A field method for determination of groundwater and groundwater-sediment associated potentials for degradation of xenobiotic organic compounds

Determination of the degradation potentials for a mixture of eight organic trace contaminants (benzene, toluene, o-xylene, naphthalene, tetrachloromethane, 1,1,1-trichloroethane, trichloroethene, tetrachloroethene) has been made by specially developed in situ microcosms under aerobic and anaerobic aquifer conditions. The developed in situ microcosms allowed for determination of the degradation potentials in the aquifer as represented by the combined groundwater and sediment and by the groundwater only. Six out of eight microcosms functioned hydraulically well as determined by means of a hydraulic tracer. Control experiments showed that the in situ microcosms were not subject to unaccounted losses of the contaminants except from sorption to sediment in the beginning of the experiments. All compounds were studied at initial concentrations of approximately 120 μg/l for a 90 days period. In all experiments the groundwater alone exhibited a degradation potential for the same compounds as those in the case of groundwater plus sediment. These results may have implications for the use of groundwater test systems as means for an evaluation of biodegradation potentials in aquifers.