Acidic reaction products of monoterpenes and sesquiterpenes in atmospheric fine particles in a boreal forest (original) (raw)
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Atmospheric Chemistry and Physics Discussions, 2014
Biogenic acids were measured from PM 2.5 aerosols at SMEAR II station (Station For Measuring Forest Ecosystem-Atmosphere Relations) in Finland from June 2010 until October 2011. The measured organic acids were pinic, pinonic, caric, limonic and caryophyllinic acids from oxidation of α-pinene, β-pinene, limonene, ∆3-carene and 5 β-caryophyllene. Due to lack of authentic standards caric, limonic and caryophyllinic acids were synthesized at the Laboratory of Organic Chemistry, University of Helsinki.
Environmental Science & Technology, 2009
Novel secondary organic aerosol (SOA) products from the monoterpene R-pinene with unique dimer-forming properties have been identified as lactone-containing terpenoic acids, i.e., terpenylic and 2-hydroxyterpenylic acid, and diaterpenylic acid acetate. The structural characterizations were based on the synthesis of reference compounds and detailed interpretation of mass spectral data. Terpenylic acid and diaterpenylic acid acetate are early oxidation products generated upon both photooxidation and ozonolysis, while 2-hydroxyterpenylic acid is an abundant SOA tracer in ambient fine aerosol that can be explained by further oxidation of terpenylic acid. Quantum chemical calculations support that noncovalent dimer formation involving double hydrogen bonding interactions between carboxyl groups of the monomers is energetically favorable.
Tellus B: Chemical and Physical Meteorology, 2001
The contribution of monoterpenes to aerosol formation processes within and above forests is not well understood. This is also true for the particle formation events observed during the BIOFOR campaigns in Hyytiälä, Finland. Therefore, the diurnal variation of the concentrations of several biogenic volatile organic compounds (BVOCs) and selected oxidation products in the gas and particle phase were measured on selected days during the campaigns in Hyytiälä, Finland. a-pinene and D3-carene were found to represent the most important monoterpenes above the boreal forest. A clear vertical gradient of their concentrations was observed together with a change of the relative monoterpene composition with height. Based on concentration profile measurements of monoterpenes, their fluxes above the forest canopy were calculated using the gradient approach. Most of the time, the BVOC fluxes show a clear diurnal variation with a maximum around noon. The highest fluxes were observed for a-pinene with values up to 20 ng m−2 s−1 in summer time and almost 100 ng m−2 s−1 during the spring campaign. Furthermore, the main oxidation products from a-pinene, pinonaldehyde, and from b-pinene, nopinone, were detected in the atmosphere above the forest. In addition to these more volatile oxidation products, pinic and pinonic acid were identified in the particle phase in a concentration range between 1 and 4 ng m−3. Beside these direct measurement of known oxidation products, the chemical sink term in the flux calculations was used to estimate the amount of product formation of the major terpenes (a-pinene, b-pinene, D3-carene). A production rate of very low volatile oxidation products (e.g., multifunctional carboxylic) from ΩOHand O 3-reaction of monoterpenes of about 1.3Ω104 molecules cm−3 s−1 was estimated for daylight conditions during summer time. Additionally, model calculations with the one-dimensional multilayer model CACHE were carried out to investigate the diurnal course of BVOC fluxes and chemical degradation of terpenes.
Atmospheric Chemistry and Physics, 2021
Secondary organic aerosols (SOAs) formed from biogenic volatile organic compounds (BVOCs) constitute a significant fraction of atmospheric particulate matter and have been recognized to significantly affect the climate and air quality. Atmospheric SOA particulate mass yields and chemical composition result from a complex mixture of oxidation products originating from a diversity of BVOCs. Many laboratory and field experiments have studied SOA particle formation and growth in the recent years. However, a large uncertainty still remains regarding the contribution of BVOCs to SOA. In particular, organic compounds formed from sesquiterpenes have not been thoroughly investigated, and their contribution to SOA remains poorly characterized. In this study, a Filter Inlet for Gases and Aerosols (FI-GAERO) combined with a high-resolution time-of-flight chemical ionization mass spectrometer (CIMS), with iodide ionization, was used for the simultaneous measurement of gas-phase and particle-phase oxygenated compounds. The aim of the study was to evaluate the relative contribution of sesquiterpene oxidation products to SOA in a springtime hemiboreal forest environment. Our results revealed that monoterpene and sesquiterpene oxidation products were the main contributors to SOA particles. The chemical composition of SOA particles was compared for times when either monoterpene or sesquiterpene oxidation products were dominant and possible key oxidation products for SOA particle formation were identified for both situations. Surprisingly, sesquiterpene oxidation products were the predominant fraction in the particle phase in some periods, while their gas-phase concentrations remained much lower than those of monoterpene products. This can be explained by favorable and effective partitioning of sesquiterpene products into the particle phase. The SOA particle volatility determined from measured thermograms increased when the concentration of sesquiterpene oxidation products in SOA particles was higher than that of monoterpenes. Overall, this study demonstrates that sesquiterpenes may have an important role in atmospheric SOA formation and oxidation chemistry, in particular during the spring recovery period. 1 Introduction Volatile organic compounds (VOCs) are ubiquitous constituents of Earth's atmosphere that are emitted from both biogenic and anthropogenic sources (e.g., Kansal, 2009). Anthropogenic VOCs (AVOCs) may predominate in urban areas, but the source strength of biogenic VOCs (BVOCs) ex-Published by Copernicus Publications on behalf of the European Geosciences Union.
