Oxygen-18 Studies of Atmospheric Sulfate Formation

摘要

An analytical method was developed for the determination of the delta sup 18 O of H sub 2 O sub 2 (ppB range) in rainwater. According to our new method, rainwater, collected in 25-L plastic bottles by four 1-m sup 2 funnels (inverted plastic skylights, connected to the bottles by plastic hose), was acidified and kept refrigerated to prevent autodecomposition of the peroxide until the time of analysis. Dissolved air was removed from a 20-L sample of the rainwater by combined evacuation, ultrasonic agitation, and helium sparge (VUS). The peroxide in the rainwater was then oxidized to O sub 2 by KMnO sub 4 ; the O sub 2 was removed from the water sample by the VUS treatment, and carried in the helium stream through a bed of charcoal and platinum where it was quantitatively converted to CO sub 2 . The CO sub 2 , containing the oxygen atoms derived from the peroxide, was measured to determine the concentration of peroxide in the atmosphere and analyzed mass spectromically to determine its delta sup 18 O. (ERA citation 11:051938)