Browsing by Author "Xu, Lu"
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Item Hydroxymethanesulfonate (HMS) Formation during Summertime Fog in an Arctic Oil Field(ACS, 2021-06-28) Liu, Jun; Gunsch, Matthew J.; Moffett, Claire E.; Xu, Lu; Asmar, Rime El; Zhang, Qi; Watson, Thomas B.; Allen, Hannah M.; Crounse, John D.; Clair, Jason St.; Kim, Michelle; Wennberg, Paul O.; Weber, Rodney J.; Sheesley, Rebecca J.; Pratt, Kerri A.Hydroxymethanesulfonate (HMS) is produced in the aqueous-phase reaction of formaldehyde (HCHO) and sulfur dioxide (SO2) and has been proposed as a significant contributor to midlatitude wintertime pollution events. Here we report HMS detection within submicrometer atmospheric aerosols during frequent late summer, regional fog events in an Arctic oil field. The number fraction of individual particles containing HMS increased during fog periods, consistent with aqueous-phase formation. The single-particle mass spectra showed the primary particle signature (oil field emissions), plus secondary oxidized organics and sulfate, consistent with aqueous-phase processing. HMS mass concentrations ranged from below the ion chromatography limit of detection (0.3 ng/m3) to 1.6 ng/m3, with sulfate concentrations of 37–222 ng/m3. HCHO and SO2 measurements suggest that the fog HMS production rate is ∼10 times higher in the oil fields than in the upwind Beaufort Sea. Aqueous-phase reactions of local oil field emissions during frequent summertime regional fog events likely have downwind impacts on Arctic aerosol composition. The potential for fog-based HMS production was estimated to be an order of magnitude higher in Fairbanks and Anchorage, AK, than in the oil fields and may explain the missing organosulfate source contributing to Fairbanks air quality.Item Southeast Atmosphere Studies: learning from model-observation syntheses(Copernicus Publications, 2018-02-22) Mao, Jingqiu; Carlton, Annmarie; Cohen, Ronald C.; Brune, William H.; Brown, Steven S.; Wolfe, Glenn M.; Jimenez, Jose L.; Pye, Havala O. T.; Ng, Nga Lee; Xu, Lu; McNeill, V. Faye; Tsigaridis, Kostas; McDonald, Brian C.; Warneke, Carsten; Guenther, Alex; Alvarado, Matthew J.; Gouw, Joost de; Mickley, Loretta J.; Leibensperger, Eric M.; Mathur, Rohit; Nolte, Christopher G.; Portmann, Robert W.; Unger, Nadine; Tosca, Mika; Horowitz, Larry W.Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.