The subject of the study was the effect of monoterpene oxidation on the growth of particles during new-particle formation (NPF) events at the SMEAR II measurement station in Hyytiälä, southern Finland, during 2006-2011. The nighttime oxidation capacity, i.e. how readily the atmosphere can oxidize monoterpenes, was found to be dominated by the nitrate radical, whereas the daytime oxidation capacity was mainly dominated by ozone. The mean lifetimes of monoterpenes ranged from about one hour to several hours, depending on the time of year and day. A strong link was found between the growth rate of particles of 7-20 nm in diameter during the NPF events and monoterpene oxidation by ozone during the preceding night. Our findings suggest that during nighttime a build-up of primarily oxidized monoterpenes in the atmosphere occurs, and that these compounds can be oxidized by the hydroxyl radical after sunrise, promoting the particle growth.
Chemodiversity in terpene emissions at a boreal Scots pine stand
Biogeosciences Discussions
Atmospheric chemistry in background areas is strongly influenced by natural vegetation. Coniferous forests are known to produce large quantities of volatile vapors, especially terpenes to the surrounding air. These compounds are reactive in the atmosphere, and contribute to the formation and growth of atmospheric new particles. Our aim was to analyze the variability of mono-and sesquiterpene emissions between Scots pine trees, in order to clarify the potential errors caused by using emission data obtained from only a few trees in atmospheric chemistry models. We also aimed at testing if stand history and seed origin has an influence on the chemotypic diversity. The inherited, chemotypic variability in mono-and sesquiterpene emission was studied in a seemingly homogeneous 47-yr-old stand in Southern Finland, where two areas differing in their stand regeneration history could be distinguished. Sampling was conducted in August 2009. Terpene concentrations in the air had been measured at the same site for seven years prior to branch sampling for chemotypes. Two main compounds, α-pinene and ∆ 3-carene formed together 40-97 % of the monoterpene proportions in both the branch emissions and in the air concentrations. The data showed a bimodal distribution in emission composition, in particular in ∆ 3carene emission within the studied population. 10 % of the trees emitted mainly αpinene and no ∆ 3-carene at all, whereas 20 % of the trees where characterized as high ∆ 3-carene emitters (∆ 3-carene forming > 80 % of total emitted monoterpene spectrum). An intermediate group of trees emitted equal amounts of both α-pinene and ∆ 3-carene. The emission pattern of trees at the area established using seeding as the artificial regeneration method differed from the naturally regenerated or planted trees, being mainly high ∆ 3-carene emitters. Some differences were also seen in e.g. camphene and limonene emissions between chemotypes, but sesquiterpene emissions did not differ significantly between trees. The atmospheric concentrations at the site were found to reflect the species and/or chemodiversity rather than the emissions measured from any single tree, and were strongly dominated by α-pinene. We also tested the 10578
J Environ Manage, 2005
This paper studies the reaction products of α-pinene, β-pinene, sabinene, 3-carene and limonene with OH radicals and of α-pinene with ozone using FT-IR spectroscopy for measuring gas phase products and HPLC-MS-MS to measure products in the aerosol phase. These techniques were used to investigate the secondary organic aerosol (SOA) formation from the terpenes. The gas phase reaction products were all quantified using reference compounds. At low terpene concentrations (0.9–2.1 ppm), the molar yields of gas phase reaction products were: HCHO 16–92%, HCOOH 10–54% (OH source: H2O2, 6–25 ppm); HCHO 127–148%, HCOOH 4–6% (OH source: CH3ONO, 5–8 ppm). At high terpene concentrations (4.1–13.2 ppm) the results were: HCHO 9–27%, HCOOH 15–23%, CH3(CO)CH3 0–14%, CH3COOH 0–5%, nopinone 24% (only from β-pinene oxidation), limona ketone 61% (only from limonene oxidation), pinonaldehyde was identified during α-pinene degradation (OH source H2O2, 23–30 ppm); HCHO 76–183%, HCOOH 12–15%, CH3(CO)CH3 0–12%, nopinone 17% (from β-pinene oxidation), limona ketone 48% (from limonene oxidation), pinonaldehyde was identified during α-pinene degradation (OH source CH3ONO, 14–16 ppm). Pinic acid, pinonic acid, limonic acid, limoninic acid, 3-caric acid, 3-caronic acid and sabinic acid were identified in the aerosol phase. On the basis of these results, we propose a formation mechanism for pinonic and pinic acid in the aerosol phase explaining how degradation products could influence SOA formation and growth in the troposphere.
Atmospheric Environment, 2006
Recent research pointed out the question of missing OH reactivity in a forest system and the question for unknown highly reactive biogenic emissions. In this study we show that coniferous forests are an important source of highly reactive hydrocarbons, the sesquiterpenes. We investigated the seasonality of terpene emissions from Scots pine to work out influences on atmospheric chemistry in different seasons for both mono-and sesquiterpenes. Especially sesquiterpenes (C 15 ) change dramatically in their contribution to the terpene emissions of Scots pine. Fourteen sesquiterpenes and oxygenated compounds were found in the emissions. In spring, the pattern was most complex with all 14 compounds being emitted, whereas in summer and fall it was reduced to 1,8-cineol and camphor. The emission pattern of the monoterpenes varied only slightly. The main compounds emitted were a-pinene, b-pinene, and 3-carene representing up to 90% of the total terpene emission. The total monoterpene emission rates varied from below detection limit to 460 pmol m À2 s À1 with highest emission rates found in June. Standard emission rates of the main compounds calculated from the monthly measured diurnal emission courses varied considerably over the year. Highest values were found in spring and early summer with up to 700 pmol m À2 s À1 .