Nie Wei    Ding Aijun    Wang Tao    Veli matti Kerminen    George Christian    Likun Xue    王文兴    Zhang Qingzhu    Tuukka Petäj̈ä T.    Qi Ximeng    Gao Xiaomei    Xinfeng Wang    杨修群    Congbin Fu    Markku Kulmala    

Scientific Reports

2015

Formation of highly oxidized, multifunctional products in the ozonolysis of three endocyclic alkenes, 1- methylcyclohexene, 4-methylcyclohexene, and α-pinene, was investigated using a chemical ionization atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometer with a nitrate ion (NO3^-) based ionization scheme. The experiments were performed in borosilicate glass flow tube reactors at room temperature (T = 293 ± 3 K) and at ambient pressure. An ensemble of oxidized monomer and dimer products was detected, with elemental compositions obtained from the high-resolution mass spectra. The monomer product distributions have O/C ratios from 0.8 to 1.6 and can be explained with an autocatalytic oxidation mechanism (=autoxidation) where the oxygen-centered peroxy radical (RO2) intermediates internally rearrange by intramolecular hydrogen shift reactions, enabling more oxygen molecules to attach to the carbon backbone. Dimer distributions are proposed to form by homogeneous peroxy radical recombination and cross combination reactions. These conclusions were supported by experiments where H atoms were exchanged to D atoms by addition of D2O to the carrier gas flow. Methylcyclohexenes were observed to autoxidize in accordance with our previous work on cyclohexene, whereas in α-pinene ozonolysis different mechanistic steps are needed to explain the products observed.

Rissanen Matti    Kurtén    Sipilä Mikko    Thornton    Kausiala Oskari    Garmash Olga    Henrik Kjaergaard    Tuukka Petäj̈ä T.    Douglas Worsnop    Ehn    Markku Kulmala    

Journal of Physical Chemistry A

2015

Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget.

Jokinen    Berndt Torsten    Makkonen    Veli matti Kerminen    Heikki Junninen    Paasonen    Stratmann Frank    Hartmut Herrmann    Alex Guenther    Worsnop Doug R.    Markku Kulmala     Ehn    Sipilä Mikko   

Proceedings of the National Academy of Sciences of the United States of America

2015

Very recent studies have reported the existence of highly oxidized multifunctional organic compounds (HOMs) with O/C ratios greater than 0.7. Because of their low vapor pressure, these compounds are often referred as extremely low-volatile organic compounds (ELVOCs), and thus, they are able to contribute significantly to organic mass in tropospheric particles. While HOMs have been successfully detected in the gas phase, their fate after uptake into particles remains unclear to date. Hence, the present study was designed to detect HOMs and related oxidation products in the particle phase and, thus, to shed light on their fate after phase transfer. To this end, aerosol chamber investigations of α-pinene ozonolysis were conducted under near environmental precursor concentrations (2.4 ppb) in a continuous flow reactor. The chemical characterization shows three classes of particle constituents: (1) intact HOMs that contain a carbonyl group, (2) particle-phase decomposition products, and (3) highly oxidized organosulfates (suggested to be addressed as HOOS). Besides chamber studies, HOM formation was also investigated during a measurement campaign conducted in summer 2013 at the TROPOS research station Melpitz. During this field campaign, gas-phase HOM formation was found to be correlated with an increase in the oxidation state of the organic aerosol. (Figure Presented).

Mutzel Anke    Laurent Poulain    Berndt Torsten    Iinuma Yoshiteru    Rodigast Maria    Böge Olaf    Richters    Gerald Spindler    Sipila¨ Mikko    Jokinen    Markku Kulmala     Hartmut Herrmann   

Environmental Science and Technology

2015

Over the last few years, several condensation particle counters (CPCs) capable of measuring in the sub-3 nm size range have been developed. Here we study the performance of CPCs based on diethylene glycol (DEG) at different temperatures during Cosmics Leaving OUtdoor Droplets (CLOUD) measurements at CERN. The data shown here are the first set of verification measurements for sub-3 nm CPCs under upper tropospheric temperatures using atmospherically relevant aerosol particles. To put the results in perspective we calibrated the DEG-CPC at room temperature, resulting in a cut-off diameter of 1.4 nm. All diameters refer to mobility equivalent diameters in this paper. At upper tropospheric temperatures ranging from 246.15 K to 207.15 K, we found cut-off sizes relative to a particle size magnifier in the range of 2.5 to 2.8 nm. Due to low number concentration after size classification, the cut-off diameters have a high uncertainty (±0.3 nm) associated with them. Operating two laminar flow DEG-CPCs with different cut-off sizes together with other aerosol instruments, we looked at the growth rates of aerosol population in the CLOUD chamber for particles smaller than 10 nm at different temperatures. A more consistent picture emerged when we normalized the growth rates to a fixed gas-phase sulfuric acid concentration. All of the instruments detected larger growth rates at lower temperatures, and the observed growth rates decreased as a function of temperature, showing a similar trend for all instruments. The theoretical calculations had a similar but much smaller temperature dependency.

