151
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Stinson JL, Kathmann SM, Ford IJ. A classical reactive potential for molecular clusters of sulphuric acid and water. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1090027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Jake L. Stinson
- Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, London, United Kingdom
| | - Shawn M. Kathmann
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Ian J. Ford
- Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, London, United Kingdom
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152
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Mongin D, Slowik JG, Schubert E, Brisset JG, Berti N, Moret M, Prévôt ASH, Baltensperger U, Kasparian J, Wolf JP. Non-linear photochemical pathways in laser-induced atmospheric aerosol formation. Sci Rep 2015; 5:14978. [PMID: 26450172 PMCID: PMC4598870 DOI: 10.1038/srep14978] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/15/2015] [Indexed: 11/09/2022] Open
Abstract
We measured the chemical composition and the size distribution of aerosols generated by femtosecond-Terawatt laser pulses in the atmosphere using an aerosol mass spectrometer (AMS). We show that nitric acid condenses in the form of ammonium nitrate, and that oxidized volatile organics also contribute to particle growth. These two components account for two thirds and one third, respectively, of the dry laser-condensed mass. They appear in two different modes centred at 380 nm and 150 nm. The number concentration of particles between 25 and 300 nm increases by a factor of 15. Pre-existing water droplets strongly increase the oxidative properties of the laser-activated atmosphere, substantially enhancing the condensation of organics under laser illumination.
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Affiliation(s)
- Denis Mongin
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
| | - Jay G Slowik
- Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, CH-5232 Villigen, Switzerland
| | - Elise Schubert
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
| | - Jean-Gabriel Brisset
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland.,Max-Born-Institut, Max-Born-Strasse 2A, 12489 Berlin, Germany
| | - Nicolas Berti
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
| | - Michel Moret
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
| | - André S H Prévôt
- Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, CH-5232 Villigen, Switzerland
| | - Urs Baltensperger
- Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, CH-5232 Villigen, Switzerland
| | - Jérôme Kasparian
- Université de Genève, GAP-Non-linear, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
| | - Jean-Pierre Wolf
- Université de Genève, GAP-Biophotonics, Chemin de Pinchat 22, CH-1211 Geneva 4, Switzerland
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153
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Chen H, Varner ME, Gerber RB, Finlayson-Pitts BJ. Reactions of Methanesulfonic Acid with Amines and Ammonia as a Source of New Particles in Air. J Phys Chem B 2015; 120:1526-36. [DOI: 10.1021/acs.jpcb.5b07433] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Haihan Chen
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Mychel E. Varner
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - R. Benny Gerber
- Department of Chemistry, University of California, Irvine, California 92697, United States
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154
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Tsona NT, Henschel H, Bork N, Loukonen V, Vehkamäki H. Structures, Hydration, and Electrical Mobilities of Bisulfate Ion–Sulfuric Acid–Ammonia/Dimethylamine Clusters: A Computational Study. J Phys Chem A 2015; 119:9670-9. [DOI: 10.1021/acs.jpca.5b03030] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Narcisse T. Tsona
- Division
of Atmospheric Sciences,
Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland
| | - Henning Henschel
- Division
of Atmospheric Sciences,
Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland
| | - Nicolai Bork
- Division
of Atmospheric Sciences,
Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland
| | - Ville Loukonen
- Division
of Atmospheric Sciences,
Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland
| | - Hanna Vehkamäki
- Division
of Atmospheric Sciences,
Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland
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155
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Elm J, Myllys N, Hyttinen N, Kurtén T. Computational Study of the Clustering of a Cyclohexene Autoxidation Product C6H8O7 with Itself and Sulfuric Acid. J Phys Chem A 2015; 119:8414-21. [PMID: 26154271 DOI: 10.1021/acs.jpca.5b04040] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the molecular interactions between sulfuric acid and a recently reported C6H8O7 ketodiperoxy acid formed through autoxidation from cyclohexene and ozone. Structurally similar but larger ELVOC (extremely low volatility organic compound) products formed from autoxidation of monoterpenes are believed to play a major role in the formation and early growth of atmospheric aerosol particles. Utilizing density functional theory geometries, with a DLPNO-CCSD(T)/def2-QZVPP single point energy correction, the stepwise Gibbs free energies of formation have been calculated, and the stabilities of the molecular clusters have been evaluated. C6H8O7 interacts weakly with both itself and sulfuric acid, with standard free energies of formation (ΔG at 298 K and 1 atm) around or above 0 kcal/mol. This is due to the presence of strong intramolecular hydrogen bonds in the peroxyacid groups of C6H8O7. These stabilize the isolated molecule with respect to its clusters, and lead to unfavorable interaction energies. The addition of sulfuric acid to clusters containing C6H8O7 is somewhat more favorable, but the formed clusters are still far more likely to evaporate than to grow further in atmospheric conditions. These findings indicate that the O/C ratio cannot exclusively be used as a proxy for volatility in atmospheric new particle formation involving organic compounds. The specific molecular structure, and especially the number of strong hydrogen binding moieties, are equally important. The interaction between the C6H8O7 compound and aqueous phase sulfate ions indicates that ELVOC-type compounds can contribute to aerosol mass by effectively partitioning into the condensed phase.
