| 1. |
- Crippa, M., et al.
(författare)
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Organic aerosol components derived from 25 AMS data sets across Europe using a consistent ME-2 based source apportionment approach
- 2014
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 14:12, s. 6159-6176
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Tidskriftsartikel (refereegranskat)abstract
- Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) and the intensive campaigns of European Monitoring and Evaluation Programme (EMEP) during 2008 (May-June and September-October) and 2009 (February-March). In this paper we focus on the identification of the main organic aerosol sources and we define a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 data sets accounting for two urban, several rural and remote and two high altitude sites; therefore it is likely suitable for the treatment of AMS-related ambient data sets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Generally, our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling purposes.
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| 2. |
- Kiendler-Scharr, A., et al.
(författare)
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Ubiquity of organic nitrates from nighttime chemistry in the European submicron aerosol
- 2016
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Ingår i: Geophysical Research Letters. - 0094-8276. ; 43:14, s. 7735-7744
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Tidskriftsartikel (refereegranskat)abstract
- In the atmosphere nighttime removal of volatile organic compounds is initiated to a large extent by reaction with the nitrate radical (NO3) forming organic nitrates which partition between gas and particulate phase. Here we show based on particle phase measurements performed at a suburban site in the Netherlands that organic nitrates contribute substantially to particulate nitrate and organic mass. Comparisons with a chemistry transport model indicate that most of the measured particulate organic nitrates are formed by NO3 oxidation. Using aerosol composition data from three intensive observation periods at numerous measurement sites across Europe, we conclude that organic nitrates are a considerable fraction of fine particulate matter (PM1) at the continental scale. Organic nitrates represent 34% to 44% of measured submicron aerosol nitrate and are found at all urban and rural sites, implying a substantial potential of PM reduction by NOx emission control.
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| 3. |
- Kulmala, M., et al.
(författare)
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General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) - integrating aerosol research from nano to global scales
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:24, s. 13061-13143
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their effects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several new aerosol parameterizations and computations modules for chemical transport and global climate models were developed and evaluated. These achievements and related studies have substantially improved our understanding and reduced the uncertainties of aerosol radiative forcing and air quality-climate interactions. The EUCAARI results can be utilized in European and global environmental policy to assess the aerosol impacts and the corresponding abatement strategies.
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| 4. |
- Li, J. J., et al.
(författare)
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Characterization of Aerosol Aging Potentials at Suburban Sites in Northern and Southern China Utilizing a Potential Aerosol Mass (Go:PAM) Reactor and an Aerosol Mass Spectrometer
- 2019
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Ingår i: Journal of Geophysical Research-Atmospheres. - : American Geophysical Union (AGU). - 2169-897X .- 2169-8996. ; 124:10, s. 5629-5649
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol mass spectrometry was used to characterize submicron aerosols before and after aging in a Gothenburg Potential Aerosol Mass (Go:PAM) reactor at two suburban sites in China, one in northern China at Changping (CP), Beijing, and a second in southern China at Hong Kong (HK). Organic aerosol (OA) dominated in the ambient nonrefractory particulate matter <1m (NR-PM1) for both CP (42-71%) and HK (43-61%), with a large contribution from secondary OA factors that were semivolatile oxygenated (SVOOA) and low-volatility oxygenated (LVOOA). Under constant OH exposure, OA enhancement (78-98%) dominated the NR-PM1 mass increment at both sites, while nitrate was enhanced the most among the inorganic species (7-9%). Overall, the CP site exhibited higher OA oxidation potential and more enhancement of SVOOA than LVOOA (7.5 vs. 2.7g/m(3)), but the reverse was observed in HK (0.8 vs. 2.6g/m(3)). In CP, more enhancement of the less oxygenated SVOOA suggests that aerosol aging was more sensitive to the abundant locally emitted primary OA and volatile organic compound precursors. On the contrary, the more formation of the highly oxidized LVOOA in HK indicates that aerosol aging mainly escalated the degree of oxygenation of OA as ambient aerosol was already quite aged and there was a lack of volatile organic compound precursors. The comparative measurements using the same oxidation system reveal distinct key factors and mechanisms that influence secondary aerosol formation in two suburban locations in China, providing scientific insights to assist formulation of location-specific mitigation measures of secondary pollution. Plain Language Summary Atmospheric submicron particles have significant impacts on the climate and human health. A large part of these particles are formed secondarily through successive aging of primary emissions. To study such aging processes, we used a reactor that can provide highly oxidizing conditions to simulate the oxidation of ambient aerosols at accelerated rates. An online mass spectrometer was connected after the reactor to measure changes in aerosol mass concentration and chemical composition between the ambient samples and the oxidized ones. We presented the first comparative measurements of the aging potentials of ambient aerosols in two suburban sites in northern and southern China (Changping District in Beijing, and Hong Kong). Results showed that generally aerosols at the Changping site had higher aging potentials after passing through the oxidation reactor, probably due to more local emissions of precursors, while air masses in Hong Kong were already in a higher oxidation state with lower aging potentials, mainly because of strong impacts from long-range transported pollution sources. Distinct aerosol aging pathways related to different ambient precursors were observed at the two sites. Understanding of the different characteristics of aerosol aging processes can lead to advances in air quality modeling and pollution management.