Daniela Wimmer    Lehtipalo    Nieminen Tuomo    Jonathan Duplissy    Sebastian Ehrhart    João Almeida    Linda Rondo    Alessandro Franchin    Kreissl Fabian    Federico Bianchi    Manninen Hanna E.    Markku Kulmala     Curtius    Peta¨ja¨   

Atmospheric Chemistry and Physics

2015

Sulfuric acid is an important gas influencing atmospheric new particle formation (NPF). Both the binary (H2SO4-H2O) system and the ternary system involving ammonia (H2SO4-H2O-NH3) may be important in the free troposphere. An essential step in the nucleation of aerosol particles from gas-phase precursors is the formation of a dimer, so an understanding of the thermodynamics of dimer formation over a wide range of atmospheric conditions is essential to describe NPF. We have used the CLOUD chamber to conduct nucleation experiments for these systems at temperatures from 208 to 248 K. Neutral monomer and dimer concentrations of sulfuric acid were measured using a chemical ionization mass spectrometer (CIMS). From these measurements, dimer evaporation rates in the binary system were derived for temperatures of 208 and 223 K. We compare these results to literature data from a previous study that was conducted at higher temperatures but is in good agreement with the present study. For the ternary system the formation of H2SO4·NH3 is very likely an essential step in the formation of sulfuric acid dimers, which were measured at 210, 223, and 248 K. We estimate the thermodynamic properties (dH and dS) of the H2SO4·NH3 cluster using a simple heuristic model and the measured data. Furthermore, we report the first measurements of large neutral sulfuric acid clusters containing as many as 10 sulfuric acid molecules for the binary system using chemical ionization-atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometry.

Kürten    Münch    Linda Rondo    Federico Bianchi    Jonathan Duplissy    Jokinen    Heikki Junninen    Sarnela Nina    Siegfried Schobesberger    Simon Mario    Sipilä Mikko    João Almeida    Amorim A.    Josef Dommen    Neil mc pherson Donahue    Eimear Dunne    Richard Flagan    Alessandro Franchin    Jasper Kirkby    Agnieszka Kupć    Makhmutov    Tuukka Petäj̈ä T.    Praplan    Riccobono Francesco    Steiner Gerhard    António Tomé    Georgios Tsagkogeorgas    Wagner    Daniela Wimmer    Urs Baltensperger    Markku Kulmala     Douglas Worsnop    Curtius   

Atmospheric Chemistry and Physics

2015

The gas-phase reaction of ozone with C-C cycloalkenes has been investigated in a free-jet flow system at atmospheric pressure and a temperature of 297 ± 1 K. Highly oxidized RO radicals bearing at least 5 O atoms in the molecule and their subsequent reaction products were detected in most cases by means of nitrate-CI-APi-TOF mass spectrometry. Starting from a Criegee intermediate after splitting-off an OH-radical, the formation of these RO radicals can be explained via an autoxidation mechanism, meaning RO isomerization (ROO QOOH) and subsequently O addition (QOOH + O R′OO). Time-dependent RO radical measurements concerning the ozonolysis of cyclohexene indicate rate coefficients of the intramolecular H-shifts, ROO QOOH, higher than 1 s. The total molar yield of highly oxidized products (predominantly RO radicals) from C-C cycloalkenes in air is 4.8-6.0% affected with a calibration uncertainty by a factor of about two. For the most abundant RO radical from cyclohexene ozonolysis, O,O-CH(OOH)O (O,Ostands for two O atoms arising from the ozone attack), the determination of the rate coefficients of the reaction with NO, NO, and SO yielded (1.6 ± 0.5) × 10, (3.4 ± 0.9) × 10, and <10 cm molecule s, respectively. The reaction of highly oxidized RO radicals with other peroxy radicals (R′O) leads to detectable accretion products, RO + R′O ROOR′ + O, which allows to acquire information on peroxy radicals not directly measurable with the nitrate ionization technique applied here. Additional experiments using acetate as the charger ion confirm conclusively the existence of highly oxidized RO radicals and closed-shell products. Other reaction products, detectable with this ionization technique, give a deeper insight in the reaction mechanism of cyclohexene ozonolysis.