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Affiliation(s)
- Jonas Elm
- †Department of Physics and ‡Department of Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Nanna Myllys
- †Department of Physics and ‡Department of Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Noora Hyttinen
- †Department of Physics and ‡Department of Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Theo Kurtén
- †Department of Physics and ‡Department of Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland
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156
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Activation of defence pathways in Scots pine bark after feeding by pine weevil (Hylobius abietis). BMC Genomics 2015; 16:352. [PMID: 25943104 PMCID: PMC4422480 DOI: 10.1186/s12864-015-1546-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 04/17/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND During their lifetime, conifer trees are exposed to numerous herbivorous insects. To protect themselves against pests, trees have developed a broad repertoire of protective mechanisms. Many of the plant's defence reactions are activated upon an insect attack, and the underlying regulatory mechanisms are not entirely understood yet, in particular in conifer trees. Here, we present the results of our studies on the transcriptional response and the volatile compounds production of Scots pine (Pinus sylvestris) upon the large pine weevil (Hylobius abietis) feeding. RESULTS Transcriptional response of Scots pine to the weevil attack was investigated using a novel customised 36.4 K Pinus taeda microarray. The weevil feeding caused large-scale changes in the pine transcriptome. In total, 774 genes were significantly up-regulated more than 4-fold (p≤0.05), whereas 64 genes were significantly down-regulated more than 4-fold. Among the up-regulated genes, we could identify genes involved in signal perception, signalling pathways, transcriptional regulation, plant hormone homeostasis, secondary metabolism and defence responses. The weevil feeding on stem bark of pine significantly increased the total emission of volatile organic compounds from the undamaged stem bark area. The emission levels of monoterpenes and sesquiterpenes were also increased. Interestingly, we could not observe any correlation between the increased production of the terpenoid compounds and expression levels of the terpene synthase-encoding genes. CONCLUSIONS The obtained data provide an important insight into the transcriptional response of conifer trees to insect herbivory and illustrate the massive changes in the host transcriptome upon insect attacks. Moreover, many of the induced pathways are common between conifers and angiosperms. The presented results are the first ones obtained by the use of a microarray platform with an extended coverage of pine transcriptome (36.4 K cDNA elements). The platform will further facilitate the identification of resistance markers with the direct relevance for conifer tree breeding.
