Ventilation of liquefied petroleum gas components from the Valley of Mexico
- Earth and Environmental Science Division, Geoanalysis Group, Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
- Chemistry Department, University of California, Irvine (United States)
- Atmospheric Sciences Department, University of California, Los Angeles (United States)
- Technology and Safety Assessment Division, Energy and Environmental Analysis Group, Los Alamos National Laboratory, Los Alamos, New Mexico (United States)
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania (United States)
- Instituto Mexicano del Petroleo, Gerencia de Ciencias del Ambiente, (Mexico) D.F.
The saturated hydrocarbons propane and the butane isomers are both indirect greenhouse gases and key species in liquefied petroleum gas (LPG). Leakage of LPG and its component alkanes/alkenes is now thought to explain a significant fraction of the volatile organic burden and oxidative potential in the basin which confines Mexico City. Propane and the butanes, however, are stable enough to escape from the basin. The gas chromatographic measurements which have drawn attention to their sources within the urban area are used here to estimate rates of ventilation into the free troposphere. The calculations are centered on several well studied February/March pollution episodes. Carbon monoxide observations and emissions data are first exploited to provide a rough time constant for the removal of typical inert pollutant species from the valley. The timescale obtained is validated through an examination of meteorological simulations of three-dimensional flow. Heuristic arguments and transport modeling establish that propane and the butanes are distributed through the basin in a manner analogous to CO despite differing emissions functions. Ventilation rates and mass loadings yield outbound fluxes in a box model type computation. Estimated in this fashion, escape from the Valley of Mexico constitutes of the order of half of 1{percent} of the northern hemispheric inputs for both propane and n-butane. Uncertainties in the calculations are detailed and include factors such as flow into the basin via surface winds and the size of the polluted regime. General quantification of the global propane and butane emissions from large cities will entail studies of this type in a variety of locales.{copyright} 1997 American Geophysical Union
- OSTI ID:
- 587123
- Journal Information:
- Journal of Geophysical Research, Vol. 102, Issue D17; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
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