Fossil fuel combustion, biomass burning and biogenic sources of fine carbonaceous aerosol in the Carpathian Basin

Salma, Imre; Vasanits-Zsigrai, A.; Machon, Attila; Varga, Tamás; Major, István; Gergely, Virág; Molnár, Mihály

doi:10.5194/acp-20-4295-2020

Cited by 28 publications

(31 citation statements)

References 86 publications

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“…The trends, i.e. the smoothed curves over the 7 months, are in line with the distributions of the monthly median concentrations of the species at identical locations determined for several years (Salma et al, 2020b).…”

Section: Time Series Of Concentrationssupporting

confidence: 78%

“…The latter process occurs as a daily phenomenon with a typical shape of its monthly occurrence frequency (Salma and Németh, 2019). This distribution changes in Budapest from year to year without any tendentious character (Salma et al, 2020b). Particles with a diameter from 25 to 100 nm (N 25-100 ) in cities are mainly emitted by incomplete combustion or consist of grown new particles by condensation, while the size fraction with a diameter from 100 to 1000 nm (N 100-1000 ) expresses physically and chemically aged particles; thus, they represent larger spatial extents (Salma et al, 2014;Mikkonen et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…The higher O 3 concentration could partly be associated with the lower concentrations of NO. Ozone exhibits a strong seasonal dependency (Salma et al, 2020b). Lower concen- Figure 7.…”

Section: Quantification Of Concentration Changesmentioning

confidence: 99%

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What can we learn about urban air quality with regard to the first outbreak of the COVID-19 pandemic? A case study from central Europe

Salma¹,

Vörösmarty²,

Gyöngyösi³

et al. 2020

Atmos. Chem. Phys.

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Abstract. Motor vehicle road traffic in central Budapest was reduced by approximately 50 % of its ordinary level for several weeks as a consequence of various limitation measures introduced to mitigate the first outbreak of the COVID-19 pandemic in 2020. The situation was utilised to assess the real potentials of urban traffic on air quality. Concentrations of NO, NO2, CO, O3, SO2 and particulate matter (PM) mass, which are ordinarily monitored in cities for air quality considerations, aerosol particle number size distributions, which are not rarely measured continuously on longer runs for research purposes, and meteorological properties usually available were collected and jointly evaluated in different pandemic phases. The largest changes occurred over the severest limitations (partial lockdown in the Restriction phase from 28 March to 17 May 2020). Concentrations of NO, NO2, CO, total particle number (N6–1000) and particles with a diameter < 100 nm declined by 68 %, 46 %, 27 %, 24 % and 28 %, respectively, in 2020 with respect to the average reference year comprising 2017–2019. Their quantification was based on both relative difference and standardised anomaly. The change rates expressed as relative concentration difference due to relative reduction in traffic intensity for NO, NO2, N6–1000 and CO were 0.63, 0.57, 0.40 and 0.22 (%/%), respectively. Of the pollutants which reacted in a sensitive manner to the change in vehicle circulation, it is the NO2 that shows the most frequent exceedance of the health limits. Intentional tranquillising of the vehicle flow has considerable potential for improving the air quality. At the same time, the concentration levels of PM10 mass, which is the most critical pollutant in many European cities including Budapest, did not seem to be largely affected by vehicles. Concentrations of O3 concurrently showed an increasing tendency with lower traffic, which was explained by its complex reaction mechanism. Modelling calculations indicated that spatial gradients of NO and NO2 within the city became further enhanced by reduced vehicle flow.

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Section: Time Series Of Concentrationssupporting

confidence: 78%

Section: Methodsmentioning

confidence: 99%

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What can we learn about urban air quality with regard to the first outbreak of the COVID-19 pandemic? A case study from central Europe

Salma¹,

Vörösmarty²,

Gyöngyösi³

et al. 2020

Atmos. Chem. Phys.

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“…Thus, it can be regarded as an urban background site. The local sources comprise residential and household emissions including seasonal heating, exhaust of vehicle traffic and some industrial sources (Salma et al, 2017(Salma et al, , 2020a(Salma et al, , 2020b. Long-range transport of air masses can also play a role in shorter time intervals.…”

Section: Experimental Partmentioning

confidence: 99%

“…and N6-25 was significant (0.875) during the measurement year. The latter size fraction mainly contains freshly emitted particles from road vehicles in most of the time (Salma et al, 2017), which typically exhibit low hygroscopicity (Burkart et al, 2011;Rose et al, 2011;Enroth et al, 2018 former ratio was substantially lower (WSOC/OC ratios from 20 to 39 %), while the latter ratio was considerably larger (EC/OC ratios from 14-20%) in comparison with the aerosol that was already chemically aged or at regional or remote areas (Salma et al, 2007(Salma et al, , 2020a and references therein). All this implies that the average N30-1000,>70%/NCCN,1.0% ratio has to be extended or even preceded by the slope of the regression line and R of the two data sets as suggestive metrics for quality assurance.…”

Section: Data Qualitymentioning

confidence: 99%

Cloud droplet activation in a continental Central European urban environment

Salma¹,

Thén²,

Vörösmarty³

et al. 2021

Preprint

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Abstract. Collocated measurements by condensation particle counter, differential mobility particle sizer and cloud condensational nuclei counter instruments were realised in parallel in central Budapest from 15 April 2019 to 14 April 2020 to gain insight into the droplet activation behaviour of urban aerosol particles. The median total particle number concentration was 10.1 × 103 cm−3. The median concentrations of cloud condensation nuclei (CCN) at water vapour supersaturations (Ss) of 0.1, 0.2, 0.3, 0.5 and 1.0 % were 0.59, 1.09, 1.39, 1.80 and 2.5 × 103 cm−3, respectively. They represented from 7 to 27 % of the total particles. The effective critical dry particle diameters (dc,eff) were derived utilising the CCN concentrations and particle number size distributions. Their medians were 207, 149, 126, 105 and 80 nm, respectively. They were all positioned within the accumulation mode of the typical particle number size distribution. Their frequency distributions revealed a single peak, which geometric standard deviation increased monotonically with S. The broadening indicated larger time variability in the activation properties of smaller particles. The frequency distributions also showed a fine structure. Its several compositional elements seemed to change in a tendentious manner with S. They were related to the size-dependent chemical composition and external mixtures of particles. The relationships between the critical S and dc,eff suggested that the urban aerosol particles in Budapest with a diameter larger than approximately 130 nm showed similar hygroscopicity than the continental aerosol in general, while the smaller particles appeared to be less hygroscopic than that. Seasonal cycling of the CCN concentrations and activation fractions implied modest alterations and for the larger Ss only. They likely reflected the changes in particle number concentrations, chemical composition and mixing state of particles. The seasonal dependencies for dc,eff were featureless, which indicated that the urban particles exhibited more or less similar droplet activation properties over the measurement year. This is different from non-urban locations. The hygroscopicity parameters (κ values) were computed without determining time-dependent chemical composition of particles. Their medians were 0.16, 0.10, 0.07, 0.04 and 0.02, respectively. The averages suggested that the larger particles exhibited considerably higher hygroscopicity than the smaller particles. The urban aerosol was characterised by substantially smaller kappa values than for regional or remote locations. All these could be virtually linked to specific source composition in cities. The relatively large variability in the hygroscopicity parameter sets for a given S emphasized that their individual values represented the CCN population in the ambient air, while the averages stood mainly for the particles with a size close to the effective critical dry particle diameters.

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