ABSTRACT
Cesium-137 (,37Cs) has been widely used to determine soil loss rate. Many calibration relationships have been employed to estimate erosion rates from 137Cs loss. However, there is some uncertainty since these models did not consider depth distribution pattern of 137Cs in the soil profile and the 137Cs fallout deposition during different times. As a result, they may over estimate or under estimate erosion rates. This paper presents a quantitative model to relate the amount of 137Cs loss from the soil profile to the rate of soil erosion. According to the mass balance model, the depth distribution pattern of 137Cs in the soil profile, radioactive decay of 137Cs, sampling year and the difference in the amount of 137Cs fallout each year were considered. Relationships between the amount of 137Cs loss from the soil profile to the rate of soil erosion were developed by introducing an erosion constant, which is defined as the mean annual amount of relative reduction of 137Cs and depth distribution functions of 137Cs in the soil profile.