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| 5. |
- Fountoukis, C., et al.
(författare)
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Organic aerosol concentration and composition over Europe: insights from comparison of regional model predictions with aerosol mass spectrometer factor analysis
- 2014
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 14:17, s. 9061-9076
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Tidskriftsartikel (refereegranskat)abstract
- A detailed three-dimensional regional chemical transport model (Particulate Matter Comprehensive Air Quality Model with Extensions, PMCAMx) was applied over Europe, focusing on the formation and chemical transformation of organic matter. Three periods representative of different seasons were simulated, corresponding to intensive field campaigns. An extensive set of AMS measurements was used to evaluate the model and, using factor-analysis results, gain more insight into the sources and transformations of organic aerosol (OA). Overall, the agreement be-tween predictions and measurements for OA concentration is encouraging, with the model reproducing two-thirds of the data (daily average mass concentrations) within a factor of 2. Oxygenated OA (OOA) is predicted to contribute 93% to total OA during May, 87% during winter and 96% during autumn, with the rest consisting of fresh primary OA (POA). Predicted OOA concentrations compare well with the observed OOA values for all periods, with an average fractional error of 0.53 and a bias equal to -0.07 (mean error = 0.9 mu g m(-3), mean bias =-0.2 mu g m(-3)). The model systematically underpredicts fresh POA at most sites during late spring and autumn (mean bias up to -0.8 mu g m(-3)). Based on results from a source apportionment algorithm running in parallel with PMCAMx, most of the POA originates from biomass burning (fires and residential wood combustion), and therefore biomass burning OA is most likely underestimated in the emission inventory. The sensitivity of POA predictions to the corresponding emissions' volatility distribution is discussed. The model performs well at all sites when the Positive Matrix Factorization (PMF)-estimated low-volatility OOA is compared against the OA with saturation concentrations of the OA surrogate species C* <= 0.1 mu g m(-3) and semivolatile OOA against the OA with C* > 0.1 mu g m(-3).
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| 6. |
- Nøjgaard, J. K., et al.
(författare)
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A local marine source of atmospheric particles in the High Arctic
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 285
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Tidskriftsartikel (refereegranskat)abstract
- The chemical composition of non-refractory submicron aerosol (NR-PM1) was characterized at the Villum Research Station (Villum) at Station Nord in North Greenland during spring-summer 2016 using a Time of Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). The composition is dominated by sulfate (48%) and organic species (40%). Positive Matrix Factorization (PMF) identified three key factors corresponding to a primary hydrocarbon-like organic aerosol (HOA), and two types of secondary organic aerosol: oxygenated organic aerosol (OOA) and a marine organic aerosol (MOA). The HOA factor accounts for 5% of the organic aerosol mass, which is consistent with previous findings at Villum. The OOA factor accounts for 77% of the organic aerosol mass and correlates with accumulation mode particles, which supports previous findings indicating that oxidized organic aerosols are predominantly from long-range transport during winter and spring at Villum. The MOA factor was characterized by mass spectral fragments of methane sulfonic acid (MSA) from atmospheric oxidation of dimethyl sulfide, for which reason the MOA factor is considered to be of biogenic origin. MOA accounts for 18% of the organic aerosol mass and correlates with locally produced Aitken mode particles. This indicates that biogenic processes are not only a significant source of aerosols at Villum, but MOA also appears to be formed in the vicinity of the measurement site. This local geographical origin was confirmed through air mass back trajectory modelling and source-receptor analysis. During May, air masses frequently arrived from the east, with source regions for the MOA factor and therewith MSA located in the Barents Sea and Lincoln Sea with lesser contributions from the Greenland Sea. During June, air mass origin shifted to the west, with source regions for the MOA factor and MSA shifting correspondingly to Baffin Bay and the Canadian Arctic Archipelago. While shifting transport patterns between May and June lead to shifting source regions, sea ice likely played a role as well. During May, marginal ice zones were present in the Barents Sea between Svalbard and Franz Josef Land, while during June, sea ice in the northern part of Baffin Bay retreated and sea ice in the Canadian Arctic Archipelago decreased. Although May and June experienced different transport patterns and sea ice conditions, levels of the MOA factor and MSA were similar between the months. This is likely due to similarities between marine biological activities in the Barents Sea and Baffin Bay. This research highlights the complex relationship between transport patterns, sea ice conditions, and atmospheric particle concentrations. Multiyear aerosol chemical composition from several High Arctic sites is encouraged to determine the full effects of ocean-atmosphere interactions and transport patterns on atmospheric aerosol concentrations.
