Conference Report: NIST SPECIATION WORKSHOP Gaithersburg, MD June 13–15, 1995

program has been successful in making available to the community natural matrix materials that are very useful for the evaluation of radiochemical-measurement techniques. Traditionally, measurements of environmental radiological contamination have focused on the determination of total concentrations, a very useful tool for initial site characterization of impacted areas. It is clear, however, that total concentration does not describe the environmental behavior or bioavailability of contaminating radionuclides. Rather, the time-dependent spread of radiological contaminants is a function of ‘‘partitioning’’ or ‘‘speciation’’ of radionuclides within soils and sediments. In the United States and many other parts of the world, there remains an enormous task ahead for remediating radiologically contaminated environments and monitoring the impact of man-made radioactivity on the natural environment. The U.S. Department of Energy (DOE) faces contamination plumes of greater than 2.3310 m of contaminated groundwater and greater than 150310 m of contaminated soil (Wyrick, SAIC, workshop presenter). Furthermore, current technologies for cleaning up and preventing further migration of radioactive contaminants are costly and often ineffective. The development of strategies for remediation, restoration, and mitigation of radiologically contaminated areas is necessarily constrained by budgetary concerns. Therefore, for long-term risk assessment analyses, regulatory bodies need information which takes the mobility and bioavailability of radiological contaminants into consideration. Although the need exists for the continued development of more accurate, efficient, and sensitive radioanalytical techniques, there is also a need for more information concerning what fraction of the contamination in a given environmental sample is ‘‘environmentally available.’’ Presently, there is no acceptable measure of the bioavailability of radioactive elements in contaminated soils and sediments [1].