Ethylene

CAS RN:74-85-1

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 13(SRC), determined from a structure estimation method(2), indicates that ethylene is expected to have very high mobility in soil(SRC). Volatilization of ethylene from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 0.228 atm-cu m/mole(3). Ethylene is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 5.21X10+4 mm Hg at 25 deg C(4). Biodegradation data in soil were not available(SRC, 2017). However, ethylene was biodegraded to ethylene oxide using acclimated cell free extracts(8).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 13(SRC), determined from a structure estimation method(2), indicates that 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 0.228 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 2 hrs and 2 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 2.6(SRC), from its log Kow of 1.13(6) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data in water were not available(SRC, 2017). However, ethylene was biodegraded to ethylene oxide using acclimated cell free extracts(7).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), ethylene, which has a vapor pressure of 5.21X10+4 mm Hg at 25 deg C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase ethylene 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 2 days(SRC), calculated from its rate constant of 7.9X10-12 cu cm/molecule-sec at 25 deg C(3). Gas-phase ethylene will also be degraded in the atmosphere by reaction with ozone and nitrate radicals with respective half-lives of 6.5 and 190 days(4-6). Ethylene absorbs UV at wavelength 175.2 nm(7) and, therefore, is not expected to be susceptible to direct photolysis by sunlight since sunlight consists of wavelengths above 290 nm(SRC).
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