Understanding Formaldehyde and Glyoxal for New Satellite Measurements

Lead Research Organisation: University of Leeds
Department Name: Sch of Chemistry

Abstract

Man-made emissions of organic compounds such as toluene and ethene contribute to poor air quality and climate change. Currently there is a lot of interest in air quality issues focusing on the significant health and economic impacts of air pollution. In order to formulate, monitor and evaluate control measures it is vital that we are able to monitor the amount, composition and spatial distribution of anthropogenic emissions.

Satellite measurements have already provided important data relevant for air quality issues, for example pictures of the distribution of NO2 emissions relevant for air quality. Satellites provide large scale pictures of emissions and the movement and development of airmasses, for example an airmass from an emissions source (e.g. an industrial area, or biogenic sources) being advected over rural areas. However, satellites cannot see the primary organic emissions discussed above, but they can see two of their oxidation products: glyoxal and formaldehyde. The ratio of glyoxal to formaldehyde (RGF) varies with different types of hydrocarbons e.g. biogenic vs anthropogenic emissions and also different types of anthropogenic emissions (e.g. toluene and ethene are predicted to have different RGF) although there is a lack of direct measurements of RGF for important anthropogenic emissions. Satellite measurements of RGF can therefore provide information on the nature of the emissions and can be used to verify emission inventories.

The driver for this proposal comes from recent and planned launches of satellites that will significantly improve measurements of glyoxal, formaldehyde and NO2. In 2017 the Sentinel 5P satellite was launched which will provide a step change in spatial resolution (allowing identifications of pollution hot-spots within large conurbations). This will be followed in 2021 by Sentinel 4 which will be launched into a geostationary orbit observing Europe and providing both high spatial and temporal measurements of RGF. These data can only be fully utilized if the yield of formaldehyde and glyoxal from important anthropogenic emissions such as ethene and aromatic compounds is known accurately.

UNFOGS will develop and characterise spectroscopic measurement techniques of formaldehyde and glyoxal and develop a new UK capability for detection of methylglyoxal, a closely related compound to glyoxal which may be monitored in future satellite campaigns. An atmospheric simulation chamber will be used to study the oxidation of key anthropogenic glyoxal and methylglyoxal forming compounds such as toluene, benzene, ethene and glycolaldehyde. The chamber measurements measure overall processes which are a combination of several elementary reactions. The chamber measurements will be supported, where appropriate, by complementary direct studies of key elementary reactions.

An important component of UNFOGS is to work with our partners, who are working on satellite measurements, to develop appropriate models to interpret satellite measurements so that the full potential of these new instruments and measurements can be utilized to benefit air quality studies, an understanding of emissions, and links to health.

Planned Impact

1) Impact to the Satellite Community - UNFOGS is already strongly linked into the satellite community through Palmer and project partners Burrows (Bremen) and Sainz-Lopez (Madrid). However, as part of UNFOGS we would plan to host a workshop during year 3 bringing together key players in the modelling, measurement and satellite communities. £4 k is requested to help support this activity. (THIS NEEDS A BIT MORE THOUGHT AND DETAIL - it is a standard impact activity, but would be very important here as we don't want the data to stall in a journal publication, but rather to get through to the community. As mentioned, we are doing this via Paul P and partners, but perhaps could identify some key participants)

2) Instrument development - The instruments validated and developed as part of UNFOGS are focused on chamber and laboratory studies but are based on field instruments. Part of the impact and legacy of UNFOGS will be validated field instruments. We would envisage these instruments contributing to future field campaigns, either ground based, or on the FAAM aircraft. There is currently no FAAM capability for glyoxal (GL) or methylglyoxal (MGL) detection. Once the instruments are commissioned we will be monitoring plans for future FAAM campaigns and if appropriate flights are planned, we would apply for additional funds to 'piggy-back' these instruments onto these campaigns, to enhance the species coverage of these flights.
(Could also put something here about links to PP's MAX-DOAS and intercomparison, also possibility of intercomparison with other instruments or deployment into other chambers - EUROCHAMP)

3) Health and Policy - Formaldehyde (FA), GL and MGL have important air quality and health impacts and accurately determining their yields from the atmospheric oxidation of key anthropogenic hydrocarbon emissions will therefore provide useful information to the wider air quality and health community. Academic links will be made through conference presentations and publications. The Air Quality Expert Group (members include Prof Alison Tomlin, University of Leeds, Prof Mat Heal, University of Edinburgh) provides a link through to policy. SOMETHING ABOUT HEALTH?

4) Academic and Public Dissemination - The Leeds and Edinburgh groups have an excellent record of publications and conference participation which will ensure academic impact. Links through the departmental websites will provide up to date information on the progress of UNFOGS to academic and non-specialist audiences. The nature of UNFOGS, linking space measurements with an understanding of local emissions and their links to health and climate change, provide excellent opportunities for attracting interest from school pupils and undergraduates. The investigators would use UNFOGS to provide material for schools lectures and also examples for undergraduate projects that could excite a new generation of PhD students.

Publications

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Description Although this project has only started in the last 6 months, we have already identified some key issues relating to the chemistry of formaldehyde, HCHO, one of our key target molecules. The difficulties in accurately determining the concentration of HCHO have been underestimated in a number of important studies. We have developed methods for making in situ measurements of HCHO and are currently pursuing a novel method of determining the absorption cross section of HCHO, a key parameter in both laboratory and satellite measurements.

Since the last reporting period, we have extended our work on OH + HCHO measurements including the development of new infrastructure resource described above, and a publication should soon be forthcoming. Similar measurements are commencing on OH + glyoxal and glycoaldehyde, important reactions in WP2. We have worked on our laser development aspects for monitoring HCHO, glyoxal and methylglyoxal and intercomparisons with other techniques are about to start.
Exploitation Route Outcome will be of relevance to other laboratory studies and for satellite measurements.
Sectors Environment

 
Title In Situ Absorption Measurements 
Description For a number of reactions relevant to UNFOGS monitoring the concentration of reactants in situ is required. This is because many of the reactants are 'sticky' and so calculated concentrations based on flow rates are not possible. As part of UNFOGS Dr Graham Boustead has set up and tested an in situ UV absorption system. The apparatus will be described in a forthcoming publication on the reactions of OH with HCHO 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? No  
Impact Once published, this method will be available to other researchers working in the field.