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EFFECT OF GREEN LEAF VOLATILES (GLVs) ON SECONDARY
ORGANIC AEROSOL FORMATION
Andebo Abesha Waza
MSc thesis in Atmosphere-Biosphere studies
Department of Applied Physics
Faculty of Science and Forestry
University of Eastern Finland
November 2014
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UNIVERSITY OF EASTERN FINLAND, Faculty of Science and Forestry
Department of Applied Physics
ANDEBO ABESHA WAZA: Effect of Green Leaf Volatiles (GLVs) on secondary organic aerosol
formation.
MSc thesis: 60 pages, 3 appendixes (18 pages)
Supervisors: Jorma Joutsensaari, D.Sc. (Tech.), Docent and Pasi Yli-Pirila, MSc
November 2014
_______________________________________________________________________________
Key words: Aerosol particles, secondary organic aerosol, ozonolysis, biogenic volatile organic
compounds, green leaf volatiles, monoterpenes, formation rate, growth rate, yield, hygroscopicity
ABSTRACT
Climate change is one of the biggest challenges facing the world in the 21st century. Human activities,
like combustion of fossil fuel result in emissions of different radiation-modifying substances like
aerosol particles and greenhouse gases that have a profound influence on our climate system through
either by warming or cooling earth's surface. Secondary organic aerosol (SOA) particles, which are
formed by nucleation and condensation processes, accounts for a greater fraction of atmospheric
aerosol particles and thus, it is important to have detailed understanding of SOA formation, properties
and transformation processes and thereby to assess the impact on earth’s climate system and health
effects. Green leaf volatiles (GLVs) are an important component of biogenic volatile organic
compounds (BVOCs) released by vegetation during mechanical damage, herbivory attack, pathogen
infection and abiotic stress. They play a major role in contributing to the formation of secondary
organic aerosol particles in atmosphere. Reaction chamber experiments have been conducted to
investigate SOA formation from ozonolysis of three major GLV compounds: trans-2-hexenal, cis3-hexen-1-ol and cis-3- hexenylacetate by using series of experiments performed in humid conditions
(~50% RH). Similar experiments were also conducted with α-pinene and mixtures of terpenes (αpinene, sabinene, limonene, β-myrcene, ocimene, linalool and β-caryophyllene) as well as mixtures
of GLVs and terpenes. We found that ozonolysis of VOCs emitted from green leaf plants play a very
important role in new particle formation in chamber when they appear as a mixture with terpenes,
whereas ozonolysis of GLVs alone is less effectively involved in particle formation. We also
instigated that ozonolysis of monoterpenes (MTs) produced the highest SOA mass concentrations
and GLVs produced the lowest while mixture of MTs and GLVs being intermediate indicating that
monoterpenes plays a constitutive role during SOA formation process while GLVs have a suppressing
effect on SOA formation. We have also studied the hygroscopic growth of SOA particles and found
that SOA particles have low hygroscopicity showing very low water uptake with growth factor values
in between 1.01-1.03.
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ACKNOWLEDGMENTS
First and foremost, my utmost heartfelt gratitude goes to my main supervisor Jorma Joutsensaari
(D.Sc. Tech., Docent) for his unquestionable and continual support, valuable comments and patience.
Throughout this work, no matter how many times I came into his office without any appointment, I
cannot remember a single day that he said, "Sorry, I am busy.” I am extremely lucky to have him as
my thesis supervisor. I owe my special thanks to my second supervisor Pasi Yli-Pirila, MSc. His
guidance in laboratory greatly helped me to complete my thesis successfully. I benefited a lot from
his expertise in the laboratory work.
I would like to extend my gratitude to Annele Virtanen (Associate Professor) for funding the
experimental part of this research.
I would like to extend my thanks to my examiner Prof. Jarmo Holopainen. I must also thank Kim
Jaeseok (post doc) for all support and information he provided on topics related to H-TDMA
measurements.
I would like to express my appreciation to coordinator of Master's programme, Jussi Malila, MSc.
His continues academic guidance and administrative interventions whenever I asked him helped me
a lot to complete my study successfully. I'm so grateful for all his helps.
I owe sincere and earnest thankfulness to my friend Mengistu Mengesha for his unwavering
friendship over the years. His unparalleled support and unwavering encouragement over the past two
years were sources of my strength. Without his helps, it couldn’t have been possible to complete my
study.
I am also very grateful to the department of applied physics for providing me all research facilities to
carry out the work.
Above all, my greatest thanks goes to the omnipresent God for giving me strength and determination
to complete my study successfully.
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ABBREVIATIONS
1. BSOA: Biogenic Secondary Organic Aerosol
2. BVOC: Biogenic Volatile Organic Compounds
3. CCN: Cloud Condensation Nuclei
4. CPC: Condensation Particle Counter
5. DMA: Differential Mobility Analyzer
6. DMS: Dimethyl sulfide
7. GF: Growth Factor
8. GLVs: Green Leaf Volatiles
9. H-TDMA: Hygroscopic Tandem Differential Mobility Analyzer
10. IPCC: Intergovernmental Panel on Climate Change
11. MT: Monoterpene
12. NPF: new particle formation
13. OH: Hydroxide radical
14. PTR-MS: Proton-Transfer-Reaction Mass Spectrometer
15. RH: Relative Humidity
16. SMPS: Scanning Mobility Particle Sizer
17. SOA: Secondary Organic Aerosol
18. TME: tetramethylethylene
19. VOC: Volatile Organic Compounds
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TABLE OF CONTENTS
ABSTRACT ........................................................................................................................................ii
ACKNOWLEDGMENTS ................................................................................................................iii
ABBREVIATIONS ........................................................................................................................... iv
LIST OF FIGURES .........................................................................................................................vii
LIST OF TABLES ..........................................................................................................................viii
Chapter 1: BACKGROUND ............................................................................................................. 1
1.1
Introduction ........................................................................................................................... 1
1.2
Aim of study .......................................................................................................................... 2
1.3
Research questions ................................................................................................................ 2
1.4
Thesis outline ........................................................................................................................ 2
Chapter 2: LITERATURE REVIEW .............................................................................................. 3
2.1 Secondary organic aerosol (SOA) formation and its general properties .................................... 4
2.2 Biogenic volatile organic compounds ........................................................................................ 6
2.3 Green leaf volatiles as a global source of biogenic secondary organic aerosol ......................... 6
2.4 Instruments for aerosol size distribution measurement .............................................................. 8
2.5 Hygroscopicity of SOA particles ............................................................................................... 8
Chapter 3: MATERIALS AND METHODS ................................................................................. 10
3.1 Reaction chamber ..................................................................................................................... 10
3.2 Reagents and Chemicals ........................................................................................................... 12
3.3 Aerosol size distribution measurement .................................................................................... 12
3.4 Monitoring VOC change .......................................................................................................... 13
3.5 Tandem Differential Mobility Analyzer (H-TDMA) measurements ....................................... 15
3.6 Calculation of SOA mass yield ................................................................................................ 15
3.7 Overview of the experiments ................................................................................................... 16
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Chapter 4: RESULTS AND DISCUSSION ................................................................................... 17
4.1 Analysis of aerosol characterization......................................................................................... 18
4.1.1 Blank chamber tests ........................................................................................................... 18
4.1.2 Particle formation and growth measurements ................................................................... 18
4.2 SOA mass concentration and yield analysis............................................................................. 28
4.3 Growth Factor (GF) values....................................................................................................... 31
Chapter 5: CONCLUSIONS AND RECOMMENDATIONS ..................................................... 36
5.1 Conclusions .............................................................................................................................. 36
5.2 Recommendation for further research ...................................................................................... 37
REFERENCES ................................................................................................................................. 38
APPENDIXES .................................................................................................................................. 42
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LIST OF FIGURES
Figure 1: Schematic picture of SOA formation ................................................................................... 5
Figure 2: Picture indicating causes of GLV emission.......................................................................... 7
Figure 3: Reaction chamber ............................................................................................................... 11
Figure 4: SMPS experimental setup during ozonolysis experiment .................................................. 13
Figure 5: PTR-MS machine used in our experiment ......................................................................... 14
Figure 6: Schematic representation of H-TDMA experimental setup .............................................. 15
Figure 7: SOA formation from ozonolysis of cic-3-hexenol experiment .......................................... 20
Figure 8: SOA formation from ozonolysis of 3-hexenyl acetate experiment .................................... 21
Figure 9: SOA formation from ozonolysis of α-pinene experiment .................................................. 24
Figure 10: SOA formation from ozonolysis of α-pinene and GLV-mix experiment ........................ 25
Figure 11: Plot of growth factor as function of time for ozonolysis of trans-2-hexenol ................... 33
Figure 12: Plot of growth factor as function of time for ozonolysis of α-pinene .............................. 34
Figure 13: Plot of growth factor as function of time for ozonolysis of MT-mix and GLV-mix ....... 35
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LIST OF TABLES
Table 1: Overview of the experiments ............................................................................................... 16
Table 2: Analysis of particle total concentration (Ntot), formation rate and growth rate ................... 23
Table 3: Summary of literature values showing particle number concentration and growth rate
observed at different locations across the globe ................................................................................ 27
Table 4: Analysis of VOC consumption, ozone conc. change over time, ΔM
tot
max and SOA yields
............................................................................................................................................................ 29
Table 5: Summary of the mean values of growth factor (GF) values for some selected dry particle
sizes .................................................................................................................................................... 32
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x
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Chapter 1: BACKGROUND
1.1 Introduction
Atmospheric aerosols, which are liquid or solid particles suspended by carrier gas (air), play an
important role in environmental and atmospheric processes. For instance, they take part in
heterogeneous chemical reactions in the atmosphere which affects the distribution and the abundance
of trace gases in atmosphere (Andreae and Crutzen, 1997; Haywood and Boucher, 2000). Aerosol
particles can also influence the climate system by changing the earth’s energy budget in several ways.
For example, they can scatter and absorb the radiation directly (the direct effect) (Haywood and
Boucher, 2000). Aerosol particles can also act as cloud condensation nuclei (CCN), around which
clouds can form (which is known as the indirect effect) which modifies the radiative properties, the
amount and the lifetime of clouds (Haywood and Boucher, 2000). In light of these, it has been said
that aerosol particles evidently affect the radiative balance in earth’s atmosphere and hence they play
a major role in Earth’s climate system (IPCC, 2007).
