Ethane is a gas and therefore volatilization from soil and water is expected to be the most important fate process. The Henry's Law constant for ethane is estimated as 0.5 atm-cu m/mole(SRC) derived from its vapor pressure, 3.15X10+4 mm Hg(1), and water solubility, 60.2 mg/L(2). This Henry's Law constant indicates that ethane is expected to volatilize rapidly from water surfaces(3). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 1.6 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 2.2 days(SRC). Ethane's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Volatilization of ethane from dry soil surfaces will occur(SRC) based upon its vapor pressure(1).
Literature: (1) Daubert TE, Danner RP; Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, DC: Taylor and Francis (1989) (2) McAuliffe C; J Phys Chem 70: 1267-75 (1966) (3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990)
The Koc of ethane is estimated as 37(SRC), using a log Kow of 1.81(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that ethane is expected to have very high mobility in soil.
Literature: (1) Hansch C et al; Exploring QSAR. Hydrophobic, Electronic, and Steric Constants. ACS Prof Ref Book. Heller SR, consult. ed., Washington, DC: Amer Chem Soc p. 4 (1995) (2) US EPA; Estimation Program Interface (EPI) Suite. Ver. 4.1. Nov, 2012. Available from, as of November 18, 2013: http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm (3) Swann RL et al; Res Rev 85: 17-28 (1983)