Localization of point sources of PCBs pollution in rivers using LDPE passive samplers, a Swiss case study

Due to its situation of “Europe’s water reservoir”, Switzerland has a particular responsibility towards downstream countries. It must ensure an optimal quality of its surface waters, following thus the example of the EU members which have to reach by 2015 the good status for surface water set by the Water Frame Directive. In order to achieve that goal, there is a need to localize sources of pollution to reduce emissions to water. In this study, an investigation was conduct along the “Venoge” River to localize potential sources of PCBs pollution contaminating it. A simple, rapid and easy method using passive samplers of Low-density polyethylene (LDPE), known to adsorb PCBs, has been established. It is therefore an accessible technology and requires no power source or specialized equipment in situ. The passive samplers were placed over 2 iron bars at each measurement site. They were fully immersed during the duration of the experiment, typically 4 to 6 weeks. Once out, PCBs from the LDPE samplers were extracted using dichloromethane, purified by adsorption chromatography and analysed by gas chromatography (GC-ECD). Results show the great interest of LDPE passive samplers in the localization of sources of contamination in rivers. One industrial site, a former landfill and a wastewater treatment plant receiving waters from an industrial zone were pointed out as sources of PCBs. On-going experiments are carried out to compare LDPE with silicone in the “Venoge” River in order to determine the most appropriate polymer for point sources localization. For both polymers, the uptake kinetics of PCBs present in the river and the release kinetics of PRCs spiked on the samplers before exposure are studied.