Hybrid multiple-site mass closure and source apportionment of PM2.5 and aerosol acidity at major cities in the Po Valley

Masiol, Mauro; Formenton, Gianni; Khan, Badiuzzaman; Hopke, Philip K.; Nenes, Athanasios; Pandis, Spyros Ν.; Tositti, Laura; Benetello, Francesca; Visin, Flavia; Pavoni, Bruno

doi:10.1016/j.scitotenv.2019.135287

Cited by 57 publications

(38 citation statements)

References 93 publications

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“…The pH of marine aerosol increases with particle size, with the highest value equal to 4.5 for the 2.5-5 μm and 5-10 μm ranges, as sea salt is emitted mainly at the super-micron range and is the main aerosol component. Over the continental region, average PM1 pH ranges 170 between 1 to 3 with the highest values in the northern coastal parts of Europe and northern Italy; in these regions, acidity is reduced by the high levels of NH3 present from agriculture and livestock emissions combined with high NOx and RH levels (Guo et al, 2018;Masiol et al, 2019). PM1-2.5 is less acidic with pH values from 1 to 4 over the continental region with the higher values in the northern coastal areas of Europe (e.g., parts of the United Kingdom).…”

Section: Size Dependence Of Aerosol Phmentioning

confidence: 99%

“…5)which is exclusively an effect of relative humidity decrease. A secondary effect is that the lower concentration of aerosol tends to drive partitioning of semi-volatile species (nitrate, ammonium) to the gas phase (Nenes et al, 2019). As a result, particles of all sizes that are acidic at ground level become more acidic when they move higher in the atmosphere.…”

Section: Ph Variation With Heightmentioning

confidence: 99%

“…Acidity is an aerosol property of central importance driving gas-particle partitioning and heterogeneous chemistry (Pye et al, 2019). pH affects the formation of semi-volatile particulate 30 matter and the nitrogen cycle by modulating HNO3/NO3and NH3/NH4 + gas-particle partitioning (Meskhidze et al, 2003;Guo et al, 2017;Nenes et al, 2019). Aerosol acidity can influence pH-https://doi.org/10.5194/acp-2019-1146 Preprint.…”

Section: Introductionmentioning

confidence: 99%

“…realization, aerosol pH and liquid water content emerge as powerful aerosol state variables (Nenes et al, 2019) that could help elucidate the complex impacts of aerosol on public health, ecosystems and 360 climate.…”

mentioning

confidence: 99%

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Size-resolved aerosol pH over Europe during summer

Ζακούρα¹,

Kakavas²,

Nenes³

et al. 2020

Preprint

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Abstract. The dependence of aerosol acidity on particle size, location and altitude over Europe during a summertime period is investigated using the hybrid version of aerosol dynamics in the chemical transport model PMCAMx. The pH changes more with particle size in northern and southern Europe owing to the enhanced presence of non-volatile cations (Na, Ca, K, Mg) in the larger particles. Differences of up to 1&#8211;4 pH units are predicted between sub- and super-micron particles, while the average pH of PM1&#8211;2.5 can be as much as 1 unit higher than that of PM1. Most aerosol water over continental Europe is associated with PM1, while PM2.5&#8211;5 and PM5&#8211;10 dominate the water content in the marine and coastal areas due to the relatively higher levels of hygroscopic sea salt. Particles of all sizes become increasingly acidic with altitude (0.5&#8211;2 units pH decrease over 2.5&#8201;km) primarily because of the decrease in aerosol liquid water content (driven by humidity changes) with height. Inorganic nitrate is strongly affected by aerosol pH with the highest average nitrate levels predicted for the PM2.5&#8211;5 range and over locations where the pH exceeds 3. Dust tends to increase aerosol water levels, aerosol pH and nitrate concentrations for all particle sizes. This effect of dust is quite sensitive to its calcium content. The size-dependent pH differences carry important implications for pH-sensitive processes in the aerosol.

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Section: Size Dependence Of Aerosol Phmentioning

confidence: 99%

Section: Ph Variation With Heightmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Size-resolved aerosol pH over Europe during summer

Ζακούρα¹,

Kakavas²,

Nenes³

et al. 2020

Preprint

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“…The aerosol pH was calculated for all samples by the model, as well as aerosol water content (AWC. Table S3), details of the calculation of pH and AWC can be found elsewhere (Liu et al, 2017b;Masiol et al, 2020). The calculated aerosol pH results of 10 labs are presented in Fig.…”

Section: Aerosol Ph Using Isorropia-iimentioning

confidence: 99%

An inter-laboratory comparison of aerosol in organic ion measurements by Ion Chromatography: implications for aerosol pH estimate

Xu¹,

Song²,

Harrison³

et al. 2020

Preprint

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Abstract. Water soluble inorganic ions such as ammonium, nitrate, and sulfate are major components of fine aerosols in the atmosphere and are widely used in the estimation of aerosol acidity. However, different experimental practices and instrumentation may lead to uncertainties in ion concentrations. Here, an inter-comparison experiment was conducted in 10 different laboratories (labs) to investigate the consistency of inorganic ion concentrations and resultant aerosol acidity estimates using the same set of aerosol filter samples. The results mostly exhibited good agreement for major ions Cl−, SO42−, NO3−, NH4+ and K+. However, F−, Mg2+ and Ca2+ were observed with more variations across the different labs. The Aerosol Chemical Speciation Monitor (ACSM) data of non-refractory SO42−, NO3−, NH4+ generally correlated very well with the filter analysis based data in our study, but the absolute concentrations differ by up to 42 %. Cl− from the two methods are correlated but the concentration differ by more than 3 times. The analyses of certified reference materials (CRMs) generally showed good recovery of all ions in all the labs, the majority of which ranged between 90 % and 110 %. Better agreements were found for Cl−, SO42−, NO3−, NH4+ and K+ across the labs after their concentrations were corrected with CRM recoveries; the coefficient of variation (CV) of Cl−, SO42−, NO3−, NH4+ and K+ decreased 1.7 %, 3.4 %, 3.4 %, 1.2 % and 2.6 %, respectively, after CRM correction. We found that the ratio of anion to cation equivalent concentrations (AE/CE) is not a good indicator for aerosol acidity estimates, as the results in different labs did not agree well with each other. Ion balance (anions – cations) calculated from SO42−, NO3− and NH4+ gave more consistent results, because of their relatively large concentrations and good agreement among different labs. In situ aerosol pH calculated from the ISORROPIA-II thermodynamic equilibrium model with measured ion and ammonia concentrations showed a similar trend and good agreement across the 10 labs. Our results indicate that although there are important uncertainties in aerosol ion concentration measurements, the estimated aerosol pH from the ISORROPIA-II model is more consistent.

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