Development of a novel passive sampling system for the time-averaged measurement of a range of organic pollutants in aquatic environments

A new sampling system has been developed for the measurement of time-averag ed concentrations of organic micropollutants in aquatic environments. The s ystem is based on the diffusion of targeted organic compounds through a rat e-limiting membrane and the subsequent accumulation of these species in a b ound, hydrophobic, solid-phase material. It provides a novel and robust sol ution to the problem of monitoring in situations where large temporal fluct uations in pollutant levels may occur. Accumulation rates are regulated by choice of diffusion-limiting membrane and bound solid-phase material and ha ve been found to be dependent on the physico-chemical properties of individ ual target analytes. Two separate prototype systems are described: one suit able for the sampling of non-polar organic species with log octanol/water p artition coefficient (log P) values greater than 4, the other for more pola r species with log P values between 2 and 4. Both systems use the same soli d-phase material (47 mm C-18 Empore(TM) disk) as a receiving phase but are fitted with different rate-limiting membrane materials (polysulfone for the polar and polyethylene for the non-polar analytes). The two systems comple ment each other and together can be used for sampling a wider range of orga nic analytes than generally possible using current passive sampling techniq ues. Calibration data are presented for both devices. In each case, linear uptake kinetics were sustained, under constant conditions, for deployment p eriods of between 1 and 9 days. The effects of water temperature and turbul ence on sampling rates have been quantitatively assessed. The performance o f the system was further investigated by means of field exposures for one a nd two weeks in marine environments where calibrated samplers were used to determine the time-averaged concentrations of the polar biocides diuron and irgarol 1051. The quantitative results obtained using the passive sampler were compared with those obtained using spot sampling.