BIOGEOCHEMICAL CHARACTERIZATION OF A GASOLINE-CONTAMINATED AQUIFER
Water and sediment samples were collected along the flow path of the contaminated aquifer. Unstable parameters and redox-sensitive species were tested in the field and groundwater and sediment samples taken at various, corresponding depths. PCR-DGGE was utilized to look for changes in community composition, and backscatter scanning electron (BSE) microscopy was used to look for patterns in colonization of sediments.
Groundwater chemistry shows reducing conditions are occurring at contaminated sites, causing iron reduction. PCR-DGGE data is pending. BSE microscopy showed microbial communities from gasoline-contaminated wells preferentially adsorbed to sediments with higher concentrations of iron and trace amounts of arsenic, suggesting that arsenic release could be related to active reduction of either iron or arsenic, or both. Future work will determine differences in community composition, including the presence or absence of arsenate-respiring microorganisms, in contaminated and uncontaminated sites.