Photochemical and microbial degradation of 2,4,5-trichloroaniline in a freshwater lake.

Surface waters from a eutrophic lake in northern Georgia were incubated with C-labeled 2,4,5-trichloroaniline to study the disappearance of the parent compound and production of CO(2). There was no degradation of the compound in the dark. Under 12 h of sunlight and 12 h of darkness, 28% of the trichloroaniline was degraded in both poisoned and untreated samples. Mineralization after 24 h in poisoned and untreated lake water was 5.5 and 6.8%, respectively. Thus, 81% of the mineralization was attributable to photochemical processes, and 19% was attributable to microbial processes. Most biological mineralization was due to microbes of bacterial size (<1.0 mum). Approximately 90% of the trichloroaniline bioaccumulated was associated with organisms larger than 1.0 mum, e.g., algae. When algae were removed by filtration, the amount of trichloroaniline mineralized increased to 9.4%, compared with 6.8% in the presence of algae. The excretion of organic compounds by algae may have inhibited bacterial mineralization of photoproducts.