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OPTIMIZING NIST SEQUENTIAL EXTRACTION METHOD FOR LAKE SEDIMENT (SRM4354)
Citation:
OUTOLA, L., R. FORD, AND K. INN. OPTIMIZING NIST SEQUENTIAL EXTRACTION METHOD FOR LAKE SEDIMENT (SRM4354). Presented at 52nd Annual Radiobioassay and Radiochemical Measurements Conference, Chicago, IL, October 23 - 27, 2006.
Impact/Purpose:
To inform the public.
Description:
Traditionally, measurements of radionuclides in the environment have focused on the determination of total concentration. It is clear, however, that total concentration does not describe the bioavailability of contaminating radionuclides. The environmental behavior depends on speciation of radionuclides in soils and sediments. We are developing the NIST Standard Sequential Extraction Protocol for determining the geochemical fractionation of U and Pu in lake sediment SRM 4354. The fractions studied are: 1) Exchangeable, 2) Bound to carbonates, 3) Bound to Mn and Fe oxides, 4) Bound to organic matter, 5) Persistently bound. The protocol is broadly based on the procedure developed by Tessier et al (1979). The goal is to maximize the dissolution of the target phase while minimizing the non-targeted phases. The optimization is achieved through full factorial design and three parameters were studied in the protocol: temperature, concentration of solution and time. Both stable element and radionuclide data are used in optimization of the procedure. Results will be discussed for the first two fractions: exchangeable and bound to carbonates.