Biodegradation is predicted to be the dominant transformation process in eutrophic waters, but four times slower than photolysis in oligotrophic waters. Dilution is more important than biodegradation in rivers. Sorption and volatilization are unimportant in all waters . While photolysis is catalyzed by the presence of humic acids, there are no experiments that evaluate whether this process is important in some eutrophic waters. These model results are not entirely in agreement with experiments, where degradation half-lives were only a few hours in eutrophic waters but may be preceeded by a lag period ranging from hours to days and where degradation occurred in an oligotrophic lakes in 6 days.
Degradation is much slower under anaerobic conditions - weeks instead of hours in screening studies.
However in the only study in a natural system, no mineralization occurred in 29 weeks in anaerobic lake sediment. 10 hr while at night it is 4 min. The dominant reactions are with hydroxyl radical during daylight hours and with nitrate radicals at night. Daytime half-lives will be reduced under smog conditions. Hayashida River in Tatsumo City Japan - site of leather industry 204 ppb .