Abstract:
in previous studies we have indicated a relationship between a decline in macro-invertebrate population densities and riverine endosulfan concentrations measured using passive samplers (Hyne et al. , 1999; Leonard et al. , 2000). These passive samplers, constructed of low density polyethylene membrane bags containing the solvent 2,2,4-trimethylpentane (TRIMPS), were then used in the Department of Land and Water Conservation(ELWC) NW region water quality program for comparison to traditional grab sampling procedures (Muschal, 1999). The TRIMPS detected three pesticides in river water that were not detected by routine manual sampling. The TRlMPS were also able to show that endosulfan and profenofos concentrations were higher downstream of irrigated agriculture than upstream of this area (Muschal, 1999). Environment Australia has also drawn attention to the utilisation of passive samplers in the Existing Chemical Review Program (ECRP) for endosulfan and for the registration of certain organophosphorus pesticides.
There was a need to develop a field validated model of the operation of passive samplers. The kinetics of pesticide uptake and release from the passive samplers needed to be understood. The influences of changes in river flow, turbidity and biofouling or ageing on the absorption of pesticides into the passive samplers also needed to be assessed. In addition, the influence of solvent type and frequency of sampling needed to be assessed in laboratory studies.
