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Molnar A.,MTA PE Air Chemistry Research Group | Parkanyi D.,Hungarian Academy of Sciences | Imre K.,MTA PE Air Chemistry Research Group | Gacser V.,University of Pannonia | Czagler E.,Hungarian Meteorological Service
Idojaras | Year: 2016

In this study, we present our results from an investigation into the use of visibility data as a viable tool for the survey of long-term variations in air quality. We found that visibility data in general can be used to estimate atmospheric aerosol extinction coefficients, and that PM10 can be successfully estimated from aerosol chemical composition. Our results indicate that PM10 concentrations provide a good basis for the reconstruction of aerosol extinction coefficients. It was also shown that both derived (from visibility) and reconstructed aerosol extinction coefficients were in good accordance with each other, mainly in the case of dry aerosols. Ambient values can be determined if an adequate hygroscopic growth rate for aerosol extinction is considered. We also found that a rather precise estimation of extinction coefficient can be reached if a modified version of the widely used IMPROVE formula is applied. © 2016, Hungarian Meteorological Service. All rights reserved.

Toth A.,University of Pannonia | Hoffer A.,MTA PE Air Chemistry Research Group | Nyiro-Kosa I.,MTA PE Air Chemistry Research Group | Posfai M.,University of Pannonia | And 2 more authors.
Atmospheric Chemistry and Physics | Year: 2014

Atmospheric tar balls are particles of special morphology and composition that are fairly abundant in the plumes of biomass smoke. These particles form a specific subset of brown carbon (BrC) which has been shown to play a significant role in atmospheric shortwave absorption and, by extension, climate forcing. Here we suggest that tar balls are produced by the direct emission of liquid tar droplets followed by heat transformation upon biomass burning. For the first time in atmospheric chemistry we generated tar-ball particles from liquid tar obtained previously by dry distillation of wood in an all-glass apparatus in the laboratory with the total exclusion of flame processes. The particles were perfectly spherical with a mean optical diameter of 300 nm, refractory, externally mixed, and homogeneous in the contrast of the transmission electron microscopy (TEM) images. They lacked any graphene-like microstructure and exhibited a mean carbon-to-oxygen ratio of 10. All of the observed characteristics of laboratory-generated particles were very similar to those reported for atmospheric tar-ball particles in the literature, strongly supporting our hypothesis regarding the formation mechanism of atmospheric tar-ball particles. © Author(s) 2014.

Paasonen P.,University of Helsinki | Paasonen P.,International Institute For Applied Systems Analysis | Asmi A.,University of Helsinki | Petaja T.,University of Helsinki | And 26 more authors.
Nature Geoscience | Year: 2013

Atmospheric aerosol particles influence the climate system directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. Apart from black carbon aerosol, aerosols cause a negative radiative forcing at the top of the atmosphere and substantially mitigate the warming caused by greenhouse gases. In the future, tightening of controls on anthropogenic aerosol and precursor vapour emissions to achieve higher air quality may weaken this beneficial effect. Natural aerosols, too, might affect future warming. Here we analyse long-term observations of concentrations and compositions of aerosol particles and their biogenic precursor vapours in continental mid- and high-latitude environments. We use measurements of particle number size distribution together with boundary layer heights derived from reanalysis data to show that the boundary layer burden of cloud condensation nuclei increases exponentially with temperature. Our results confirm a negative feedback mechanism between the continental biosphere, aerosols and climate: aerosol cooling effects are strengthened by rising biogenic organic vapour emissions in response to warming, which in turn enhance condensation on particles and their growth to the size of cloud condensation nuclei. This natural growth mechanism produces roughly 50% of particles at the size of cloud condensation nuclei across Europe. We conclude that biosphere-atmosphere interactions are crucial for aerosol climate effects and can significantly influence the effects of anthropogenic aerosol emission controls, both on climate and air quality. © 2013 Macmillan Publishers Limited. All rights reserved.

