ATMOSPHERIC CARBON MONOXIDE 



139 



Swinnerton, Lamontague, and Linnenbom 1 5 found concentrations of CO in 

 rainwater collected at widely diverse locations corresponding to up to 200-fold 

 supersaturation relative to the partial pressure of CO in the atmosphere. They 

 concluded that the results indicated a natural source of CO that had not 

 previously been considered. They tentatively attributed the production to the 

 photochemical oxidation of organic matter or to the dissociation of carbon 

 dioxide induced by electrical discharges, or to both. No attempt was made to 

 estimate the annual production. 



One other suggestion relating to sources of atmospheric CO should be 

 mentioned. Weinstock and Niki, 1 6 on the basis of steady-state equations for 

 stable CO and for radioactive CO in the troposphere, concluded that CO is 

 produced in the troposphere at a rate of 5 X 10 15 g/year, "some 25 times 

 greater than the rate of carbon monoxide production from combustion." They 

 suggest that the source is the sequence of reactions 



3 + hu^0 2 + 0( ! D) 

 0( X D) + H 2 0^20H 



(1) 

 (2) 



OH + CH 4 ^H 2 + CH 3 



(3) 



followed by the oxidation of CH 3 to form CO. 



The above-mentioned production estimates are summarized in Table 1. 



TABLE 1 



ESTIMATES FROM VARIOUS SOURCES OF THE ANNUAL 

 PRODUCTION OF CARBON MONOXIDE 



*Suggestion of Weinstock and Niki 



1 6 