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157
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Zhang R, Wang G, Guo S, Zamora ML, Ying Q, Lin Y, Wang W, Hu M, Wang Y. Formation of urban fine particulate matter. Chem Rev 2015; 115:3803-55. [PMID: 25942499 DOI: 10.1021/acs.chemrev.5b00067] [Citation(s) in RCA: 472] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Renyi Zhang
- §State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China
| | | | - Song Guo
- §State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China
| | | | | | | | | | - Min Hu
- §State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Yuan Wang
- #Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91125, United States
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158
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von Schneidemesser E, Monks PS, Allan JD, Bruhwiler L, Forster P, Fowler D, Lauer A, Morgan WT, Paasonen P, Righi M, Sindelarova K, Sutton MA. Chemistry and the Linkages between Air Quality and Climate Change. Chem Rev 2015; 115:3856-97. [PMID: 25926133 DOI: 10.1021/acs.chemrev.5b00089] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Paul S Monks
- ‡Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
| | | | | | | | - David Fowler
- ∇Centre for Ecology and Hydrology, Natural Environment Research Council, Edinburgh EH26 0QB, United Kingdom
| | - Axel Lauer
- †Institute for Advanced Sustainability Studies, 14467 Potsdam, Germany
| | | | - Pauli Paasonen
- ○Department of Physics, University of Helsinki, 00100 Helsinki, Finland
| | - Mattia Righi
- ◆Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, 82234 Oberpfaffenhofen, Germany
| | - Katerina Sindelarova
- ¶UPMC Univ. Paris 06, Université Versailles St-Quentin; CNRS/INSU; LATMOS-IPSL, UMR 8190 Paris, France.,□Department of Atmospheric Physics, Faculty of Mathematics and Physics, Charles University, 116 36 Prague, Czech Republic
| | - Mark A Sutton
- ∇Centre for Ecology and Hydrology, Natural Environment Research Council, Edinburgh EH26 0QB, United Kingdom
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159
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Ma N, Birmili W. Estimating the contribution of photochemical particle formation to ultrafine particle number averages in an urban atmosphere. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 512-513:154-166. [PMID: 25617781 DOI: 10.1016/j.scitotenv.2015.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 01/05/2015] [Accepted: 01/05/2015] [Indexed: 06/04/2023]
Abstract
Ultrafine particles (UFPs, diameter<100 nm) have gained major attention in the environmental health discussion due to a number of suspected health effects. Observations of UFPs in urban air reveal the presence of several, time-dependent particle sources. In order to attribute measured UFP number concentrations to different source type contributions, we analyzed observations collected at a triplet of observation sites (roadside, urban background, rural) in the city of Leipzig, Germany. Photochemical new particle formation (NPF) events can be the overwhelming source of UFP particles on particular days, and were identified on the basis of characteristic patterns in the particle number size distribution data. A subsequent segmentation of the diurnal cycles of UFP concentration yielded a quantitative contribution of NPF events to daily, monthly, and annual mean values. At roadside, we obtained source contributions to the annual mean UFP number concentration (diameter range 5-100 nm) for photochemical NPF events (7%), local traffic (52%), diffuse urban sources (20%), and regional background (21%). The relative contribution of NPF events rises when moving away from roadside to the urban background and rural sites (14 and 30%, respectively). Their contribution also increases when considering only fresh UFPs (5-20 nm) (21% at the urban background site), and conversely decreases when considering UFPs at bigger sizes (20-100 nm) (8%). A seasonal analysis showed that NPF events have their greatest importance on UFP number concentration in the months May-August, accounting for roughly half of the fresh UFPs (5-20 nm) at the urban background location. The simplistic source apportionment presented here might serve to better characterize exposure to ambient UFPs in future epidemiological studies.
