Trans-1,2-dichloroethylene (alias of E-12-Dichloroethene)

CAS RN:156-60-5

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), a reported Koc value of 59(2), indicates that trans-1,2-dichloroethylene is expected to have high mobility in soil(SRC). Volatilization of trans-1,2-dichloroethylene from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 9.38X10-3 atm-cu m/mole(3). trans-1,2-Dichloroethylene is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 331 mm Hg at 25 deg C(4). trans-1,2-Dichloroethylene, present at 2.32 mg/L, reached 0% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 1 drop/L in the Japanese MITI test(5), suggesting that aerobic biodegradation is not an important environmental fate process in soil(SRC). However, trans-1,2-Dichloroethylene had soil field biodegradation rates of 0.229 and 0.215/week(6).

AQUATIC FATE: Based on a classification scheme(1), a reported Koc value of 59(2), indicates that trans-1,2-dichloroethylene 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 9.38X10-3 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 3 hours and 4 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 11(SRC), from its log Kow of 2.09(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). trans-1,2-Dichloroethylene is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(8). No biodegradation occurred in a river die-away test(9). Under anoxic conditions using uncontaminated organic sediment from the Everglades, 73% of the chemical was lost in 6 months with the accompanying formation of vinyl chloride(10), suggesting that anaerobic biodegradation is 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), trans-1,2-dichloroethylene, which has a vapor pressure of 331 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase trans-1,2-dichloroethylene is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals, ozone and nitrate radical(SRC); the half-lives for these reactions in air are estimated to be 6.6, 5.7 and 310 days(SRC), calculated from its rate constants of 2.34X10-12(3), 2.0X10-18(4) and 1.07X10-16 cu cm/molecule-sec(5), respectively. trans-1,2-Dichloroethylene does not contain chromophores that absorb at wavelengths >290 nm(6) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

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