SAMPLING AND PARTITION OF NEUTRAL ORGANIC CONTAMINANTS IN SURFACE WATERS WITH REGARD TO LEGISLATION, ENVIRONMENTAL-QUALITY AND FLUX ESTIMATIONS

The distribution of neutral organic contaminants among the different phases in surface water is predicted from the octanol-water partition coefficient (K(ow)), resulting in a reasoned sampling approach. Most pitfalls in methodology of sampling and the determination of partition coefficients appear to origin from adsorption. For contaminants with K(ow) values <10(4) environmental quality of surface waters, represented by the truly dissolved contaminants, can be determined by simply sampling the dissolved phase. For more hydrophobic contaminants sampling suspended particulate matter (SPM) is prefered as this method is hardly afflicted by adsorption problems. The contaminants truly dissolved content then can be estimated through the partition coefficient. Results of the SPMs contaminant contents, expressed per weight units organic carbon, allow spatial and temporal comparison to be achieved. Estimating fluxes of contaminants, mainly bound to organic matter (particulate and/or colloidal), should be focused on accurately determining the flux of this organic matter. Application of continuous-flow centrifugation for sampling suspended matter shows many advantages.