DETERMINATION OF HENRY LAW CONSTANTS FOR HEXACHLOROCYCLOHEXANES IN DISTILLED WATER AND ARTIFICIAL SEAWATER AS A FUNCTION OF TEMPERATURE

Henry's law constants were determined for alpha- and gamma-hexachlorocyclohexane (HCH) as a function of temperature (0.5-45-degrees-C) in artificial seawater (SW; 30 parts per thousand) and distilled water (DW) using the gas stripping method. Water samples (1-5 ml) were withdrawn from the stripping vessel during the stripping process (30-360 h), solvent extracted and analyzed by gas chromatography-electron-capture detection. The effect of bubbling depth was checked to ensure that bubbles leaving the system were at equilibrium with HCHs in the aqueous phase. Henry's law constants determined at 35 and 45-degrees-C in SW were significantly higher (P less-than-or-equal-to 0.05) than in DW for both alpha- and gamma-HCH, but not at lower temperatures. The slopes (m) and intercepts (b) of log H vs. 1/T plots were: alpha-HCH (DW, 0.5-45-degrees-C); m = - 2810 +/- 110, b = 9.31 +/- 0.38; alpha-HCH (SW, 0.5-23-degrees-C); m = - 2969 +/- 218, b = 9.88 +/- 0.76; gamma-HCH (DW, 0.5-45-degrees-C); m = - 2382 +/- 160, b = 7.54 +/- 0.54; gamma-HCH (SW, 0.5-23-degrees-C); m = - 2703 +/- 276, b = 8.68 +/- 0.96. Henry's law constants determined in this study compared well with those calculated from reported vapor pressure and solubility data.