Microcosm method for investigating the biodegradation of organic compounds in rhizosphere soils
- Utah State Univ., Logan, UT (United States)
Information regarding biodegradability is critical for assessing the environmental fate and impact of organic chemicals in soil/plant systems. However, quantitative information describing the biodegradation of organic chemicals in soils and the effect of vegetation is lacking, primarily due to the difficulty and expense associated with experimentally measuring biodegradation rates. Typically, biodegradation rates in soils are determined directly by measuring the disappearance of the chemical of interest over time or indirectly by measuring evolved CO{sub 2} or O{sub 2} consumption. Indirect methods are generally simpler, less expensive and less time consuming than direct methods. The focus of this study was to develop a simple microcosm approach, utilizing measurements of O{sub 2} consumption, to investigate the biodegradability of selected organic compounds in rhizosphere soil. The microcosms consisted of 100 mL glass vials fitted with Mininert{reg_sign} valves and typically contained 40 grams of either rhizosphere or control soil. The rhizosphere soil was obtained from a vegetated plot, while the control soil from a unvegetated plot. All compounds were added directly to the soil, without a carrier solvent, resulting in a soil concentration of approximately 200 ppm. Headspace concentrations of O{sub 2}, converted to percent of theoretical oxygen demand (%ThOD), were analyzed over time using a gas chromatograph equipped with a thermal conductivity detector. The indirect microcosm technique provided a simple, inexpensive method for comparing the aerobic biodegradation of several aromatic hydrocarbons in rhizosphere versus soil.
- OSTI ID:
- 491037
- Report Number(s):
- CONF-9406250--
- Country of Publication:
- United States
- Language:
- English
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