Bacterial Diversity in Soil Exposed to Highway Runoff and De-icing Agents

Abstract

Bacterial communities were profiled through two drilled soil cores below an infiltration basin that receives highway runoff and de-icing agents. Analyses of groundwater dissolved oxygen, physical and chemical properties of the soil complemented molecular phylogenetic determinations to distinguish ambient and contaminated plume zones. The bacterial community was previously characterized (when the site received high levels of acetate as de-icing agent) by being dominated by members of Geobacteraceae family. In this study, bacterial 16S rDNA gene clones showed highly diverse microbial communities, both into the plume and in the ambient aquifer, in which Geobacter spp. represents only a small fraction of them. The clones were affiliated with 32 and 23 classes identified from the sediment cores along the contaminant plume. The plume in the infiltration basin was anaerobic and iron-reducing, while the sediments in the underlying ambient aquifer were dominated by aerobes due to the presence of aerated ambient groundwater. These data indicate shifts in microbial communities in correlation with depth, substrate and oxygen availability in a de-icing agent impacted subsurface.

Keywords:

• bacterial diversity
• iron reduction
• 16S rDNA gene clone library
• highway runoff

ACKNOWLEDGMENTS

We thank Joy Ward for PCR sequencing and Dr. Chul Park for TOC and COD analyses. This research was funded by the Executive Office of Transportation, Massachusetts under Interagency Service Agreement No. 56565. The views, opinions, and findings contained in this paper are those of its authors, and do not necessarily reflect the official view or policies of the Office of Transportation. This paper does not constitute a standard, specification, or regulation.