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S. Keßel, J. Auld, J. Crowley, A. Horowitz, R. Sander, P. Veres, J. Williams
There is a large volume of published studies describing the role of carbon dioxide and carbon monoxide in the atmosphere. The aim of this work was to analyze both source and sink terms of another carbon oxide, called carbon suboxide (C3O2), which atmospheric relevance is yet relatively unknown. Therefore we started our studies with developing a simple method to synthesise C3O2 out of malonic acid and phosphorous pentoxide. Afterwards a calibrated detetection method was needed to identify and quantify C3O2 in the atmosphere. We used a proton transfer reaction time of flight mass spectrometer to monitor online in a tropical green house, pipe smoke, ambient air in Mainz and offline a volcanic air sample from Stromboli (Italy). Only the ambient air measurement in Mainz showed evidence of C3O2 in the atmosphere. Furthermore we studied different possibilities for C3O2 losses in the atmosphere. To describe the behavior of C3O2 on aqueous surfaces the Henry-constant (kH = 1.56 ± 0.01 M atm-1 at pH = 6) and hydrolysis constant (kHyd = 0.039 ± 0.002 s-1 at pH = 6) were determined. Hence, the lifetime of C3O2 in the presence of fog and clouds is 7 to 10 days and of aerosols 104 years. In addition the rate constants of C3O2 at room temperature (298±3 K) and 1000 mbar with atmospheric oxidizing agents like ozone (kO3 = (1.5 ± 0.3) · 10-21 cm3 s-1 molecules-1) and OH radicals (kOH = (2.6 ± 0.5) · 10-12 cm3 s-1 molecules-1) were determined via fourier transform infrared spectrometer measurements. The measured UV-spectrum was used to derive the photolysis rates, in the pressure range 10 mbar to 1000 mbar and zenith angles 10° to 90°, based on model calculations. |
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