Cesium-137 in floodplain sediments of the Lower Three Runs Creek on the DOE Savannah River Site

The legacy of nuclear weapons production has resulted in vast tracks of land contaminated with fission products, mainly Cs-137, and at the U.S. Department of Energy's Savannah River Site (SRS) alone there is over 120 km(2) of land contaminated with low-levels of Cs-137. Soils on the SRS are highly weathered and dominated by sand-sized quartz grains with the clay fraction consisting primarily of kaolinite and crystalline and poorly crystalline iron oxides (<5%). Our results showed that the majority of Cs-137 in the Lower Three Runs Creek floodplain were retained in the sand-sized fraction (>52 mu m) of the soil. Frayed edge site measurements were performed in order to probe the interaction between Cs-137 and the sand fraction, with the results indicating that the vast majority of the Cs-137 was strongly retained and existed in the residual fraction. These results prompted examination into the mineralogy of the soils in a hope to elucidate the mechanisms of Cs-137 retention by the sand fraction. The results from this study provide new evidence for selective retention of Cs-137 in larger-grained particles than previously demonstrated.