| 환경 거동 | TERRESTRIAL FATE: Based on a classification scheme(1), a Koc value of 399(2) indicates that 1,1,1,2-tetrachloroethane is expected to have moderate mobility in soil(SRC). Volatilization of 1,1,1,2-tetrachloroethane from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 2.50X10-3 atm-cu m/mole(3). 1,1,1,2-Tetrachloroethane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 12.0 mm Hg(4). Biodegradation data are not available for 1,1,1,2-tetrachloroethane(SRC, 2008)however, biodegradation data for the isomer 1,1,2,2-tetrachloroethane indicate that degradation will be slow under aerobic conditions, but may proceed under anaerobic conditions(5).AQUATIC FATE: Based on a classification scheme(1), a Koc value of 399(2) indicates that 1,1,1,2-tetrachloroethane is expected to adsorb very little to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon a Henry's Law constant of 2.50X10-3 atm-cu m/mole(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 4.2 hours and 5.3 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 12(SRC), from a water solubility of 1.07X10+3 mg/L at 25 °C(6) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Hydrolysis of 1,1,1,2-tetrachloroethane is expected to be slow under environmental conditions based on reported half-lives of 46.8 and 350 years at 25 °C and pH 7(7,8). Biodegradation data are not available for 1,1,1,2-tetrachloroethane(SRC, 2008)however, biodegradation data for the isomer 1,1,2,2-tetrachloroethane indicate that degradation will be slow under aerobic conditions, but may proceed under anaerobic conditions(9).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 1,1,1,2-tetrachloroethane, which has a vapor pressure of 12.0 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 1,1,1,2-tetrachloroethane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC)the half-life for this reaction in air is calculated to be 891 days(SRC), based on a rate constant of 1.80X10-14 cu cm/molecule-sec at 25 °C(3). 1,1,1,2-Tetrachloroethane does not contain chromophores that absorb at wavelengths >290 nm(4) and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC). |
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