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Affiliation(s)
- N Ma
- Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
| | - W Birmili
- Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
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160
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Vereecken L, Glowacki DR, Pilling MJ. Theoretical Chemical Kinetics in Tropospheric Chemistry: Methodologies and Applications. Chem Rev 2015; 115:4063-114. [DOI: 10.1021/cr500488p] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Luc Vereecken
- Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - David R. Glowacki
- PULSE
Institute and Department of Chemistry, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
- Department
of Computer Science, University of Bristol, Bristol BS8 1UB, United Kingdom
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161
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Nozière B, Kalberer M, Claeys M, Allan J, D'Anna B, Decesari S, Finessi E, Glasius M, Grgić I, Hamilton JF, Hoffmann T, Iinuma Y, Jaoui M, Kahnt A, Kampf CJ, Kourtchev I, Maenhaut W, Marsden N, Saarikoski S, Schnelle-Kreis J, Surratt JD, Szidat S, Szmigielski R, Wisthaler A. The molecular identification of organic compounds in the atmosphere: state of the art and challenges. Chem Rev 2015; 115:3919-83. [PMID: 25647604 DOI: 10.1021/cr5003485] [Citation(s) in RCA: 203] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Barbara Nozière
- †Ircelyon/CNRS and Université Lyon 1, 69626 Villeurbanne Cedex, France
| | | | | | | | - Barbara D'Anna
- †Ircelyon/CNRS and Université Lyon 1, 69626 Villeurbanne Cedex, France
| | | | | | | | - Irena Grgić
- ○National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | | | | | - Yoshiteru Iinuma
- ¶Leibniz-Institut für Troposphärenforschung, 04318 Leipzig, Germany
| | | | | | | | - Ivan Kourtchev
- ‡University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Willy Maenhaut
- §University of Antwerp, 2000 Antwerp, Belgium.,□Ghent University, 9000 Gent, Belgium
| | | | | | | | - Jason D Surratt
- ▼University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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162
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Malila J, McGraw R, Laaksonen A, Lehtinen KEJ. Communication: Kinetics of scavenging of small, nucleating clusters: First nucleation theorem and sum rules. J Chem Phys 2015; 142:011102. [DOI: 10.1063/1.4905213] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jussi Malila
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
| | - Robert McGraw
- Biological, Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Ari Laaksonen
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
- Finnish Meteorological Institute, Climate Research, P.O. Box 503, 00101 Helsinki, Finland
| | - Kari E. J. Lehtinen
- Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
- Finnish Meteorological Institute, Atmospheric Research Centre of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
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163
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Chen H, Ezell MJ, Arquero KD, Varner ME, Dawson ML, Gerber RB, Finlayson-Pitts BJ. New particle formation and growth from methanesulfonic acid, trimethylamine and water. Phys Chem Chem Phys 2015; 17:13699-709. [DOI: 10.1039/c5cp00838g] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Water participates in the formation of initial clusters to enhance particle formation from methanesulfonic acid and trimethylamine.
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Affiliation(s)
- Haihan Chen
- Department of Chemistry
- University of California, Irvine
- Irvine
- USA
| | - Michael J. Ezell
- Department of Chemistry
- University of California, Irvine
- Irvine
- USA
| | | | - Mychel E. Varner
- Department of Chemistry
- University of California, Irvine
- Irvine
- USA
| | | | - R. Benny Gerber
- Department of Chemistry
- University of California, Irvine
- Irvine
- USA
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164
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Abstract
Natural aerosols define a preindustrial baseline state from which the magnitude of anthropogenic aerosol effects on climate are calculated and are a major component of the large uncertainty in anthropogenic aerosol-cloud radiative forcing. This uncertainty would be reduced if aerosol environments unperturbed by air pollution could be studied in the present--day atmosphere, but the pervasiveness of air pollution makes identification of unperturbed regions difficult. Here, we use global model simulations to define unperturbed aerosol regions in terms of two measures that compare 1750 and 2000 conditions-the number of days with similar aerosol concentrations and the similarity of the aerosol response to perturbations in model processes and emissions. The analysis shows that the aerosol system in many present-day environments looks and behaves like it did in the preindustrial era. On a global annual mean, unperturbed aerosol regions cover 12% of the Earth (16% of the ocean surface and 2% of the land surface). There is a strong seasonal variation in unperturbed regions of between 4% in August and 27% in January, with the most persistent conditions occurring over the equatorial Pacific. About 90% of unperturbed regions occur in the Southern Hemisphere, but in the Northern Hemisphere, unperturbed conditions are transient and spatially patchy. In cloudy regions with a radiative forcing relative to 1750, model results suggest that unperturbed aerosol conditions could still occur on a small number of days per month. However, these environments are mostly in the Southern Hemisphere, potentially limiting the usefulness in reducing Northern Hemisphere forcing uncertainty.
