Table / Examples of log Kow for Some Environmentally Significant Chemicals Chemical Phthalic acid Benzene Trichloroethylene Tetrachloroethylene Toluene 2,4-Dichlorophenoxyacetic acid Naphthalene 1,2,4,5-Tetrachlorobenzene Phenanthrene Pyrene Hexabromobiphenyl 2,3,7,8-Tetrachlorodibenzo-p-dioxin Dec 3.11 log Kow 0.73 2.17 2.42 2.88 2.69 2.81 3.33 4.05 4.57 5.13 6.39 6.64 8.58 abromobiphenyl le/3.11 Determination of Koc from Kow The log Kow for anthracene is 4.68. What is anthracene's soil-water partition coefficient normalized to organic carbon? solution Use an appropriate correlation between log Koe and log Kow (such as provided in Figure 3.11). Note that this correlation requests log Koer not Kow log Koc 0.903(4.68) +0.094 4.32 Therefore, Koc 10 32 cm3/g organic carbon. example/3.12 Use of Koe to Predict Aqueous Concentration Anthracene has contaminated harbor sediments, and the solid portion of sediment with the pore water. If the organic carbon content of sediments is 5 percent and the solid sediment anthracene concentration is 50 ug/kg sediment, what is the pore water concentration of anthracene at equilibrium? In Example 3.11, log Koc for anthracene was estimated to be 4.32. s is in equilibrium solution An organic carbon (OC) content of 5 percent means that the fraction of organic carbon, foc, is 0.05. Use Equation 3.33 (from Table 3.9) to find the sediment-specific partition coefficient, K: cm3 10432 cm3 0.05 g OC g sedimentgOC gsediment 1045 cm3/g sediment The equilibrium aqueous-phase concentration, C, is then derived from the equilibrium expression given in Equation 3.32 (Table 3.9): 50 ?g 1,000 g x-mh3 x 1000 ml mL 0.048 ?g C=-=.kg sediment 1,045 cm g sediment Note th at the aqueous-phase concentration of anthracene is relatively low compared with the sediment-phase concentration (50 ppbm in the sediments and 0.048 ppbm in the pore water). This is e anthracene is hydrophobic. Its aqueous solubility is low (and Kow is high), so it prefers to Also, the solid phase is high in organic carbon content. A sand-gravel aquifer would be much lower in organic carbon (foe very low); therefore, less of the anthracene would partition from the aqueous into partition into the solid phase. the solid phase
