Heavy metal contamination and health risk assessment in the vicinity of mining area in Bac Kan province, Vietnam

Abstract

Mining activities have resulted in potential contamination by heavy metals which adversely affects soil, water, and food quality and poses a threat to human health. Na Dieu lead-zinc mine locates in Thuong Quan commune, Ngan Son district, Bac Kan province of northern Vietnam. Because of the exploitation activities, a large amount of hazardous wastes has been generated during the metal mining operations and it caused environmental contamination and finally health effects on local residents. Surface water, soil, sediment, and rice grain samples were collected in the vicinity and nearby stream from the mining site. Sampling was conducted in October 2019 in the rainy season. The concentration of 11 elements (As, Cd, Co, Cu, Cr, Fe, Hg, Mn, Ni, Pb, and Zn) in water, soil, sediment, rice, and husk were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS); Cold Vapour Atomic Fluorescence Spectroscopy (CV-AFS) and Directly Mercury Analyzer (DMA) were used for the Hg analysis. The results showed that concentrations of As (5.63-380.54 mg/kg), Cd (0.44-6.52 mg/kg), Pb (9.7-1099.2 mg/kg) and Zn (42.76-237.28) in soil were higher than the Vietnam standard for forestry soil. Arsenic concentration (15.58-26.62 mg/kg) in agriculture soil was also higher than the Vietnam standard for agriculture soil. For sediment, the As concentration in all samples (25.15-377.55 mg/kg) were higher than the Vietnam standard for sediment. Especially, As level in rice (0.18-0.4 mg/kg) was significantly higher than the Codex standard for polished rice. The Geo-accumulation index were also calculated and revealed the contamination risk in soil and sediment near Pac Lang gold mine and Na Dieu lead mine in soil and sediment. The principal component analysis, and Spearman correlation analysis were applied for preliminary identification of the contamination sources in soil. The mineralogical analysis, statistic results and the comparison with different studies indicated that the contamination sources in soil were the combination of anthropogenic and geogenic source. Health risk assessment in soik showed that children is in higher risk than the adult in non-carcinogenic and carcinogenic risk. For a comprehensive assessment on environmental contamination, the quality of soil, air, water and food should be investigated in further study and the solutions of environmental remediation need to be suggested urgently.