Simultaneous Determination of Multiple Actinide Elements in a Variety of Soils Utilizing a Standardized Sequential Extraction Protocol

摘要

To obtain a better understanding of the mobility of actinide element contaminants in the environment, the association of the contaminants with specific host phases of soils and sediments must be investigated. This investigation is most commonly conducted using sequential extraction techniques that employ the selective dissolution of soil phases with increasingly aggressive chemical treatment. Though several sequential extraction studies exist in literature, conclusions cannot be made by direct comparison of data due to the lack of uniformity in the protocols used. This work aims to continue development of a standard sequential extraction protocol and expanding its capabilities to include the analysis of multiple actinide elements across a broad range of soil types.A five-step sequential extraction procedure was used to analyze extraction behaviors of 232Th, 238U, 239,240Pu and 241Am from four standard reference materials chosen to represent a broad range of geochemical soil types. Radioanalytical separations were performed using an extraction chromatography based separation procedure prior to CeF3 microprecipitation sample mounting and counting by alpha spectroscopy. Stable element analysis of aluminum, iron, manganese, and strontium was performed by inductively coupled plasma - mass spectrometry to monitor phase selectivity and model potential fission product mobility. An investigation of complete dissolution techniques for a potential sixth fraction was conducted for the application to soils with high concentrations of insoluble metals. Results show variations in leaching behaviors potentially caused by the geochemical host phase of the soil, chemical form of the extracted elements, and environmental weathering conditions.