Study of soil erosion using environmental isotope cesium-137 (137Cs)

The environmental tracer hay a potential to be used to trace sediment movement. Caesium (Cs), a radionuclide released from nuclear weapon tests is strongly absorbed on clay. The '1'3'7 Cs content in soil profile has been used to estimate soil loss due to water erosion in agricultural land. Soil samples were collected at the study and reference sites using a sampling frame with dimensions of 20 cm x 50 cm x 24 cm. In each depth-incremental soil sampling, the plate was placed on the soil surface and hammered into the soil, a scrapper plate was used to slice off soil in 2 cm increment to a depth of 40 cm. The '1'3'7 Cs content in an undisturbed site accumulated in the upper portion of the soil profile whereas in the disturbed sites the contents are nearly mixed within the plough layer. The eroded soil contained less '1'3'7 Cs compared to the uneroded sites. An empirical model is used to quantify the soil loss. The estimated erosion rates on slopes located at D, E, F are found to be 0. 54 ± 0. 03 tonne/hectare/year, 1.42 ± 0.12 tonne/hectare/year and 0.060 ± 0.009 tonne/hectare/year giving the average of 0.069 ± 0.08 tonne/hectare/year. This result suggest '1'3'7 Cs have the considerable value in data collection for long term-erosion studies. (author)