Modelling air-water exchange process of pentachlorophenol in the aquatic environment

To study the effects of the surface microlayer (SM) on the air-water exchange process of pentachlorophenol (PCP), simulated experients were carried out in a microcosm containing air, water and sediment. A four-compartment (i.e., air, SM, water and sediment) fugacity model was successfully applied to the simulated experiments in the microcosm. Data obtained from the four-compartment model calculation yielded a more satisfactory fit with experimental results than the use of a model that does not address the effects of the SM compartment. Results of model calculation show that 97.8% of PCP is distributed to the water phase in the aquatic environment, and 82.2% PCP is removed by the advective outflow and biodegradation in the water phase. The results obtained demonstrate that the higher photodegradation rate of PCP in the SM reduces the concentration of PCP in the air phase.