Uptake and surface chemistry of SO2 on natural Icelandic volcanic dusts under simulated atmospheric conditions
International audience Volcanic dust (v-dust) is a highly variable source of natural particles in the atmosphere, and during the period of high volcanic activity it can provide a large surface for heterogeneous interactions with other atmospheric compounds. With an area of 103,000 km2, Iceland is th...
| Main Authors: | , , , |
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| Other Authors: | , |
| Format: | Other/Unknown Material |
| Language: | English |
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HAL CCSD
2020
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/egusphere-egu2020-530 https://hal.archives-ouvertes.fr/hal-03158536 |
| Summary: | International audience Volcanic dust (v-dust) is a highly variable source of natural particles in the atmosphere, and during the period of high volcanic activity it can provide a large surface for heterogeneous interactions with other atmospheric compounds. With an area of 103,000 km2, Iceland is the biggest volcanic desert on earth. It was chosen as a case study due to frequency of volcanic eruptions and high aeolian activity in the area. This is a comprehensive study of the heterogeneous reactivity of Icelandic volcanic dust with sulfur dioxide (SO2) gas. First, we focused on the kinetics of the reaction of SO2 with natural v-dust samples under atmospheric conditions using coated wall flow tube reactor. Steady-state uptake coefficients were measured to represent the long-term phenomena of the processing of aerosols in the atmosphere and the values obtained can be directly incorporated in chemical transport modeling. Second, the mechanism of the reaction of SO2 with natural v-dust samples was studied using infrared Fourier transform spectroscopy (DRIFTS). Both sulfites and sulfates were observed on the surface of v-dust, with sulfates being the final oxidation product, attesting to SO2 heterogeneous reactivity. Surface hydroxyl groups were found to play a crucial role in the conversion of SO2 to sulfates as evidenced from both flow tube and DRIFTS experiments. Based on these experimental results, a mechanism for SO2 interaction with different surface sites of v-dust was proposed and discussed. Third, in order to monitor the amount of sulfites and sulfates formed on the surface of mineral dusts of different origins a simple, accurate and precise reversed-phase liquid chromatography method was developed and validated to stabilize and analyze sulfites and sulfates in the extract of dusts exposed to SO2. Besides SO2 gas, v-dust reacts with other atmospheric pollutants, such as NO2 and O3, proving that heterogeneous processes play an important role in the atmospheric chemistry. One must keep in mind that as a result ... |
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