Lead pollution recorded in sediments of three lakes located at the middle and lower Yangtze River basin, China

Sedimentary cores were collected from Honghu Lake, Guchenghu Lake, Taihu Lake during 2002–2005. The total organic carbon (TOC) and metals (Pb, Al, Fe, and Ti) were analyzed. Combined with 137Cs or 210Pb dating method, average sedimentation rates were calculated to be 0.15 cm/a at Honghu core, 0.067 cm/a at Guchenghu core and 0.35–0.41 cm/a at Taihu core. Regression model between lead and geogenic tracer elements and TOC was established. The relationship between lead and geogenic tracer elements or TOC was significant. Pb contamination was estimated based on the natural contribution using regression model. The results indicated anthropogenic lead in the three lakes. The onset of lead pollution was estimated to be early 1970s based on sedimentations from 137Cs or 210Pb dating method. It means the possibility of using lead as time marker. According to the sediment quality guideline (SQG), the sediment was unpolluted except the surface sediment at Honghu and Guchenghu Lake cores. The lead concentrations of Taihu Lake core were higher than that from the other two lakes, but still lower than heavily polluted level. However, anthropogenic lead load to Guchenghu and Honghu increased which should cause the attention of scientist and lake managers.