| 환경 거동 | TERRESTRIAL FATE: Based on a classification scheme(1), a reported log Koc value of 0.91 in soil(2) indicates that 1,1,1,2-tetrafluoroethane is expected to have very high mobility in soil(SRC). Volatilization of 1,1,1,2-tetrafluoroethane from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 0.05 atm-cu m/mole(3). 1,1,1,2-Tetrafluoroethane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 4990 mm Hg at 25 °C(4). Using aerobic screening tests, 4% biodegradation was observed(5) and little to no degradation was seen anaerobically(6-7), suggesting that biodegradation is not an important environmental fate process in soil(SRC).AQUATIC FATE: Based on a classification scheme(1), a reported log Koc value of 0.91 in soil(2), indicates that 1,1,1,2-tetrafluoroethane is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon a Henry's Law constant of 0.05 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 3 hours and 4 days, respectively(SRC). Hydrolysis is not expected to be an important environmental fate process in the environment since this chemical lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9)(5). According to a classification scheme(6), an estimated BCF of 6(SRC), from an estimated log Kow of 1.68(7) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Using aerobic screening tests, 4% biodegradation was observed(8) and little to no degradation was seen anaerobically(9-10), suggesting that biodegradation is not an important environmental fate process in water(SRC).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 1,1,1,2-tetrafluoroethane, which has a vapor pressure of 4990 mm Hg at 25 °C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase 1,1,1,2-tetrafluoroethane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC)the half-life for this reaction in air is estimated to be 5.2-11.6 years(SRC), calculated from rate constants of 3.8X10-15 to 8.44X10-15 cu cm/molecule-sec(3-7). 1,1,1,2-Tetrafluoroethane does not contain chromophores that absorb at wavelengths >290 nm(8) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC). Atmospheric life-times for 1,1,1,2-tetrafluoroethane have been reported as 13.1-16.3 years(4-5,9-12). 1,1,1,2-Tetrafluoroethane has estimated 20, 100 and 500 year Global Warming Potentials of 3300-4845, 1300-1896 and 420-589, respectively(4-5,9-12). |
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