Effects of equilibration time on photoreactivity of the pollutant DDE sorbed on natural sediments

Photolysis of the hydrophobic pollutant 1,1-$\text{bis}$($\text{p}$-chlorophenyl)-2,2-dichloroethylene (DDE) was studied in aqueous suspensions of three well-characterized sediments. Results of the study can be described by equations that are based on a kinetic model that takes into account sorption kinetics. Analysis of the kinetic data using this model indicates that the sorbed DDE is, at equilibrium, about half in reactive sites and half in sites where the DDE is unreactive.