The Limitation of Using Cesium-137 for Investigating Soil Erosion in Devastated Hills in Southeastern China

摘要

At the lower part of the hillslope, the microbiotic crust did not allow considerable ~(137)Cs penetration, since the microbiotic crusts promote surface runoff (Figure 5). The penetrated ~(137)Cs was readily adsorbed by the topsoil with relatively high carbon content. Thus, the ~(137)Cs activity exponential decreased with the depth. Since the erosion rate was small, we can see the exponential decrease of ~(137)Cs activity. In contrast, at the upper part of the hillslope with no vegetation cover, the penetrated ~(137)Cs was greater than that of the lower part (Figure 5). The penetrated ~(137)Cs was not fully absorbed by the topsoil, since the carbon content of the topsoil was extremely low. Thus, large amount of ~(137)Cs moved to the deeper soil. The results of this study indicated that the ~(137)Cs technique is difficult to use for the evaluation of soil flux from the devastated hillslopes where the carbon contents were extremely low and the infiltration capacity varied. Additional approaches (i.e., in-situ experiments and measurements of erosion depth) and/or information (i.e., spatial variability of infiltration capacity) are necessary for describing surface erosion process and quantifying soil flux on the devastated hills.