Author
Tuukka Petäjä
Other affiliations: Helsinki Institute of Physics, National Center for Atmospheric Research, University of Tyumen ...read more
Bio: Tuukka Petäjä is an academic researcher from University of Helsinki. The author has contributed to research in topics: Aerosol & Particle. The author has an hindex of 82, co-authored 526 publications receiving 30572 citations. Previous affiliations of Tuukka Petäjä include Helsinki Institute of Physics & National Center for Atmospheric Research.
Topics: Aerosol, Particle, Nucleation, Cloud condensation nuclei, Particle size
Papers published on a yearly basis
Papers
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TL;DR: In this article, the authors investigated the contribution of ion-induced nucleation for both positively and negatively charged particles and found that the median contribution at 2 nm was around 6.4% with a median absolute deviation (MAD) of 2.0%.
Abstract: In this paper, we investigate the participation of ion-induced nucleation in atmospheric new-particle formation. We present one year of Ion-DMPS data from the SMEAR II station in Hyytiala, southern Finland (22 September 2005 to 22 September 2006). We measured continuously the concentrations of ions in ambient and charge equilibrated air in seven size bins over a diameter range 3–15 nm. All new-particle formation event days were classified according to observed particle charging states and analysed based on a new theoretical tool by which the measured charging states can be extrapolated down to smaller particle sizes. We investigated the contribution of ion-induced nucleation for both positively and negatively charged particles. The median contribution of ion-induced nucleation at 2 nm during the one year of measurements was around 6.4% with a median absolute deviation (MAD) of 2.0%,. The smallest contribution was 1.7% (MAD = 1.6%) whereas the maximum was 16.5% (MAD = 2.2%). We also analysed the data on a seasonal basis and found the largest contribution of ion-induced nucleation during summer (7.6%) and lower during the rest of the year (4.9%). DOI: 10.1111/j.1600-0889.2008.00347.x
50 citations
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Goethe University Frankfurt1, University of Innsbruck2, University of Vienna3, University of Colorado Boulder4, CERN5, University of Lisbon6, Paul Scherrer Institute7, Carnegie Mellon University8, University of California, Irvine9, Helsinki Institute of Physics10, California Institute of Technology11, Pusan National University12, Finnish Meteorological Institute13, National Research Council14, Nanjing University15, Russian Academy of Sciences16, University of Leeds17, University of Eastern Finland18, University of Beira Interior19
TL;DR: In this article, the authors show that a decrease in temperature (from +25 to −50 ∘ C) results in a reduced HOM yield and a reduced oxidation state of the products, whereas the increase in NPF rates (J 1.7nm ) increase substantially.
Abstract: . Highly oxygenated organic molecules (HOMs) contribute
substantially to the formation and growth of atmospheric aerosol particles,
which affect air quality, human health and Earth's climate. HOMs are formed
by rapid, gas-phase autoxidation of volatile organic compounds (VOCs) such
as α -pinene, the most abundant monoterpene in the atmosphere. Due to
their abundance and low volatility, HOMs can play an important role in
new-particle formation (NPF) and the early growth of atmospheric aerosols,
even without any further assistance of other low-volatility compounds such
as sulfuric acid. Both the autoxidation reaction forming HOMs and their
NPF rates are expected to be strongly dependent on
temperature. However, experimental data on both effects are limited.
Dedicated experiments were performed at the CLOUD (Cosmics Leaving OUtdoor
Droplets) chamber at CERN to address this question. In this study, we show
that a decrease in temperature (from +25 to −50 ∘ C) results in
a reduced HOM yield and reduced oxidation state of the products, whereas the
NPF rates ( J1.7 nm ) increase substantially.
Measurements with two different chemical ionization mass spectrometers
(using nitrate and protonated water as reagent ion, respectively) provide
the molecular composition of the gaseous oxidation products, and a
two-dimensional volatility basis set (2D VBS) model provides their volatility
distribution. The HOM yield decreases with temperature from 6.2 % at 25 ∘ C to 0.7 % at −50 ∘ C. However, there is a strong
reduction of the saturation vapor pressure of each oxidation state as the
temperature is reduced. Overall, the reduction in volatility with
temperature leads to an increase in the nucleation rates by up to 3
orders of magnitude at −50 ∘ C compared with 25 ∘ C. In
addition, the enhancement of the nucleation rates by ions decreases with
decreasing temperature, since the neutral molecular clusters have increased
stability against evaporation. The resulting data quantify how the interplay
between the temperature-dependent oxidation pathways and the associated
vapor pressures affect biogenic NPF at the molecular
level. Our measurements, therefore, improve our understanding of pure
biogenic NPF for a wide range of tropospheric
temperatures and precursor concentrations.
50 citations
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TL;DR: In this paper, the authors show that the most important parameter determining the nucleation probability in the sub-3 nm size range was the seed chemical composition, rather than the seed size.
