Distribution characteristics and health risk assessment of heavy metals in atmospheric deposition from a typical smelting area in southern Hunan Province

To study the distribution characteristics and health risk of heavy metals in atmospheric deposition in a typical smelting area, five sampling sites were set up downwind of prevailing wind direction from a smelting plant in southern Hunan Province, arranged by distance from near to far (Sites 1 to 5). Over a period of one year (April 2023 to April 2024), atmospheric deposition samples were collected and the concentrations and the atmospheric deposition fluxes of nine heavy metals in those samples were analyzed. The health risks of these metals were also assessed. The results showed that Pb and Zn had the highest average deposition fluxes among the heavy metals, at 24.58 and 20.72 g/hm², respectively. The average concentrations of heavy metals decreased in the order of Pb>Zn>As>Mn>Ni>Cu>Sb>Cd >Cr. The concentrations and flux of heavy metals in atmospheric deposition decreased with increasing distance, indicating that smelting activities were the main source of atmospheric deposition. In terms of non-carcinogenic risks, the non-carcinogenic risk coefficient (HI) of arsenic (As) was the highest at 5.53×10⁻³, but it was below 1.0, indicating that none of these nine heavy metals posed non-carcinogenic health risks or the risks were relatively low. Additionally, the HQ values for children were generally higher than those for adults, suggesting that children were more vulnerable to their health effects. Regarding carcinogenic risks, the total carcinogenic risk coefficient of arsenic (As) was the largest at 1.66×10⁻⁷, which did not exceed 10⁻⁶, indicating that the carcinogenic risk was minimal in this smelting area. Therefore, the study recommended establishing a dynamic monitoring system for atmospheric deposition of heavy metals in the southern Hunan smelting area, with the priority given to controlling As pollution sources, to accurately assess the potential health risks of heavy metals in atmospheric deposition.