A New Analyzer for Sulfuric Acid and Sulfur Aerosols in Ambient Air: Development And Measurements
Summary
A semi-continuous analyzer has been developed for simultaneous monitoring of ambient sulfuric acid and sulfur aerosols. Sulfur aerosol concentration is measured directly with a flame photometric detector. Sulfuric acid is first adsorbed and accumulated in a heated diffusion denuder. Subsequently it is released by increasing the temperature to 700°C and analyzed by the same detector. With a time resolution of 30 min. the detection limit of the analyzer amounts to 0.1 µg m-3 for sulfuric acid and 1.0 µg m-3 for sulfur aerosols (calculated as S04 2-). The automated and computer controlled analyzer was applied to a clean and highly polluted air region (Edelmannshof; Berlin West)) and a smog chamber. Sulfuric acid was detected only in winter, where it reached up to 2.7 µg m-3 at Edelmannshof and up to 0.74 µg m-3 in Berlin (West). Corresponding S02 concentrations were much lower at Edelmannshof. In summer the ratio of S04 2-/S02 was found to be 10 times higher at Edelmannshof than in Berlin (West). The photochemical experiments, which were carried out with α-pinene, S02, NOx, 03, H20 and light in Teflon bags, showed good reproducibility. The relative humidity influenced greatly the composition of the formed sulfur aerosols. More than 90% of these aerosols were identified as S04 2- using ion chromatographic analysis. Up to 50% of the converted S02 were recovered as suspended aerosols in the bag.
Keywords
Measurement Campaign Sulfur Aerosol Simultaneous Monitoring Teflon Film Smog ChamberPreview
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References
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