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GLOBAL DISTRIBUTION OF SELECTED HALOCARBONS, HYDROCARBONS, SF6, AND N2O
Citation:
Singh, H., L. Salas, H. Shigeishi, AND E. Scribner. GLOBAL DISTRIBUTION OF SELECTED HALOCARBONS, HYDROCARBONS, SF6, AND N2O. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-78/100 (NTIS PB289925), 1978.
Description:
Northern and Southern hemispheric distributions of halogenated species, hydrocarbons, SF6, and N2O are presented. The atmospheric growth rates of selected halocarbons and N2O are characterized. The fluorocarbon 11 and 12 global burden and hemispheric distribution is consistent with the view that no significant sinks in the troposphere exist. The north-south gradients of fluorocarbon 11, 12, 113, 114, CCl4, and SF6 suggest rapid global mixing with an interhemispheric exchange rate of about one year. Within each hemisphere, these species are well mixed. N2O shows the least variations around the globe. The global distribution of CH3CCl3 is found to be complex and suggests higher HO levels in the southern hemisphere and around the equator, when compared to the northern hemispheric HO levels. The global distribution of CH3Cl is almost uniform and a significant natural source has been identified in the ocean. It is also shown that large anthropogenic primary or secondary sources of CH3Cl and CCl4 exist. Species such as CHCl3, CH2Cl2, C2HCl3, and C2Cl4 show very large north-south gradients. The atmospheric growth of fluorocarbons 11, 12, CH3CCl3, and CCl4 appear to be consistent with the emissions of these constituents.