Passive sampling has been used many times to monitor aquatic environment. it isinexpensive, very sensitive and can provide time weighted average (TWA) concentrations of the free dissolved fraction of monitored pollutants. It has many advantages compared to traditional water sampling. Indeed, results obtained by spot sampling are not always representative of the level of contamination because episodic pollution could be missed. Automatic sampling system is more representative than spot sampling but it is expensive and needs power. In addition, for nonpolar contaminants (such as PCB) which are at low concentration in water, it requires to collect high quantities of water. The transport of these water samples to the laboratory incurs the risk of losses of contaminants through wall adsorption. By measuring free dissolved concentrations, passive sampling provides precious data about pollutant bioavailability (concentrations to which organisms are exposed)
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