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A method for detecting the presence of organic fraction in nucleation mode sized particles

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Petri Vaattovaara at University of Eastern Finland
Petri Vaattovaara
Räsänen M
Räsänen M
Räsänen M
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Kühn T
Kühn T
Kühn T
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Joutsensaari J
Joutsensaari J
Joutsensaari J
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Abstract and Figures

New particle formation and growth has a very important role in many climate processes. However, the overall knowlegde of the chemical composition of atmospheric nucleation mode (particle diameter, d<20 nm) and the lower end of Aitken mode particles (d≤50 nm) is still insufficient. In this work, we have applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer) method to shed light on the presence of an organic fraction in the nucleation mode size class in different atmospheric environments. The basic principle of the organic fraction detection is based on our laboratory UFO-TDMA measurements with organic and inorganic compounds. Our laboratory measurements indicate that the usefulness of the UFO-TDMA in the field experiments would arise especially from the fact that atmospherically the most relevant inorganic compounds do not grow in subsaturated ethanol vapor, when particle size is 10 nm in diameter and saturation ratio is about 86% or below it. Furthermore, internally mixed particles composed of ammonium bisulfate and sulfuric acid with sulfuric acid mass fraction ≤33% show no growth at 85% saturation ratio. In contrast, 10 nm particles composed of various oxidized organic compounds of atmospheric relevance are able to grow in those conditions. These discoveries indicate that it is possible to detect the presence of organics in atmospheric nucleation mode sized particles using the UFO-TDMA method. In the future, the UFO-TDMA is expected to be an important aid to describe the composition of atmospheric newly-formed particles.
A schematic picture of the UFO-TDMA system.
A schematic picture of the UFO-TDMA system.
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Experimental growth factors (GFs) of ultrafine (10, 20, 30 and 50 nm, respectively) ammonium bisulfate particles as a function of ethanol saturation ratio (S%). Error limits are inside the data points in the figure. Also GFs for 100 nm ammonium bisulfate particles (Joutsensaari et al., 2004) are shown in the figure.
Experimental growth factors (GFs) of ultrafine (10, 20, 30 and 50 nm, respectively) ammonium bisulfate particles as a function of ethanol saturation ratio (S%). Error limits are inside the data points in the figure. Also GFs for 100 nm ammonium bisulfate particles (Joutsensaari et al., 2004) are shown in the figure.
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Experimental and theoretical growth factor (GF) ratio, respectively, for two consecutive ammonium bisulfate dry particle sizes (i.e. 100/50, 50/30, 30/20 and 20/10) at 86% saturation ratio. Also shown are Kelvin term ratios (theoretical/experimental), for 100, 50, 30, 20 and 10 nm particles. The denominators determine (e.g. 50/30->30 nm; 50/50->50 nm) the position on the x-axis.
Experimental and theoretical growth factor (GF) ratio, respectively, for two consecutive ammonium bisulfate dry particle sizes (i.e. 100/50, 50/30, 30/20 and 20/10) at 86% saturation ratio. Also shown are Kelvin term ratios (theoretical/experimental), for 100, 50, 30, 20 and 10 nm particles. The denominators determine (e.g. 50/30->30 nm; 50/50->50 nm) the position on the x-axis.
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Experimental and theoretical growth factor (GF) ratio, respectively, for two consecutive tartaric acid dry particle sizes (i.e. 50/30, 30/20, 20/10, 10/8 and 8/6) at 86% saturation ratio (experimental GF values for 8 and 6 nm are at S∼85%). Also shown are Kelvin term ratios (theoretical/experimental), for 50, 30, 20, 10, 8 and 6 nm particles. The denominators determine (e.g. 50/30>30 nm; 50/50->50 nm) the position on the x-axis.
Experimental and theoretical growth factor (GF) ratio, respectively, for two consecutive tartaric acid dry particle sizes (i.e. 50/30, 30/20, 20/10, 10/8 and 8/6) at 86% saturation ratio (experimental GF values for 8 and 6 nm are at S∼85%). Also shown are Kelvin term ratios (theoretical/experimental), for 50, 30, 20, 10, 8 and 6 nm particles. The denominators determine (e.g. 50/30>30 nm; 50/50->50 nm) the position on the x-axis.
