Investigations of Pb and Cu Isotopes to Trace Contamination Sources from the Artificial Shihwa Lake in Korea

Abstract

The concentrations of heavy metals and Pb and Cu isotopes in sediments from five streams (A-G) around the Shihwa National Industrial Complex in Korea were investigated with the aim of identifying sources of metal pollution. The average concentration of Zn (21,106 mg/kg) was the highest, followed by Cu (2,804 mg/kg), Ni (2,126 mg/kg), Pb (897 mg/kg), Cr (807 mg/kg), As (18 mg/kg), Cd (8.0 mg/kg), and Hg (1.4 mg/kg). The concentrations tended to be highest in sediments from stream G. The Pb-206/Pb-207 and Pb-208/Pb-206 ratios of stream sediments ranged from 1.1302 to 1.1626 and 2.0983 to 2.1990, respectively. The Pb isotopes in stream sediments showed linear trends both Chinese Pb ore and Korean Pb-Zn Ore deposit. The Pb isotopic composition overlapped with Shihwa road dust values. The delta Cu-65 AE647 values of stream sediments ranged from -0.16 parts per thousand to 0.64 parts per thousand, clustering in two groups, one relatively enriched in the light Cu isotope (0.08 parts per thousand-0.13 parts per thousand) and another enriched in the heavy Cu isotope (0.37 parts per thousand-0.48 parts per thousand). Our results indicate that streams F and G are relatively enriched in heavy Cu isotopes. Pb-208/Pb-206 vs. delta Cu-65 AE647 plots indicate that the two branches of the Shingil stream (E and F) are noticeably distinguished, with their isotopic compositions suggesting different pollution sources. The Cu and Pb isotopic compositions reflect those of road dust, and suggest that the stream sediments were affected by road dust transported in stormwater runoff. Thus, road dust may be a potential source of metal pollution in the stream sediments of industrial regions in Korea.