health risk assessment based on bioaccessibility for the identification of health priority control pollutants at coal resource-based cities. Hence, dust and soil samples were collected from urban parks in Datong, Shanxi Province, known as the coal capital of China, to evaluate the pollution level, bioaccessibility, and source-specific health risk assessment. The results revealed severe contamination of As, Cd, and Pb in both soil and dust, with particularly high levels of Cd, which reached 16.07 and 15.09 times the background values in dust and soil, respectively. Overall, HM pollution and the corresponding ecological risks in dust and soil were categorized as moderate and high, respectively. Manganese (30.55 %) and Cr (1.36 %) in dust showed the highest and lowest percent bioaccessibility in the gastrointestinal system, respectively. High bioaccessibilities and high concentrations of HMs reflect the prevalence and severity of dust and soil pollution in Datong. Multivariate statistical analysis showed that natural sources, traffic sources, and industrial sources are the three determinants of HM accumulation. Their contribution rates to dust and soil are as follows: 40.35 %, 21.54 %, 6.89 %, and 32.21 %, 18.92 %, 13.09 %, respectively. Once bioaccessibility was accounted for, lower non-carcinogenic and carcinogenic risks of HMs were observed than those based on total HM concentrations. However, the average total carcinogenic risk value for adults and children still exceeded the safety threshold (1.0E-06). Among coal resource–based cities, natural sources were identified as the priority pollution source, and As emerged as the critical pollutant. In conclusion, this research provides insights into the prevention and control of HM pollution and health risk assessment in urban ecosystems.