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Microbial availability of different forms of phenanthrene in soils
Yu Yang1, Wesley Hunter, Shu Tao
1Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing, China.
Environmental Science & Technology
|April 17, 2009
Summary
Microbial degradation of hydrophobic organic compounds (HOCs) is governed by chemical availability. This study shows that freely dissolved concentrations, not total amounts, dictate HOC degradation rates in soil.
Area of Science:
- Environmental Science
- Microbiology
- Soil Science
Background:
- Microbial degradation is key for removing hydrophobic organic compounds (HOCs) from soil and sediment.
- Chemical availability significantly influences HOC degradation rates, but the role of sorbed HOCs remains debated.
Purpose of the Study:
- To investigate the relationship between freely dissolved phenanthrene (PHE) concentration and its microbial degradation.
- To determine how soil properties like organic carbon and porosity affect PHE bioavailability.
Main Methods:
- Utilized polydimethylsiloxane (PDMS) fibers to measure the freely dissolved concentration (Cfree) of PHE.
- Applied rigorous kinetics analysis to correlate Cfree with PHE mineralization rates by a PAH-degrading bacterium (PYR-1).
- Analyzed the impact of varying soil organic carbon (OC) content and porosity on PHE bioavailability.
Main Results:
- PHE's Cfree decreased significantly with increasing soil OC content.
- Bacterial degradation rates were strongly correlated with Cfree and reversibly sorbed PHE, indicating these pools are utilized first.
- Soil OC content and surface area showed a compounded effect on PHE's microbial availability.
Conclusions:
- Freely dissolved concentration (Cfree) is a critical determinant of microbial degradation for HOCs like PHE in soil.
- Kinetics analysis using Cfree provides a robust method to assess HOC bioavailability.
- This approach can be extended to understand the microbial availability of other HOCs under diverse environmental conditions.
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