137Cs finger printing technique for erosion and sedimentation studies

137Cs is an artificial radionuclide with a half -life of 30.2 years, which was released into the environment as a byproduct of atmospheric testing of nuclear weapons during the period of 1950s to 1970s with a peak deposition in 1963. 137Cs fallout was strongly and rapidly adsorbed by soil particles when it deposited on the ground mostly with precipitation. Its following movements will associate with the adsorbed particles. 137Cs tracing technique has been widely used in soil erosion and sedimentation studies since 1980s. This paper introduces the basis of the technique and shows several case studies of assessment of soil erosion rates, investigation of sediment sources and dating of reservoir deposits by using the technique in the Loess Plateau and the Upper Yangtze River Basin.