Abstract
International regulations are under consideration for methyl bromide because of its high time dependent ozone depletion potential. Geocycling of the species is not well understood, and removal may occur in several types of natural water incuding the oceanic and those in soils. The hydrolysis reaction is a dominant loss pathway in environmental aqueous systems, but rate constants have generally been reported only in distilled water and at greater than room temperature. Here we present measurements in sodium chloride solutions and in seawater in addition to pure water, and at temperatures across the oceanographic range. The reaction could be followed even in solutions near the freezing point because product methanol was monitored in the method of initial rates. Time constants for methyl bromide hydrolysis fall between 10 and 1000 days over the temperatures of the sea, and are always within an order of magnitude of the fastest abiotic destruction mode, chlorination. Activation energies for the two processes are similar so that the ratio of their time scales does not vary with oceanic location. Hydrolysis rate constants are also listed for the closely related compounds methyls iodide and chloride. Solvolysis of the methyl halides in natural waters acts as a source of methanol to the ocean and atmosphere.
Similar content being viewed by others
References
Arnold, F. and Henschen, G., 1982, Positive ion composition measurements in the upper stratosphere: Evidence for an unknown aerosol component,Planetary and Space Sci. 30(1), 101–108.
Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, R. F., Kerr, J. A., and Troe, J., 1989, Evaluated kinetic and photochemical data for atmospheric chemistry: Supplement III,J. Phys. Chem. Ref. Data 18(2), 881–1097.
Barbash, J. E. and Reinhard, M., 1989, Reactivity of sulfur nucleophiles toward halogenated orgnaic compounds in natural waters, in E. Saltzman and W. J. Cooper (eds.),Biogenic Sulfur in the Environment, American Chemical Society, Washington D.C., pp. 101–137.
Blandamer, M. J., Burgess, J., Robertson, R. E., and Scott, J. M. W., 1982, Dependence of equilibrium and rate constants on temperature and pressure,Chem. Rev. 82(3), 259–286.
Blandamer, M. J., Scott, J. M. W., and Robertson, R. E., 1985, Solvolysis revisited,Progress Phys. Org. Chem. 15, 149–196.
Castro, C. E. and Belser, N. O., 1981, Photohydrolysis of methyl bromide and chloropicrin,J. Agric. Food Chem. 29(5), 1005–1008.
Cicerone, R. J., Stedman, D. H., and Stolarski, R. S., 1975, Estimates of 1974 stratospheric concentration of gaseous chlorine compounds,Geophys. Res. Lett. 2, 219–222.
Crutzen, P. J., 1988, Tropospheric ozone: An overview, in I. S. A. Isaksen (ed.),Tropospheric Ozone, D. Reidel, Dordrecht, pp. 3–32.
Demore, W. B., Sander, S. P., Golden, D. M., Molina, M. J., Hampson, R. F., Kurylo, M. J., Howard, C. J., and Ravishankara, A. R., 1990, Chemical kinetics and photochemical data for use in stratospheric modeling: Evaluation number 9. Jet Propulsion Laboratory publication 90-1.
Elliott, S., 1984, The chemistry of some atmospheric gases in the ocean, Ph.D. thesis, University of California Irvine.
Elliott, S. and Rowland, F. S., 1993, Nucleophilic substitution rates and solubilities for methyl halides in seawater,Geophys. Res. Lett. 20(11), 1043–1046.
Fells, I. and Moelwyn-Hughes, E. A., 1959, The kinetics of the hydrolysis of the chlorinated methanes,J. Chem. Soc., 398–409.
Gentille, J. A., Ferraris, L., and Crespi, S., 1989, Degradation of methyl bromide in fresh water,Pesticide Science 25, 261–272.
Hoyt, S. D. and Rasmussen, R. A., 1985, Determining trace gases in air and seawater,Adv. Chem. 209, 31–56.
Laughton, P. M. and Robertson, R. E., 1956, Solvolysis in deuterium and hydrogen oxide,Can. J. Chem. 34, 1714–1718.
Mabey, W. and Mill, T., 1978, Critical review of hydrolysis of organic compounds in water for environmental conditions,J. Phys. Chem. Ref. Data 7(2), 383–415.
Mellouki, A., Talukdar, R., Schmoltner, A. M., Gierczak, T., Mills, M. J., Solomon, S., and Ravishankara, A. R., 1992, Atmospheric lifetimes and ozone depletion potentials of methyl bromide and dibromomethane,Geophys. Res. Lett. 19, 2059–2062.
Moelwyn-Hughes, E. A., 1938, The hydrolysis of the methyl halides,Proc. Roy. Soc. A 164, 295–306.
Oremland, R. S., Miller, L. G., Blunden, T. M., Culvertson, C. W., Coulatkis, M. D., and Jahnke, L. L., 1993a, Degradation of atmospheric halogenated methanes I: Activity of soil methanotrophic bacteria, submitted toEnviron. Sci. Technol.
Oremland, R. S., Miller, L. G., and Strohmaier, F. E., 1993b, Degradation of atmospheric halogenated methanes II: Chemical and bacterial attack on methyl bromide in anaerobic sediments, submitted toEnviron. Sci. Technol.
Oyama, S. T. and Somorjai, g. A., 1988, Homogeneous, heterogeneous, and enzymatic catalysis,J. Chem. Ed. 65(9), 765–769.
Riley, J. P. and Skirrow, G., 1975,Chemical Oceanography, Academic Press, New York.
Robertson, R. E., Heppolette, R. L., and Scott, J. M. W., 1959, A survey of thermodynamic parameters for solvolysis in water,Can. J. Chem. 37, 803–824.
Singh, H. B. and Kanakidou, M., 1993, An investigation of the atmospheric sources and sinks of methyl bromide,Geophys. Res. Lett. 20(2), 133–136.
Singh, H. B., Salas, L. J., and Stiles, R. E., 1983, Methyl halides in and over the Eastern Pacific,J. Geophys. Res. 88(C6), 3684–3690.
Solomon, S. and Albritton, D. L., 1992, Time dependent ozone depletion potentials for short and long term forecasts,Nature 357, 33–37.
Streitwieser, A., 1956, Solvolytic displacement reactions at saturated carbon atoms,Chem. Rev. 56, 571–752.
Sverdrup, H. U., Johnson, M. W., and Fleming, R. H., 1942,The Oceans, Prentice Hall, Englewood Cliffs, New Jersey.
Wofsy, S. C., McElroy, M. B., and Yung, Y. L., 1975, The chemistry of atmospheric bromine,Geophys. Res. Lett. 2(6), 215–218.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Elliott, S., Rowland, F.S. Methyl halide hydrolysis rates in natural waters. J Atmos Chem 20, 229–236 (1995). https://doi.org/10.1007/BF00694495
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00694495