PRELIMINARY INVESTIGATIONS ON THE USE OF 137Cs TO ESTIMATE EROSION IN SASKATCHEWAN

Abstract

Records of radioactive fallout on the Canadian Prairies indicate that 137Cs should be present in soils at levels that can be counted relatively accurately. Less than 7% of total 137Cs appears to have fallen during the winter months, so that redistribution of 137Cs with blowing snow should not seriously impair the possibility of using 137Cs as a tracer for soil erosion. Methodology for measuring 137Cs in soil samples is described, as is a semi-empirical method for correcting for the effect of bulk density of the sample on counting efficiency. Preliminary data indicate that noneroded soils in the Saskatoon area contain about 6.4 pC 137Cs/cm2. There was little variation in 137Cs with slope position on gently rolling sites under native vegetation, whereas there was considerable redistribution in cultivated fields. It was estimated that a knoll in one cultivated field had lost about 10% of its topsoil since the early 1960s when most 137Cs was deposited.