Lead (Pb) contamination represents environmental and human health hazards. Our work has shown diverse fungal isolates derived from contaminated firing range soils have the ability to solubilize and transform Pb-carbonate and Pb-phosphate forms into more reactive complexes such as Pb-oxalate via the secretion of low molecular weight organic acids (LMWOAs). The objective of our current studies have been to understand how Pb in soils may be influenced by, or have influence upon, soil microbial community structure at an abandoned small-arms firing range. We have approached this by; 1) spatially explicit sampling across the firing range and surrounding forest to geostatistically correlate microbial community properties with soil parameters and Pb availability and, 2) recently conducting controlled laboratory experiments with phosphate treated and untreated soils that include native communities, litter amendments, and addition of fungal species known to secrete LMWOAs. Microbial measures use a combination of qPCR and DNA sequencing methods. Pb availability has been measured using sequential extractions and in-vitro methods. Pb speciation has been measured via XANES analyses. Soil Total Pb concentrations ranged from below detection limits to over 9,000 mg/kg with the highest Pb concentrations geographically located along the slope of a firing backstop and lowest Pb found furthest from the backstop. Soil microbial properties measured to date have not been highly correlated with soil properties but areas of high fungal abundance spatially overlapped with areas of high total and extractable soil Pb and sulfate. We are in the process of completing analyses of the laboratory soil incubation experiment; DNA sequencing that will give us more precise definition of microbial characteristics and XANES analyses of the mineral forms of Pb in both experiments. Since many fungi seem capable of transforming Pb under ideal laboratory conditions, a more complete understanding of Pb-microbial interactions within soils is warranted.

Understanding microbial communities, lead availability, and their potential Interactions at an abandoned firing range in Oak Ridge, TN

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.