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| 7. |
- Omelekhina, Yuliya, et al.
(författare)
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Application of positive matrix factorization (PMF) to real time aerosol mass spectrometry measurements in an occupied apartment in Sweden
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction Given that in developed countries we spend about 65% of our time in private homes (Brasche et al. 2005), understanding the exposures in homes is of outmost importance. Airborne particle concentrations indoors can be affected by particles of indoor and outdoor origins, as well as physico-chemical processes indoors, outdoor infiltration affected by tightness of the building envelope and ventilation (Morawska and Salthammer, 2003). In occupied indoor environments, indoor sources may occur simultaneously or as a sequence of the activities. Contribution of airborne particles from different emission sources and various dynamic transformation processes result in 'cocktail effect' in confined indoor spaces. Application of Positive matrix factorization (PMF) source apportionment allows estimating particle contribution from individual sources indoors. The aim of this work was to apply PMF to organic matrix from Aerosol Mass Spectrometer dataset to identify sources contributing to the observed mixture indoors and estimate the relative contributions of organic aerosol types. We present the results of measurements for a three-week period.Methods Indoor and outdoor measurements, using automatic switching valve, were performed in an occupied residence in Malmö, Sweden. Time-of-Flight Aerosol Mass Spectrometer (AMS, DeCarlo et al., 2006) was used to measure non-refractory aerosol mass concentrations indoors and outdoors. Positive matrix factorization (PMF) algorithm was applied to indoor organic aerosol dataset for source identification using the bilinear model through a multilinear engine (ME-2). We used graphical user interface SoFi 6.3 H (Source Finder) (Canonaco et. al, 2013) for source apportionment.Conclusions Positive matrix factorization source apportionment of the organic aerosol matrix identified three primary factors and one secondary factor: cooking OAI (COAI), cooking OAII (COAII), electronic cigarette OA (EOA), oxygenated outdoor OA (OOA) factors using PMF unconstrained runs. The electronic cigarette was the dominant contributor (51%) to indoor concentrations and resulted in average particle mass concentrations of 5.08 μg m-3. Cooking were frequent events in the studied apartment (n=29). On the basic of the activity logbooks 10 activities were identified as cooking, 6 as baking, 12 as frying, and 1 as deep frying. Cooking activities contributed with average mass concentrations of 3.7 μg m-3 (37 %). Two cooking factors, COAI and COAII, were retrieved during PMF analysis. Both COA factor profiles had characteristic peaks at m/z’s 41, 43, 55, 57, 60, 73 similar to results in previous studies (Allan et al., 2010; Crippa et al., 2013). However, the intensity of m/z’s 60 and 73 of COAI was less pronounced compared to COAII, which can be explained by the presence of degraded sugars during cooking (Barham, 1950). Oxygenated outdoor OA (OOA) factor reflected penetration of oxygenated organic species and was the least pronounced (1.2 μg m-3, 12 %) source indoors. OA mass spectrum was dominated by the CO2+ ion, and formed as a result of decomposition of oxygenated organic acids, as reported earlier by Ng et al. 2010. PMF also enabled identification of unknown sources such as electronic cigarette (by tracing glycerine peak at m/z 61) and some cooking activities.PMF source apportionment has shown to be useful tool for separation and identification of contributing sources indoors. However, PMF was ineffective for identification of candle burning. Due to similarity of COAI and candle burning mass spectrum, it was decided to proceed with PMF analysis without candle burning profile. Indoor sources, such as vaping of the electronic cigarette and cooking activities were the main contributors of organic submicrometer-size range particles in studied apartment during the three week measurement period. Thus, these should not be neglected when considering possible health effects. This work was financed by the Swedish Research Council FORMAS (Project Dnr 942-2015-1029) and COST Action, CA 16109.
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