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Sea salt aerosols play an important role in the radiation budget and atmospheric composition over the Arctic, where the climate is rapidly changing. Previous observational studies have shown Arctic sea ice leads to be an important source of sea salt aerosols, and modeling efforts have also proposed blowing snow sublimation as a source. In this study, size-resolved atmospheric particle number concentrations and chemical composition were measured at the Arctic coastal tundra site of Utqiaġvik, Alaska during spring (April 3 – May 7, 2016). Blowing snow conditions were observed during 25 % of the five-week study period and were over-predicted by a commonly used blowing snow parameterization based solely on wind speed and temperature. Throughout the study, open leads were present locally. During periods when blowing snow was observed, significant increases in the number concentrations of 0.01–0.06 μm particles (factor of six, on average) and 0.06–0.3 μm particles (67 %, on average), and a significant decrease (82 %, on average) in 1–4 μm particles, were observed, compared to low wind speed periods. These size distribution changes were likely caused by the generation of ultrafine particles from leads and/or blowing snow, with scavenging of supermicron particles by blowing snow. At elevated wind speeds, both submicron and supermicron sodium and chloride mass concentrations were enhanced, consistent with wind-dependent local sea salt aerosol production. At moderate wind speeds below the threshold for blowing snow, as well as during observed blowing snow, individual sea spray aerosol particles were measured. These individual salt particles were enriched in calcium relative to sodium in seawater, due to the binding of this divalent cation with organic matter in the sea surface microlayer and subsequent enrichment during seawater bubble bursting. The chemical composition of the surface snowpack also showed contributions from sea spray aerosol deposition. Overall, these results show the contribution of sea spray aerosol production from leads on both aerosols and the surface snowpack. Therefore, if blowing snow sublimation contributed to the observed sea salt aerosol, the snow being sublimed must have been impacted by sea spray aerosol deposition, rather than upward brine migration through the snowpack. Sea spray aerosol production from leads is expected to increase, with thinning and fracturing of sea ice in the rapidly warming Arctic.

Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), a key isoprene oxidation product, with inorganic sulfate aerosol yields substantial amounts of secondary organic aerosol (SOA) through the formation of organosulfur. The extent and implications of inorganic-to-organic sulfate conversion, however, are unknown. Herein, we reveal that extensive consumption of inorganic sulfate occurs, which increases with the IEPOX-to-inorganic sulfate ratio (IEPOX:Sulfinorg), as determined by laboratory and field measurements. We further demonstrate that organosulfur greatly modifies critical aerosol properties, such as acidity, morphology, viscosity, and phase state. These new mechanistic insights reveal that changes in SO2 emissions, especially in isoprene-dominated environments, will significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX:Sulfinorg will play a central role in understanding historical climate and determining future impacts of biogenic SOA on global climate and air quality.

Andrew Ault is a graduate student in the Faculty of Business Administration at Lakehead University.

Given the capacity for public opinion to be swayed by media organizations, it is highly important that such organizations are ethical in their decisions as to which aspects of public life to expose, the context in which they situate them within, and the source of data being presented as fact. Hence, this study examines the relationship between a nation’s level of democracy, and the emphasis of democratic values expressed in such country’s most prominent media ethics codes. In specific, this paper will address three preeminent and interrelated questions: (1) Does the breadth and depth of democratic values in media ethics codes of the world’s leading democratic countries correlate to any marginal difference in its level of democracy? (2) Which values do media ethics codes, overall, adequately emphasize and on which values can they improve? (3) Is there great variance in the democratic values expressed in media ethics codes’ between those created by third sector associations and private sector publications in democracies with significant English speaking media? This study finds that (i) marginal democracy is correlated to the strongest private sector publication within its jurisdication and thus ethics codes remain important, (ii) that values relating to opinion poll citations, digital ethics and understanding media's role on society are widely excluded from codes and (iii) that ethics codes created by publications themselves are much more comprehensive than their third sector counterparts.