Secondary organic aerosol particles (SOA) are formed from condensation of low volatility
compounds by chemical oxidation from both biogenic and anthropogenic volatile organic compounds
(Robinson et al., 2007). Plants are the largest contributor to the organic fraction of atmospheric fine
particulate matter, which can be through direct emissions or through SOA formation (Seinfeld and
Pandis, 1998). Despite improvements in study of SOA formation, many of the basic processes
governing formation, growth, chemical and physical properties of SOA particles are still poorly
understood. Recent studies on estimate of global secondary organic aerosol production based on VOC
flux expected that there could be significant missing SOA precursors that are currently unknown
(Goldstein and Galbally, 2007). Thus, it is suspected that the Green leaf volatiles (GLVs) could be
important parts of the missing global source of SOA. Moreover, in most chamber studies, only single
organic precursors (typically α-pinene or toluene) are used as exemplary compounds to study the
SOA formation (Hao et al., 2009). However, since the mechanism of SOA formation involves
complex steps, it is very much unclear as to what degree the results obtained from single monoterpene
chamber studies could be generalized to the actual atmospheric conditions (Van Reken et al., 2006).
Therefore, we believe that more realistic and important information can be obtained if we extend our
studies to green leaf volatiles.
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1.2 Aim of study
The main objective of this chamber study was to examine the SOA formation from ozonolysis of
various GLVs (trans-2-hexenal, cis-3-hexenol and 3-hexynyl acetate) by using series of chamber
experiments performed in humid conditions (~50% RH). Similar experiments were also conducted
with α-pinene and mixtures of monoterpenes (MT, α-pinene, sabinene, limonene, β-myrcene,
ocimene, linalool and β-caryophyllene) and then the results were used as a reference. Furthermore,
experiments with mixtures of GLV and MT were conducted. The SOA formation yields obtained
from ozonolysis of GLVs were then compared to those obtained from α-pinene and MT-mixture. In
order to examine the water absorbing capacity, the study also examined the hygroscopicity of SOA
particle produced and the results were compared with the literature values.
1.3 Research questions
1. How does the VOC emission profile affect the secondary organic aerosol formation?
2. Can GLVs suppress the secondary organic aerosol formation in chamber study?
3. How hygroscopic are SOA particles those which generated from ozonolysis of GLVs and how
would hygroscopicity of SOA particles whose precursors are GLVs be compared to SOA
particles whose precursors are monoterpenes and other inorganic species?
1.4 Thesis outline
The overall structure of the thesis is organized in five chapters. The first chapter introduces the general
background of study, research frame, objective and significance of the study as well as research
questions. Chapter two deals with literature review. In this section more detailed description of the
research topics is covered. In chapter three, materials and methods are briefly discussed. In chapter
four, results and discussion are clearly presented. In this session, results of size distribution
measurement, yield calculation and growth factor values are discussed in detail. Finally, chapter five
presents conclusions and recommendation remarks based on the main findings of the study.
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Chapter 2: LITERATURE REVIEW
There seems to be strong evidence that the Earth's climate is now changing. Human activities take
greater share of climate change problem by causing changes in the amounts of the greenhouse gases,
aerosols, and cloudiness on atmosphere which can significantly modify the earth’s energy balance
either warming or cooling the climate system. This could lead to several severe and irreversible
problems if no proper action (such as adaptation and mitigation strategies) is to be taken.
According to the IPCC (2007) report, the largest range of uncertainty in the radiative forcing is
coming mainly from the direct and indirect aerosol effect on climate change. The net effect of aerosols
on earth’s climate is to cooling the climate system directly by reflecting the incoming sunlight back
to space, and also indirectly by increasing the brightness and cover of clouds that in turn also reflect
more sunlight to space again (Kaufman, 2006). In addition to affecting the climate, atmospheric
aerosols can also cause adversarial health effects such as premature death, increases in respiratory
illness, and cardiopulmonary mortality (Laden et al., 2000). Therefore to decrease the negative
impacts for the present and future generations it is inevitable to study aerosols, to know their
formation and growth mechanism in atmosphere, sources, and chemical composition as well as their
physical and chemical properties.
Aerosol particles can be either emitted as primary aerosols (such as dust or soot particles) or they can
also be formed by chemical reactions from the condensation and gas-particle partitioning in
atmosphere. Sources of aerosols could be either natural (e.g. mineral and volcanic dust, sea salt,
dimethyl sulfide (DMS), volcanic sulfur dioxide (SO2), biogenic volatile organic compounds) or
manmade (such as soot, SO2 from fuel combustion, nitrogen oxides (NOx), anthropogenic volatile
organic compounds) (Seinfeld and Pandis, 2006). Aerosol particles can also vary in size ranging from
nanometers up to few micrometers in diameter (Raes et al., 2000). Similarly, the concentration could
also differ interim of spatial and temporal distribution. For example, the number concentration of
aerosol particles can range from 10-100000 particles per cm-3 and similarly its mass concentration
can vary from 0.1μgm-3 (in rural or unpolluted regions) to100μgm-3 in urban (polluted regions)
(Seinfeld and Pandis, 2006).
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2.1 Secondary organic aerosol (SOA) formation and its general properties
Organic aerosol is the most important part of submicron particles (Zhang et al., 2007). It can exist in
particle phase as primary organic aerosol or secondary organic aerosol (Robinson et al., 2007).
Organic aerosol particles significantly contribute to the total fine aerosol mass at both continental
midlatitudes and tropical forested areas (Seinfeld and Pankow, 2008). SOA particles are formed in
atmosphere by chemical reaction from condensation and gas-particle partitioning of semivolatile
products of hydrocarbon oxidation species (i.e. OH, O3 and NO3) (Kanakidou et al., 2005). Kanakidou
et al. (2005) also reported that 60% of organic aerosol mass on the global scale is secondary organic
aerosol while at regional level; they even estimated it to be higher than the reported global amount.
This indicates aerosol concentration is largely due to secondary particle production in atmosphere.
And therefore, detailed understanding of SOA formation process is important to assess its impact on
earth’s climate system.
Several studies have been conducted in the last few years to better understand the formation and
evolution of organic aerosols in atmosphere (Kroll and Seinfeld, 2008). However, there are still
uncertainties regarding the formation of SOA via the oxidation products (Hallquist et al., 2009). For
example, one of the problems associated with SOA formation from VOC oxidation in the gas phase
is that each VOC can undergo a number oxidation processes to produce different oxidized products,
which may or may not necessarily contribute to formation and growth secondary organic aerosol
(Hallquist et al., 2009). Moreover, once they are formed, SOA particles can undergo coagulation,
structural rearrangement and also phase transition which makes SOA formation process more
complex (Fuzzi et al., 2006). Relative humidity, concentration of organics and oxidants, rate constants
for oxidation, absorption ability, properties of the species and the ability to form solutions with
compounds already present in the aerosol phase are among the factors known to affect the SOA
formation (Ervens and Kreidenweis, 2007). About 85-90% of secondary organic aerosol particles are
produced mainly from oxidation of biogenic precursors (Stavrakou et al., 2009). Figure (1) shows
the schematic of SOA formation paths and its growth mechanism from semivolatile oxidation
products.
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Figure 1: Schematic picture of SOA formation (Source: Griffin et al. 2005)
Chung and Seinfeld (2002) indicated that 91% of SOA formation is caused by O3 and OH oxidation
while Kanakidou et al. (2005) suggested that ozonolysis dominates SOA production when compared
to OH and NOx oxidation. Similarly, Bonn et al. (2002) also reported that ozone has the highest
potential to form new particles by nucleation through reaction with α-pinene.
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2.2 Biogenic volatile organic compounds
Volatile organic compounds (VOCs) are generally compounds that are capable of vaporizing into the
atmosphere under normal temperature and pressure. They have sufficiently high saturation vapor
pressure that enables them to evaporate (either partly or completely) to the atmosphere. The sources
can be either biogenic or anthropogenic; however, the biogenic VOCs represent greater part of the
total VOC emissions (Guenther et al., 1995). Terrestrial biosphere is the main source of the biological
volatile organic compounds (BVOCs) and it provides a link between the earth’s surface and
atmosphere (Dudareva et al., 2006). BVOCs can cause a significant effect on the chemical
composition and physical characteristics of the earth’s atmosphere (Laothawornkitkul et al., 2009).
For example, they can affect atmospheric oxidation cycles such as ozone formation and formation of
secondary organic aerosol particles (Riipinen et al., 2011).
Plants release different kinds of biogenic volatile organic compounds (BVOCs) into the atmosphere.
Some of these chemical species can be classified as terpenoids (e.g., isoprene, monoterpenes, and
sesquiterpenes) while others can be classified as non-terpenoids (such as methanol, acetaldehyde, and
acetone) (Kesselmeier and Staudt, 1999). Among oxygenated organic compounds categorized as
plant emissions: 1,8-cineole is known to be emitted from eucalyptus, linalool is identified to be
emitted from orange blossoms while cis-3-hexen-1-o1 (leaf alcohol), cis-3-hexenenylacetate (leaf
acetate), and trans-2-hexenal (leaf aldehyde) are emitted from grasses and other agricultural crops
and are called green leaf volatiles (Arey et al., 1991). In the atmosphere, these oxygenated organic
compounds react with OH radicals, NO3 radicals, and O3 (Atkison, 1988) and form secondary organic
aerosols (Guenther et al., 1995).
2.3 Green leaf volatiles as a global source of biogenic secondary organic aerosol
The green leaf volatiles (GLVs) are one of the most significant groups of these BVOCs and are a
group of unsaturated oxygenated hydrocarbons which are produced from the biochemical conversion
of linoleic and linolenic acid within plant cells (Hamilton et al., 2009). They are ‘wound-induced’
VOCs emitted to atmosphere by several plant species when plants undergo stress or mechanical
damage (e.g. during grass cutting or grazing of animals and other stress factors such as herbivory
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attack, pathogen infection (Hamilton et al., 2009). Local weather conditions (temperature change)
can also cause the release of GLVs. For example, high concentrations of GLVs were emitted in the
Alps after a freezing spell, and were then attributed to emission from damaged cells upon thawing
(Karl et al., 2001). Variation in emission amount has also been reported among different ecosystems.
