Evaluation of Microcosm System for Determining the Persistence of Chlorocatechols in the Aquatic Environment

Under aerobic conditions, the spiked 3,4,5-trichlorocatechol was partitioned into the sediment phase, and during the course of the experiment, its concentration diminished by ca. 95 % during 50d without evidence for the synthesis of metabolites. By contrast that of the endogenous substrate diminished by only ca. 60 %. Under anaerobic conditions, the concentration of the endogenous chlorocatechols was essentially constant during 8 w, during which time the exogenous 3,4,5-trichlorocatechol was transformed by ca. 70 % plausibly to a mixture of dichlorocatechol isomers. 6-chlorovanillin was retained in the aqueous phase and under aerobic conditions its concentration diminished to zero within 15 d. The concentrations of endogenous C12 to C18 fatty acids and a range of diterpenes diminished during the later part of the experiments, although in separate experiments, the concentrations of dissolved dehydroabietic acid and 12,14-dichlorodehydroabietic acid were reduced to zero during incubation with pure cultures of aerobic bacteria. All of these results underscore the environmental signficance of bioavailability in determining the persistence of organic compounds in the environment