Preliminary assessment of using 210Pbex radionuclide to estimate soil redistribution rate in kouhin dry farming region

Abstract

Over the past decades, the 137Cs approach has been successfully applied in Iran for estimating soil erosion and sedimentation rates. By the progressive reduction in 137Cs activity due to radioactive decay, however, it is essential to investigate the use of an alternative environmental radionuclide with a constant deposition through time, such as Lead-210. In this study, soil samples were collected within seven hectares cultivated field to determine the magnitude and spatial pattern of soil redistribution budgets. The net erosion rates for 137Cs and 210Pbex techniques were estimated to be 4.6 and 12.3t ha-1 yr-1 respectively and the sediment delivery ratio reached 52 and 60 percent respectively using mass balance model 2. Totally, soil erosion and deposition mean estimated from the 210Pbex measurements were much higher than those of 137Cs, since in the case of 137Cs, the results provided an estimate of the mean erosion rate over a period from 1963 to the time of sampling, whereas for the 210Pbextechnique, the estimates reflect a longer time period. The changes in the land management and rainfall characteristics that have occurred during the past century in the area under the study have had important influence on the soil redistribution estimates by the 210Pbex. This study has demonstrated the potential of using 210Pbex measurements to estimate soil erosion and deposition in semiarid regions.

Keywords

• 210pbex
• 137cs
• soil erosion
• fallout radionuclides
• mass balance models