MTA PE Air Chemistry Research Group

Veszprém, Hungary

MTA PE Air Chemistry Research Group

Veszprém, Hungary
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Hoffer A.,MTA PE Air Chemistry Research Group | Toth A.,University of Pannonia | Posfai M.,University of Pannonia | Chung C.E.,Desert Research Institute | And 2 more authors.
Atmospheric Measurement Techniques | Year: 2017

Black carbon (BC) aerosols have often been assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and near-infrared radiation significantly. Tar balls were produced in a laboratory experiment, and their chemical and optical properties were measured. The absorption of these particles in the range between 470 and 950 nm was measured with an aethalometer, which is widely used to measure atmospheric aerosol absorption. We find that the absorption coefficient of tar balls at 880 nm is more than 10% of that at 470 nm. The considerable absorption of red and infrared light by tar balls also follows from their relatively low absorption Ångström coefficient (and significant mass absorption coefficient) in the spectral range between 470 and 950 nm. Our results support the previous finding that tar balls may play an important role in global warming. Due to the non-negligible absorption of tar balls in the near-infrared region, the absorption measured in the field at near-infrared wavelengths cannot solely be due to soot particles. © The Author(s) 2017.

Acs A.,University of Pannonia | Kovacs A.W.,Hungarian Academy of Sciences | Csepregi J.Z.,Babes - Bolyai University | Toro N.,MTA PE Air Chemistry Research Group | And 5 more authors.
Toxicon | Year: 2013

Ecotoxicity of four Cylindrospermopsis raciborskii strains (ACT 9502, ACT 9503, ACT 9504, ACT 9505) isolated from Lake Balaton (Hungary) was evaluated in four aquatic bioassays including the Thamnocephalus platyurus acute lethality test; Daphnia magna acute immobilization assay; D. magna feeding inhibition assay and Danio rerio embryo developmental toxicity assay, assisted by chemical screening for known toxins by HPLC-MS. For reference, we analyzed in parallel the toxin content and toxic effects of two previously characterized toxin-producing strains: the Australian cylindrospermopsin producer AQS C. raciborskii and the anatoxins producer Oscillatoria sp. PCC 6506. Bioassays were used to evaluate the overall toxicity of the hydrophilic bioactive metabolites pool synthesized by the selected cyanobacteria.Chemical screening has proven that the ACT C. raciborskii extracts investigated did not contained cylindrospermopsins and anatoxins. The relative toxicity of the ACT C. raciborskii aqueous extracts observed in each bioassay was comparable to the effects recorded for the anatoxins producer PCC 6506 strain while toxicity values (EC50/LC50) calculated for the AQS extract were in general one order of magnitude lower.Concerning sublethal effects of ACT C. raciborskii extracts to the D. rerio embryogenesis, the general morphological abnormality observed was a significant retardation of development.Overall, our results suggest that C. raciborskii populating Lake Balaton produce metabolites with significant bioactive potencies. Therefore, continued investigation of these unknown compounds is required. © 2013 Elsevier Ltd.

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.

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.

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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