Photochemical reactions on aerosols at West Antarctica: A molecular case-study of nitrate formation among sea salt aerosols

Gonçalves, Sandro Aparecido; Weis, Johannes; China, Swarup; Evangelista, Heitor; Harder, Tristan H.; Müller, Simon; Sampaio, Marcelo; Laskin, Alexander; Gilles, Mary K.; Godoi, Ricardo H. M.

doi:10.1016/j.scitotenv.2020.143586

Cited by 11 publications

(10 citation statements)

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“…The variability within individual atmospheric particles has been well documented by both model and field measurements across different regions worldwide such as urban (Wang et al, 2010;Ault et al, 2010Ault et al, , 2012Wang et al, 2012;Fraund et al, 2017;Ren et al, 2018), rural (Vakkari et al, 2018;Tomlin et al, 2020), remote forests (Bondy et al, 2018), Arctic (Gunsch et al, 2017;Gonçalves et al, 2021), and marine (Ault et al, 2013;Zheng et al, 2020a, b). Long-range transport and meteorological processes such as dry intrusions (DIs) and vertical mixing of air also play a significant role in the continuous evolution of particle composition in the atmosphere (Raes, 1995;Pratt and Prather, 2010;Cubison et al, 2011;Igel et al, 2017;Zheng et al, 2020b).…”

Section: Introductionmentioning

confidence: 99%

Impact of dry intrusion events on the composition and mixing state of particles during the winter Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA)

et al. 2021

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Abstract. Long-range transport of continental emissions has a far-reaching influence over remote regions, resulting in substantial change in the size, morphology, and composition of the local aerosol population and cloud condensation nuclei (CCN) budget. Here, we investigate the physicochemical properties of atmospheric particles collected on board a research aircraft flown over the Azores during the winter 2018 Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA) campaign. Particles were collected within the marine boundary layer (MBL) and free troposphere (FT) after long-range atmospheric transport episodes facilitated by dry intrusion (DI) events. Chemical and physical properties of individual particles were investigated using complementary capabilities of computer-controlled scanning electron microscopy and X-ray spectromicroscopy to probe particle external and internal mixing state characteristics. Furthermore, real-time measurements of aerosol size distribution, cloud condensation nuclei (CCN) concentration, and back-trajectory calculations were utilized to help bring into context the findings from offline spectromicroscopy analysis. While carbonaceous particles were found to be the dominant particle type in the region, changes in the percent contribution of organics across the particle population (i.e., external mixing) shifted from 68 % to 43 % in the MBL and from 92 % to 46 % in FT samples during DI events. This change in carbonaceous contribution is counterbalanced by the increase in inorganics from 32 % to 57 % in the MBL and 8 % to 55 % in FT. The quantification of the organic volume fraction (OVF) of individual particles derived from X-ray spectromicroscopy, which relates to the multi-component internal composition of individual particles, showed a factor of 2.06 ± 0.16 and 1.11 ± 0.04 increase in the MBL and FT, respectively, among DI samples. We show that supplying particle OVF into the κ-Köhler equation can be used as a good approximation of field-measured in situ CCN concentrations. We also report changes in the κ values in the MBL from κMBL, non-DI=0.48 to κMBL, DI=0.41, while changes in the FT result in κFT, non-DI=0.36 to κFT, DI=0.33, which is consistent with enhancements in OVF followed by the DI episodes. Our observations suggest that entrainment of particles from long-range continental sources alters the mixing state population and CCN properties of aerosol in the region. The work presented here provides field observation data that can inform atmospheric models that simulate sources and particle composition in the eastern North Atlantic.

