Composition and secondary formation of fine particulate matter in the Salt Lake Valley: Winter 2009

Kuprov, Roman; Eatough, Delbert J.; Cruickshank, Tyler; Olson, Neal; Cropper, Paul M.; Hansen, Jaron C.

doi:10.1080/10962247.2014.903878

Cited by 48 publications

(52 citation statements)

References 14 publications

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“…In contrast, in Fresno the nighttime surface O 3 levels during Episode 1 were nearly zero, suppressing surface NO − 3 (p) formation. This near-zero nocturnal O 3 is similar to observations by Kuprov et al (2014) made a few years before Baasandorj et al (2017) at one of the same valley floor sites in Utah, reflecting year-to-year differences.…”

Section: Linking To Other Regionssupporting

confidence: 71%

“…It may be that production of NO − 3 (p) via the N 2 O 5 hydrolysis pathway may be significant in the aloft RL in other regions with similar geographical and meteorological conditions, such as Salt Lake Valley, Utah (Kuprov et al, 2014;Baasandorj et al, 2017). However, in valley regions with lower NO x or O 3 the nocturnal P NO − 3 may be lower, thus limiting the importance of this pathway (Akira et al, 2005;Bigi et al, 2012).…”

Section: Linking To Other Regionsmentioning

confidence: 99%

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Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

et al. 2017

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Abstract. This study discusses an analysis of combined airborne and ground observations of particulate nitrate ) concentrations made during the wintertime DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically resolved observations relevant to Air Quality) study at one of the most polluted cities in the United States -Fresno, CA -in the San Joaquin Valley (SJV) and focuses on developing an understanding of the various processes that impact surface nitrate concentrations during pollution events. The results provide an explicit case-study illustration of how nighttime chemistry can influence daytime surface-level NO 3 (p) in the RL, along with daytime photochemical production, can contribute substantially to the buildup and sustaining of severe pollution episodes. The exceptionally shallow nocturnal boundary layer (NBL) heights characteristic of wintertime pollution events in the SJV intensify the importance of nocturnal production aloft in the residual layer to daytime surface concentrations. The observations also demonstrate that dynamics within the RL can influence the earlymorning vertical distribution of NO − 3 (p) , despite low wintertime wind speeds. This overnight reshaping of the vertical distribution above the city plays an important role in determining the net impact of nocturnal chemical production on local and regional surface-level NO − 3 (p) concentrations. Entrainment of clean free-tropospheric (FT) air into the boundary layer in the afternoon is identified as an important process that reduces surface-level NO − 3 (p) and limits buildup during pollution episodes. The influence of dry deposition of HNO 3 gas to the surface on daytime particulate nitrate concentrations is important but limited by an excess of ammonia in the region, which leads to only a small fraction of nitrate existing in the gas phase even during the warmer daytime. However, in the late afternoon, when diminishing solar heating leads to a rapid fall in the mixed boundary layer height (BLH), the impact of surface deposition is temporarily enhanced and can lead to a substantial decline in surface-level particulate nitrate concentrations; this enhanced deposition is quickly arrested by a decrease in surface temperature, whichPublished by Copernicus Publications on behalf of the European Geosciences Union. 14748 G. Prabhakar et al.: Particulate nitrate formation in the wintertime drops the gas-phase fraction to near zero. The overall importance of enhanced late-afternoon gas-phase loss to the multiday buildup of pollution events is limited by the very shallow nocturnal boundary layer. The case study here demonstrates that mixing down of NO − 3 (p) from the RL can contribute a majority of the surface-level NO − 3 (p) in the morning (here, ∼ 80 %), and a strong influence can persist into the afternoon even when photochemical production is maximum. The particular day-to-day contribution of aloft nocturnal NO − 3 (p) production to surface concentrations will depend on prevailing chemical and meteorological ...

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Section: Linking To Other Regionssupporting

confidence: 71%

Section: Linking To Other Regionsmentioning

confidence: 99%

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

et al. 2017

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“…20 Chemical composition measurements of PM and their precursor gases, together with a detailed understanding of the meteorology are key to identifying sources and developing mitigation strategies. Previous studies showed that ammonium nitrate (NH4NO3) dominates the aerosol mass during pollution episodes (Hansen et al, 2010;Kelly et al, 2013;Kuprov et al, 2014;Long et al, 2003;Long et al, 2005a;Long et al, 2005b;Mangelson et al,1997;Silva et al, 2007). Analysis of ground-25 based data suggests and that its formation, at least in the Salt Lake Valley and Cache Valley is likely to be nitric acid limited (Kuprov et al, 2014;Mangelson et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies showed that ammonium nitrate (NH4NO3) dominates the aerosol mass during pollution episodes (Hansen et al, 2010;Kelly et al, 2013;Kuprov et al, 2014;Long et al, 2003;Long et al, 2005a;Long et al, 2005b;Mangelson et al,1997;Silva et al, 2007). Analysis of ground-25 based data suggests and that its formation, at least in the Salt Lake Valley and Cache Valley is likely to be nitric acid limited (Kuprov et al, 2014;Mangelson et al, 1997). The Great Salt Lake is a potential source of chloride in the area, and chloride may also play a role during pollution episodes, although its role is much less clear.…”

