Development of soil and groundwater monitoring for natural hazard by soil and water quality measurement system

Abstract

Heavy metals from mines affect soil and groundwater cause a severe impact on the health of local residents. The soil samples were characterized the distribution and chemical speciation and then estimated the human health risks of two mine-affected soils after stabilization. Two extraction techniques (Tessier and Wenzel sequential extraction methods) were applied to fractionate metals such as arsenic (As) and zinc (Zn), quantify the chemical status of metals in the soils. The hazardous indices (HI) for non-carcinogenic risk and carcinogenic risk (CR) to humans were evaluated according to the pseudo-total concentrations of metal in soils. The study sites were polluted by As and lead (Pb). The CR values of carcinogenic for As were within the ranges from 1.38 × 10-4 to 1.25 × 10-3 and 3.71 × 10-4 to 3.35 × 10-3 for both YD and DS, respectively. But, according to US Environmental Protection Agency (US EPA) the CR values were threshold limits (1 and 1 × 10-6, respectively) in both the soils. The HI for non-carcinogenic risk was highest for As in YD (2.77) and DS (7.46) soils, which covered approximately 96 and 84% of HI, respectively. In summary, contribution of As to risk from heavy metals was dominant, however, chemical fraction in the soil was mainly amorphous Fe and Al oxides, crystalline Fe and Al oxides, and residual forms, which were relatively strongly-bounded in soil. The weathering could change chemical fraction of As to more soluble fraction. Keyword: Heavy metals, Risk assessment, Mine-affected soil, Sequential extraction method