For example, grasslands are estimated to emit up to 130 mg C m–2 GLVs annually, while the reactive
lawn-GLV emissions are found to be 3.9 to 6.3 Gg C annually (Brilli et al., 2012). These emissions
are said to be a significant source of VOCs in the atmosphere. Isoprene, monoterpenes, sesquiterpenes
and methanol are the dominant compounds emitted under unperturbed conditions. Although the
emission rates of GLVs are lower when compared to the emission rates of the more commonly studied
isoprenoids, they are still considered to be an important group of chemicals (Arey et al., 1991; Konig
et al., 1995). GLVs play a significant role in atmospheric chemistry and physics (Atkinson, 1997).
For example, they can increase the levels of SOA in atmosphere over healthy plants (Joutsensaari et
al., 2005) and thus are important aerosol precursors. Figure (2) indicates the causes of GLV emission
from plants.
Figure 2: Picture indicating causes of GLV emission (Source: Holopainen., 2014).
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2.4 Instruments for aerosol size distribution measurement
Nowadays, atmospheric particle formation and growth have received considerable attention. And as
result, many advanced instrumental techniques for measuring concentrations of freshly formed
particle have been developed (Raes et al., 1997). Particle formation and growth are the most important
parameter to characterize the intensity of new particle formation (NPF) events. The scanning mobility
particle sizer (SMPS) technique is one of the most commonly employed method for measuring
particle size distribution (Sandip and David, 2005) and thus determination of particle formation rate
and particle growth rate. Particle formation rate defines the number of particles formed in unit volume
and time. On other side, since major aerosol effects depend on the diameter of aerosol particles, GR
is one most important parameter to look into (Yli-Juuti et al., 2011). It measures an increases particle
diameter unit time. In atmosphere, aerosol particles growth takes place mainly through selfcoagulation, coagulation scavenging and condensation (Leppä et al., 2011). Condensational growth
is the condensation of vapors onto the pre-existing particles (Sarangi et al., 2013). Aerosol growth by
coagulation is a kinetic process in which particles in in relative motion undergo collision with each
other and fuse (Yu and Turco, 1998).
2.5 Hygroscopicity of SOA particles
The capability of atmospheric aerosol to absorb water is one of important properties of aerosol
particles. Water uptake affects the particle size as well as phase and therefore it influences the
physicochemical characteristics of the aerosol particles, including optical properties of aerosols,
atmospheric lifetime, and chemical reactivity (Heintzenberg et al., 2001). Moreover, water uptake
property of aerosol particles can also define the capacity of aerosol particles to serve as a cloud
condensation nucleus (CCN). And this leads to modification in both direct and indirect radiative
forcing of the climate (IPCC, 2001). Hygroscopicity is the change in submicron particle size change
due to water uptake by particles (Peter and Mark, 1989). It defines how aerosol particles interact with
water vapor at different saturation conditions (McFiggans et al., 2006). In addition to their climatic
relevance, the hygroscopicity of aerosols can bring an adverse impact on the human health associated
with health effect of particulate matter (Stapleton et al., 1994; Davidson et al., 2005). As atmosphere
contains both inorganic and organic species, thus we need to understand the hygroscopicity of both
inorganic and organic species in atmosphere. However, there are still large uncertainties in our
9
understanding of the hygroscopicity of the organic species and these understanding gaps present
further challenge in simulating aerosol indirect radiative forcing (Petters et al., 2009). Hygroscopicity
of aerosol particles is commonly described in terms of particle size or mass changes as a function of
relative humidity (RH) under some saturation conditions. There has been variety of experimental
techniques that have been used to measure the hygroscopic growth of aerosol particles with its
specific advantages and limitations. After introduced by Liu et al. (1978) for the first time, the TDMA
technique has been used to study the change in particle size due to imposed aerosol processing
(Swietlicki et al., 2008). And the technique have been commonly used to study the size change of
particles associated with humidification (H-TDMA), evaporation (V-TDMA), chemical reactions
(R-TDMA) and uptake of organic vapor (O-TDMA) (Swietlicki et al., 2008). H-TDMA has been
mostly used over the last two decades to characterize the hygroscopic properties (i.e. size changes of
submicron particles after a treatment such as exposure to high relative humidity) of atmospheric
aerosol particles across the globe (Duplissy et al., 2008). The main aim of H-TDMA measurements
is to obtain the distribution of growth factors (GF) exhibited by the particles of some selected dry
particle size upon exposure to high RH (Swietlicki et al., 2008). The GF is defined as the ratio of the
diameter of humidified particle (D(RH)) to that of the initial dry classified particle diameter (D0) at
some well-defined relative humidity RH.
GF =D(RH)/D0 (Swietlicki et al., 2008).
Hygroscopicity of atmospheric aerosol particles can range from non-hygroscopic (i.e. such as primary
organic aerosol which are directly emitted from fossil fuel combustion) to highly hygroscopic
biomass burning organic aerosol particles (Petters et al., 2009). Hygroscopicity of secondary organic
aerosols particles was reported in previous studies. For example, Varutbangkul et al. (2006) measured
the GF values for SOA particles at 85% RH and found the values in between 1.09–1.16 from
ozonolysis of cycloalkenes, 1.01–1.04 for photooxidation of sesquiterpene and 1.06–1.10 for the
monoterpene and oxygenated terpene. Similarly, Virkkula et al. (1999) also measured the growth
factor (GF) values for SOA particles at 85%RH using (NH4)2SO4 as seed particles and found GF
value to be 1.1 from ozonolysis of α-pinene, β-pinene and limonene. Similarly, Saathoff et al. (2003)
also measured GF values for SOA particle produced from ozonolysis of α-pinene (at 200 nm) and the
reported value were: 1.106 at 85% RH for nucleated SOA, 1.55 for SOA with (NH4)2SO4 seed, 1.08
for SOA with diesel soot seed.
10
Chapter 3: MATERIALS AND METHODS
3.1 Reaction chamber
The experiments were performed in 9.8m3 rectangular Teflon TM FEP film chamber (see figure 3) at
Physics research laboratory (in Department of Applied Physics) at University of Eastern Finland
during 06–23 May 2014. After cleaning, the chamber humidification was made by using the Perma
Pure humidifier (Model FC-125-240-SMP, Perma Pure, and New Jersey) and heated water bath. The
relative humidity (RH) was adjusted to be around 50 ± 5 %. Approximately 30-45 min was allowed
for the RH value inside the chamber to reach 50% RH value. After attaining the 50% RH value, the
ozone enriched air at a flow rate of 15 liter per minute was introduced into the chamber through a
fitting that is connected the chamber horizontally. The ozone was produced by a UV light ozone
generator (i.e. with wave length of 185nm). Ozone concentration in the chamber was controlled by a
UV Photometric ozone analyzer (49i, Thermo Fisher Scientific Inc., MA) that samples air at a rate of
1.5 liter per minute. It took approximately 10-15 min for ozone generator to produce the ozone
concentration level of our interest (200 ppb ±10%). Finally VOCs were injected by syringe into the
reaction chamber. Carrier gas was used to introduce VOCs into the chamber. Ozonolysis reactions
were performed when ozone concentration in chamber reaches about 200ppb ±10%. Clean air was
supplied to the chamber by passing a compressed air through an air cleaning system that includes a
homemade compressed air dryer to remove moisture and particles and other contaminates. All
experiments were carried out under darkness to remove the possible photochemical effects. Before
performing each experiment, the chamber was constantly flushed with laboratory compressed clean
air until the chamber is clean of any particle. Similarly, after each of the experiments, cleaning of the
chamber was performed. No radical scavenger or seed aerosol was used.
11
Figure 3: Reaction chamber
12
3.2 Reagents and Chemicals
For our work, GLV solutions were prepared using commercially-available liquid green leaf volatiles
which were bought from Sigma-Aldrich (Milwaukee, WI, USA) and received without any further
purification. The GLVs used in this study were: trans-2-hexenal (98%), cis-3-hexanol (98%) and 3hexynyl acetate (98%). Furthermore, α-pinenene (99%) and mixtures of terpenes (α-pinene, sabinene,
limonene, β-myrcene, ocimene, linalool and β-caryophyllene) were used in these experiments.
Tetramethylethylene (TME; 99+%, Aldrich) was also added to the reaction chamber to initiate the
production of the OH radicals inside the chamber after two GLV/MT addition. The main purpose of
adding TME was to see the role of OH in the new particle production. TME was injected to the
chamber by syringe containing some fixed volume of TME (about 10µl, 200ppb). As suggested by
Lambe et al. (2007), OH radicals are produced when tetramethylethylene (TME) reacts with O3.
3.3 Aerosol size distribution measurement
The formation and evolution of SOA during ozone exposure in the chamber was determined by the
aerosol particle number size distribution measurement with a scanning mobility particle sizer, SMPS
system (TSI long-DMA 3081). The SMPS consists of a TSI long-DMA 3081 Differential Mobility
Analyzer (DMA) which is used to classify the aerosol particles based on their electrical mobility and
a TSI Model 3775 Condensation Particle Counter (CPC) which is then used to measure the
concentration of those size-classified particles (see figure 5). The DMA was operated with aerosol
and sheath flows of 0.3 and 3.0 liter per minute, respectively to measure the size distribution of the
particles in the 15–700 nm range. The size distributions were measured for every 3 min. Figure (4)
shows our SMPS experimental setup.
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Figure 4: SMPS experimental setup during ozonolysis experiment
3.4 Monitoring VOC change
Besides the particle formation measurement, the VOC measurements were also conducted
simultaneously with a Proton-Transfer-Reaction Mass Spectrometer (PTR-TOFMS, Ionicon Analytik
GmbH, see Fig. 5) to determine the concentration change over time. PTR-MS has been widely used
to study the link between new particle formation and VOC concentration change (Jordan et al 1995).
It is a very sensitive technique for online monitoring of VOCs in ambient air and is developed by
scientists at the Institut für Ionenphysik at the Leopold-Franzens University in Innsbruck, Austria
(Jordan et al 1995). A typical PTR-MS instrument consists of four components (1) an ion source that
14
is directly connected to a drift tube, (2) a drift tube (3) an ion transfer chamber (4) an ion an analyzing
system (time-of-flight mass spectrometer).
For off-line analysis, the VOCs were sampled onto about 150mg Tenax TA adsorbent (Supelco, mesh
60/80) for 15-20 min and analyzed with thermo desorption gas-chromatograph mass spectrometer.
