Uptake and surface chemistry of SO2 on natural Icelandic volcanic dusts under simulated atmospheric conditions

• Main Authors: Urupina, Darya, Romanias, Manolis, Thevenet, Frederic, Lasne, Jerome
• Other Authors: Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Lille Douai), Institut Mines-Télécom Paris (IMT)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDE]Environmental Sciences; Iceland
• Online Access: https://hal.science/hal-03158536; https://doi.org/10.5194/egusphere-egu2020-530

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 km 2 , 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 (SO 2 ) gas. First, we focused on the kinetics of the reaction of SO 2 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 SO 2 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 SO 2 heterogeneous reactivity. Surface hydroxyl groups were found to play a crucial role in the conversion of SO 2 to sulfates as evidenced from both flow tube and DRIFTS experiments. Based on these experimental results, a mechanism for SO 2 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 SO 2 . Besides SO 2 gas, v-dust reacts with other atmospheric pollutants, such as NO 2 and O 3 , proving that heterogeneous processes play an important role in the atmospheric chemistry. One must keep in mind ...