Increases in wintertime PM2.5 sodium and chloride linked to snowfall and road salt application

Kolesar, Katheryn R.; Mattson, Claire N.; Peterson, Peter K.; May, Nathaniel W.; Prendergast, Rashad K.; Pratt, Kerri A.

doi:10.1016/j.atmosenv.2018.01.008

Cited by 52 publications

(52 citation statements)

References 66 publications

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“…6.3 for a discussion of phase separation in the context of acidity). The strong acidity property of aerosol (Koutrakis et al, 1988) has historically been associated with adverse health effects (Dockery et al, 1993Thurston et al, 1994;Spengler et al, 1996;Gwynn et al, 2000;EPA, 2009). One reason for this could be that aerosol acidity influences solubilization and the concentrations of toxic forms of trace species, such as transition and heavy metals, that have been linked to negative health effects (Kelly and Fussell, 2012;Lippmann, 2014;Rohr and Wyzga, 2012;Chen and Lippmann, 2009;Frampton et al, 1999).…”

Section: The Importance Of Atmospheric Aciditymentioning

confidence: 99%

“…In the 1980s-1990s, experimental methods were developed to estimate the apparent net fine-particle (< 2.5 µm) strong acidity (Koutrakis et al, 1988(Koutrakis et al, , 1992Purdue, 1993). These methods, synthesized in a workshop report (EPA, 1999;Purdue, 1993), resulted in an officially documented method for estimating H + air from measurements.…”

Section: Proxies Based On Electroneutralitymentioning

confidence: 99%

“…The method relies on efficient particle collection with minimal filter artifacts and low amounts of nitrate compared to sulfate (EPA, 1999). For example, ammonia could displace H + and neutralize acidic particles during collection without an efficient denuder (Koutrakis et al, 1988). Extraction and dilution of ambient samples modify their chemical environment such that the conditions during measurement are different from those in the ambient atmosphere, potentially affecting gasparticle partitioning of total ammonium and dissociation of weak acids including bisulfate (Purdue, 1993).…”

Section: Proxies Based On Electroneutralitymentioning

confidence: 99%

“…For a set of submicrometer particles with homogeneous composition (i.e., an internal mixture, as often found in aged aerosols), this assumption is often satisfied, particularly at higher RH. The simplest bulk method, first utilized in the late 1980s, involved adding a known volume of water to a filter and then utilizing a standard electrochemical pH probe to infer so-called strong acidity (Koutrakis et al, 1988). As discussed here and in Sect.…”

Section: Bulk Ph Measurementsmentioning

confidence: 99%

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The acidity of atmospheric particles and clouds

et al. 2020

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Abstract. Acidity, defined as pH, is a central component of aqueous chemistry. In the atmosphere, the acidity of condensed phases (aerosol particles, cloud water, and fog droplets) governs the phase partitioning of semivolatile gases such as HNO3, NH3, HCl, and organic acids and bases as well as chemical reaction rates. It has implications for the atmospheric lifetime of pollutants, deposition, and human health. Despite its fundamental role in atmospheric processes, only recently has this field seen a growth in the number of studies on particle acidity. Even with this growth, many fine-particle pH estimates must be based on thermodynamic model calculations since no operational techniques exist for direct measurements. Current information indicates acidic fine particles are ubiquitous, but observationally constrained pH estimates are limited in spatial and temporal coverage. Clouds and fogs are also generally acidic, but to a lesser degree than particles, and have a range of pH that is quite sensitive to anthropogenic emissions of sulfur and nitrogen oxides, as well as ambient ammonia. Historical measurements indicate that cloud and fog droplet pH has changed in recent decades in response to controls on anthropogenic emissions, while the limited trend data for aerosol particles indicate acidity may be relatively constant due to the semivolatile nature of the key acids and bases and buffering in particles. This paper reviews and synthesizes the current state of knowledge on the acidity of atmospheric condensed phases, specifically particles and cloud droplets. It includes recommendations for estimating acidity and pH, standard nomenclature, a synthesis of current pH estimates based on observations, and new model calculations on the local and global scale.

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Section: The Importance Of Atmospheric Aciditymentioning

confidence: 99%

Section: Proxies Based On Electroneutralitymentioning

confidence: 99%

Section: Proxies Based On Electroneutralitymentioning

confidence: 99%

Section: Bulk Ph Measurementsmentioning

confidence: 99%

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The acidity of atmospheric particles and clouds

et al. 2020

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“…Only a small fraction is mobilized to the gas phase as HCl or other species. Additional minor sources of tropospheric chlorine include open fires, coal combustion, waste incineration, industry, road salt application, and ocean emission of organochlorine compounds (McCulloch et al, 1999;Lobert et al, 1999;WMO, 2014;Kolesar et al 2018). It is useful to define Cly as total gas-phase inorganic chlorine, excluding particle phase Cl -.…”

Section: Introductionmentioning

confidence: 99%

The role of chlorine in tropospheric chemistry

Wang¹,

Jacob²,

Eastham³

et al. 2018

Preprint

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Abstract. We present a comprehensive simulation of tropospheric chlorine within the GEOS-Chem global 3-D model of oxidant-aerosol-halogen atmospheric chemistry. The simulation includes explicit accounting of chloride mobilization from sea-salt aerosol by acid displacement of HCl and by other heterogeneous processes. Additional sources of tropospheric chlorine (combustion, organochlorines, transport from stratosphere) are small in comparison. Reactive gas-phase chlorine Cl*, including Cl, ClO, Cl2, BrCl, ICl, HOCl, ClNO3, ClNO2, and minor species, is produced by the HCl + OH reaction and by heterogeneous conversion of sea-salt aerosol chloride to BrCl, ClNO2, Cl2, and ICl. The model simulates successfully the observed mixing ratios of HCl in marine air (highest at northern mid-latitudes) and the associated HNO3 decrease from acid displacement. It captures the high ClNO2 mixing ratios observed in continental surface air at night with chlorine of sea salt origin transported inland as HCl and fine aerosol. It simulates successfully the vertical profiles of HCl measured from aircraft, where enhancements in the continental boundary layer can again be explained by transport inland of the marine source. It does not reproduce the boundary layer Cl2 mixing ratios measured in the WINTER aircraft campaign (1&#8211;5&#8201;ppt in the daytime, low at night); the model is too high at night compared to WINTER observations, which could be due to uncertainty in the rate of the ClNO2 + Cl&#8722; reaction, but we have no explanation for the daytime observations. The global mean tropospheric concentration of Cl atoms in the model is 620&#8201;cm&#8722;3 and contributes 1.0&#8201;% of the global oxidation of methane, 20&#8201;% of ethane, 14&#8201;% of propane, and 4&#8201;% of methanol. Chlorine chemistry increases global mean tropospheric BrO by 85&#8201;%, mainly through the HOBr + Cl&#8722; reaction, and decreases global burdens of tropospheric ozone by 7&#8201;% and OH by 3&#8201;% through the associated bromine radical chemistry. ClNO2 chemistry drives increases in ozone of up to 8&#8201;ppb over polluted continents in winter.

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