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Experimental and theoretical growth factor (GF) ratio, respectively, for two consecutive benzoic acid dry particle sizes (i.e. 50/30, 30/20, 20/10, 10/8 and 8/6) at 86% saturation ratio (experimental GF values for 10 and 6 nm particles are at S∼85). Also shown are Kelvin term ratios (theoretical/experimental), for 50, 30, 20, 10, 8 and 6 nm particles. The denominators determine (e.g. 50/30->30 nm; 50/50->50 nm) the position on the x-axis.
Experimental and theoretical growth factor (GF) ratio, respectively, for two consecutive benzoic acid dry particle sizes (i.e. 50/30, 30/20, 20/10, 10/8 and 8/6) at 86% saturation ratio (experimental GF values for 10 and 6 nm particles are at S∼85). Also shown are Kelvin term ratios (theoretical/experimental), for 50, 30, 20, 10, 8 and 6 nm particles. The denominators determine (e.g. 50/30->30 nm; 50/50->50 nm) the position on the x-axis.
… 
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... The ultrafine organic tandem differential mobility analyser (UFO-TDMA, Vaattovaara et al., 2005;Joutsensaari et al., 2001) was used to calculate moderately oxidised organic volume fractions of SSA particles by measuring how much the particle grows in subsaturated (82 % ± 2 %) ethanol vapour. The growth factor of the SSA samples in ethanol vapour was measured at preselected mobility diameters of 15, 30 and 50 nm using the UFO-TDMA. ...
... The growth factor of the SSA samples in ethanol vapour was measured at preselected mobility diameters of 15, 30 and 50 nm using the UFO-TDMA. Growth of sodium chloride and ammonium sulfate in ethanol vapour has been shown to be negligible for preselected diameters up to 100 nm (Vaattovaara et al., 2005;Joutsensaari et al., 2001), while oxidised organics (tartaric, benzoic and citric acid) have growth factors of 1.3 to 1.6 in subsaturated (86 %) ethanol vapour. UFO-TDMA and H-TDMA measurements of sample U7520 were pre-treated using a thermodenuder (heated in 10 • C steps up to 500 • C). ...
... Ethanol growth factors measured using the UFO-TDMA for preselected 50 nm diameter SSA were 1.22 ± 0.02 (mean ± SD) and were largely invariable for all of the water samples examined. The ZSR assumption was used with an organic growth factor of 1.5 and a sea salt growth factor of 1, based on UFO-TDMA measurements of oxidised organics (tartaric, benzoic and citric acid) and sodium chloride, respectively (Vaattovaara et al., 2005;Joutsensaari et al., 2001). The measured ethanol growth factors correspond to moderately oxidised organic volume fractions averaging 35 ± 5 %, when the two-component ZSR model above is applied. ...
Sea spray aerosol organic enrichment, water uptake and surface tension effects
Article
Full-text available
  • Sep 2019
  • ACP
The aerosol driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote southern hemisphere are scarce, and are therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 day voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in-situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 % of the sea spray mass for particles with diameter less than approximately 1 μm, and up to 87 % of the particle volume in the Aitken mode. The composition of the organic fraction was consistent throughout the voyage and was largely comprised of a polysaccharide-like component, characterised by very low alkane to hydroxyl concentration ratios of approximately 0.1–0.2. The enrichment of organics was compared to the output from the chlorophyll-a based sea spray aerosol parameterisation suggested by Gantt et al. (2011) and the OCEANFILMS models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll-a, in particular when the co-adsoprtion of polysaccharides was included, however the model still under predicted the proportion of polysaccharides by an average of 33 %. Nascent sea spray aerosol hygroscopic growth factors averaged 1.93 ± 0.08, and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms, and was attributed to the surface partitioning of the organic components which leads to a decrease in particle surface tension and an increase in hygroscopicity. The compressed film model was used to estimate the influence of surface partitioning and the error in the modelled hygroscopicity was low only when the entire organic fraction was available to partition to the particle surface. The modelled sea spray aerosol hygroscopicity at high organic fractions was underestimated when only a portion of the organic component was available to be partitioned to the surface. The findings from the SOAP voyage highlight the influence of biologically-sourced organics on sea spray aerosol composition, these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake.
