Radiocesium-137 movement in a southern coastal plain ecosystem

The movement of radiocesium (137Cs) in an open ecosystem under natural conditions was investigated at the Louisiana State University Radioecology Field Laboratory. Approximately 80 mCi of 137Cs were transferred to an experimental plot in September 1979. Observations over a six-month period beginning February 1981 indicated that the 137Cs content of plants growing naturally in the plot was low (0.98 Bq/g of plant tissue, dry wt). The vertical mobility of 137Cs to more than 10 cm was also found to be low (up to 1.32 Bq/g of soil, dry wt). The horizontal migration of 137Cs along water drainage directions from the plot was limited to the area of a small ditch that surrounds the experimental plot. No 137Cs above background was found in the fields beyond the 10 m X 10 m plot boundary. The overall results demonstrated that greater than 99.9% of the 137Cs remained within the top 10 cm of the soil profile of the experimental plot under natural field conditions.