Key factors controlling microbial distribution on a DNAPL source area

Area of Science:

• Environmental microbiology
• Geochemistry
• Subsurface science

Background:

• Chlorinated solvents are widespread groundwater contaminants.
• Microorganisms are crucial for the natural attenuation of these solvents.
• The in situ soil microbial community's response to contamination is not well understood.

Purpose of the Study:

• Investigate microbial community distribution in a perchloroethene (PCE) contaminated source area.
• Identify key factors controlling microbial community structure in contaminated subsoil.
• Relate microbial data to lithological, geochemical, and chloroethene data.

Main Methods:

• Terminal restriction fragment length polymorphism (T-RFLP) analysis.
• Clone library analysis for microbial identification.
• Correlation analysis with lithological, geochemical, and isotopic data.

Main Results:

• Proteobacteria, Actinobacteria, and Firmicutes were the dominant bacterial phyla.
• Microbial community structure is significantly influenced by fine sediment granulometry.
• Oxygen tolerance, terminal electron-acceptor processes, and contaminant toxicity are key controlling factors.

Conclusions:

• This study enhances understanding of microbial community dynamics in chlorinated solvent-contaminated subsoils.
• Identified environmental factors provide insights into microbial adaptation and function.
• Findings contribute to strategies for natural attenuation of groundwater contaminants.