Recent sedimentation rates in lakes in lower Yangtze River basin

摘要

This study attempted to quantify the lake sedimentation and its role in recording catchment soil erosion in the lower reaches of the Yangtze River basin, using cesium-137 (~(137)Cs, anthropogenic) and lead-210 (~(210)Pb, natural) dating. Six cores taken from five lakes, including the two largest lakes in the region (Taihu, Chaohu), were selected for understanding the change of sedimentation rates. High rates of sediment accumulation between the late 1920s and the late 1960s in the three lakes of the Qinyi-Shuiyang River basin showed good correlation with farmland change in adjacent counties, indicating enhanced human-induced soil erosion in the catchment. Chaohu Lake core to some extent also recorded catchment erosion, e.g., high flux in the late 1960s consistent with catchment disturbance. However, at Taihu Lake, sediment accumulation rates do not generally reflect catchment erosion history. Sediment accumulation rates of large shallow lakes in the lower Yangtze River basin do not accurately record soil erosion, whereas relatively small lakes may be sensitive to catchment disturbance.