Abstract: Heterogeneous nucleation of vapor on a seed particle surface is dependent on the seed properties such as size, chemical composition, and electric charging state, of which the significance of the charging state has not been uncovered unambiguously. The underlying problem is that, on the molecular level, the charging state and the chemical composition of the seed are connected and cannot be well separated without a direct mass spectrometric measurement of the ion. By generating sub-3 nm size selected seeds of different size, chemical composition, electric charging state, and letting three different vapors nucleate onto the seeds, we show that heterogeneous nucleation does not clearly prefer either positive or negative seeds. Rather, the most important parameter determining the nucleation probability in the sub-3 nm size range was the seed chemical composition. Our findings help to understand the dynamics in various nanoparticle systems, such as nucleation chambers, industrial processes, or atmospheric aerosols.
50 citations
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Paul Scherrer Institute1, Carnegie Mellon University2, Finnish Meteorological Institute3, University of Eastern Finland4, University of Helsinki5, CERN6, Goethe University Frankfurt7, University of Vienna8, University of Innsbruck9, Helsinki Institute of Physics10, University of Lisbon11, University of Beira Interior12, California Institute of Technology13, Russian Academy of Sciences14, National Center for Atmospheric Research15
TL;DR: 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, and the growth rate is then probably limited by the arrival rate of sulfurIC acid or cluster-cluster collision.
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.
50 citations
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TL;DR: In this article, the authors reported size-segregated particle number concentrations observed at a newly developed Beijing station during the winter of 2018, and correlated the particle number with concentrations of trace gases and other parameters measured at the station.
Abstract: . The spatial and temporal variability of the number size distribution of
aerosol particles is an indicator of the dynamic behavior of Beijing's
atmospheric pollution cocktail. This variation reflects the strength of different
primary and secondary sources, such as traffic and new particle formation,
as well as the main processes affecting the particle population. In this
paper, we report size-segregated particle number concentrations observed at
a newly developed Beijing station during the winter of 2018. Our
measurements covered particle number size distributions over the diameter
range of 1.5 nm–1 µ m (cluster mode, nucleation mode, Aitken mode and
accumulation mode), thus being descriptive of a major fraction of the
processes taking place in the atmosphere of Beijing. Here we focus on
explaining the concentration variations in the observed particle modes, by
relating them to the potential aerosol sources and sinks, and on
understanding the connections between these modes. We considered haze days
and new particle formation event days separately. Our results show that
during the new particle formation (NPF) event days increases in cluster mode
particle number concentration were observed, whereas during the haze days
high concentrations of accumulation mode particles were present. There was a
tight connection between the cluster mode and nucleation mode on both NPF
event and haze days. In addition, we correlated the particle number
concentrations in different modes with concentrations of trace gases and
other parameters measured at our station. Our results show that the particle
number concentration in all the modes correlated with NOx , which
reflects the contribution of traffic to the whole submicron size range. We
also estimated the contribution of ion-induced nucleation in Beijing, and
we found this contribution to be negligible.
50 citations
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TL;DR: Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices.
Abstract: Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.
7,092 citations
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University of Illinois at Urbana–Champaign1, Joint Institute for the Study of the Atmosphere and Ocean2, Cooperative Institute for Research in Environmental Sciences3, University of Leeds4, University of Oslo5, United States Environmental Protection Agency6, University of Michigan7, Pacific Northwest National Laboratory8, German Aerospace Center9, United States Department of Energy10, Max Planck Society11, University of Tokyo12, National Oceanic and Atmospheric Administration13, Forschungszentrum Jülich14, Norwegian Meteorological Institute15, Indian Institute of Technology Bombay16, China Meteorological Administration17, Peking University18, Met Office19, Desert Research Institute20, Clarkson University21, Stanford University22, European Centre for Medium-Range Weather Forecasts23, International Institute of Minnesota24, Goddard Institute for Space Studies25, Yale University26, University of Washington27, University of California, Irvine28
TL;DR: In this paper, the authors provided an assessment of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice.
Abstract: Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr−1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m−2 with 90% uncertainty bounds of (+0.08, +1.27) W m−2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m−2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m−2 with 90% uncertainty bounds of +0.17 to +2.1 W m−2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m−2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (−0.50 to +1.08) W m−2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (−0.06 W m−2 with 90% uncertainty bounds of −1.45 to +1.29 W m−2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.
4,591 citations
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01 Jan 2014
TL;DR: Myhre et al. as discussed by the authors presented the contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) 2013: Anthropogenic and Natural Radiative forcing.
Abstract: This chapter should be cited as: Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Coordinating Lead Authors: Gunnar Myhre (Norway), Drew Shindell (USA)
3,684 citations
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University of Gothenburg1, University College Cork2, Paul Scherrer Institute3, Weizmann Institute of Science4, Chalmers University of Technology5, Norwegian Meteorological Institute6, University of Antwerp7, Carnegie Mellon University8, University of Lyon9, Centre national de la recherche scientifique10, University of California, Berkeley11, University of York12, Leibniz Institute for Neurobiology13, University of Mainz14, University of Florida15, University of Colorado Boulder16, Forschungszentrum Jülich17, Ghent University18, University of Manchester19, Aix-Marseille University20, California Institute of Technology21
TL;DR: In this article, an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and analytical techniques used to determine the chemical composition of SOA is presented.
Abstract: Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed.
3,324 citations