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Section: Introductionmentioning

confidence: 99%

Impact of dry intrusion events on the composition and mixing state of particles during the winter Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA)

et al. 2021

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“…Therefore, the formation of additional products contributes to chlorine depletion. More specifically, the role of the photochemical process on these sea salt particles for the subsequent formation of sodium nitrate (NaNO 3 ) can be found elsewhere 20 .…”

Section: Resultsmentioning

confidence: 99%

“…Their interaction with inorganic acids in the atmosphere, such as nitric acid (HNO 3 ) and sulfuric acid (H 2 SO 4 ), and gases like nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ), through heterogeneous reactions, releases hydrochloric acid (HCl) and others gaseous reactive chlorine compounds, such as chlorine gas (Cl 2 ), chlorine nitrite (ClNO 2 ), and hypochlorous acid (HOCl) [16][17][18] . Consequently, a deficit of chloride ion (Cl − ) relative to sodium ion (Na + ) is observed in processed sea salt particles over the open ocean, the sea ice, and the continental ice when compared to fresh sea salt [19][20][21][22] .…”

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Stratospheric ozone depletion in the Antarctic region triggers intense changes in sea salt aerosol geochemistry

Gonçalves

Evangelista

Weis

et al. 2023

Commun Earth Environ

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Since the early 1980s, the Antarctic environment has served as a natural field laboratory for researchers to investigate the effects of stratospheric ozone depletion, which has resulted in increased surface ultraviolet radiation levels. However, its effective threats still present gaps. We report new pieces of evidence of increased ultraviolet radiation impacting West Antarctica sea salt aerosols. Salt aerosols, particularly in the Southern Ocean Sea, play an important role in the radiative earth balance. To disclose the molecular details of sea salt aerosols, we used a synchrotron-based multi-element microscopic speciation of individual microparticles (Scanning Transmission X-ray Microscopy with Near-Edge X-ray Absorption Fine Structure Spectroscopy combined with Computer-Controlled Scanning Electron Microscopy). Here we identified substantial abundances of chlorine-enriched aerosols in sea salt generated by photolytic products, whereas ice core records revealed increased chlorine depletion from the onset of ozone depletion. Our findings reveal that modern sea salt modification has no Holocene precedent.

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“…However, most of the corresponding (Cl + N + 0.5S)/(Na + 0.5Mg) values are about 0.5, indicating that formation sulfates and nitrates cannot account for the observed chloride loss. More speci cally, the role of the photochemical process on these sea salt particles for the subsequent formation of NaNO 3 can be found elsewhere 34 .…”

Section: Resultsmentioning

confidence: 99%

Ozone depletion in the Antarctic region triggers intense changes in sea salt geochemistry

Gonçalves

Evangelista

Weis³

et al. 2022

Preprint

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The Antarctic environment has been used as a natural field laboratory to investigate the impacts of enhanced UV-B radiation over the polar terrestrial biota, marine life, and the cryosphere. UV-B increased levels occur due to the stratospheric ozone depletion detected since the early 80s’ decade. The real dimension of the ozone depletion threat to the Antarctic environments and the atmospheric chemistry remains uncertain. This work presents new pieces of evidence of this impact on individual aerosol particles sampled in West Antarctica, using a synchrotron-based multi-element microscopic/molecular speciation method. We used the Scanning Transmission X-ray microscopy with Near-Edge X-ray Absorption Fine Structure Spectroscopy combined with Computer-Controlled Scanning Electron Microscopy to identify the molecular changes in sea salt particles due to photolytic processes involving chlorine-enriched particles during the ozone depletion period since the 80´s decade. Combining our data with ice core records, we deduce that the modern effects of UV-B on the tropospheric chlorine geochemistry have no precedent for the Holocene.

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Photochemical reactions on aerosols at West Antarctica: A molecular case-study of nitrate formation among sea salt aerosols

Cited by 11 publications

References 63 publications

Impact of dry intrusion events on the composition and mixing state of particles during the winter Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA)

Impact of dry intrusion events on the composition and mixing state of particles during the winter Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA)

Stratospheric ozone depletion in the Antarctic region triggers intense changes in sea salt aerosol geochemistry

Ozone depletion in the Antarctic region triggers intense changes in sea salt geochemistry

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