The Henry's Law constant for acetylene is estimated as 2.2X10-2 atm-cu m/mole(SRC) derived from its vapor pressure, 3.65X10+4 mm Hg(1), and water solubility, 1,200 mg/L(2). This Henry's Law constant indicates that acetylene 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 1.5 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 days(SRC). Acetylene's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of acetylene from dry soil surfaces will exist(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 (1998) (2) Yalkowsky SH et al; Handbook of Aqueous Solubility Data. 2nd ed. Boca Ratin, FL: CRC Press, p. 20 (2010) (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 acetylene is estimated as 2(SRC), using a log Kow of 0.37(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that acetylene is expected to have very high mobility in soil. Less than 1 ppm of gas acetylene was absorbed to dry soil and a maximum of 90 ppm of acetylene was absorbed to moist soil samples taken from 6 soil samples from Oregon, Iowa and Saskatchewan, Canada(4).
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 Jan 15, 2014: http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm (3) Swann RL et al; Res Rev 85: 17-28 (1983) (4) Smith et al.; Soil Science 116: 313-319 (1973)