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... An ultrafine organic tandem differential mobility analyzer (UFO-TDMA, Fig. 1; [12], [13]) was used to determine the contribution of sulfate and organic components to nucleation mode size (d<15nm) particles composition. The main principle of operation of the DMA ( [14], [15]) is to select a narrow band of an aerosol size distribution by applying high voltage to its central rod thus selecting particles with a particular electrical mobility. ...
... Indeed, [17] recently studied in CLOUD (Cosmics Leaving Outdoor Droplets) chamber nanoparticle formation and growth experiments that sulfuric acid was transformed to pure ammonium sulfate from 2nm diameter. Furthermore, iodine compounds do not grow [12]. On the other hand, particles composed of biogenic organics (e.g. ...
... On the other hand, particles composed of biogenic organics (e.g. citric acid or tartaric acid; [12]) or 10nm diameter secondary organics [18] do grow (i.e. OGF is clearly over 1) and generally, moderately oxidized organic do grow very well [18]. ...
The Contribution of Sulfate and Oxidized Organics in Climatically Important Ultrafine Particles at a Coral Reef Environment
Article
Full-text available
  • Oct 2013
In order to investigate the properties of coral reef origin secondary aerosol and especially the contribution of secondary organic aerosol, ethanol affinity to atmospheric nucleation mode particles (diameter<15nm) was measured at the Heron reef marine environment in the South Pacific Ocean during the first coral reef aerosol characterization experiment in May-June 2011 using an ultrafine organic tandem differential mobility analyzer. Our campaign study at Heron reef showed that the nucleation mode size particles (diameter =10nm) composition contain internally mixed sulfate and oxidized organic components in approximately equal proportion in sunny and still conditions around low tide time, indicating local biogenic sources. The produced secondary compounds and aerosols have potential to contribute to cloud condensation nuclei formation and properties that may affect local low-level cloud formation over the GBR. Additionally, primary marine sea-salt and organic material during windy conditions and anthropogenic/biogenic sources during continental air masses can affect the properties of these particles.
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... In this study, the measurement systems used to characterize the newly-formed particles consisted of the UFO-TDMA (ultrafine organic tandem differential mobility analyzer [10]), measuring the 10-50 nm (in mobility diameter) particles, the VH-TDMA (volatile and hygroscopicity tandem differential mobility analyzer [11]), measuring particles with 16nm mobility diameter and H-TDMA (hygroscopicity tandem differential mobility analyzer) measuring the Aitken mode sized particles. A HR PTR-ToFMS (high resolution proton transfer reaction time of flight mass spectrometer [12]) was used to measure the gaseous particle precursors as well as to check for anthropogenic traces in the air masses. ...
... World Academy of Science, Engineering and Technology International Journal of Chemical, Materials Science and Engineering Vol:7 No:10, 2013 ...
Secondary organic contribution to particles formed on the ice melted Arctic Ocean
Article
Full-text available
  • Oct 2013
Due to climate warming and consequently due to ice and snow melting of the Arctic Ocean, the highly biologically active ocean surface area has been expanding quickly making possible longer marine biota growth seasons during polar summers. That increase the probability of the remote marine environment secondary contribution, especially secondary organic contribution, to the particle production and particle growth events and particle properties, consequently effecting on the open ocean, pack ice and ground based regions radiation budget and thus on the feedbacks between arctic biota, particles, clouds, and climate.