Cavalli F.,European Commission - Joint Research Center Ispra | Alastuey A.,Institute Diagnostico Ambiental y Estudios Del Agua | Areskoug H.,University of Stockholm | Ceburnis D.,National University of Ireland | And 20 more authors.
Atmospheric Environment | Year: 2016

Although particulate organic and elemental carbon (OC and EC) are important constituents of the suspended atmospheric particulate matter (PM), measurements of OC and EC are much less common and more uncertain than measurements of e.g. the ionic components of PM. In the framework of atmospheric research infrastructures supported by the European Union, actions have been undertaken to determine and mitigate sampling artefacts, and assess the comparability of OC and EC data obtained in a network of 10 atmospheric observatories across Europe. Positive sampling artefacts (from 0.4 to 2.8 μg C/m3) and analytical discrepancies (between −50% and +40% for the EC/TC ratio) have been taken into account to generate a robust data set, from which we established the phenomenology of carbonaceous aerosols at regional background sites in Europe. Across the network, TC and EC annual average concentrations range from 0.4 to 9 μg C/m3, and from 0.1 to 2 μg C/m3, respectively. TC/PM10 annual mean ratios range from 0.11 at a Mediterranean site to 0.34 at the most polluted continental site, and TC/PM2.5 ratios are slightly greater at all sites (0.15–0.42). EC/TC annual mean ratios range from 0.10 to 0.22, and do not depend much on PM concentration levels, especially in winter. Seasonal variations in PM and TC concentrations, and in TC/PM and EC/TC ratios, differ across the network, which can be explained by seasonal changes in PM source contributions at some sites. © 2016 The Authors

Krassovan K.,University of Pannonia | Kertesz Z.,Hungarian Academy of Sciences | Imre K.,MTA PE Air Chemistry Research Group | Gelencser A.,University of Pannonia | Gelencser A.,MTA PE Air Chemistry Research Group
Aerosol and Air Quality Research | Year: 2015

The role of the atmosphere in the biogeochemical cycle of phosphorus (P) is generally associated with the emission of soil dust, sea-salt particles, bioaerosols and industrial aerosols. Quite independently, a reduced gaseous phosphorus compound (phosphine, PH3) was measured over various sources such as marshes and sewage plants and also in the global troposphere. Given that phosphine is a reactive gas that rapidly yields low-volatility phosphoric acid in the atmosphere, secondary aerosol formation can be an important sink that has never been considered in the global phosphorus cycle. In our study we present mass size-distribution measurements of phosphorus in aerosol samples collected at two locations in Hungary. The bimodal size distribution of phosphorus indicated two distinct formation mechanisms in the fine (d < 1 µm) and coarse modes (d > 1 µm). As expected, the mass concentration of phosphorus was dominated by the coarse particles; the contribution of fine mode phosphorus to the total was in the range of 11–61% (median 19%). The contribution of biomass burning and to a lesser extent bioaerosols to the fine mode phosphorus was inferred from measured ambient potassium (K) concentrations and P/K ratios reported for biomass smoke. It was found that biomass burning accounted for only a small fraction of fine mode phosphorus, the rest of which likely formed as secondary aerosol component from gaseous phosphine. Secondary aerosol phosphorus can be even more important in providing this essential nutrient for remote ecosystems because it is associated with fine aerosol particles which have longer residence time and thus are more prone to long-range atmospheric transport than coarse primary particles. © Taiwan Association for Aerosol Research.

