Surface Sediment Contamination by Uranium Mining/Milling Activities in South China

The distribution and the contamination level of uranium (U) and thorium (Th) radionuclides and potentially toxic metals, Cu, Li, Mn, Sr, and Zn were investigated in surface sediments from aquifer systems around a uranium industrial site in the northern Guangdong Province, China. Total contents of these elements and other major elements, including Fe, Al, Mg, Na, Ca, and K, were analyzed by inductively coupled plasma optical emission spectrometry. The results show that the contents of U, Th, Cu, and Mn are elevated in the sediments from a recipient stream that drains the industrial site and the reservoir downstream. Metal contents varied significantly among the sampling locations, and generally displayed a decreasing trend as the distance from the U industrial site increased. However, the highest level of U, Th, Cu, and Mn is observed in the terminal of the recipient stream, where is the inlet of a reservoir. Assessment of elemental enrichment in the sediments using enrichment factor and geoaccumulation index indicates that among the analyzed metals, U, Th, and Cu are the major contaminants, while contaminations of Li, Mn, Sr, and Zn which displayed depletion to minimal enrichment are not significant.