Pollution Characteristics and Health Risk Assessment of Potentially Toxic Elements in the Black Soil Region of Southern Jilin Province, China

Abstract

To investigate the spatial distribution, pollution status, sources, and health risks of potentially toxic elements (PTEs) in the topsoil of three counties/cities (Shuangliao City, Lishu County, and Gongzhuling City) in southern Jilin Province, 138 topsoil samples (0–20 cm depth) were collected and analyzed for eight elements (As, Cd, Cr, Pb, Hg, Cu, Ni, and Zn). Spatial distribution patterns were examined using Kriging interpolation. Pollution levels were assessed via the single-factor pollution index, Nemerow comprehensive pollution index, and potential ecological risk index. Source identification was conducted by integrating correlation analysis, cluster analysis, and principal component analysis. Health risks for adults and children were quantified using the U.S. Environmental Protection Agency (EPA) exposure model. The results showed average concentrations of 16.758 mg/kg for Cu, 21.415 mg/kg for Ni, 0.076 mg/kg for Cd, 47.161 mg/kg for Cr, 19.382 mg/kg for Pb, 16.681 μg/kg for Hg, 47.630 mg/kg for Zn, and 7.047 mg/kg for As. Spatially, the elements exhibited a pattern of “higher in the east, lower in the west”. Coefficients of variation indicated a strong variation for Hg, Cd, and As and moderate variation for the remaining elements, reflecting a notable anthropogenic influence. Pollution assessment revealed that the average single-factor pollution indices ranged from 0.007 to 0.235, and the Nemerow comprehensive pollution index was 0.694, corresponding to an overall nonpolluted status. The average potential ecological risk index (RI) was 73.417, indicating low ecological risk, with only 18.39 and 7.97% of samples showing moderate risk for Cd and Hg, respectively. Source analysis indicated that Cu, Ni, Cr, and Zn originated mainly from soil parent material (natural sources with minor human input), Cd and Hg derived primarily from agricultural fertilization, and Pb and As were associated with combined traffic and agricultural emissions. Health risk assessment showed an average non-carcinogenic hazard indices (HI) of 7.43 × 10–2 for adults and 4.18 × 10–1 for children (both <1), and average carcinogenic risks (TCR) of 3.81 × 10–5 for adults and 5.32 × 10–5 for children, all within acceptable ranges. Oral ingestion was the dominant exposure pathway (>90%), with As, Cr, and Pb as the main contributors to non-carcinogenic risk, and Ni, Cr, and As as the primary contributors to carcinogenic risk. In conclusion, the black soil region of southern Jilin Province exhibits low PTE pollution, low ecological risk, and controllable health risks.