Acs A.,Balaton Limnological Research Institute | Acs A.,University of Pannonia | Imre K.,MTA PE Air Chemistry Research Group | Kiss Gy.,MTA PE Air Chemistry Research Group | And 4 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2015

The multixenobiotic defense mechanism (MXR) in aquatic organisms was recognized as a first-line defense system, and its potential use as an early biomarker of exposure to environmental stress has raised attention in the last two decades. To evaluate the relevance of this biomarker in the freshwater mussel Dreissena polymorpha, we studied its responsiveness within laboratory exposures to contaminants sequestered in freshwater sediments affected by moderate anthropogenic impact. The effectiveness of this biomarker was assessed by comparing the MXR-transporter activities determined in bivalves first with toxicity scores recorded with the D. rerio embryo developmental assay. Both bioassays were applied in the sediment contact test format. As a second evaluation approach, MXR activities determined in exposed mussels were compared with sediment-contamination data integrated into toxic units on the basis of acute toxicity to Daphnia magna. In D. polymorpha subjected to acute exposure with moderately polluted sediments, we detected limited (22-33 %) but statistically significant induction of MXR activity. Mean MXR activities significantly correlated with TU values computed for test sediments. MXR activities in mussels showed strong positive correlation with the metal load of sediments and proved to be unrelated to the contamination with polycyclic aromatic compounds. MXR activity in laboratory-exposed mussels showed low variability within treatments and thus reliably reflected even low contaminant differences between the negative reference and moderately polluted harbor sediments. The strong correlation found in this study between the MXR-transporter activity in exposed mussels and environmentally realistic sediment contamination underscores the fairly good sensitivity of this biomarker in laboratory testing conditions to signal the bioavailability of sediment bound contaminants, and it may also anticipate even the incidence of toxicity to biota. © 2015 Springer Science+Business Media.

Molnar A.,MTA PE Air Chemistry Research Group | Becsi Z.,University of Pannonia | Imre K.,MTA PE Air Chemistry Research Group | Gacser V.,University of Pannonia | Ferenczi Z.,Hungarian Meteorological Service
Aerosol and Air Quality Research | Year: 2016

The aim of this paper is to study the wintertime physical properties of atmospheric aerosol particles on the basis of data observed at the K-puszta regional background station in Hungary. In Hungary wintertime smog episodes are linked to strong stable air (high pressure blocking events) with thermal inversion. These atmospheric conditions are frequently formed during winter months (November-February) due to the special geographical location of the country. The formation of smog events is highly probable in cases of thermal inversion periods sustaining for at least 4 days. We discuss in the paper the role of high-pressure blocking events in aerosol properties in terms of PM10 concentrations, aerosol size distributions, new particle formation and optical properties. We found that high-pressure blocking events have significant impacts on the size distribution and particle formation processes. At K-puszta the aerosol is in highly aged state with size distribution dominated by the accumulation mode. This is further supported by the optical properties, e.g., by high scattering Ångstrom exponent and by relatively weak absorption. The most significant effect of extreme episodes is manifested in the changes in PM10 concentrations and, consequently, in aerosol optical properties. The PM10 concentrations, scattering coefficients and absorption coefficients considerably increase to extreme values that are characteristic of a heavily polluted atmosphere rather than rural air. Our results indicate that in winter, the air quality at Kpuszta is often influenced by regional air pollution as shown by spatial distribution of PM10 concentration. It is found that PM10 had almost the same concentration in regional background air and in different types of urban environments. The special meteorological conditions and the role of regional-scale transport can explain why local abatements in cities cannot lead to significant improvement of the air quality during smog events. © Taiwan Association for Aerosol Research.

Nemeth Z.,Eötvös Loránd University | Posfai M.,University of Pannonia | Nyiro-Kosa I.,MTA PE Air Chemistry Research Group | Aalto P.,University of Helsinki | And 2 more authors.
Atmospheric Environment | Year: 2015

Atmospheric aerosol particles were collected in Budapest, Hungary in April-June onto lacey Formvar substrates by using an electrostatic precipitator during the beginning phase of the particle growth process in ten nucleation and growth events. Median contribution of the nucleated particles - expressed as the concentration of particles with a diameter between 6 and 25 nm to the total particle number concentration - was 55%, and the median electrical mobility diameter of the particles was approximately 20 nm. The sample was investigated using high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy. Major types of individual particles such as soot, sulphate/organic and tar ball particles were identified in the sample. In addition, particles with an optical diameter range of 10-30 nm were also observed. They clearly differed from the other particle types, showed homogeneous contrast in the bright-field TEM images, and evaporated within tens of seconds when exposed to the electron beam. They were interpreted as representatives of freshly nucleated particles. © 2015 Elsevier Ltd.

