GeoChip-Based Analysis
of Microbial Functional Gene
Diversity in a Landfill Leachate-Contaminated Aquifer
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Abstract
The functional gene diversity and structure of microbial
communities
in a shallow landfill leachate-contaminated aquifer were assessed
using a comprehensive functional gene array (GeoChip 3.0). Water samples
were obtained from eight wells at the same aquifer depth immediately
below a municipal landfill or along the predominant downgradient groundwater
flowpath. Functional gene richness and diversity immediately below
the landfill and the closest well were considerably lower than those
in downgradient wells. Mantel tests and canonical correspondence analysis
(CCA) suggested that various geochemical parameters had a significant
impact on the subsurface microbial community structure. That is, leachate
from the unlined landfill impacted the diversity, composition, structure,
and functional potential of groundwater microbial communities as a
function of groundwater pH, and concentrations of sulfate, ammonia,
and dissolved organic carbon (DOC). Historical geochemical records
indicate that all sampled wells chronically received leachate, and
the increase in microbial diversity as a function of distance from
the landfill is consistent with mitigation of the impact of leachate
on the groundwater system by natural attenuation mechanisms
