Investigation on Cause of Lead Contamination in Irrigation Reservoir under Shooting Range Using Lead Isotope Ratio

Abstract

To clarify the origin of lead (Pb) in an irrigation reservoir with a shooting range in upstream, sediments of a small stream located in the shooting range, sediments and soil from upstream of the shooting range, sediments in the irrigation reservoir, and river water have been observed. It is well known that the Pb stable isotope ratio has an original value in each Pb mine. The Pb stable isotope ratios in soil and sediment were totally different between the samples from upstream and downstream of the shooting range. On the basis of the composition ratios of Pb and other metals (zinc and copper) used in the brass coating of bullets, the distance index (D.I.) was calculated and the results were applied for cluster analysis. Both D.I. and cluster analysis results indicated that soil and sediment samples from the upstream and downstream are clearly different. Our results indicate that our integrated approach of using the Pb isotope ratio, D.I. and cluster analysis is a good indicator of the origin of Pb contamination in soil and sediment.