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... In contrast, the average CCN activation ratio for B3a was lower at 0.13 ± 0.06. Nucleation mode particles (10 and 15 nm) were measured by ultrafine organic tandem differential mobility analyzer (UFO-TDMA; Vaattovaara et al., 2005) and Aitken mode particles (50 nm) by UFO-TDMA and a volatility and hygroscopicity tandem differential mobility analyzer (VH-TDMA; Johnson et al., 2004;Villani et al., 2008). This analysis typically identified a significant (up to 50 % volume fraction) secondary organic component during sunny conditions in bloom regions, particularly during B1. ...
Overview and preliminary results of the Surface Ocean Aerosol Production (SOAP) campaign
Article
Full-text available
  • Nov 2017
  • ATMOS CHEM PHYS
Establishing the relationship between marine boundary layer (MBL) aerosols and surface water biogeochemistry is required to understand aerosol and cloud production processes over the remote ocean and represent them more accurately in earth system models and global climate projections. This was addressed by the SOAP (Surface Ocean Aerosol Production) campaign, which examined air–sea interaction over biologically productive frontal waters east of New Zealand. This overview details the objectives, regional context, sampling strategy and provisional findings of a pilot study, PreSOAP, in austral summer 2011 and the following SOAP voyage in late austral summer 2012. Both voyages characterized surface water and MBL composition in three phytoplankton blooms of differing species composition and biogeochemistry, with significant regional correlation observed between chlorophyll a and DMSsw. Surface seawater dimethylsulfide (DMSsw) and associated air–sea DMS flux showed spatial variation during the SOAP voyage, with maxima of 25 nmol L−1 and 100 µmol m−2 d−1, respectively, recorded in a dinoflagellate bloom. Inclusion of SOAP data in a regional DMSsw compilation indicates that the current climatological mean is an underestimate for this region of the southwest Pacific. Estimation of the DMS gas transfer velocity (kDMS) by independent techniques of eddy covariance and gradient flux showed good agreement, although both exhibited periodic deviations from model estimates. Flux anomalies were related to surface warming and sea surface microlayer enrichment and also reflected the heterogeneous distribution of DMSsw and the associated flux footprint. Other aerosol precursors measured included the halides and various volatile organic carbon compounds, with first measurements of the short-lived gases glyoxal and methylglyoxal in pristine Southern Ocean marine air indicating an unidentified local source. The application of a real-time clean sector, contaminant markers and a common aerosol inlet facilitated multi-sensor measurement of uncontaminated air. Aerosol characterization identified variable Aitken mode and consistent submicron-sized accumulation and coarse modes. Submicron aerosol mass was dominated by secondary particles containing ammonium sulfate/bisulfate under light winds, with an increase in sea salt under higher wind speeds. MBL measurements and chamber experiments identified a significant organic component in primary and secondary aerosols. Comparison of SOAP aerosol number and size distributions reveals an underprediction in GLOMAP (GLObal Model of Aerosol Processes)-mode aerosol number in clean marine air masses, suggesting a missing marine aerosol source in the model. The SOAP data will be further examined for evidence of nucleation events and also to identify relationships between MBL composition and surface ocean biogeochemistry that may provide potential proxies for aerosol precursors and production.
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... In contrast, the average CCN activation ratio for B3a was 0.13 ± 0.06. Nucleation mode particles (10 nm and 15 nm), were measured by ultra-fine organic tandem differential mobility analyser (UFO-TDMA, Vaattovaara et al., 2005), and Aitken mode particles (50 nm The first in situ measurements of aqueous phase SMA precursors dicarbonyls, glyoxal and methylglyoxal were obtained over the remote Southern Ocean during SOAP (Lawson et al., 2015). Parallel measurements of known dicarbonyl precursors, measured by PTR-MS, were used to calculate the expected yields of glyoxal and methyl glyoxal, which accounted for < 30% of observed mixing ratios indicating an unidentified source of dicarbonyls (Lawson et al., 2015). ...