Figure 5: PTR-MS machine used in our experiment
15
3.5 Tandem Differential Mobility Analyzer (H-TDMA) measurements
H-TDMA measurements have also been conducted in chamber to investigate the water uptake
properties of secondary organic aerosol particles generated by ozonolysis of GLVs and monoterpenes.
H-TDMA consists of Vienna type, short DMA and a TSI 3025 CPC. The flow rates of aerosol and
sheath air were 1 and 6 liter per min respectively and was operated at constant high RH value of
approximately 90%. The measured particle size was 30, 50, 100, 150 nm depending on particle
concentration. DMAs had a closed-loop sheath air circulation system. Relative humidity of sample
aerosol and excess air in DMA 2 were measured with a capacitive sensor (VaisalaHMP110) and a
dew point meter (Dewmaster), receptively. Finally the GF values obtained in this work were
compared with existing values in the literatures. And in doing this, the agreement of our work to the
previous works was evaluated. Figure (6) shows the schematic representation of H-TDMA
experimental setup.
Figure 6: Schematic representation of H-TDMA experimental setup
3.6 Calculation of SOA mass yield
16
SOA mass yield (Y) is commonly obtained by calculating the ratio of the total aerosol mass
concentration Mo (in μgm−3) to the amount of total precursor VOCs reacted (in μgm−3) at the end of
every experiment. That is: Y=Mo∕ΔVOCs (Jay et al., 1996). The type of organic precursor molecules
and the mass of organic aerosol are among other factors known to affect the yield of SOA particles.
To our knowledge, there was very limited study conducted on SOA yield obtained from ozonolysis
of green leaf volatiles. In this work, we calculated the mass yield of the secondary organic aerosol
particles produced from ozonolysis of the GLVs and then obtained result was again compared to those
obtained from α-pinene as reference. Furthermore, experiments with a mixture of GLV and MT were
also carried out. The aerosol yield is calculated from size distribution measurement made with SMPS
and gases concentrations measured with PTR-MS.
3.7 Overview of the experiments
We performed 13 experiments – three with only GLVs and two were only for MTs while the rest are
the mixture of GLVs and MT. Table (1) summarizes all the experiments that we conducted in the
laboratory. During these ozonolysis experiments, we were also interested to know whether the
concentration VOCs affects the aerosol formation and growth and thus we injected more GLVs in the
second injection round. The concentration of MT was held constant (40ppb) during the time when
more GLVs were injected to the reaction for second time. The concentration of GLVs was between
2µl-2.6µl (40ppb-41ppb). For all of experiments, injection of VOCs for second time performed
around in between 10:20-11:00.
Table 1: Overview of the experiments
17
Exp.
Exp. days
numbers
Terpenes
GLV(ppb)
(ppb)
O3 (ppb)
O3 (ppb) during
during the first
the second inj.
RH (%)
inj.
1
7.5.2014
-
trans-2-
44
42
50
219
195
50
204
182
50
hexenal_40+40
2
8.5.2014
-
cis-3-hexenol
_40+40
3
9.5.2014
-
3-hexynyl
acetate_40 +40
4
12.5.2014
a-pin_40
-
212
185
50
5
13.5.2014
a-pin_40
trans-2-hexenal
201
177
50
201
155
50
210
167
50
223
190
50
-
210
127
50
MT-mix
trans-2-hexenal
209
199
50
_40
_40+40
MT-mix
cis-3-hexenol
210
178
50
_40
_40+40
MT-mix
3-hexynyl acetate
225
185
50
_40
_40 +40
MT-mix
GLV-mix 40+40
215
189
50
_40+40
6
14.5.2014
a-pin_40
cis-3-hexenol
_40+40
7
15.5.2014
a-pin_40
3-hexynylacetate
_40 +40
8
16.5.2014
a-pin_40
GLV-mix_40+40
9
19.5.2014
MT-mix
_40
10
11
12
13
20.5.2014
21.5.2014
22.5.2014
23.5.2014
_40
Chapter 4: RESULTS AND DISCUSSION
18
4.1 Analysis of aerosol characterization
In this section, we present results from chamber studies of new particle formation from ozonolysis of
green leaf volatiles and monoterpenes. As already mentioned in the introduction part, monoterpenes
were used for comparison purpose. Figures in appendix (A1.1-A1.8) characterize a contour plot of
aerosol particle number size distributions, total aerosol particle number and mass concentration,
ozone concentrations and VOC concentration during ozonolysis of GLVs and MTs.
4.1.1 Blank chamber tests
Blank chamber tests were performed before each ozonolysis experiment. During this blank chamber
tests, we measured particle and VOC concentration before adding any ozone or VOC to make sure
that chamber was clean at the beginning of the each experiment. The main importance of this blank
chamber test was because we believe that the volatile organics that were injected into the reaction
chamber could be adsorbed on chamber walls and thus it would react with ozone during ozonolysis
experiment forming new particles. We recorded the background particle concentration and mass
concentrations. We disregarded the effects of NOX and SO2 in our works as their concentration was
negligible (i.e. each with concentrations lower than 0. 1 ppb). The test was performed prior to
beginning of ozonolysis experiment.
The average particle concentration counted during this blank chamber test was very small
(approximately 50 #/cm3) which is arguably insignificant. Thus we concluded that there was no
significant particle formation detected during this chamber ozonolysis. The absence of new particle
formation during this blank chamber test indicates that SOA formation observed during ozonolysis
experiments were due to ozonolysis of GLVs and MTs compounds injected into the reaction chamber
but not because of impurities adsorbed on the chamber walls.
4.1.2 Particle formation and growth measurements
In this section, we describe the variability in new particle formation over ozonolysis of different green
leaf volatiles and monoterpenes. Both growth rate and particle formation rates are calculated from
19
SMPS data. Several methods have been used for calculating aerosols growth rates from atmospheric
observation, however, in this work; we used the geometric mean diameter to characterize the growth
rate.
On the first day experiment (i.e. ozonolysis of trans-2-hexenal), particle formation was not detected.
However, clear new particle formation was detected during ozonolysis of cis-3-hexenol and 3hexenyl acetate. For instance, particle formation rate detected when cis-3-hexenol reacted with ozone
was about 1.98 cm−3 s−1 while it was about 0.22 cm−3 s−1 in the case of ozonolysis of 3-hexenyl
acetate. The particle growth rates, on the other hand, were also found to be 27nmh−1 and 18nmh−1
respectively. The lowest growth was observed for ozonolysis of 3-hexenyl acetate (about 17.8 nmh−1).
But generally when compared to MTs, weak SOA particle formation event was observed during
ozonolysis of GLVs. Figures (7 and 8) show the plot SOA formation from ozonolysis cis-3-hexenol
and 3-hexenyl acetate respectively.
We believe that during ozonolysis, the fragmentation of the precursors to more volatile products
which cannot produce SOA could be the main reason for why there is weak SOA formation from
ozonolysis of pure GLVs when compared to MTs. For example, Harvey et al. (2014) suggested that
ozonolysis of linear alkenes produce less SOA because their fragmentation products are too volatile
to enter the particle phase. Moreover, it is observed that ozonolysis of cis-3-hexanol produced more
SOA particles than ozonolysis of 3-hexenyl acetate. The main explanation for why ozonolysis of cis3-hexanol produced more SOA particles than ozonolysis of 3-hexenyl acetate is because of in the
case of ozonolysis of cis-3-hexanol, there may be more SOA particles as reaction product than in the
case of ozonolysis of 3-hexenyl acetate. Moreover, we would suspect that the difference in the
reaction rate with ozone could also resulted in difference in SOA formation between cis-3-hexanol
and 3-hexenyl acetate. For example, Atkinson et al (1995) investigated that reaction constant for cis3-hexen-1-ol when it reacts with ozone was about (6.4 ± 1.7) × 10−17 cm3 molecule−1 s−1 while the
reaction constant of cis-3-hexenylacetate for reaction with O3 about (5.4 ± 1.4) × 10−17 cm3
molecule−1 s−1.
20
Figure 7: SOA formation from ozonolysis of cic-3-hexenol experiment
(From top to down-a contour plot of aerosol particle number size distributions (measured with the
SMPS), aerosol particle number (from SMPS results), total organic mass (Mtot), ozone (O3) and
VOC concentrations)
21
Figure 8: SOA formation from ozonolysis of 3-hexenyl acetate experiment
(From top to down-a contour plot of aerosol particle number size distributions (measured with the
SMPS), aerosol particle number concentrations (from SMPS results), total organic mass
concentration (Mtot), ozone (O3) concentration and VOC concentration).
During ozonolysis of MTs, more intensive SOA particle formation was observed at beginning stages
of reaction and then growth continued as far as VOCs are there to react with ozone (see figure 9 and
10). For example, in ozonolysis of pure α-pinene, we found that the particle formation rate as high as
224 cm−3 s−1. However, it has been also seen that SOA formation decreases when α-pinene mixed
22
with pure GLVs or mixture of GLVs. The particle formation for α-pinene reduced from 224 cm−3 s−1
to about 33 cm−3 s−1 when α-pinene is mixed with GLVs. It was also observed that the particle
formation rate in ozonolysis of MT-mix was higher when compared to the ozonolysis of GLVs alone.
Moreover, because of the involvement of α-pinene, which is more responsible for nucleation, the
particle formation rate observed during ozonolysis of the mixture of α-pinene and cis-3-hexenol was
approximately 40 times higher than that in ozonolysis of pure cis-3-hexenol and also this trend was
consistent with ozonolysis of and cis-3-hexenol. But the particle formation rate when α-pinene mixed
with cis-3-hexenol was higher than pure ozonolysis of cis-3-hexenol. Similarly, on average more
growth rate was observed in the case of ozonolysis of GLVs when they were mixed with MTs than
when they react with ozone alone. The particle growth rates observed in these experiments was in the
range of 21 nmh−1-42 nmh−1. A similar growth rate was obtained for ozonolysis of MTs (α-pinene
and MT-mix). The maximum growth (42 nmh−1) was found when α-pinene was mixed with 3-hexynyl
acetate while the minimum growth rate was detected during ozonolysis of 3-hexynyl acetate.
