Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon and the Atlantic and Pacific oceans. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of -30 °C and -50 °C.
View Article and Find Full Text PDFEnviron Sci Technol
January 2024
Highly oxygenated organic molecules (HOMs) are a major source of new particles that affect the Earth's climate. HOM production from the oxidation of volatile organic compounds (VOCs) occurs during both the day and night and can lead to new particle formation (NPF). However, NPF involving organic vapors has been reported much more often during the daytime than during nighttime.
View Article and Find Full Text PDFThe main nucleating vapor in the atmosphere is thought to be sulfuric acid (HSO), stabilized by ammonia (NH). However, in marine and polar regions, NH is generally low, and HSO is frequently found together with iodine oxoacids [HIO, i.e.
View Article and Find Full Text PDFBiogenic vapors form new particles in the atmosphere, affecting global climate. The contributions of monoterpenes and isoprene to new particle formation (NPF) have been extensively studied. However, sesquiterpenes have received little attention despite a potentially important role due to their high molecular weight.
View Article and Find Full Text PDFIodine is a reactive trace element in atmospheric chemistry that destroys ozone and nucleates particles. Iodine emissions have tripled since 1950 and are projected to keep increasing with rising O surface concentrations. Although iodic acid (HIO) is widespread and forms particles more efficiently than sulfuric acid, its gas-phase formation mechanism remains unresolved.
View Article and Find Full Text PDFNew particle formation in the upper free troposphere is a major global source of cloud condensation nuclei (CCN). However, the precursor vapours that drive the process are not well understood. With experiments performed under upper tropospheric conditions in the CERN CLOUD chamber, we show that nitric acid, sulfuric acid and ammonia form particles synergistically, at rates that are orders of magnitude faster than those from any two of the three components.
View Article and Find Full Text PDFAerosol particles negatively affect human health while also having climatic relevance due to, for example, their ability to act as cloud condensation nuclei. Ultrafine particles (diameter < 100 nm) typically comprise the largest fraction of the total number concentration, however, their chemical characterization is difficult because of their low mass. Using an extractive electrospray time-of-flight mass spectrometer (EESI-TOF), we characterize the molecular composition of freshly nucleated particles from naphthalene and β-caryophyllene oxidation products at the CLOUD chamber at CERN.
View Article and Find Full Text PDFCommun Earth Environ
November 2020
Isoprene is emitted from the biosphere into the atmosphere, and may strengthen the defense mechanisms of plants against oxidative and thermal stress. Once in the atmosphere, isoprene is rapidly oxidized, either to isoprene-hydroxy-hydroperoxides (ISOPOOH) at low levels of nitrogen oxides, or to methyl vinyl ketone (MVK) and methacrolein at high levels. Here we combine uptake rates and deposition velocities that we obtained in laboratory experiments with observations in natural forests to show that 1,2-ISOPOOH deposits rapidly into poplar leaves.
View Article and Find Full Text PDFIn most organisms, the concentration of free Zn is controlled by metallothioneins (MTs). In contrast, no significant proportions of Zn are bound to MTs in the slug, Arion vulgaris. Instead, this species possesses cytoplasmic low-molecular-weight Zn (LMW Zn) binding compound that divert these metal ions into pathways uncoupled from MT metabolism.
View Article and Find Full Text PDFThis report discusses advances in instrumentation based on soft chemical ionization followed by high-resolution real-time mass spectrometry (HR-MS), specifically in relation to developments in proton transfer reaction mass spectrometry (PTR-MS) technology. It is part of a Journal of Breath Research series that describes recent technical developments in breath related research relevant to human health and analytical chemistry from scientific conferences. Herein we discuss the current state of PTR-MS as presented at the 8th International Conference on Proton Transfer Reaction - Mass Spectrometry held in Innsbruck, Austria, February 2-8, 2019, attended by the authors.
View Article and Find Full Text PDFIn this study, we present reactions of with a series of analytes (A): acetone (CHO), methyl vinyl ketone (CHO), methyl ethyl ketone (CHO), and eight monoterpene isomers (CH) using a Selective Reagent Ionization Time-of-Flight Mass Spectrometer (SRI-ToF-MS). We studied the ion-molecule reactions at collision energies of 55 and 80 meV. The ketones, having a substantially lower proton affinity than NH, produce only cluster ions (A) in detectable amounts at 55 meV.
View Article and Find Full Text PDFThroughout the temperate zones, plants face combined drought and heat spells in increasing frequency and intensity. Here, we compared periodic (intermittent, i.e.
View Article and Find Full Text PDFA major fraction of atmospheric aerosol particles, which affect both air quality and climate, form from gaseous precursors in the atmosphere. Highly oxygenated organic molecules (HOMs), formed by oxidation of biogenic volatile organic compounds, are known to participate in particle formation and growth. However, it is not well understood how they interact with atmospheric pollutants, such as nitrogen oxides (NO ) and sulfur oxides (SO ) from fossil fuel combustion, as well as ammonia (NH) from livestock and fertilizers.
View Article and Find Full Text PDFα-Pinene (CH) represents one of the most important biogenic emissions in the atmosphere. Its oxidation products can significantly contribute to the secondary organic aerosol (SOA) formation. Here, we report on the formation mechanism of C and C accretion products from α-pinene oxidation, which are believed to be efficient SOA precursors.
View Article and Find Full Text PDFHydrocarbons are emitted into the Earth's atmosphere in very large quantities by human and biogenic activities. Their atmospheric oxidation processes almost exclusively yield RO radicals as reactive intermediates whose atmospheric fate is not yet fully unraveled. Herein, we show that gas-phase reactions of two RO radicals produce accretion products composed of the carbon backbone of both reactants.
View Article and Find Full Text PDFWe have developed and characterized the novel PTR3, a proton transfer reaction-time-of-flight mass spectrometer (PTR-TOF) using a new gas inlet and an innovative reaction chamber design. The reaction chamber consists of a tripole operated with rf voltages generating an electric field only in the radial direction. An elevated electrical field is necessary to reduce clustering of primary hydronium (HO) and product ions with water molecules present in the sample gas.
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