An Overview of the Surface Ocean Aerosol Production (SOAP) campaign
Article
Full-text available
  • Jun 2017
  • ACP
Establishing the relationship between marine boundary layer (MBL) aerosols and surface water biogeochemistry over the remote ocean is required to understand aerosol and cloud production processes, and also represent them accurately in Earth System Models and global climate projections. This was addressed in the SOAP (Surface Ocean Aerosol Production) campaign, which examined air-sea interaction over biologically-productive frontal waters east of New Zealand. This overview details the objectives, regional context, sampling strategy, and provisional findings of a pilot study, PreSOAP, in austral summer 2011, and the following SOAP voyage in late austral summer 2012. Both voyages characterised surface water and MBL composition in three phytoplankton blooms of differing species composition and biogeochemistry, with significant regional correlation observed between chlorophyll-a and DMSsw. Surface seawater dimethylsulfide (DMSsw) and associated air-sea DMS flux showed spatial variation during the SOAP voyage, with maxima of 25 nmol L−1 and 100 µmol m−2 d−1, respectively, recorded in a dinoflagellate bloom. Inclusion of SOAP data in a regional DMSsw compilation confirmed that the current climatological mean is an underestimate for this region of the South-west Pacific. Estimation of the DMS gas transfer velocity (kDMS) by independent techniques of eddy covariance and gradient flux showed good agreement, although both exhibited periodic deviations from model estimates. Flux anomalies were related to surface warming and sea surface microlayer enrichment, and also reflected the heterogeneous distribution of DMSsw and the associated flux footprint. Other aerosol precursors measured included the halides and various volatile organic carbon compounds, with the first measurements of the short-lived gases glyoxal and methylglyoxal in pristine Southern Ocean marine air indicating an unidentified local source. The application of a real-time clean-sector, contaminant markers, and a common aerosol inlet facilitated multi-sensor measurement of uncontaminated air. Aerosol characterisation identified variable Aitken mode, and consistent sub-micron sized accumulation and coarse modes. Sub-micron aerosol mass was dominated by secondary particles containing ammonium sulfate/bisulfate under light winds, with an increase in sea-salt under higher wind-speeds. MBL measurements and chamber experiments identified a significant organic component in primary and secondary aerosols. Comparison of SOAP aerosol number and size distributions reveals an underprediction in GLOMAP-mode aerosol number in clean marine air masses, suggesting a missing marine aerosol source in the model. The SOAP data will be further examined for evidence of nucleation events, and also for relationships between MBL composition and surface ocean biogeochemistry with the aim of identifying potential proxies for aerosol precursors and production.
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... Two tandem differential mobility analyzers (TDMA) were measuring particle growth fac-20 tors (GF), defined as droplet size after exposing a dry particle to a solvent vapour divided by the dry size. The hygroscopicity TDMA (HTDMA) measures growth factors in water vapour (Rader and McMurry, 1986;Hämeri et al., 2000;Ehn et al., 2007a) and the organic TDMA (OTDMA) uses ethanol vapour (Joutsensaari et al., 2001;Vaattovaara et al., 2005). ...
Physicochemical properties and origin of organic groups detected in boreal forest using an aerosol mass spectrometer
Article
Full-text available
  • Oct 2009
  • ACP
An Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) was deployed in Hyytiälä, a forested rural measurement site in southern Finland, during a 2-week measurement campaign in spring 2005. Q-AMS measures mass concentrations of non-refractory species including sulphate, nitrate, ammonium and organics from submicron particles. A positive matrix factorization method was used in identifying two oxygenated organic aerosol (OOA) groups from the measured total organic mass. The properties of these groups were estimated from their diurnal concentration cycles and correlations with additional data such as air mass history, particle number size distributions, hygroscopic and ethanol growth factors and particle volatility. It was found that the aged and highly oxidized background organic aerosol (OOA1) species have a wide range of hygroscopic growth factors and volatilization temperatures, but on the average OOA1 is the less volatile and hygroscopic organic group. It seems that hygroscopic properties and volatilities of the OOA1 species are correlated so that the less volatile species have higher hygroscopic growth factors. The other less oxidized organic aerosol group (OOA2) is more volatile and non-hygroscopic. Trajectory analysis showed that OOA1 and the inorganic species are mainly long-range transported anthropogenic pollutions. On the other hand, OOA2 species and its precursor gases have short atmospheric life times, so they are from local sources. Current results are in good agreement with previous studies, but additional data especially from other seasons is required to verify the generality of the conclusions.