Ozonolysis of pure α-pinene has more particle formation rate (224 cm−3 s−1) when compared to
particle formation rate of pure MTs (129cm−3 s−1). The main explanation for difference in particle
formation rate between α-pinene and MTs is that some of the compounds in the mixture of MT could
not be easily reacting with O3 and as the result, the particle formation in the mixture of MTs could be
lower than the pure α-pinene.
Generally, the implication of these results is that ozonolysis of VOCs emitted from green leaf plants
play a very important role in nucleation process through suppressing the SOA formation. See the
summary of particle formation rate, growth rate and total particle concentration (Ntot max) in table
(2).
23
Table 2: Analysis of particle total concentration (Ntot), formation rate and growth rate
N tot max
Formation rate
Growth rate
(cm -3s-1)
(nmh-1)
Exp.date
MT
GLVs
07-05-2014
--------------
trans-2-hexenal
N/A
N/A
N/A
08-05-2014
---------------
cis-3-hexenol
4350
2
27
09-05-2014
--------------
1370
0.2
18
12-05-2014
α-pinene
-----------------
89600
224
35
13-05-2014
α-pinene
trans-2-hexenal
49900
198
36
14-05-2014
α-pinene
cis-3-hexenol
35500
76
33
15-05-2014
α-pinene
32100
33
42
16-05-2014
α-pinene
GLV-mix
43800
54
39
19-05-2014
MT-mix
----------------
26700
129
33
20-05-2014
MT-mix
trans-2-hexenal
99600
184
28
21-05-2014
MT-mix
cis-3-hexenol
76300
104
27
22-05-2014
MT-mix
150000
471
22
23-05-2014
MT-mix
127000
295
23
3-hexynyl
acetate
3-hexynyl
acetate
3-hexynyl
acetate
GLV-mix
(#/ cm3)
24
Figure 9: SOA formation from ozonolysis of α-pinene experiment
(From top to down-a contour plot of aerosol particle number size distributions (measured with the
SMPS), aerosol particle number concentrations (from SMPS results), total organic mass
concentration (Mtot), ozone (O3) concentration and VOC concentration)
25
Figure 10: SOA formation from ozonolysis of α-pinene and GLV-mix experiment
(From top to down-a contour plot of aerosol particle number size distributions (measured with the
SMPS), aerosol particle number concentrations (from SMPS results), total organic mass
concentration (Mtot), Ozone (O3) concentration and VOC concentration)
The maximum particle concentration found in these days was about 150000 particle cm−3 (during
ozonolysis of MT-mix and 3-hexynyl acetate) while the minimum particle concentration was about
26
1370 particle cm−3 (ozonolysis of 3-hexynyl acetate). Generally, lower particle number concentration
was obtained from ozonolysis of GLVs when compared to MTs. But mixing MTs with GLVs during
ozonolysis decreased total number concentration when compared to ozonolysis of ozonolysis of pure
MTs. For example, the maximum total number concentration obtained during ozonolysis of pure αpinene was about 89600 particle cm−3 but when α-pinene was mixed with GLV-mix, the particle
number concentration decreased to 43800 from 89600 particle cm−3. Since fragmentation products of
GLVs are too volatile to enter the particle phase, it is therefore somehow convincing to get less total
number concentration from ozonolysis of GLVs. Comparatively higher particle number concentration
was obtained in ozonolysis of cis-3-hexanol when compared to ozonolysis of 3-hexenyl acetate. The
differences between these compounds on particle formation could possibly be explained interims of
their reaction rate with ozone. When compared, acetates found to have higher reaction rate with ozone
than alcohols. It was also observed that the total number concentration found to be decreasing over
time shortly after showing an increase in the very beginning of the experiments (for the first 1520min). This sounds logical. Particle coagulation, deposition process and condensation taking place
inside the chamber resulted in decrease of the particle concentration and increase of particle size (for
instance, see figures 9, 10 and 11 and table 2).
Generally, in this study, particle formation rate is found to be higher than the particle formation rates
observed in ambient air, which is found to vary in between 0.01–10 cm−3 s−1 (Kulmala et al., 2004).
The lower range of the growth rate obtained in our experiment matches to the typical the growth rates
of particles formed in atmosphere with the maximum observed growth rate being around 20nmh−1
(Kulmala et al., 2004). Table (3) summarizes literature values for particle number concentration and
growth rate values observed in different locations across the globe.
27
Table 3: Summary of literature values showing particle number concentration and growth rate
observed at different locations across the globe (Source: Sarangi et al., 2013, p.8).
Location
Idaho Hill, Corolado
Particle size range
(nm)
Considered
nucleation
mode
size range (nm)
Average
number concentration
(particles/cm3
Average
growth rate
(nm/hr)
References
15–500
3-20
10000
1.6
weber et al., 1997
Rural Ontario, Canada
11–457
10–43
20000
4.2
Verheggen
Northern Finland
7-500
7-15
870
2.9
Komppula et al.,
Rural continental site
3-800
3-20
5000
2.6
Birmili et al., 2003
Po Valley, Italy
3-600
3-20
1200
7
Hamed et al., 2007
Hyytiälä, Finland
3-500
<25
n/a
3
Dal Maso et al.,
and Mozurkewich, 2002
2003
in Southern
Germany
2007
Tokyo, Japan
5-200
n/a
1000
8-17
Mochida et al.,
2008
Antarctic
3-1000
3-25
374
1.3
Asmi et al., 2010
Toronto, Cananda
3-100
14–25
105000
6.7
Jeong et al.,2010
Mexico city
10–478
10–15
21000
11.6
Kalafut-Pettibone
Beijing, China
12–550
12–25
1000
2.43–13.9
Zhang et al., 2013
Brisbane, Australia
4-110
4-30
560
4.6
Chenung et al.,
et al., 2010
2011
Shanghai, China
10–500
10–20
13000
4.38
Du et al., 2012
Marikana, South
10–840
12–20
10000
8
Hirsikko et al.,
Africa
2012
Atlanata, USA
3-500
1-3
1000–10000000
5.5-7-6
Kuang et al., 2012
Wakayama Forest
14–710
14–30
11000
9.2
Han et al., 2013
9-425
9-25
37200
15.4
Sarangi et al., 2013
Research station,
Japan
National Physical
Laboratory NPL,
New Delhi
28
The main explanation for the disparity between formation rate and growth rates found in our study
and that observed in ambient air could be the difference in concentration of species. Higher
concentration of O3, GLVs and MTs has been used in our chamber study than actual atmospheric
concentration of the compounds. The other reason for the disparity could be due to differences in
actual experimental conditions (e.g., residence times, fluctuations in ozone concentration, fluctuation
in RH inside the chamber).
4.2 SOA mass concentration and yield analysis
In this section we present the yield of particle mass in secondary organic aerosol (SOA) obtained
formed from ozonolysis the GLVs and/or MT in our chamber study. As mentioned in section 3.3,
aerosol yields can be determined from progressive changes in VOC concentration and in aerosol mass
concentration during the chamber experiment. The yield determination was based on the result
obtained from two independent instruments namely the SMPS for size distribution measurement and
the PTR for the measurement of concentration. The mass distribution is obtained in the way that we
first obtained the size distribution measurement from SMPS data and then we converted the size
distribution measurement to the mass distribution measurement assuming the particle density to be
1gcm-3. We are aware that there might be some error on our result as the density of particle could also
be a bit more than 1gcm-3. Therefore, we took this into account while analyzing the result.
During the second injection period, the concentration of GLVs was increased almost twice (varying
between 80-82ppb). As can be clearly seen from the table (4), for all experiments, the mass of SOA
particles produced after injection of more VOCs for second time has significantly increased. The
maximum mass produced from ozonolysis of α-pinene was about 39gm-3 and 101gm-3 during first
and second addition of VOCs respectively. The maximum mass produced after mixing α-pinene with
GLV mixture was about 38gm-3 and 53gm-3 during first and second injection respectively. Overall,
SOA mass from ozonolysis of GLVs and MTs increased significantly with increasing concentration.
And this implies that the concentration of compounds can significantly affect the particle formation
and growth in atmosphere. Injection of TME (following VOCs for second time) has resulted in more
particle formation from ozonolysis of GLVs and thus increasing mass of the SOA particles. Table (4)
shows that for all of the experiments, more SOA particles mass was produced after TME injection.
This means our study supports the role of OH in particle formation process. Injection of TME into
reaction chamber increased SOA mass production from GLVs, because TME produced OH radicals
29
which would soon react with GLVs producing more SOA. And this is the main reason why injection
TME increased the potential of GLVs to produce more SOA particles. Similar finding was also
reported by Atkinson et al. (1995). They suggested that GLVs are highly reactive towards hydroxyl
radicals and thus producing more SOA particles.
Ozonolysis of pure α-pinene and MT-mix produced more SOA mass when compared to SOA mass
produced in ozonolysis of mixture of α-pinene with GLVs or MTs with GLVs. For example, the
maximum SOA mass produced during ozonolysis of α-pinene alone was about 104gm-3 while the
mass SOA produced when monoterpens mixed with the GLVs was about 51 gm-3. So this means there
is a decrease in SOA mass when MT is mixed with GLVs than when MT is ozonolysed alone. This
implies MTs plays a constitutive role during SOA formation process while GLVs have a suppressing
effect on SOA particle formation. On other hand, SOA particle mass concentration slightly increases
with time early in the experiments, but then it starts decreasing gradually with time. Losses of particles
to the walls of chambers are the main reason for decrease of particle concentration over time. We had
also analyzed the yields for each of the experiment (see table 4). Our yield calculation method was
basically similar to what has been used by Mentel et al. (2013). They used the VOC consumptions as
sum of the individual VOCs when two are more compounds are reacting in the chamber. To determine
the yield, we obtained the maximum change in SOA particles mass (∆M tot (µgm-3)) before and after
injection of compounds into chamber and then divided by the change in VOC concentration due to
consumption (ΔVOC) concentration. The change in VOC consumption was obtained by taking the
difference between the maximum VOC consumption and minimum VOC consumption from VOCtime plot. Refer to figures (8, 9, 10, and 11) to see change in VOC concentration over time before and
after addition of the GLVs and MTs in to reaction chamber. It was hardly possible to determine the
yield from ozonolysis of trans-2-hexenal as in this day we did not observe any significant particle
formation and thus the yield calculation was excluded. The yields calculated from ozonolysis of cis3-hexenol and 3-hexynyl acetate were also comparatively low (less than 0.5). Convincingly,
ozonolysis of MTs has resulted in higher yield. But during ozonolysis of MT-mix with GLVs, SOA
mass yield is found to be decreased. This is because, in ozonolysis of GLVs, the reaction products
can be partitioning to gaseous parts decreasing the particles formation and thus the mass of SOA and
hence low yield of GLVs. Table (4) shows the summery of the analysis of VOC consumption, ozone
conc. change over time, ΔM tot max and the yields obtained during ozonolysis.
