Soil Ventilation: Effects on Microbial Populations in Gasoline‐Contaminated Subsurface Soils
| Autor: | W. J. Hickey |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
chemistry.chemical_classification
education.field_of_study Environmental Engineering Moisture Chemistry Soil vapor extraction Population Management Monitoring Policy and Law Pollution Soil contamination Nutrient Hydrocarbon Environmental chemistry Soil water Gasoline education Waste Management and Disposal Water Science and Technology |
| Zdroj: | Journal of Environmental Quality. 24:571-582 |
| ISSN: | 1537-2537 0047-2425 |
| DOI: | 10.2134/jeq1995.00472425002400040003x |
| Popis: | Short- and long-term effects of vapor extraction (VE) in an unsaturated subsurface soil and in situ biodegradation of gasoline were evaluated in a field study. Subsurface temperature, moisture, solid- and gas-phase contaminant levels, atmospheric gases, nutrient levels, and microbial population densities were measured during and after soil VE for 462 d. Microbial activity, based on in situ O{sub 2} consumption rates, measured 7 d after VE started averaged 3.8% O{sub 2} d{sup -1}; by Day 62 these rates dropped to 0.2% O{sub 2} d{sup -1}. Soil VE was stopped on Day 180 and about 70 d elapsed before renewed, low-level (0.05% O{sub 2} d{sup -1}) activity was detectable. Following a second round of VE, average O{sub 2} consumption rates increased to 0.11% O{sub 2} d{sup -1}. Microbial population densities did not consistently reflect activity changes measured by O{sub 2} consumption. Activity increases in the latter part of the study were not adequately accounted for by changes in subsurface moisture levels, temperature, or contaminant vapor concentrations. At the study`s completion, 400 kg of gasoline was volatilized from the soil and another 139 kg estimated to be biodegraded in situ. A two-phase process is proposed to account for the effects of VEmore » on microbial activity. The initial phase is characterized by declining microbial activity levels in response to substrate reduction. Microbial activity slowly increases as a result of interactions between gasoline vapor concentrations and possibly changes in degradative activities of the microbial population. More work is needed to identify the gasoline constituents serving as substrates for microbial populations before and after ventilation. 31 refs., 8 figs., 5 tabs.« less |
| Databáze: | OpenAIRE |
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