Source and distribution of lead in the surface sediments from the South China Sea as derived from Pb isotopes

Rapid economic development in East Asian countries has inevitably resulted in environmental degradation in the surrounding seas, and concern for the environment and its protection against pollutants is increasing. Identification of sources of contaminants and evaluation of current environmental status are essential to environmental pollution management, but relatively little has been done in the South China Sea (SCS). In order to investigate the abundance, distribution, and sources of Pb within the SCS, stable Pb isotopes and their ratios were employed to assess the contamination status and to differentiate between natural and anthropogenic origins of Pb in the surface sediments. The total Pb concentrations in sediments varied from 4.18 to 58.7 mg kg−1, with an average concentration of 23.6 ± 8.9 mg kg−1. The observed Pb isotope ratios varied from 18.039 to 19.211 for 206Pb/204Pb, 15.228 to 16.080 for 207Pb/204Pb, 37.786 to 39.951 for 208Pb/204Pb, 1.176 to 1.235 for 206Pb/207Pb, and 2.468 to 2.521 for 208Pb/207Pb. The majority of these ratios are similar to those reported for natural detrital materials. Combined with Pb enrichment factor values, our results show that Pb found within most of the SCS sediments was mainly derived from natural sources, and that there was not significant Pb pollution from anthropogenic sources before 1998. Further studies are needed to reconstruct deposition history and for trend analysis.