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

Abstract

Records of radioactive fallout on the Canadian Prairies indicate that 137 Cs should be present in soils at levels that can be counted relatively accurately. Less than 7% of total 137 Cs appears to have fallen during the winter months, so that redistribution of 137 Cs with blowing snow should not seriously impair the possibility of using 137 Cs as a tracer for soil erosion. Methodology for measuring 137 Cs 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 137 Cs/cm 2 . There was little variation in 137 Cs 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 137 Cs was deposited.