Molecular environmental science : an assessment of research accomplishments, available synchrotron radiation facilities, and needs.

Synchrotron-based techniques are fundamental to research in ''Molecular Environmental Science'' (MES), an emerging field that involves molecular-level studies of chemical and biological processes affecting the speciation, properties, and behavior of contaminants, pollutants, and nutrients in the ecosphere. These techniques enable the study of aqueous solute complexes, poorly crystalline materials, solid-liquid interfaces, mineral-aqueous solution interactions, microbial biofilm-heavy metal interactions, heavy metal-plant interactions, complex material microstructures, and nanomaterials, all of which are important components or processes in the environment. Basic understanding of environmental materials and processes at the molecular scale is essential for risk assessment and management, and reduction of environmental pollutants at field, landscape, and global scales. One of the main purposes of this report is to illustrate the role of synchrotron radiation (SR)-based studies in environmental science and related fields and their impact on environmental problems of importance to society. A major driving force for MES research is the need to characterize, treat, and/or dispose of vast quantities of contaminated materials, including groundwater, sediments, and soils, and to process wastes, at an estimated cost exceeding 150 billion dollars through 2070. A major component of this problem derives from high-level nuclear waste. Other significant components come from mining and industrial wastes, atmospheric pollutants derived from fossil fuel consumption, agricultural pesticides and fertilizers, and the pollution problems associated with animal waste run-off, all of which have major impacts on human health and welfare. Addressing these problems requires the development of new characterization and processing technologies--efforts that require information on the chemical speciation of heavy metals, radionuclides, and xenobiotic organic compounds and their reactions with environmental materials. To achieve this goal, both fundamental and targeted studies of complex environmental systems at a molecular level are needed, and examples of both types of studies are presented herein. These examples illustrate the fact that MES SR studies have led to a revolution in our understanding of the fundamental physical and chemical aspects of natural systems. The MES SR user community has continued to experience strong growth at U.S. SR laboratories, with MES researchers comprising up to 15% of the total user base. Further growth and development of the MES community is being hindered by insufficient resources, including support personnel, materials preparation facilities, and available beam time at U.S. SR laboratories. EnviroSync* recommends the following actions, in cooperation with U.S. SR laboratory directors, to meet the MES community's needs