Registration Dossier

Diss Factsheets

Environmental fate & pathways

Phototransformation in water

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Ahel et al. /1994) assessed the rates of photochemical transformation of octylphenol (OP) in natural waters by exposing the solutions in filtered lake water (dissolved organic carbon, DOC=4 mg/L) to sunlight. 

Key value for chemical safety assessment

Additional information

The first-order rate constant of sunlight photolysis (kp) for OP was estimated to be between 0.10 and 0.05 h-1. This corresponds to a half-life of approximately 7 -14 hours under continous clear sky, noon, summer sunlight in the surface layer of natural waters.

The photolysis rate in the deeper layers is strongly attenuated, being approximately 1.5 times slower at depths of 20-25 cm than at the surface.

Although sunlight photolysis rates of OP were found to be much slower than previously reported for some other alkylphenols (Faust and Hoigné, 1987, as cited in Ahel et al., 1994), the results suggest that a significant portion (30 %) of OP could be photochemically degraded in the surface layer of natural waters within one day.