- Program Areas
- Energy and Water
- Environmental Restoration
- Munitions Response
- Resource Conservation and Climate Change
- Weapons Systems and Platforms
Lead and Antimony Speciation in Shooting Range Soils: Molecular Scale Analysis, Temporal Trends, and Mobility
Contamination of soils is a concern at many firearms training facilities. Lead is the primary metal of concern as it makes up approximately 90% by mass of a typical bullet and is a common constituent in rockets, mortars, grenades, and Howitzer rounds. In addition to lead, a number of other potentially toxic trace metals and metalloids are of concern. Bullet alloys generally include antimony, arsenic, bismuth and silver, and bullets are commonly encased in a copper or nickel jacket. Fragments of bullets and other munitions are highly susceptible to oxidation and weathering processes in soil systems, leading to the release of aqueous metal(loid) species into soils. The potential for metal(loids) stored in soils to migrate from shooting ranges into surface or subsurface aquatic systems is a public health concern. Detailed knowledge of the processes controlling mobilization versus retention of metal(loid) species associated with bullet fragment weathering in small arms training range soils is essential for assessing long-term environmental risk, for understanding the efficacy of remediation scenarios, and for identifying what materials to incorporate into future training range or impact area designs.
The objective of this project is to improve the molecular- and nano-scale understanding of metal(loid) transport and bioavailability in range soils (lead and antimony in particular) with a focus on the rates and geochemical mechanism(s) of metallic fragment weathering, the rate and extent of oxidized metal(loid) dispersion, how metal(loid) dispersion is correlated with speciation, and how rates and extent of reaction are influenced by soil properties.
A series of interrelated field and laboratory measurements will be completed to identify temporal and spatial trends of lead and antimony speciation in shooting range soils. Geochemical analyses and speciation methods will be applied to studies of constructed and instrumented shooting range berms, historical berms, and laboratory simulations. Speciation measurements will be made using synchrotron x-ray absorption and scattering methods. These studies will include both the analysis of fine-grained soil materials to study metal(loid) speciation (changes) and the analysis of pristine reactive substrates that will be used as passive sensors in impact berms. The substrates are amenable to use with highly surface sensitive analytical tools; surface x-ray diffraction and grazing angle spectroscopy will provide molecular- and nano-scale speciation information from mineral and metal fragment surfaces.
This project will improve understanding of the fundamental processes controlling the rates of metal fragment weathering, metal(loid) speciation and dispersion, and ultimate bioavailability of metals on training ranges. The use of pristine reactive substrates as passive sensors also will be explored. These sensors, coupled with high resolution synchrotron speciation methods, can provide novel information regarding the molecular- and nano-scale chemical constraints on soil (bio)geochemical processes that control metal(loid) fate and bioavailability in training range soils. (Anticipated Project Completion - 2013)
Points of Contact
Dr. Thomas Trainor
University of Alaska Fairbanks
SERDP and ESTCP
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