PASSIVE SAMPLER FOR CHLORINATED PESTICIDES IN ESTUARINE WATERS

Monitoring organic contaminants in the marine environment and identity ing their bioconcentration pathways presents great difficulties, as th e analytical techniques require preconcentration steps that are time-c onsuming and tedious. Samplers have been developed that can concentrat e extremely low levels of hydrophobic compounds, such as organochlorin e pesticides, from water bodies, for direct analysis with minimal samp le preparation. The passive samplers consist of polyethylene tubes fil led with iso-octane that are deployed within weighted wire cages in es tuaries and rivers for a period of three weeks. Hydrophobic compounds such as chlorinated pesticides are continuously partitioned from the w ater column into the solvent within the tube, providing an integrated sample over the duration of exposure. Pesticides are concentrated 200- 300 fold in three weeks. Upon retrieval, the contents can be analysed directly by gas chromatography-electron capture detector (GC-ECD) or c oncentrated for analysis by gas chromatography-mass spectrometry (GC-M S). Laboratory experiments to determine the uptake rate of the compoun ds into the sampler enable the calculation of average water concentrat ion over the sampling period. The samplers are cheap and easy to prepa re, enabling their deployment in numerous sites over long periods if r equired. They are envisaged as being a quick and easy monitor for back ground levels of these contaminants within our waterways.