Are glyoxal and methylglyoxal critical to the formation of a missing fraction of SOA (Secondary Organic Aerosol)?: (Pho-SOA).
Lead Research Organisation:
University of Leicester
Department Name: Chemistry
Abstract
Atmospheric aerosols are ubiquitous in the Earth's atmosphere. They are made up of complex colloidal mixtures of liquid and solid particulate matter and understanding their chemical and physical properties is crucial in elucidating their environmental and health impacts. However, despite much scientific effort over the last decade, the true impact of aerosols on the Earth's atmosphere is yet to be elucidated owing to large uncertainties and lack of fundamental knowledge on their sources, composition (hence physical properties) and formation mechanisms. Recent experimental findings indicate organic aerosols (OA) are predominantly secondary in nature and can account for a significant fraction (10-70%) of total ambient atmospheric aerosol5. However, current models significantly underestimate SOA (Secondary Organic Aerosol) production and their rate of formation. Accretion or oligomerization reactions of light weight volatiles such as glyoxal (GLY, CH(O)CHO) and methylglyoxal (MGLY, CH3C(O)CHO), which have been shown to be a potentially important source of global SOA, have been proposed to justify such disagreement. The magnitude, type (reversible or irreversible) and mechanism of particle formation owing to alfa-dicarbonyls are still substantial questions. The aim of this project is to quantitatively demonstrate the hypothesis that heterogeneous uptake of GLY and MGLY in aerosols can explain a significant fraction of the missing SOA in models. To address this aim, the project will carry out an extensive series of outdoor chamber experiments that will address the main limitations of previous studies. The experimental work will be supported by detailed chamber modelling using the Master Chemical Mechanism (MCM). GLY or MGLY will either be introduced directly into the chamber or generated in-situ by the reaction of OH + alkynes. The chamber experiments will be carried out in the presence (and absence) of natural solar radiation in the highly instrumented outdoor European Photoreactor (EUPHORE) in order to investigate whether reactive uptake of these dicarbonyl compounds and SOA growth is photochemically activated (photosensitized) and relative humidity dependent. The gas and aerosol phase evolution of the precursor and oxidation products, together with HOx radicals (OH + HO2) will be monitored using novel chemical ionisation reaction (time-of-flight, quadrupole and Hadamard Transform) mass spectrometry (CIR-MS), Aerosol Time of Flight Mass Spectrometry (ATOFMS), Fourier Transform Ion Cyclotron resonance Mass Spectrometry (FTICR-MS), liquid chromatography-ion trap mass spectrometry (LC-MSn) and laser induced fluorescence (LIF). Moreover, model sensitivity simulations using the MCM coupled to a representation of absorptive gas-to-aerosol partitioning incorporating parameterisations from the findings of this study will be carried out in order to investigate the atmospheric implications of SOA formation via heterogeneous uptake of dicarbonyl compounds for urban environment where aromatics compounds (significant sources of dicarbonyls) have been proposed as key urban SOA sources. These experiments are critical to quantifying a key potential formation pathway for SOA. .
Organisations
People |
ORCID iD |
Paul Monks (Principal Investigator) |
Publications

Alfarra M
(2013)
Water uptake is independent of the inferred composition of secondary aerosols derived from multiple biogenic VOCs
in Atmospheric Chemistry and Physics

Alfarra M
(2012)
The effect of photochemical ageing and initial precursor concentration on the composition and hygroscopic properties of ß-caryophyllene secondary organic aerosol
in Atmospheric Chemistry and Physics

Hamilton J
(2011)
Investigating the use of secondary organic aerosol as seed particles in simulation chamber experiments
in Atmospheric Chemistry and Physics

Hamilton JF
(2013)
Online and offline mass spectrometric study of the impact of oxidation and ageing on glyoxal chemistry and uptake onto ammonium sulfate aerosols.
in Faraday discussions

Jenkin M
(2012)
Development and chamber evaluation of the MCM v3.2 degradation scheme for ß-caryophyllene
in Atmospheric Chemistry and Physics

Pang X
(2014)
A smog chamber comparison of a microfluidic derivatisation measurement of gas-phase glyoxal and methylglyoxal with other analytical techniques
in Atmospheric Measurement Techniques

Thalman R
(2015)
Instrument intercomparison of glyoxal, methyl glyoxal and NO<sub>2</sub> under simulated atmospheric conditions
in Atmospheric Measurement Techniques