Table 4: Analysis of VOC consumption, ozone conc. change over time, ΔM tot max and SOA yields
30
Reagents
Exp. days
MT
GLV
ΔM tot
ΔM
tot
max
max after
after
inj. one
inj. two
-3
(µgm )
(µgm-3)
ΔM tot
max after
TME
(µgm-3)
ΔVOC
after
inj. one
(µgm-3)
ΔVOC
after
inj.
two
(µgm3
)
Ozon
Ozone Yield
e
conc.
one
conc.
at inj. at inj.
(inj.one
one
two
)
(ppb) (ppb)
Yield
two
(inj.
two)
7.5.2014 No
trans-2hexenal
N/A
N/A
N/A
N/A
N/A
44
42
N/A
N/A
8.5.2014 No
cis-3hexenol
0.05
0.26
No inj.
54.5
105
219
195
0.09
0.25
9.5.2014 No
trans-2hexenal
0.04
0.13
No inj.
117
256
204
182
0.03
0.05
12.5.201 α4 pinene
No inj.
39.4
101
104
281
291
212
185
14
19
13.5.201 α4 pinene
trans-2hexenal
30
37.6
48.7
247
128
201
177
12
6.3
14.5.201 α4 pinene
cis-3hexenol
44
55
51
1889
305
201
155
2
2.4
15.5.201 α4 pinene
3hexynyl
acetate
36.5
44.8
50.5
509
319
210
167
7.2
2
16.5.201 α4 pinene
GLV
mix
38
38
54
726
272
223
190
5
3.5
19.5.201 MT4 mix
No inj.
33.5
70
89
197
136
210
127
17
25.7
20.5.201 MT4 mix
trans-2hexenal
15
20
34
135
148
209
199
11
3
21.5.201 MT4 mix
cis-3hexenol
19
21
32
343
275
210
178
5.5
1
29.5
30
36.7
220
337
225
185
13
0.2
23
27
32.5
178
272
215
189
13
0.9
22.5.201 MT4 mix
23.5.201 MT4 mix
3hexynyl
acetate
GLVmix
Yield has significantly increased after second injection of VOCs (see table 4). One of the reasons for
increase of yield after second injection is because of higher VOC concentration. More VOC
concentration in the chamber means more possibility to produce SOA mass (as far as VOCs are
available in reaction chamber, the reaction would continue producing more SOA mass) and thus the
yield increases. Moreover, it is possible to have some seed particles left in the chamber after addition
of the first one, and this could also increase the yield.
31
Previously, few mass yield studies have been reported from chamber studies obtained for SOA
particles generated from oxidation of BVOC of real plants. For example, Mentel et al. (2009) reported
an incremental mass yields of SOA from OH/O3 initiated pine/spruce emissions. The mass yields
obtained in their study were found to be 9%, 8% and 4% for α-pinene, pine and spruce SOA,
respectively. Their reported values are slightly lower than the value we found in our study. We suspect
this difference in mass yields could be due to differences in experimental conditions (e.g., different
reaction chamber system, reactant and ozone concentration and humidity).
4.3 Growth Factor (GF) values
In H-TDMA experiments, we measured the diameter-based hygroscopic GF of the SOA particles as
function of time. Therefore, in this section, we report the GF values obtained from H-TDMA
measurements. Among other figures located on the appendix (A2.1-A2.9), figures (1411, 1512, and
1613) and table (5) (6) shows growth factor data measurement obtained from H-TDMA
measurements.
All SOA particles generated in this study were found to be less hygroscopic (or showed smaller water
uptake property when compared to that of typical inorganic aerosol substances (such as (NH4)2SO4)).
The maximum GF value obtained in the measurement is 1.1305 which is measured at dry diameter
of 50nm. We found GF values in between 1.01–1.13 for SOA particles formed from ozonolysis of
both GLVs and monoterpenes. It was also observed that for each precursor, the GF values computed
from different dry diameters agree with each other (i.e. there is no such a significant difference among
the measured GF values). Overall, this result suggests that the SOA obtained from ozonolysis of
monoterpens and GLVs has very low hygroscopicity showing very little water uptake with growth
factor between 1.01-1.03. All the GFs values from monoterpenes and GLVs are contained within
narrow range of GF values (in between 1.01-1.03).
32
Table 5: Summary of the mean values of growth factor (GF) values for some selected dry particle
sizes
Exp.days
MT
07-05-2014
GLVs
GF
GF
GF
GF
(Dp=30nm) (Dp=50nm) (Dp=100nm) (Dp=150nm)
trans-2hexenal
n/a
n/a
n/a
n/a
08-05-2014
-----------
cis-3hexenol
1.13
1.13
n/a
n/a
09-05-2014
-----------
3-hexynyl
acetate
1.06
1.05
1.03
n/a
12-05-2014
α-pinene
-------------
1.06
1.07
1.07
n/a
13-05-2014
α-pinene
trans-2hexenal
1.06
1.06
1.05
1.05
14-05-2014
α-pinene
cis-3hexenol
1.06
1.06
1.05
1.04
15-05-2014
α-pinene
3-hexynyl
acetate
1.04
1.05
1.04
1.04
16-05-2014
α-pinene
GLV-mix
1.05
1.06
1.05
1.05
19-05-2014
MT-mix
----------
1.05
1.04
1.03
1.02
20-05-2014
MT-mix
trans-2hexenal
1.07
1.06
1.05
1.04
21-05-2014
MT-mix
cis-3hexenol
1.06
1.06
1.05
1.04
22-05-2014
MT-mix
3-hexynyl
acetate
1.05
1.04
1.03
1.02
23-05-2014
MT-mix
GLV-mix
1.06
1.05
1.04
1.03
33
Figure 11: Plot of growth factor as function of time for ozonolysis of trans-2-hexenol
34
Figure 12: Plot of growth factor as function of time for ozonolysis of α-pinene
35
Figure 13: Plot of growth factor as function of time for ozonolysis of MT-mix and GLV-mix
The GF range obtained in our measurement is in a good agreement with previously reported values
for some BSOA. For example, Virkkula et al. (1999) reported GF to be 1.1 at 84 %RH for products
of α-pinene and limonene which were measured at 90%RH. Similarly, Varakutbangkul et al. (2006)
also measured the GFs values (at 85%RH) and reported it to be in range between 1.09-1.16 for
ozonolysis products of cycloalkenes, 1.06-1.1 for photooxidized monoterpenes and oxygenated
terpenes and 1.01- 1.04 for photooxidized sesquiterpenes.
36
Chapter 5: CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusions
We have studied the secondary organic aerosol formation from ozonolysis of green leaf volatiles and
(monoterpenes) by using chamber experiments performed in humid conditions (50%RH). New
particle formation generated from ozonolysis were characterized. Accordingly, aerosol formation,
aerosol condensational growth, aerosol mass yield and hygroscopicity were measured and
investigated by using instruments such as SMPS, PTR-MS and H-TDMA.
SOA particle formation rate in our experiment was higher than the particle formation rates observed
in ambient air, which is found to vary in between 0.01–10 cm−3 s−1. The main reason for this disparity
could be because of higher concentration of GLVs, MTs and O3 used in our reaction than the actual
concentration of ambient air. Our study also showed that VOCs emitted from green leaf plants less
effectively involved in particle formation than from monoterpenes.
We investigated that there is a decrease in SOA mass during ozonolysis of the mixture of MT and
GLVs than when MT is ozonolysed alone. GLVs have potential to decrease the SOA particle number
concentration and thus the particle mass. So this indicates that MT plays a constitutive role during
SOA formation process while GLVs has a suppressing effect on particle formation event.
The SOA yields were: 14% for ozonolysis of α-pinene, 17% for ozonolysis of MT-mix, 12.3 % for
mixture of α-pinene and trans-2-hexenal, 2.33 % for mixture of α-pinene and cis -3- hexen-1-ol, 7.2%
for mixture of α-pinene and cis -3-hexenyl acetate and 13.2 % for the mixture MT and GLVs. The
SOA mass yield from ozonolysis of pure GLVs is much less than the above reported values.
Moreover, the yield showed a decrease when MTs is mixed with GLVs. We have also investigated
that more concentration of VOCs in chamber resulted in higher SOA mass yield values.
SOA mass yields obtained in our study are higher than previously reported studies from chamber
studies of real plant BVOC oxidation. We suspect this difference in mass yields could be due to
differences in experimental conditions (e.g., different reaction chamber system, reactant and ozone
concentration and humidity).
We have also studied hygroscopic growth of SOA particles and the result suggests that SOA particles
have very low hygroscopicity showing low water uptake property with growth factor value in between
1.01-1.03.
37
5.2 Recommendation for further research
In this study only three GLV compounds have been studied, but there are a number of other GLV
species emitted into the atmosphere from vegetation showing that the SOA potential of green leaf
volatiles may be considerably higher than what our results indicate here. Therefore, it is important to
have further work on emission fluxes, simulation chamber studies, field measurements and modelling
so as to fully evaluate the significance of GLVs to the SOA budget in atmosphere.
We still suspect that there could be a visible link between green leaf volatiles and new aerosol particle
formation. Therefore, further research and measurements are necessary in order to get more reliable
information in this regard.
In order to obtain more accurate and reliable information about SOA hygroscopicity, it is important
to have improved measurement techniques. For example, the current hygroscopicity measurements
with H-TMDA are sensitive to the RH of DMA2. So, minimizing the influence of RH is could be real
challenge. The other issue to be noted is that most of the H-TMDA measurement conducted at only
one RH (most commonly 90%), this could makes difficult to draw conclusions regarding the behavior
of hygroscopicity of particles at lower RH values. Therefore, the data will be more precise if the
investigation of hygroscopic properties of particles could be extended to different RH values.
