FATE OF VOLATILE CHLORINATED ORGANIC-COMPOUNDS IN A LABORATORY CHAMBER WITH ALFALFA PLANTS

The fate of two volatile organo chlorinated compounds, 1,1,1-trichloro ethane (TCA) and trichloroethylene (TCE), was studied in rhizosphere s oil. Laboratory experiments were performed with alfalfa (Medicago sati va) growing in sandy silt soil fed continuously with groundwater conta minated with TCA and TCE at 50 and 200 mu L/L, respectively. Methane g enerated in the groundwater provided evidence for anaerobic biodegrada tion. Groundwater samples indicated that the concentration of TCE decr eased with axial position during the steady-state period. The flow rat e of the effluent was significantly less than the inlet flow because o f active evapotranspiration. Thus, a significant fraction of TCA and T CE disappeared. Headspace ana lysis of the gas in the enclosed chamber using a FT-IR spectrophotometer showed that small quantities of TCA a nd TCE migrated into the gas phase above the alfalfa plants; no chlori nated intermediates or methane were found in this gas phase.