Binding, fractionation, and distribution of Cs, Co, and Sr in a US coastal soil under saturated and field capacity moisture regimes

The concerns of the public on safe handling of nuclear energy power facilities have increased due to the recent nuclear plant accidents in Japan and others. Cesium, cobalt, and strontium are a few of the major radionuclides released from nuclear power plant accidents. The objectives of this study are to investigate binding, distribution, fractionation, and transformation of cesium (Cs), cobalt (Co), and strontium (Sr) in a US coastal soil under saturated paste (SP) and field capacity (FC) moisture regimes. There are four major nuclear power plants in the coast region around the northern Gulf of Mexico where coastal soil often undergoes soil moisture change. A coastal soil was taken from the middle region of these major nuclear power plants and spiked with different concentrations of cesium, cobalt, and strontium salts. The sequential selective dissolution technique was used to investigate the transformation and fractionations of these metals in the coastal soils affected by moisture regime, a key factor in the coastal environment. The adsorption kinetics showed that both Co and Sr reached the adsorption plateau even after 5 h of adsorption, indicating a fast initial adsorption process in the coastal soil. Cesium, cobalt, and strontium were dominantly presented in the soluble and exchangeable form (EXC) (Cs > Co and Sr), which linearly increased with the addition levels, possessing the high bioavailability, mobility, and ecotoxicity. Saturated regime significantly reduced the soluble and exchangeable form compared to field capacity moisture regime. The current study provides the fundamental understanding for designing the cost-effective remediation technology to remediate these metals in coastal soil by targeting on the soluble and exchangeable forms and better prepare the USA for future potentially nuclear power plant accidents.