Fallout Cs signals as chrono-markers in Chinese lake sediment cores.

This study comprehensively investigated the Cs signal in 294 sediment core samples from 132 lakes including reservoir and Gobi catchment in China. First, three Cs chrono-markers were observed: the 1963 peak corresponding to the maximum deposition of radioactive debris from global fallout, and two local sub-peaks corresponding to the time of the nuclear tests at Chinese Lop Nor site with a maximum in 1976, and to the Chernobyl accident in 1986. Second, the spatial distribution of sedimentation rates based on the 1963 Cs chrono-marker in Chinese lake sediment cores was studied. It was observed that it does not usually exceed 1 cm a (∼95 %). Although the formation of Cs peak does not matter if the lake is closed or not, sedimentation rate is related to it over time. The distribution pattern of sedimentation rates is basically consistent with the area segmented by the 400 mm precipitation contour line in China. Based on the current data (n = 18, R = 0.863), a significant linear correlation was observed between sedimentation rates and Cs inventories in Lake Qinghai, the largest lake in China. This study provides reference data that supports future research on lake sediment cores in China.