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... While it seems 254 intuitive that these high concentrations in the water would lead to a higher organic volume fraction, this was 255 not observed in Coral 2 where similar concentrations of Chl-a, TOC and TIC might be expected. [Vaattovaara et al., 2005]) and a compact Time-of-Flight Aerosol Mass Spectrometer (cToF-AMS; 269 [Drewnick et al., 2005]), respectively. Comparisons between these measurements and the volatility 270 hygroscopicity measurements comparisons from the VH-TDMA show the size dependence of the semi- 271 volatile and non-volatile organic contribution. ...
Sea spray aerosol in the Great Barrier Reef and the presence of non-volatile organics: Sea spray aerosol in the GBR
Article
Full-text available
  • Jun 2016
Sea spray aerosol (SSA) particles produced from the ocean surface in regions of biological activity can vary greatly in size, number and composition, and in their influence on cloud formation. Algal species such as phytoplankton can alter the SSA composition. Numerous studies have investigated nascent SSA properties, but all of these have focused on aerosol particles produced by seawater from noncoral related phytoplankton and in coastal regions. Bubble chamber experiments were performed with seawater samples taken from the reef flat around Heron Island in the Great Barrier Reef during winter 2011. Here we show that the SSA from these samples was composed of an internal mixture of varying fractions of sea salt, semivolatile organics, as well as nonvolatile (below 550°C) organics. A relatively constant volume fraction of semivolatile organics of 10%-13% was observed, while nonvolatile organic volume fractions varied from 29% to 49% for 60nm SSA. SSA organic fractions were estimated to reduce the activation ratios of SSA to cloud condensation nuclei by up to 14% when compared with artificial sea salt. Additionally, a sea-salt calibration was applied so that a compact time-of-flight aerosol mass spectrometer could be used to quantify the contribution of sea salt to submicron SSA, which yielded organic volume fractions of 3%-6%. Overall, these results indicate a high fraction of organics associated with wintertime Aitken mode SSA generated from Great Barrier Reef seawater. Further work is required to fully distinguish any differences coral reefs have on SSA composition when compared to open oceans.
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... From 26 May to 14 June 2011, on-site measurements of aerosol in the MBL at Heron Island were made using a scanning mobility particle sizer, an aerosol mass spectrometer and a volatility-hygroscopicity-tandem differential mobility analyser (VH-TDMA). The compositional contribution of sulfate and organic components in nucleation mode particles < 15 nm diameter was determined using an ultra-fine organic tandem differential mobility analyser (UFO-TDMA) (Vaattovaara et al. 2005). The aerosol composition of new particles determined with the UFO-TDMA is reported here, while information obtained from the other instruments will be reported elsewhere. ...
Dimethyl sulfide and other biogenic volatile organic compound emissions from branching coral and reef seawater: potential sources of secondary aerosol over the Great Barrier Reef
Article
Full-text available
  • Sep 2016
  • J ATMOS CHEM
Volatile organic compounds (VOCs) in the headspace of bubble chambers containing branches of live coral in filtered reef seawater were analysed using gas chromatography with mass spectrometry (GC-MS). When the coral released mucus it was a source of dimethyl sulfide (DMS) and isoprene; however, these VOCs were not emitted to the chamber headspace from mucus-free coral. This finding, which suggests that coral is an intermittent source of DMS and isoprene, was supported by the observation of occasional large pulses of atmospheric DMS (DMSa) over Heron Island reef on the southern Great Barrier Reef (GBR), Australia, in the austral winter. The highest DMSa pulse (320 ppt) was three orders of magnitude less than the DMS mixing ratio (460 ppb) measured in the headspace of a dynamically purged bubble chamber containing a mucus-coated branch of Acropora aspera indicating that coral reefs can be strong point sources of DMSa. Static headspace GC-MS analysis of coral fragments identified mainly DMS and seven other minor reduced sulfur compounds including dimethyl disulfide, methyl mercaptan, and carbon disulfide, while coral reef seawater was an indicated source of methylene chloride, acetone, and methyl ethyl ketone. The VOCs emitted by coral and reef seawater are capable of producing new atmospheric particles < 15 nm diameter as observed at Heron Island reef. DMS and isoprene are known to play a role in low-level cloud formation, so aerosol precursors such as these could influence regional climate through a sea surface temperature regulation mechanism hypothesized to operate over the GBR.
