Radio and stable-isotope measurements of atmospheric carbon monoxide in Los Angeles

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Measurements of ¹³C/¹²C, ¹⁸O/¹⁶O and ¹⁴C/¹²C ratios of CO collected at ground surface were performed, during July, 1992 through September, 1993, on twenty-five atmospheric samples which were obtained from Burbank, Lynwood and Westwood (Los Angeles), Lake Gregory and Ojai (semi-remote areas of southern California). The ranges of ambient CO concentrations were 0.4-3.9 ppmv and the isotopic ratios measured were -24.4 to -29.0‰ for δ¹³C_V-PDB, and +16.3 to +24.9‰ for δ¹⁸O_V-SMOW, respectively, while the content of modern carbon ranged from 20 to 68%. Although it is obvious that fossil fuel combustion (presumably from automobile exhaust) is the dominant source for CO in Los Angeles, domestic wood burning in winter or some other non-fossil fuel sources may contribute as much as 17% CO to the atmospheric burden in some areas of Los Angeles.