Geochemistry, Molecular Environmental Sciences, Environmental Research & Technology Division

Large volumes of soil and sediment within the Department of Energy (DOE) complex, minimally contaminated with radioactive, hazardous or mixed wastes, are not cost-effectively treated by contaminant extraction or excavation but instead necessitate in situ treatment. The spatial heterogeneity of natural systems and kinetics of biogeochemical processes present the greatest barriers to scaling up in situ remediation methods from laboratory model system studies to field-scale implementation. The experimental methodology developed during this research program is intended to bridge laboratory and field-scale studies by combining real-time synchrotron-based spectroscopic studies of contaminant speciation in model flow-thru systems with microspectroscopy studies of contaminant distribution and speciation in 'real-world' soil and sediment. As a test-case this research will focus on two hypotheses related to biogeochemical processes known to reduce soluble U(VI) species to the relatively insoluble U(IV) species: 1) U(IV) speciation and immobilization depend on the type and relative concentration of terminal electron acceptors (e.g., oxygen, nitrate, Mn(IV) and Fe(III)) present during U(VI) reduction, and, 2) within near-surface soil and sediment profiles contaminated groundwater may encounter steep chemical gradients capable of oxidizing U(IV). These results will be used to help evaluate implementation strategies and the long-term efficacy of proposed in situ remediation methods for treating uranium-contaminated soil and sediment.

DEVELOPING ENVIROSUITE RESOURCES AT THE NATIONAL SYNCHROTRON LIGHT SOURCE

J. P. Fitts and P. Northrup

Synchrotron-based molecular environmental science (MES) research supports the Department of Energy’s (DOE) mission of protecting the environment by helping to provide the fundamental understanding required to develop and deploy cost-effective remediation strategies for the nation’s most pressing contamination issues. The EnviroSuite Initiative establishes a unified voice for this diverse community and is taking the lead in developing resources at the National Synchrotron Light Source (NSLS) required to conduct world-class MES research. The NSLS has begun operation of a new microprobe beamline at X27A and has committed a staff scientist to design and supervise upgrades, maintain and operate the beamline and train users who receive beamtime through the general user program. An EnviroSuite staff scientist with a background in both MES and synchrotron-based methods will assist in optimizing the beamline for MES research and support both affiliates of EnviroSuite and general users. Together, the NSLS and EnviroSuite scientists will promote collaborations with both general users and EnviroSuite affiliates, and therefore, will provide significant benefit to the NSLS and the DOE effort to develop a world-class user facility for conducting MES research. In addition, capital equipment additions including state-of-the-art detectors for beamlines X11A and X27A, beamline control system upgrade at beamline X15B, microprobe x-ray diffraction capabilities at beamline X27A and auxiliary wet chemistry laboratory systems (e.g., electrochemical system) will contribute to the EnviroSuite mission by providing the tools required to conduct world-class MES research at the NSLS and for establishing more beam time available to environmental science users.

ENVIRONMENTAL MOLECULAR SCIENCE INSTITUTE (EMSI) SUPPORT FOR THE CENTER FOR ENVIRONMENTAL MOLECULAR SCIENCE

P.D. Kalb, AJ Francis, J. Fitts, C.J. Dodge, M. Fuhrmann

Although much of the waste at the Department of Energy (DOE) sites has been treated and disposed, large volumes of contaminants remain in place because they are relatively low in concentration, and thus, represent limited risk. Some of these contaminants may be subject to in situ treatment. In each case, evaluating long-term performance of contaminants in the environment is one of the major challenges facing DOE. In support of this broad theme, the individual research efforts identified in this Field Work Proposal (FWP) explore basic mechanisms that govern the transport of actinides and other problematic radionuclides with a particular focus on uranium, the role of organic ligands, the impact of microbial activity in accelerating or decelerating contaminant mobility, and methods to evaluate the long-term performance of treated waste. This work is conducted in connection with the Center for Environmental Molecular Science (CEMS) an Environmental Molecular Science Institute (EMSI) collaboration between Brookhaven National Laboratory (BNL) and Stony Brook University (SBU), with contributions from Temple and Penn State Universities, co-funded by DOE and National Science Foundation (NSF). The primary focus of CEMS is the investigation of molecular-scale mechanisms that govern sequestration in natural systems, with particular emphasis on the coordination and stability of contaminant species and coordinative aspects of surfaces that affect sequestration and long-term fate of contaminants. more...

Last Modified: January 31, 2008
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