Yttri K.E.,Norwegian Institute For Air Research | Schnelle-Kreis J.,Helmholtz Center Munich | Maenhaut W.,Ghent University | Maenhaut W.,University of Antwerp | And 28 more authors.
Atmospheric Measurement Techniques | Year: 2015

The monosaccharide anhydrides (MAs) levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning (BB) aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wildfire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for BB particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied high-performance anion-exchange chromatography (HPAEC), four used high-performance liquid chromatography (HPLC) or ultra-performance liquid chromatography (UPLC) and six resorted to gas chromatography (GC). The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers.

The accuracy for levoglucosan, presented as the mean percentage error (PE) for each participating laboratory, varied from g'63 to 20%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was g'60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i.e. for 33% of the laboratories the mean PE was within ±10%. For galactosan, the mean PE for the participating laboratories ranged from g'84 to 593%, and as for mannosan 33% of the laboratories reported a mean PE within ±10%.

The variability of the various analytical methods, as defined by their minimum and maximum PE value, was typically better for levoglucosan than for mannosan and galactosan, ranging from 3.2 to 41% for levoglucosan, from 10 to 67% for mannosan and from 6 to 364% for galactosan. For the levoglucosan to mannosan ratio, which may be used to assess the relative importance of softwood versus hardwood burning, the variability only ranged from 3.5 to 24 .

To our knowledge, this is the first major intercomparison on analytical methods used to quantify monosaccharide anhydrides in ambient aerosol filter samples conducted and reported in the scientific literature. The results show that for levoglucosan the accuracy is only slightly lower than that reported for analysis of SO42-(sulfate) on filter samples, a constituent that has been analysed by numerous laboratories for several decades, typically by ion chromatography and which is considered a fairly easy constituent to measure. Hence, the results obtained for levoglucosan with respect to accuracy are encouraging and suggest that levels of levoglucosan, and to a lesser extent mannosan and galactosan, obtained by most of the analytical methods currently used to quantify monosaccharide anhydrides in ambient aerosol filter samples, are comparable.

Finally, the various analytical methods used in the current study should be tested for other aerosol matrices and concentrations as well, the most obvious being summertime aerosol samples affected by wildfires and/or agricultural fires. © 2015 Author(s). CC Attribution 3.0 License.

Ferenczi Z.,Hungarian Meteorological Service | Imre K.,MTA PE Air Chemistry Research Group
Idojaras | Year: 2016

Ground-level or tropospheric ozone (O3) is an oxidant air pollutant that has harmful effect on human health and vegetation, however, it is a short-lived greenhouse gas. Ozone is a secondary pollutant; which means that it is not directly emitted in the ambient air, but also produced from the photochemical oxidation of non-methane volatile organic compounds (NMVOCs), methane (CH4), or carbon monoxide (CO) in the presence of nitrogen oxides (NOx). It is destroyed both photochemically and through deposition to the surface. Summarizing the chemistry of ozone is complex and non-linear. Background concentrations of ground-level ozone in Europe do not show a significant downward trend, but in Hungary essential reduction (–0.28 µg/m3) was observed at K-puszta station in the last decades. In the monthly distribution the amplitude decrease with increase in altitude, at K-puszta 45.1 µg/m3, while at Nyírjes 36.6 µg/m3 amplitudes were observed. Based on our data we found that the ozone gradient is about +1.4 µg/m3/m. Breathing ozone can result in a number of negative health effects that are observed in relevant segments of the population. Ozone also is known as the air pollutant most damaging to agricultural crops and other plants. This article gives a general overview of the ozone problem focusing on the Hungarian specialties. © 2016, Hungarian Meteorological Service. All rights reserved.

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