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Atmospheric new particle formation and growth: Review of field observations
Article
Full-text available
This review focuses on the observed characteristics of atmospheric new particle formation (NPF) in different environments of the global troposphere. After a short introduction, we will present a theoretical background that discusses the methods used to analyze measurement data on atmospheric NPF and the associated terminology. We will update on our current understanding of regional NPF, i.e. NPF taking simultaneously place over large spatial scales, and complement that with a full review on reported NPF and growth rates during regional NPF events. We will shortly review atmospheric NPF taking place at sub-regional scales. Since the growth of newly-formed particles into larger sizes is of great current interest, we will briefly discuss our observation-based understanding on which gaseous compounds contribute to the growth of newly-formed particles, and what implications this will have on atmospheric cloud condensation nuclei formation. We will finish the review with a summary of our main findings and future outlook that outlines the remaining research questions and needs for additional measurements.
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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
Article
Full-text available
  • Jun 2011
  • ACP
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) the first 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. This work enabled EUCAARI to improve our understanding 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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The Particle Detection Efficiency Curve of the TSI3010 CPC as a Function of the Temperature Difference between Saturator and Condenser
Article
Full-text available
  • Aug 1995
Particle detection efficiences of the Condensation Particle Counter (CPC) TSI-3010 are measured for various temperature differences between saturator and condenser. By increasing the temperature difference from the default value of 177deg;C to the maximum value of 25°C, the particle detection efficiency curve becomes steeper and shifts to smaller particle diameters. In this way, the 50% detection efficiency diameter of the TSI-3010 CPC decreases from 10.5 to 5.7 nm, without the necessity to change its internal design. In this size range, the desired lower detection limit of the TSI-3010 can be adjusted by operating the CPC at the corresponding temperature difference between saturator and condenser.
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Effects of SO2 oxidation on ambient aerosol growth in water and ethanol vapours
Article
Full-text available
  • Nov 2004
  • ACP
Hygroscopicity (i.e. water vapour affinity) of atmospheric aerosol particles is one of the key factors in defining their impacts on climate. Condensation of sulphuric acid onto less hygroscopic particles is expected to increase their hygrocopicity and hence their cloud condensation nuclei formation potential. In this study, differences in the hygroscopic and ethanol uptake properties of ultrafine aerosol particles in the Arctic air masses with a different exposure to anthropogenic sulfur pollution were examined. The main discovery was that Aitken mode particles having been exposed to polluted air were more hygroscopic and less soluble to ethanol than after transport in clean air. This aging process was attributed to sulfur dioxide oxidation and subsequent condensation during the transport of these particle to our measurement site. The hygroscopicity of nucleation mode aerosol particles, on the other hand, was approximately the same in all the cases, being indicative of a relatively similar chemical composition despite the differences in air mass transport routes. These particles had also been produced closer to the observation site typically 3-8 h prior to sampling. Apparently, these particles did not have an opportunity to accumulate sulphuric acid on their way to the site, but instead their chemical composition (hygroscopicity and ethanol solubility) resembled that of particles produced in the local or semi-regional ambient conditions.
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Nucleation: Measurements, Theory, and Atmospheric Applications
Article
  • Oct 1995
  • ANNU REV PHYS CHEM
New experiments have succeeded in measuring actual rates of nucleation and are revealing the shortcomings of classical nucleation theory, which assumes that the molecular-scale regions of the new phase may be treated using bulk thermodynamics and planar surface free energies. In response to these developments, new theories have been developed that incorporate information about molecular interactions in a more realistic fashion. This article reviews recent experimental and theoretical advances in the study of nucleation of liquids from the vapor and of crystals from the melt, with particular emphasis on phenomena that relate to particle formation in the atmosphere.