Section: Introductionmentioning

confidence: 99%

Airborne and ground-based observations of ammonium nitrate dominated aerosols in a shallow boundary layer during intense winter pollution episodes in northern Utah

Franchin¹,

Fibiger²,

Goldberger³

et al. 2018

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Abstract. Airborne and ground-based measurements of aerosol concentrations, chemical composition and gas phase precursors were obtained in three valleys in northern Utah (U.S.A.). The measurements were part of the Utah Winter Fine 20Particulate Study (UWFPS) that took place in January-February, 2017. Total aerosol mass concentrations of PM1 were measured from a Twin Otter aircraft, with an Aerosol Mass Spectrometer (AMS). PM1 concentrations ranged from less than 2 μg m -3 during clean periods to over 100 μg m -3 during the most polluted episodes, consistent with PM2.5 total mass concentrations measured concurrently at ground sites. Across the entire region, increases in total aerosol mass above ~ 2 μg m -3 were associated with increases in the ammonium nitrate mass fraction, clearly indicating that the highest aerosol mass 25 loadings in the region were predominantly attributable to an increase in ammonium nitrate. The chemical composition was regionally homogenous for total aerosol mass concentrations above 17.5 μg m -3 , with 74±5% (average ± standard deviation) ammonium nitrate, 18±3% organic material, 6±3% ammonium sulfate, and 2±2% ammonium chloride. Vertical profiles of aerosol mass and volume in the region showed variable concentrations with height in the polluted boundary layer. Higher average mass concentrations were observed within the first few hundred meters above ground level in all three valleys during 30 pollution episodes. Gas phase measurements of nitric acid (HNO3) and ammonia (NH3) during the pollution episodes revealed that in Cache and Utah Valley, partitioning of inorganic semi-volatiles to the aerosol phase was usually limited by the amount of gas phase nitric acid, with NH3 being in excess. The inorganic species were compared with the ISORROPIA thermodynamic model. Total inorganic aerosol mass concentrations were calculated for various decreases of total nitrate and total ammonium. Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-629 Manuscript under review for journal Atmos. Chem. Phys. Discussion started: 9 July 2018 c Author(s) 2018. CC BY 4.0 License. 2For pollution episodes, our simulations of a 50% decrease in total nitrate lead to a 46±3% decrease in total PM1 mass. A simulated 50% decrease in total ammonium lead to a 36±17% µg m -3 in total PM1 mass, over the entire area of the study.Despite some differences among different locations, our results also showed a higher sensitivity to decreasing nitric acid concentrations and the importance of ammonia at the lowest total nitrate conditions. In the Salt Lake Valley, both HNO3 and NH3 concentrations controlled aerosol formation. 5

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“…The nonattainment status of an area has legislative implication for air quality mitigation. Salt Lake City failed to meet the 24-h NAAQS for PM 2.5 by the Environmental While much attention has been focused on PM 2.5 source attribution through analysis of chemical components [Long et al, 2005;Kelly et al, 2013;Kuprov et al, 2014], the sources of the carbonaceous aerosol have remained poorly characterized. However, the carbonaceous aerosol, and in particular the BC fraction, has recently gained increased recognition as a major driver of adverse air pollution health impacts.…”

Section: 1002/2017jd026519mentioning

confidence: 99%

Using radiocarbon to constrain black and organic carbon aerosol sources in Salt Lake City

et al. 2017

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Black carbon (BC) and organic carbon (OC) aerosols are important components of fine particulate matter (PM2.5) in polluted urban environments. Quantifying the contribution of fossil fuel and biomass combustion to BC and OC concentrations is critical for developing and validating effective air quality control measures and climate change mitigation policy. We used radiocarbon (14C) to measure fossil and contemporary biomass contributions to BC and OC at three locations in Salt Lake City, Utah, USA, during 2012–2014, including during winter inversion events. Aerosol filters were analyzed with the Swiss_4S thermal‐optical protocol to isolate BC. We measured fraction modern (fM) of BC and total carbon in PM2.5 with accelerator mass spectrometry and derived the fM of OC using isotope mass balance. Combined with 14C information of end‐member composition, our data set of 31 14C aerosol measurements provided a baseline of the fossil and contemporary biomass components of carbonaceous aerosol. We show that fossil fuels were the dominant source of carbonaceous aerosol during winter, contributing 88% (80–98%) of BC and 58% (48–69%) of OC. While the concentration of both BC and OC increased during inversion events, the relative source contributions did not change. The sources of BC also did not vary throughout the year, while OC had a considerably higher contemporary biomass component in summer at 62% (49–76%) and was more variable. Our results suggest that in order to reduce PM2.5 levels in Salt Lake City to meet national standards, a more stringent policy targeting mobile fossil fuel sources may be necessary.

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Composition and secondary formation of fine particulate matter in the Salt Lake Valley: Winter 2009

Cited by 48 publications

References 14 publications

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

Airborne and ground-based observations of ammonium nitrate dominated aerosols in a shallow boundary layer during intense winter pollution episodes in northern Utah

Using radiocarbon to constrain black and organic carbon aerosol sources in Salt Lake City

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