Berndt Torsten    Richters    Kaethner Ralf    Voigtländer Jens    Stratmann Frank    Sipilä Mikko    Markku Kulmala     Hartmut Herrmann   

Journal of Physical Chemistry A

2015

New particle formation (NPF) occurs frequently in the global atmosphere. During recent years, detailed laboratory experiments combined with intensive field observations in different locations have provided insights into the vapours responsible for the initial formation of particles and their subsequent growth. In this regard, the importance of sulfuric acid, stabilizing bases such as ammonia and amines as well as extremely low volatile organics, have been proposed. The instrumentation to observe freshly formed aerosol particles has developed to a stage where the instruments can be implemented as part of airborne platforms, such as aircrafts or a Zeppelin-type airship. Flight measurements are technically more demanding and require a greater detail of planning than field studies at the ground level. The high cost of flight hours, limited time available during a single research flight for the measurements, and different instrument payloads in Zeppelin airship for various flight missions demanded an analysis tool that would forecast whether or not there is a good chance for an NPF event. Here we present a methodology to forecast NPF event probability at the SMEAR II site in Hyytiälä, Finland. This methodology was used to optimize flight hours during the PEGASOS (Pan-European Gas Aerosol Climate Interaction Study)-Zeppelin Northern mission in May-June 2013. Based on the existing knowledge, we derived a method for estimating the nucleation probability that utilizes forecast air mass trajectories, weather forecasts, and air quality model predictions. With the forecast tool we were able to predict the occurrence of NPF events for the next day with more than 90 % success rate (10 out of 11 NPF event days correctly predicted). To our knowledge, no similar forecasts of NPF occurrence have been developed for other sites. This method of forecasting NPF occurrence could be applied also at other locations, provided that long-term observations of conditions favouring particle formation are available.

Nieminen Tuomo    Yli-Juuti    Manninen Hanna E.    Tuukka Petäj̈ä T.    Veli matti Kerminen    Markku Kulmala    

Atmospheric Chemistry and Physics

2015

Aerosol particles play important roles in regional air quality and global climate change. In this study, we analyzed 2 years (2011-2013) of measurements of submicron particles (6-800 nm) at a suburban site in the western Yangtze River Delta (YRD) of eastern China. The number concentrations (NCs) of particles in the nucleation, Aitken and accumulation modes were 5300 ± 5500, 8000 ± 4400, 5800 ± 3200 cm, respectively. The NCs of total particles are comparable to those at urban/suburban sites in other Chinese megacities, such as Beijing, but about 10 times higher than in the remote western China. Long-range and regional transport largely influenced number concentrations and size distributions of submicron particles. The highest and lowest accumulation-mode particle number concentrations were observed in air masses from the YRD and coastal regions, respectively. Continental air masses from inland brought the highest concentrations of nucleation-mode particles. New particle formation (NPF) events, apparent in 44% of the effective measurement days, occurred frequently in all the seasons except winter. The frequency of NPF in spring, summer and autumn is much higher than other measurement sites in China. Sulfuric acid was found to be the main driver of NPF events. The particle formation rate was the highest in spring (3.6 ± 2.4 cm s/, whereas the particle growth rate had the highest values in summer (12.8 ± 4.4 nm h/. The formation rate was typically high in relatively clean air masses, whereas the growth rate tended to be high in the polluted YRD air masses. The frequency of NPF events and the particle growth rates showed a strong year-to-year difference. In the summer of 2013, associated with a multi-week heat wave and strong photochemical processes, NPF events occurred with larger frequency and higher growth rates compared with the same period in 2012. The difference in the location and strength of the subtropical high pressure system, which influences the air mass transport pathways and solar radiation, seems to be the cause for year-to-year differences. This study reports, up to now, the longest continuous measurement records of submicron particles in eastern China and helps to achieve a comprehensive understanding of the main factors controlling the seasonal and year-to-year variation of the aerosol size distribution and NPF in this region.

Qi    丁爱军    Nie    Tuukka Petäj̈ä T.    Veli matti Kerminen    Erik Herrmann    Xie    Zheng    Manninen Hanna E.    Pasi Aalto    Sun    Xu    Chi    Huang    Boy    Virkkula A.    杨修群    Fu    Markku Kulmala    

Atmospheric Chemistry and Physics

2015

The Pan-Eurasian Experiment (PEEX) is a multidisciplinary, multiscale and multicomponent research, research infrastructure and capacity-building program. PEEX has originated from a bottom-up approach by the science communities and is aiming at resolving the major uncertainties in Earth system science and global sustainability issues concerning the Arctic and boreal pan-Eurasian regions, as well as China. The vision of PEEX is to solve interlinked, global grand challenges influencing human well-being and societies in northern Eurasia and China. Such challenges include climate change; air quality; biodiversity loss; urbanization; chemicalization; food and freshwater availability; energy production; and use of natural resources by mining, industry, energy production and transport sectors. Our approach is integrative and supra-disciplinary, recognizing the important role of the Arctic and boreal ecosystems in the Earth system. The PEEX vision includes establishing and maintaining long-term, coherent and coordinated research activities as well as continuous, comprehensive research and educational infrastructure and related capacity-building across the PEEX domain. In this paper we present the PEEX structure and summarize its motivation, objectives and future outlook.

Markku Kulmala     Lappalainen    Tuukka Petäj̈ä T.    Kurtén    Veli matti Kerminen    Viisanen Yrjö    Hari    Sorvari    Bäck    Bondur    Kasimov    Vladimir Kotlyakov    Matvienko    Baklanov    Guo    丁爱军    Hansson    Sergej Zilitinkevich   

Atmospheric Chemistry and Physics

2015