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Hygroscopic growth of ultrafine ammonium sulphate aerosol measured using an ultrafine tandem differential mobility analyzer
Article
  • Sep 2000
An ultrafine tandem differential mobility analyzer has been developed for measurements of the hygroscopicity of ultrafine aerosol particles, between 8 and 50 nm in mobility diameter. In this paper, the main operation features of the device are presented along with a detailed evaluation for the limits of its operation. The instrument is suitable for both laboratory-generated and atmospheric aerosol measurements. Hygroscopic growth data are presented for ammonium sulphate particles in the ultrafine size range, and comparisons are made with both experimental literature data and with theory. The data include determination of hygroscopic growth curves, deliquescence behavior, and hysteresis. These data will find applications in studies of the formation and growth of atmospheric aerosols.
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Aerosol classification by electric mobility: apparatus, theory, and applications
Article
  • Nov 1975
  • J AEROSOL SCI
An improved version of the Hewitt (differential) electric mobility analyzer was developed and its classifying characteristics were determined theoretically. The central mobility of the classified aerosol was found to be (qc + qm)/4πΛV, where qc and qm are the clean air and main outlet flows, respectively, Λ is a geometric factor, and Λ is the center rod voltage. The half-width of the mobility band was found to be (qa + qs)/4πΛV, where qa and qs are the aerosol and sampling outlet flows, respectively. These expressions were verified by the tests with a monodisperse aerosol of known size and low charge.
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Measurement of Ambient Aerosols by the Differential Mobility Analyzer Method: Concepts and Realization Criteria for the Size Range Between 2 and 500 nm
Article
  • Jan 1991
Requirements for aerosol spectrometer based on the differential electrical mobility method are deduced from the principles of aerosol classification and concentration determination. Data reduction and method-inherent sources of errors are discussed in detail. Criteria for the components of the arrangement to be used for ambient aerosol size distribution measurements are given with respect to size range, concentration range and time resolution.
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Observations of ultrafine aerosol particle formation and growth in boreal forest
Article
Number size distribution of ambient submicron and ultrafine aerosol particles have been measured on a continuous basis (every 10 minutes) for three quarters of the year 1996, at a forest site in Southern Finland. Continuous monitoring offers additional insight over the diurnal dynamics of the submicron size distribution, including existence of clearly separate size modes as well as events of new particle formation. Selected examples of the measured size distributions are presented, including the particle formation events observed at the measurement site. Typical characteristics of days with particle formation events versus days of no events are discussed.
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Predicted hygroscopic growth of sea salt aerosol
Article
  • Nov 2001
Organic species in sea salt particles can significantly reduce hygroscopic growth in subsaturated conditions, an important uncertainty in the radiative effect of aerosol particles on the atmosphere. This hygroscopic behavior is predicted with a numerical model of the organic-water, electrolyte-water, and organic-electrolyte interactions in complex mixtures of organic species and inorganic ions. The results show a 15% decrease in hygroscopic growth above 75% relative humidity for particles that include as little as 30% organic mass. Organic compositions of 50% organic mass reduce hygroscopic growth by 25%. This prediction relies on particle chemical composition estimated from measurements of insoluble organic species in marine-derived particles and of soluble organic species measured in seawater. Twenty insoluble and four soluble organic species are used to represent the behavior of sea salt organic composition. The hygroscopic growth is strongly sensitive to the organic fraction that is soluble or slightly soluble, although variations among different soluble or insoluble species are small above the sodium chloride deliquescence point. Interactions between organic and electrolyte species depend primarily on the ``salting out'' behavior of NaCl with alkanes, carboxylic acids, and alcohols, although interactions with other inorganic ions in sea salt were estimated to cause small changes in the hygroscopic growth. The predicted growth factors for sea salt with
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