Removal of SO2 from the marine boundary layer over the Atlantic Ocean : a case study on the kinetics of the S(IV)oxidation on marine aerosols

• Main Authors: Krischke, U., Staubes, R., Brauers, T., Gautrois, M., Burkert, J., Stöbener, D., Jaeschke, W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Union 2000
• Subjects: info:eu-repo/classification/ddc/550; J; Iceland
• Online Access: https://juser.fz-juelich.de/record/44790; https://juser.fz-juelich.de/search?p=id:%22PreJuSER-44790%22

Measurements of SO2 and NSS-SO42- were made over the Atlantic Ocean on board the RV Polarstern from October 9 to November 2, 1996, as part of the ALBATROSS campaign. The measurements were performed between 66.7 degrees N and 37.8 degrees S with a mean longitude of approximately 30 degrees W. The most frequent background values for SO2 were found to be 13 parts per trillion by volume (pptv) (0.54 mnol m(-3) at standard ambient temperature and pressure (SATP)) in the Southern Hemisphere, and 15 pptv (0.62 nmol m(-3) SATP) in the Northern Hemisphere. The mean values for total NSS-SO42- in particles with a d > 0.2 mu m were (5.99 +/- 2.93) nmol m(-3) (SATP) in the Southern Hemisphere, and (8.93 +/- 5.29) nmol m(-3) (SATP) in the Northern Hemisphere. An analysis of the size-fractionated aerosol samples (d > 1 mu m and 0.2 mu m < d < 1 mu m) of NSS-SO42-. shows that (34 +/- 13)% of the total NSS-SO42- exists in coarse mode particles with d > 1 mu m. The main fraction of this NSS-SO42-. is most likely produced by the oxidation of dissolved SO2 via heterogeneous reactions occurring in the aqueous phase of coarse mode marine aerosols. A case study on the kinetics of this oxidation pathway was conducted during ALBATROSS. October 12, 1996, the ship sailed in the plume of a volcano on Iceland during its eruption from September 30 to October 13, 1996, as indicated by trajectory analysis and by the measurements of NSS-SO42- SO2, CO, and Hg, An empirical physicochemical approach considering the atmosphere as a natural flow reactor is used for the presented case study. The determined pseudo-first-order reaction rate constant for;the oxidation of SO, on marine aerosols is 3.31 x 10(-4) s(-1) at 25 degrees C. Assuming that the occurrence of coarse mode marine aerosols is the rate-limiting variable of the reaction, the second-order reaction rate constant is found to be 1.32 x 10(-6) cm(3) s(-1) particle(-1) at 25 degrees C. These values are in good agreement with results of previous field experiments as well as with ...