Our last concluding remark is that with the respect of the green leaf volatiles, the response of the plant
ecosystems to different stress conditions should be taken into account for the future climate change
scenarios.
38
REFERENCES
Andreae Meinrat O and Crutzen Paul J (1997). Atmospheric aerosols: Biogeochemical sources and
role in atmospheric chemistry. Science, 276, 1052-1058.
Arey J, Aschmann S M, Atkinson R, Winer A M, Long W D and Morrison C L (1991). The Emission
of (Z)-3-hexen-1-ol, (Z)-3-hexenylacetate and other oxygenated hydrocarbons from agricultural plant
species. Atmos. Environ., 25, 1063–1075.
Atkinson R, Arey J, Aschmann S M, Corchnoy S B and Shu Y H (1995). Rate constants for the gasphase reactions of cis-3-hexen-1-ol, cis-3-hexenylacetate, trans-2-hexenal, and linalool with OH and
NO3 radicals and O3 at 296±2K and OH radical formation yields from the O3 Reactions. Int. J. Chem.
Kinet., 27, 941–955.
Atkinson R (1997). Gas-phase tropospheric chemistry of volatile organic compounds: Alkanes and
alkenes. J. Phys. Chem., 26, 215–290.
Atkinson R (1988). Atmospheric Transformation of Automotive Emissions, in The Automobile, Air
Pollution, and Public Health, A.Y. Watson, R.R. Bates, and D. Kennedy, Eds.: National Academy
Press, Washington, DC, pp. 99-132.
Brilli F, Hortnagl L, Bamberger I, Schnitzhofer R, Ruuskanen T. M, Hansel A, Loreto F and
Wohlfahrt G (2012). Qualitative and quantitative characterization of volatile organic compound
emissions from cut grass. Environ. Sci. Technol., 46 (7):3859– 3865.
Bonn B, Schuster G and Moortgat, G. K (2002). Influence of water vapor on the process of new
particle formation during monoterpene ozonolysis. J. Phys. Chem., 106, 2869–2881.
Bonn B and Moortgat G K (2003). Sesquiterpene ozonolysis: Origin of atmospheric new particle
formation from biogenic hydrocarbons. Geophys. Res.Lett., 30, 1585.
Chung S H and Seinfeld, J.H (2002). Global distribution and climate naceo forcing of carbous
aerosols. J. Geophys. Res. 107.
Davidson C I, Phalen R F and Solomo P A (2005). Airborne particulate matter and human health. A
review, Aerosol Sci. Technol., 39(8), 737–749.
Dudareva N, Negre F, Nagegowda D A and Orlova I (2006). Plant volatiles: recent advances and
future perspectives. Critical Reviews in Plant Sciences, 25: 417–440.
Duplissy J, Gysel M, Alfarra M R, Dommen J, Metzger A, Prevot A. S. H, Weingartner E, Laaksonen
A, Raatikainenm T, Good N, Turner F, McFiggans Gn and Baltensperger U (2008). Cloud forming
potential of secondary organic aerosol under near atmospheric conditions. Geophys. Res. Lett., 35,
L03818.
Ervens B and Kreidenweis S M (2007). SOA Formation by Biogenic and Carbonyl Compounds: Data
Evaluation and Application. Environmental Science and Technology, 41 (11), 3904‐3910.
Fuzzi S et al. (2006). Critical assessment of the current state of scientific knowledge, terminology,
and research needs concerning the role of organic aerosols in the atmosphere, global change. Atmos.
Chem. Phys., 6(7), 2017‐2038.
Griffin R J, Dabdub D and Seinfeld J H (2005). Development and initial evaluation of a dynamic
species-resolved model for gas phase chemistry and size-resolved gas/particle partitioning associated
with secondary organic aerosol formation. J. Geophys Res., D05304.
39
Goldstein A H and Globally I E (2007). Known and unexplored organic constituents in the earth’s
atmosphere. Environ. Sci. Technol., 41(5), 1514– 1521.
Guenther A, Hewitt C N, Erickson D, Fall R, Geron C, Graedel T, Harley P, Klinger L, Lerdau M,
Mckay W A, Pierce T, Scholes B, Steinbrecher R, Tallamraju R, Taylor J and Zimmerman P (1995).
A global model of natural volatile organic compound emissions. J. Geophys. Res., 100, 8873–8892.
Hamilton J F, Lewis A C, Carey T J, Wenger J C, Borras I Garcia E and Munoz A (2009). Reactive
oxidation products promote secondary organic aerosol formation from green leaf volatiles. Atmos.
Chem. Phys., 9, 3815–3823.
Hallquist M, Wenger J C, Baltensperger U, Rudich Y, Simpson D, Claeys M, Dommen J, Donahue
N M, George C, Goldstein A H, Hamilton J F, Herrmann H, Ho mann T, Iinuma Y, Jang M, Jenkin
M E, Jimenez J L, Kiendler-Scharr A, Maenhaut W, McFiggans G, Mentel T F, Monod A, Prevot A
S H, Seinfeld J H, Surratt J D, Szmigielski R and Wildt J (2009). The formation, properties and impact
of secondary organic aerosol: current and emerging issues. Atmos. Chem. Phys., 9(14), 5155-5236.
Hao L Q, Yli-Pirila P, Tiitta P, Romakkaniemi S, Vaattovaara P, Kajos M K, Rinne J, Heijari J,
Kortelainen A, Miettinen P, Kroll J H, Holopainen J K, Smith J N, Joutsensaari J, Kulmala M,
Worsnop D R and Laaksonen A (2009). New particle formation from the oxidation of direct emissions
of pine seedlings. Atmos. Chem. Phys., 9, 8121–8137.
Harvey R M, Zahardis J and Petrucci G A (2014). Establishing the contribution of lawn mowing to
atmospheric aerosol levels in American suburbs. Atmos. Chem. Phys., 14, 797–812.
Haywood James and Boucher Olivier (2000). Estimates of the direct and indirect radiative forcing
due to tropospheric aerosols. A review, Rev. Geophys., 38(4), 513–543.
Heintzenberg J, Massling A and Birmili W (2001).The connection between hygroscopic and optical
particle properties in the atmospheric aerosol. Geophys. Res. Lett., 28, 3649–3651.
Holopainen J. K (2014). Interaction Ecology, lecture notes on Plant volatiles (VOCs); ecological
functions at the University of Eastern Finland, Kuopio on 11 Oct 2013.
Intergovernmental panel on climate change (IPCC) (2001). Climate change 2001: Third Assessment
Report (Volume I). Cambridge: Cambridge University Press, Cambridge, UK.
Intergovernmental panel on climate change (IPCC): Climate Change 2007: The Physical Science
Basis, Cambridge University Press, UK.
Jay R Odum, Thorsten Hoffmann, Frank Bowman, Don Collins, Richard C Flagan and John H.
Seinfeld (1996). Gas/Particle partitioning and secondary organic aerosol yields. Environ. Sci.
Technol., 30, 2580–2585.
Jordan A, Holzinger R, Vogel W, Hansel A, Prazeller P and Lindinger W (1995). Proton transfer
reaction mass spectrometry: on-line trace gas analysis at ppb level. Int. J. of Mass Spectrom. And Ion
Proc., 149/150, 609-619.
Joutsensaari J, Loivamäki M, Vuorinen T, Miettinen P, Nerg A M, Holopainen J K and Laaksonen
A (2005). Nanoparticle formation by ozonolysis of inducible plant volatiles. Atmos. Chem. Phys., 5,
1489-1495.
Kanakidou M, Seinfeld J H, Pandis S N, Barnes I, Dentener F J, Facchini M C, Van Dingenen R,
Ervens B, Nenes A, Nielsen C J, Swietlicki E, Putaud J P, Balkanski Y, Fuzzi S, Horth J, Moortgat
40
G K, Winterhalter R, Myhre C E L, Tsigaridis K, Vignati E, Stephanou E G and Wilson J. (2005).
Organic aerosol and global climate modeling. A review. Atmos. Chem. Phys., 5, 1053-1123.
Karl T, Fall R, Crutzen P J, Jordan A, Lindinger W (2001). High concentrations of reactive biogenic
VOCs at a high altitude site in late autumn. Geophys. Res. Lett., 28, 507–510.
Kaufman Y J (2006). Satellite observations of natural and anthropogenic aerosol effects on clouds
and climate. Space science reviews, 125: 139-147.
Kesselmeier J and Staudt M (1999). Biogenic volatile organic compounds (VOC) An overview on
emission. Physiology and ecology. J. Atmos. Chem. 33: 23–88.
Kulmala M, Vehkamaki H, Peta T, DalMaso M, Lauri A, Kerminen V M, Birmili W and McMurry
P H (2004). Formation and growth rates of ultrafine atmospheric particles: a review of observations.
J. Aerosol Sci., 35, 143–176.
Konig G, Hewitt C N, Brunda M, Puxbaum H, Duckham S C and Rudolph J (1995). Relative
contribution of oxygenated hydrocarbons to the total biogenic VOC emissions of selected midEuropean agricultural and natural plant species. Atmos. Environ., 29, 861–874.
Laden F, Neas L M, Dockery D W, Schwartz J (2000). Association of fine particulate matter from
different sources with daily mortality in six US cities. Environ Health Perspect., 108 (10): 941–947.
Lambe A T, Sage A M, Zhang J Y and Donahue N M (2007). Controlled OH radical production via
Ozone-alkene reactions for use in aerosol aging studies. Environ. Sci. Technol., 41, 2357–2363.
Laothawornkitkul J, Paul ND, Taylor J E, Hewitt CN (2009). Biogenic volatile organic compounds
in the Earth system. New Phytologist, 183: 27–51.
Leppa J, Anttila T, Kerminen V M, Kulmala M and Lehtinen K E J (2011). Atmospheric New Particle
Formation: Real and Apparent Growth Of neutral and Charged Particles. Atmos. Chem. Phys., 11,
4939-4955.
Liu B Y H, Pui D Y H, Whitby K T, Kittelson D B, Kousaka Y and c McKenzie R L (1978). Aerosol
mobility chromatograph: new detector for sulfuric acid aerosols. Atmos. Environ., 12, 99–104.
Massling A, Leinert S, Wiedensohler A, Covert D (2007). Hygroscopic growth of sub-micrometer
and one-micrometer aerosol particles measured during ACE-Asia. Atmos. Chem. Phys., 7, 3249-3259.
