Photochemical degradation of phenanthrene as a function of natural water variables modeling freshwater to marine environments

► Photodegradation of phenanthrene in water follows first order kinetics. ► Photodegradation rate in sunlight in pure water is estimated to be 10.3 ± 0.7 h. ► Rate decreases in presence of humic acids due to competitive light absorption. ► No effect of varying oxygen and ionic strength suggests direct photolysis mechanism.