The fate of metal(loid)s in the environment depends on a variety of physical and geochemical factors. Assessing metal(loid) transport in soil solution and surface water requires detailed knowledge of the speciation, which can often control mobility, toxicity and bioavailability of a given element. The present study details the geochemical analyses of two end member types of systems: a ‘pristine’ Arctic watershed and a military shooting range with an overall focus on understanding lead (Pb) and antimony (Sb) mobility in shooting range soils. The project uses bulk speciation analyses coupled with micro-scale methods to quantify variations in metal(loid) concentration as a function of environmental conditions and characterize metal(loid) speciation and distribution in relation to parent source material in order to understand the impact that metal(loid) retention versus mobilization has on a given system.
In the Arctic, stream water concentrations of Al, Ba, Fe, and Mn in Imnavait Creek were highest in the late fall (September and October). This pattern appears to correlate with the depth of the active layer throughout the watershed. Increased water infiltration at the permafrost-active layer boundary could significantly impact stream water trace metal(loid) signatures due to mineral weathering of unfrozen soil. In the central Alaskan shooting range, there were significant contributions of Pb and Sb to both the soil and soil solution as a result of the weathering of fragmented bullets. Aqueous concentrations of Sb were higher than Pb in all soil types, indicating Sb is more mobile, despite the fact that bullets introduce approximately two orders of magnitude more Pb than Sb. We observed an association of both Pb and Sb with Fe in soils, which impacts remediation scenarios for ranges as Fe treatments have potential to be effective for system-wide immobilization of major contaminants. Overall, the results from this study highlight the complexity of metal(loid) speciation, transport and mobility as a function of seasonality, soil type and environmental conditions.
|Commitee:||Douglas, Thomas, Hayes, Sarah, Simpson, William|
|School:||University of Alaska Fairbanks|
|Department:||Chemistry & Biochemistry|
|School Location:||United States -- Alaska|
|Source:||DAI-B 78/04(E), Dissertation Abstracts International|
|Keywords:||Fate, Metaloids, Metals, Mobility, Speciation, Transport|
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