Development of a real-time method for the measurement of sulfur(IV) in cloud water with a counter-flow virtual impactor

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5625691

Dixon, R W

A novel method, using a counter-flow virtual impactor (CVI) to measure S(IV) concentrations in cloud water, is described. The CVI collects and evaporates cloud droplets, converting aqueous S(IV) into gaseous SO{sub 2} for analysis with a pulsed-fluorescence detector. Based on calculations and laboratory experiments with acidic droplets, S(IV), except that complexed as hydroxymethanesulfonate (HMS), is expected to be released to the gas phase during droplet evaporation. Evidence for the production of HMS in aerosol particles following droplet evaporation also was obtained from measurements of complexes S(IV) in ambient aerosol samples. Field measurements were performed with a CVI mounted on a research aircraft during the Frontal Boundary Study in Ohio to evaluate the CVI for measuring S(IV) in cloud water. From the signal of the SO{sub 2} analyzer, the aqueous S(IV) concentration was determined. Measurements in clouds showed similar temporal variation of S(IV) (aq) with other cloud parameters following required data treatment. A detection limit of 0.1 nmol per m{sup 3} of air was achieved over one minute intervals and was limited mainly by the noise of the SO{sub 2} analyzer. Determination of molar S(IV) (aq) concentrations requires simultaneous measurements of the water vapor released by the evaporated droplets collected by the CVI which was not made.

• Research Organization: Washington Univ., Seattle, WA (United States)
• OSTI ID: 5625691
• Country of Publication: United States
• Language: English

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