Abstract |
The sorption of 14C-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) from water by two uncontaminated surface soils from the Times Beach, MO, area was evaluated by using batch shake testing. Sorption isotherm plots for the soil with the lower fraction organic carbon (foc) were linear, and regression analysis was used to determine a value of the sorption coefficient (KD) of 30400 mL/g. This value corresponds to a value of log Koc of 6.66, where Koc is the partition coefficient normalized on the basis of soil organic carbon content. Significant interferences attributed to the presence of nonseparable suspended particles were apparent in the measurement of the water-phase concentrations of TCDD for experiments involving the high-foc soil. Prewashing the soil from one to five consecutive times with water appeared to reduce these interferences, as individual-point distribution ratios approached the Koc value determined for the low-foc soil. The measured value of log Koc agrees with the reported estimate of log Koc 6.6 for TCDD made by applying the cosolvent theory to isotherm data generated with water/methanol mixtures. (Copyright (c) 1989 American Chemical Society.) |