Health risk assessment of heavy metals in the soil-water-rice system around the Xiazhuang uranium mine, China

Heavy-metal pollutants in the soil and surface water of agricultural areas accumulate in rice and may have adverse effects on the health of consumers. In this study, we determined the levels of heavy-metal contamination in agricultural areas around the Xiazhuang uranium deposits in northern Guangdong Province, China, using equidistant sampling methods along a river near the mine tailings. The pH values of all the water samples were determined. The heavy-metal concentrations in water, bottom sludge, and rice were measured. The extent of contamination was evaluated by calculating Nemerow's pollution index, contamination factor, and hazard quotient. The result shows U transferred from mine to soil and rice with irrigation water. The main pollutants and their pollution indices in soil are U (6.31), Th (4.02), Pb (2.52), Cd (2.36), Zn (1.52), and Mn (1.39). The rice grain can hardly enrich U and Th but were susceptible to Cr and Ni. The contamination factors (CFs) of the pollutants in rice grain are Cr (1.98) and Ni (3.09). The hazard quotient (HQ) shows that Cu (HQ >1) could pose potential risks for humans upon long-term consumption of the rice.