Abstract
In order to develop the model for predicting the concentrations of toxic chemicals in natural aquatic systems, their relationship between water and sediment were investigated statistically with the data of “Chemicals in the Environment” published by Japan Environmental Agency. As to both the relationship at each sampling station and the relationship between sampling stations, almost all of the relationships for hydrophobic substances were significantly positive, but less significant correlations (sometimes negative) were observed for hydrophilic substances. In the case of high logKow (Octanol-water partition coefficient) (>2) substances, the calculated logKom (the ratio of concentration in mass of sediment organic matter to that in water) agreed closely with the reported ones for aromatic compounds, chlorinated hydrocarbon etc. by the sorption isotherm. In contrast, there observed from two to five degrees of magnitude differences between them in the case of low logKow (<2) substances. Ionic sorption and chemical reaction on sediment surface were most likely to be taken into consideration in order to explain the discrepancy observed for hydrophilic substances.
