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The indoor surfaces of dwellings across the United States range exhibit a wide range of chemical compositions and physical properties, which impacts semi-volatile partitioning, heterogeneous chemistry and the overall properties of indoor air. 

ABSTRACT: At fixed aerosol acidity, we recently demonstrated that dimers in isoprene epoxydiol-derived secondary organic aerosol (IEPOX-SOA) can heterogeneously react with hydroxyl radical (·OH) at faster rates than monomers. Aerosol acidity influences this aging process by enhancing the formation of oligomers in freshly generated IEPOX-SOA. Therefore, we systematically examined the role of aerosol acidity on kinetics and products resulting from heterogeneous ·OH oxidation of freshly generated IEPOX-SOA. IEPOX reacted with inorganic sulfate aerosol of varying initial pH (0.5, 1.5, and 2.5) in a steady state smog chamber to yield a constant source of freshly generated IEPOX-SOA, which was aged in an oxidation flow reactor for 0−22 equiv days of atmospheric ·OH exposure. Molecular-level chemical analyses revealed that the most acidic sulfate aerosol (pH 0.5) formed the largest oligomeric mass fraction, causing the slowest IEPOX-SOA mass decay with aging. Reactive uptake coefficients of ·OH (γOH) were 0.24 ± 0.06, 0.40 ± 0.05, and 0.49 ± 0.20 for IEPOX-SOA generated at pH 0.5, 1.5, and 2.5, respectively. IEPOXSOA became more liquid-like for pH 1.5 and 2.5, while exhibiting an irregular pattern for pH 0.5 with aging. Using kinetic and physicochemical data derived for a single aerosol pH in atmospheric models could inaccurately predict the fate of the IEPOX-SOA. 

Stereoisomers of organosulfates are formed preferentially. 

ABSTRACT: Chemical transformation of 2-methyltetrol sulfates (2-MTS), key isoprene-derived secondary organic aerosol (SOA) constituents, through heterogeneous hydroxyl radical (•OH) oxidation can result in the formation of previously unidentified atmospheric organosulfates (OSs). However, detected OSs cannot fully account for the sulfur content released from reacted 2-MTS, indicating the existence of sulfur in forms other than OSs such as inorganic sulfates. This work investigated the formation of inorganic sulfates through heterogeneous •OH oxidation of 2-MTS aerosols. Remarkably, high yields of inorganic sulfates, defined as the moles of inorganic sulfates produced per mole of reacted 2-MTS, were observed in the range from 0.48 ± 0.07 to 0.68 ± 0.07. These could be explained by the production of sulfate (SO4•−) and sulfite (SO3•−) radicals through the cleavage of C−O(S) and (C)O−S bonds, followed by aerosol-phase reactions. Additionally, nonsulfated products resulting from bond cleavage were likely volatile and evaporated into the gas phase, as evidenced by the observed aerosol mass loss (≤25%) and concurrent size reduction upon oxidation. This investigation highlights the significant transformation of sulfur from its organic to inorganic forms during the heterogeneous oxidation of 2-MTS aerosols, potentially influencing the physicochemical properties and environmental impacts of isoprene-derived SOAs. 

The Arctic is rapidly warming and has transitioned to thinner sea ice which fractures, producing leads. Sea ice loss is expected to be increasing sea spray aerosol production in the High Arctic. Few studies have investigated Arctic sea spray aerosol (SSA) produced from open ocean, leads, and melt ponds, characterized by varied salinity, microbial community, and organic composition. The concentrations, size distributions, single-particle composition, and ice-nucleating activity of the SSA experimentally-generated were measured and compared to the chemical and biological properties of the surface waters. A marine aerosol reference tank (MART) was deployed aboard the Swedish Icebreaker Oden to the high Arctic Ocean during August – September 2018 to study SSA generated from locally-collected surface water. Surface water salinity, chlorophyll-a, organic carbon, nitrogen, and microbial community composition (18s and 16s DNA-derived, flow cytometry of nano- and picoplankton) data are submitted. Experimental aerosol data submitted include type, size, mole ratio, Raman spectra, Raman type, and ice nucleating particles. High resolution Fourier Transform Ion Cyclotron Resonance mass spectrometry (FTICR-MS) data for surface water and experimentally-generated aerosol dissolved organic matter are included . 

The rapidly warming Arctic has transitioned to thinner sea ice which fractures, producing leads. Few studies have investigated Arctic sea spray aerosol (SSA) produced from open ocean, leads, and melt ponds, which vary in salinity and organic and microbial community composition. A marine aerosol reference tank was deployed aboard an icebreaker to the Arctic Ocean during August–September 2018 to study SSA generated from locally collected surface waters. Aerosol generation experiments were carried out using water collected from the marginal ice zone, a human-made hole in sea ice near the North Pole, and both lead and melt pond water during an ice floe drift period. Salinity, chlorophyll a, organic carbon, nitrogen, and microbial community composition were measured. Eukaryotic plankton and bacterial abundance were elevated in experimental water from the marginal ice zone, but the relative contributions from major eukaryotic taxonomic groups varied little across the experiments. The chemical composition of individual SSA particles was analyzed using Raman microspectroscopy and computer-controlled scanning electron microscopy with energy-dispersive X-ray spectroscopy. Individual sea salt aerosol, primary organic aerosol, and mineral dust particles were observed. Sea salt aerosol constituted 44–95% of individual submicrometer and 68–100% of supermicrometer particles, by number, generated during each experiment. Carbon was detected in 85%, by number, of the individual sea salt particles, with visible organic coatings. Carbohydrates were detected in 72% of particles, by number, with smaller contributions from long-chain fatty acids (13%) and siliceous material (15%). SSA generated from melt pond water contained only long-chain fatty acids and siliceous material. Quantification of the ice-nucleating activity showed that locally produced SSA may define the High Arctic background ice-nucleating particle population, but cannot account for the peak atmospheric concentrations observed. As the Arctic warms, the increasing SSA emissions have a complex dependence on changing biological and physical processes.