Photo-enhanced uptake of SO <sub>2</sub> on Icelandic volcanic dusts
(2022) Environmental Science: Atmospheres — Vol. 2, n° 3, p. 375-387 (2022)
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- Authors
Lasne, Jerome 
Maters, Elena
- Abstract
- Iceland is the largest volcanic dust (v-dust) desert on Earth, with an estimated area of 22 000 km 2. In addition, Iceland is one of the most active aeolian areas in the world, with frequent high-velocity winds resuspending v-dust from the ground into the atmosphere. Suspended v-dust particles can then be transferred over thousands of kilometers, reaching as far as central Europe. Once released into the atmosphere, v-dust particles can interact or react with atmospheric pollutants. In this study, we investigate the heterogeneous reactivity of sulfur dioxide (SO 2), one of the most prominent gases released by volcanic eruptions, with Icelandic v-dust particles, and the influence of relevant atmospheric parameters, such as relative humidity (RH) and ultraviolet (UV) light flux, on this reactivity. The experiments are conducted at atmospheric pressure in a coated-wall flow-tube reactor coupled with an SO 2 analyzer. To quantify the heterogeneous processes, we determine the initial number of SO 2 molecules taken up by dust, N S , and the steady-state uptake coefficient, g ss , of SO 2 on different v-dusts. N S increases with RH and with the photon flux characterized by the photolysis rate of NO 2 in the setup, J NO 2. The photo-enhanced removal of SO 2 is also found to depend on the surface elemental composition of v-dust particles, and an empirical parametrization of the photo-induced effect is proposed to account for the most important environmental factors, leading to the general expression: N S,light /N S,dark ¼ 6.1 Â (1 + 7.76 Â 10 À2 Â RH) Â (1 + 480.5 Â J NO 2) Â (Ti/Si). The steady-state uptake coefficients of SO 2 are in the 10 À8 range, once normalized to the specific surface area of v-dust. RH and UV light influence the value of g ss , but to a lesser extent than they influence N S. Our results suggest that the photo-induced heterogeneous uptake of SO 2 on v-dust particles may provide a significant sink of sulfur in volcanic clouds, and should be taken into account in atmospheric modeling. Environmental signicance SO 2 is an atmospheric pollutant that plays a key role in the environment. It is well established in the literature that SO 2 can interact/react with atmospheric particles. However, there is limited knowledge on SO 2 interaction with natural volcanic particles, despite the signicance of this heterogeneous process on air quality and climate. In this study, we investigate the heterogeneous uptake of SO 2 on natural volcanic particles. Using a well-established experimental approach, the SO 2 uptake coefficients and surface coverages are determined under atmospheric levels of relative humidity (RH) and light radiation. A multi-parametric equation is developed and applied to t SO 2 removal on volcanic particles.
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Citations
Lasne, J., Urupina, D., Maters, E., Delmelle, P., Romanias, M., & Thevenet, F. (2022). Photo-enhanced uptake of SO <sub>2</sub> on Icelandic volcanic dusts. Environmental Science: Atmospheres, 2(3), 375-387. https://doi.org/10.1039/d1ea00094b (Original work published 2022)