McFiggans G, Artaxo P, Baltensperger U, Coe H, Facchini M C, Feingold G, Fuzzi S, Gysel M,
Laaksonen A, Lohmann U, Mentel T F, Murphy D M, O'Dowd C D, Snider J R and Weingartner E
(2006). The effect of physical and chemical aerosol properties on warm cloud droplet activation.
Atmos. Chem. Phys., 6, 2593–2649.
Mentel Th F, Rudich Y, Kiendler-Scharr A, Kleist E, Tillmann R, Dal Maso M, Fisseha R, Hohaus
Th, Spahn H, Wildt J, Uerlings R, Wegener R, Griffiths PT, Dinar E and Wahner A (2009).
Photochemical production of aerosols from real plant emissions. Atmos. Chem. Phys., 9, 4387–4406.
Mentel F Th, Kleist E, Andres S, Dal Maso M, Hohaus T, Kiendler-Scharr A, Rudich Y, Springer M,
Tillmann R, Uerlings R, Wahner A and Wildt, J (2013). Secondary aerosol formation from stressinduced biogenic emissions and possible climate feedbacks. Atmos. Chem. Phys., 13, 8755–8770.
Peter H McMurry and Mark R Stolzenburg (1989). On the sensitivity of particle-size to relative
humidity for Los Angeles aerosols. Atmos. Environ., 23, 497–507.
41
Petters Markus D, Carrico Christian M, Kreidenweis Sonia M, Prenni Anthony J, DeMott Paul J,
Collett Jeffrey L, Moosmüller Hans (2009). Cloud condensation nucleation activity of biomass
burning aerosol. J. Geophys. Res., 114.
Raes Frank, Van Dingenen Rita, Cuevas Emilio, Van Velthoven Peter F J, Prospero Joseph M (1997).
Observations of aerosols in the free troposphere and marine boundary layer of the subtropical
Northeast Atlantic: Discussion of processes determining their size distribution. J. Geophys. Res., 102,
21315-21328.
Raes F, Putaud J P, Vignati E, Dingenen R V, Wilson J, Seinfeld J H and Adams P (2000). Formation
and cycling of aerosols in the global troposphere. Atmos. Environ. 34, 4215-4240.
Riipinen I, Worsnop D R, Pierce J R, Leaitch W R, Yli-Juuti T, Nieminen T, Hakkinen S, Ehn M,
Junninen H, Lehtipalo K, Petaja T, Slowik J, Chang R, Shantz N C, Abbatt J, Kerminen V M, Pandis
S N, Donahue N M and Kulmala M (2011). Organic condensation: a vital link connecting aerosol
formation to cloud condensation nuclei (CCN) concentrations. Atmos. Chem. Phys., 11, 3865-3878.
Robinson A L, Donahue N M, Shrivastava M K, Weitkamp E A, Sage A M, Grieshop A P, Lane T
E, Pierce J R and Pandis S N (2007). Rethinking organic aerosols: semivolatile emissions and
photochemical aging. Science, 315:1259-1262.
Saathoff H, Naumann KH, Schnaiter M, Schock W, Mohler O, Schurath U, Weingartner E, Gysel M
and Baltensperger U (2003). Coating of soot and (NH4)2SO4 particles by ozonolysis products of αpinene. J. Aerosol Sci., 34, 1297–1321.
Sarangi Bighnaraj, Shankar G. Aggarwal, Prabhat K Gupta (in press). A Simplified Approach to
calculate Particle Growth Rate Due to Self-Coagulation, Scavenging and Condensation Using SMPS
Measurements during Particle Growth Event in New Delhi. Aerosol and Air Quality Research
Sandip D. Shah and David R. Cocker (2005). A Fast Scanning Mobility Particle Spectrometer for
Monitoring Transient Particle Size Distributions. Aerosol Science and Technology, 39:519–526
Seinfeld J H and Pandis S N (2006). Atmospheric Chemistry and Physics - From Air Pollution to
Climate Change (2nd Edition), John Wiley & Sons.
Seinfeld John H. and Pankow James F (2003). Organic atmospheric particulate material. Annu. Rev.
Phys. Chem., 54, 121– 40.
Seinfeld J H and Pandis S (1998). Atmospheric Chemistry and Physics, John Wiley, Hoboken, N. J.
Stapleton K W, Finlay W H and Zuberbuhler P (1994). An In Vitro Method for Determining Regional
Dosages Delivered by Jet Nebulizers. J. Aerosol Med., 7, 325–344.
Stavrakou T et al. (2009). Evaluating the performance of pyrogenic and biogenic emission inventories
against one decade of space-based formaldehyde columns. Atmos. Chem. Phys., 9 (3), 1037-1060.
Swietlicki E, Hansson H-C, Hameri K, Svenningson B, Maßling A, McFiggans G, Mc-Murry P H,
Petaja T,Tunved P, Gysel M, Topping D, Weingartner E, Baltensperger U, Rissler J, Wiedensohler
A and Kulmala M (2008). Hygroscopic properties of submicrometer atmospheric aerosol particles
measured with H-TDMA instruments in various environments– a review, Tellus B, 60, 432–469.
Van Reken T M, Greenberg J P, Harley P C, Guenther A B and Smith J N (2006). Direct measurement
of particle formation and growth from the oxidation of biogenic emissions. Atmos. Chem. Phys., 6,
4403–4413.
42
Varutbangkul V, Brechtel F J, Bahreini R, Ng N L, Keywood M D, Kroll J H, Flagan R C, Seinfeld
J H, Lee A and Goldstein A H (2006). Hygroscopicity of secondary organic aerosols formed by
oxidation of cycloalkenes, monoterpenes, sesquiterpenes and related compounds. Atmos. Chem.
Phys., 6, 2367-2388.
Virkkula Aki, Van Dingenen Rita, Raes Frank, Hjorth Jens (1999). Hygroscopic proprieties of aerosol
formed by oxidation of limonene, α-pinene and β-pinene. J. Geophys. Res., vol. 104, no. D3, 3569–
3579.
Yli-Juuti T, Nieminen T, Hirsikko A, Aalto P P, Asmi E, Hõrrak U, Manninen H E, Patokoski J, Dal
Maso M, Petäjä T, Rinne J, Kulmala M and Riipinen I (2011). Growth rates of nucleation mode
particles in Hyytiälä during 2003− 2009: variation with particle size, season, data analysis method
and ambient conditions. Atmos. Chem. Phys., 11, 12865-12886.
Yu F and Turco R P (1998). The formation and evolution of aerosols in stratospheric aircraft plumes:
Numerical simulations and comparisons with observations. J. Geophys. Res., 103, 25,915-25,934.
Zhang Q, Jimenez J L, Canagaratna M R, Allan J D, Coe H, Ulbrich I, Alfarr M R, Takami A,
Middlebrook A M, Sun Y L, Dzepina K, Dunlea E, Docherty K, DeCarlo P F, Salcedo D, Onasch T,
Jayne J T, Miyoshi T, Shimono A, Hatakeyama S, Takegawa N, Kondo Y, Schneider J, Drewnick
F, Borrmann S, Weimer S, Demerjian K, Williams P, Bower K, Bahreini R, Cottrell L, Griffin R
J, Rautiainen J, Sun J Y, Zhang Y M, Worsnop D R (2000). Ubiquity and dominance of oxygenated
species in organic aerosols in anthropogenically influenced Northern Hemisphere midlatitudes.
Geophys. Res. Lett., 34.
APPENDIXES
Appendix 1: Figure (A1.1-A.8): Contour plot of aerosol particle number size
distributions, total aerosol particle number and mass concentration, O3 concentrations
and VOC concentration during ozonolysis experiments.
43
Fig.A1.1: Particle formation from ozonolysis of α-pinene and trans-2-hexenal
44
Fig.A1.2: Particle formation from ozonolysis of α-pinene and cis-3-Hexanol
45
Fig.A1.3: Particle formation from ozonolysis of α-pinene and 3-hexynyl acetate
46
Fig.A1.4: Particle formation from ozonolysis of α-pinene and GLV-mix
47
Fig.A1.05: Particle formation from ozonolysis of MT-mix
48
Fig.A1.6: Particle formation from ozonolysis of MT-mix and trans-2-hexenal
49
Fig.A1.7: Particle formation from ozonolysis of MT-mix and cis-3-hexanol
50
Fig.A1.8: Particle formation from ozonolysis of MT-mix and 3-hexynyl acetate
51
Appendix 2: Figures A2.1-A2.9 shows the hygroscopic growth factor as function of
time of ozonolysis experiment
Fig. A 2.1: A graph of growth factor as function of time for ozonolysis of cis-3-hexanol
52
Fig. A 2.2: A graph of growth factor as function of time for ozonolysis of mix of α-pinene and
trans-2-hexenal
53
Fig. A 2.3: A graph of growth factor as function of time for ozonolysis of mix of α-pinene and cis3-hexanol
54
Fig. A 2.4: A graph of growth factor as function of time for ozonolysis of mix of α-pinene and 3hexynyl acetate
55
Fig. A 2.5: A graph of growth factor as function of time for ozonolysis of mix of MT-mix and
GLV-mix
56
Fig. A 2.6: A graph of growth factor as function of time for ozonolysis of mix of MT-mix
57
Fig. A 2.7: A graph of growth factor as function of time for ozonolysis of mix of MT-mix and trans2-hexenal
58
Fig. A 2.8: A graph of growth factor as function of time for ozonolysis of mix of MT-mix and Cis3-hexanol
59
Fig. A 2.9: A graph of growth factor as function of time for ozonolysis of mix of MT-mix and 3hexynyl acetate
60
Appendix 3: Summary of work plan
Activity
Total amount of Dates
days
Finding and reading literatures and preparing thesis Four weeks
1/04/2014-31/04/2014
research plan
Designing the experiment and practicing how to use 5 days
01/05/2014-5/05/2014
the materials
Running the experiments and collecting and Four weeks
06/05/2014-31/05/2014
organizing data
Analyzing the data
Eight weeks
01/06/2014-30/072014
Writing the report
Eight Weeks
01/08/2014-30/09/2014
Submission of the first draft, Rewriting and Four weeks
01/10/2014-30/10/2014
Thorough proof-reading
MSc thesis defense and submission of the final work
Nov 2014
Nov 2014