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165
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Bianchi F, Praplan AP, Sarnela N, Dommen J, Kürten A, Ortega IK, Schobesberger S, Junninen H, Simon M, Tröstl J, Jokinen T, Sipilä M, Adamov A, Amorim A, Almeida J, Breitenlechner M, Duplissy J, Ehrhart S, Flagan RC, Franchin A, Hakala J, Hansel A, Heinritzi M, Kangasluoma J, Keskinen H, Kim J, Kirkby J, Laaksonen A, Lawler MJ, Lehtipalo K, Leiminger M, Makhmutov V, Mathot S, Onnela A, Petäjä T, Riccobono F, Rissanen MP, Rondo L, Tomé A, Virtanen A, Viisanen Y, Williamson C, Wimmer D, Winkler PM, Ye P, Curtius J, Kulmala M, Worsnop DR, Donahue NM, Baltensperger U. Insight into acid-base nucleation experiments by comparison of the chemical composition of positive, negative, and neutral clusters. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:13675-13684. [PMID: 25406110 DOI: 10.1021/es502380b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigated the nucleation of sulfuric acid together with two bases (ammonia and dimethylamine), at the CLOUD chamber at CERN. The chemical composition of positive, negative, and neutral clusters was studied using three Atmospheric Pressure interface-Time Of Flight (APi-TOF) mass spectrometers: two were operated in positive and negative mode to detect the chamber ions, while the third was equipped with a nitrate ion chemical ionization source allowing detection of neutral clusters. Taking into account the possible fragmentation that can happen during the charging of the ions or within the first stage of the mass spectrometer, the cluster formation proceeded via essentially one-to-one acid-base addition for all of the clusters, independent of the type of the base. For the positive clusters, the charge is carried by one excess protonated base, while for the negative clusters it is carried by a deprotonated acid; the same is true for the neutral clusters after these have been ionized. During the experiments involving sulfuric acid and dimethylamine, it was possible to study the appearance time for all the clusters (positive, negative, and neutral). It appeared that, after the formation of the clusters containing three molecules of sulfuric acid, the clusters grow at a similar speed, independent of their charge. The growth rate is then probably limited by the arrival rate of sulfuric acid or cluster-cluster collision.
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Affiliation(s)
- Federico Bianchi
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute , Villigen 5232, Switzerland
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166
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Abstract
As the world's second largest economy, China has experienced severe haze pollution, with fine particulate matter (PM) recently reaching unprecedentedly high levels across many cities, and an understanding of the PM formation mechanism is critical in the development of efficient mediation policies to minimize its regional to global impacts. We demonstrate a periodic cycle of PM episodes in Beijing that is governed by meteorological conditions and characterized by two distinct aerosol formation processes of nucleation and growth, but with a small contribution from primary emissions and regional transport of particles. Nucleation consistently precedes a polluted period, producing a high number concentration of nano-sized particles under clean conditions. Accumulation of the particle mass concentration exceeding several hundred micrograms per cubic meter is accompanied by a continuous size growth from the nucleation-mode particles over multiple days to yield numerous larger particles, distinctive from the aerosol formation typically observed in other regions worldwide. The particle compositions in Beijing, on the other hand, exhibit a similarity to those commonly measured in many global areas, consistent with the chemical constituents dominated by secondary aerosol formation. Our results highlight that regulatory controls of gaseous emissions for volatile organic compounds and nitrogen oxides from local transportation and sulfur dioxide from regional industrial sources represent the key steps to reduce the urban PM level in China.
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167
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Elm J, Mikkelsen KV. Computational approaches for efficiently modelling of small atmospheric clusters. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.09.060] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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168
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Neutral molecular cluster formation of sulfuric acid-dimethylamine observed in real time under atmospheric conditions. Proc Natl Acad Sci U S A 2014; 111:15019-24. [PMID: 25288761 DOI: 10.1073/pnas.1404853111] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even though the neutral particles are stable against evaporation from the SA dimer onward, the formation rates of particles at 1.7-nm size, which contain about 10 SA molecules, are up to 4 orders of magnitude smaller compared with those of the dimer due to coagulation and wall loss of particles before they reach 1.7 nm in diameter. This demonstrates that neither the atmospheric particle formation rate nor its dependence on SA can simply be interpreted in terms of cluster evaporation or the molecular composition of a critical nucleus.
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