Understanding Formaldehyde and Glyoxal Chemistry from Biogenic Emissions to Aid Satellite Measurements – UNFOGS-Bio

Understanding Formaldehyde and Glyoxal Chemistry from Biogenic Emissions to Aid Satellite Measurements – UNFOGS-Bio

 

Professor Paul Seakins (School of Chemistry, University of Leeds), Professor Dwayne Heard (School of Chemistry, University of Leeds)

Contact email: p.w.seakins@leeds.ac.uk

 

Introduction

The School of Chemistry has recently received ~£1 M funding from NERC to study the mechanisms of the formation and removal of glyoxal (GL, HC(O)C(O)H) and methyl glyoxal (MGL, CH3C(O)C(O)H) in the urban environment. The driver for the project is the launch of new, high temporal and spatial resolution satellites (the ESA Sentinel Programme). Satellites have limited capability to detect important primary organic emissions (e.g. carcenogenic aromatics), but can detect their oxidation products formaldehyde (FA, HCHO) and glyoxal (and potentially methyl glyoxal in the future). The ratio of GL to FA (RGF) is dependent on the type of organic (aromatic, alkene, alkane etc) but is poorly quantified. Therefore, if we can precisely determine RGF, we have a handle on the primary emissions. The new class of satellites (Figure 1) has a spatial resolution ~factor 10 greater than previous satellites allowing observation of FA and GL plumes within conurbations. Our quantification of the chemistry within the UNFOGS project (Understanding Formaldehyde and Glyoxal Chemistry for Satellite Measurements), in combination with modelling (Prof Paul Palmer, University of Edinburgh) will potentially allow these new satellites to monitor primary emissions to verify compliance with legislation and investigate links with health and air quality.

Figure 1 – The new high spatial resolution Sentinel Instrument

 

UNFOGS-Bio is a parallel project looking at the production of FA, GL and MGL from biogenic precursors such as isoprene and monoterpenes. UNFOGS-Bio, like the main project, is multi-disciplinary with opportunities to develop skills in instrument design and development, laboratory measurements (both elementary reactions using laser flash photolysis and simulation chamber work), and modelling. We are happy to discuss the exact balance of the project which should match your interests, the requirements of the project and how the project evolves. There will also be opportunities to interact with our project partners in Bremen and Madrid who are experts in satellite measurements.

 

Aims, Objectives and Programme

As mentioned above there are three main components to the UNFOGS-Bio project:

1) Instrument Design – Prof Heard’s group has already built a laser based apparatus for the measurement of glyoxal with high sensitivity and temporal resolution based on an instrument developed by Keutsch.[1] For this part of the project you would work with colleagues from UNFOGS to extend the technique to the measurement of methylglyoxal. Once developed, the instrument would be tested against other methods such as FTIR and PTR-MS in the HIRAC chamber.[2]

2) Laboratory work – A major component of the project would be determining RGF values for various biogenic emissions. These emissions include direct emissions from plants (e.g. isoprene and monoterpenes) but could also include the emissions from biomass burning, helping satellites to track biomass burning plumes.  Experiments will be performed in the Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC) chamber in the School of Chemistry, University of Leeds (see Figure 2).  HIRAC is a 2.25 m3 cylindrical stainless steel chamber in which temperature, pressure and photolysis can be controlled so that chemistry can be investigated over a range of atmospherically important conditions.

Figure 2 – The HIRAC Chamber

 

A major determinant of the chemistry in remote environments (e.g. Amazon rainforest) is the fate of RO2 radicals.[3] Unlike most simulation chambers, HIRAC is able to directly monitor key radical species such as OH and HO2. Under previous NERC DTP projects we have developed new instrumentation for the selective detection of RO2 species [4] and implemented a ROxLIF system for generic RO2 detection (Alex Brennan, NERC DTP PhD, 2019).  This key capability of HIRAC will open up new avenues for determining the mechanism of product formation.

3) Modelling – A knowledge of chemical modelling will be required both to interpret the HIRAC experiments and to apply the knowledge gained from these experiments to real atmospheric environments to compare model predicts with observations. You will develop skills in the Master Chemical Mechanism (MCM) a comprehensive chemical mechanism developed at Leeds and York.

 

Potential for high impact outcome

Previous NERC DTP projects have successfully lead to high profile publications [4-7] and this project has the same high potential. There are links to important NERC priorities such as satellite measurements and human health which give the project a broad appeal and hence potential for high impact.

 

Training

The student will work under the supervision of Prof Paul Seakins and Prof Dwayne Heard (School of Chemistry, Leeds). The project is very interdisciplinary. The student will develop transferrable skills in instrument and experiment design, spectroscopic characterisation techniques, development of analytical methods, chemical mechanism development and evaluation, numerical and data skills and kinetic model analysis. Training will be provided in all areas, and we expect to establish collaborations with a number of colleagues in the area of chemical kinetics and mechanism development, with potential opportunity to take part in the chamber campaigns at large, highly instrumented European photo-reactors as part of the Horizons 2020 EUROCHAMP2020 programme (http://www.eurochamp.org/).

The University Leeds, and the wider NERC PANORAMA DTP provide comprehensive training programmes for PhD students with a range of courses on both hard and soft skills. Profs Seakins and Heard both work for and with the National Centre for Atmospheric Science (NCAS), and thus the student will have access to the wider resources that NCAS provides. You will also have access to training provided by NCAS such as the Arran instrumental Summer School, the Earth System Science Summer School (ES4), and future further developments in computations and data analysis.

You will have the opportunity to present their work to the scientific community at national and international meetings and conferences and will also be encouraged to take part in outreach events organised by both the DTP and NCAS in order to disseminate the research beyond the immediate scientific community (e.g. to policymakers and the general public). There should be opportunities to work with UNFOGS partners in Edinburgh, Bremen or Madrid.

We appreciate that this PhD project encompasses several different science and technology areas, and we don’t expect applicants to have experience in many of these fields. The project is very well supported with experienced scientists and training in these new techniques and disciplines is all parts of the PhD.

 

Useful References

  1. Henry, S.B., A. Kammrath, and F.N. Keutsch, Quantification of gas-phase glyoxal and methylglyoxal via the Laser-Induced Phosphorescence of (methyl)GLyOxal Spectrometry (LIPGLOS) Method. Atmospheric Measurement Techniques, 2012. 5(1): p. 181-192.
  2. Glowacki, D.R., et al., Design of and initial results from a highly instrumented reactor for atmospheric chemistry (HIRAC). Atmospheric Chemistry and Physics, 2007. 7: p. 5371-5390.
  3. Molteni, U., et al., Formation of Highly Oxygenated Organic Molecules from alpha-Pinene Ozonolysis: Chemical Characteristics, Mechanism, and Kinetic Model Development. Acs Earth and Space Chemistry, 2019. 3(5): p. 873-883.
  4. Onel, L., et al., A new method for atmospheric detection of the CH3O2 radical. Atmospheric Measurement Techniques Discussions, 2017: p. doi:10.5194/amt-2017-122.
  5. Medeiros, D.J., et al., Kinetics of the Reaction of OH with Isoprene over a Wide Range of Temperature and Pressure Including Direct Observation of Equilibrium with the OH Adducts. Journal of Physical Chemistry A, 2018. 122(37): p. 7239-7255.
  6. Winiberg, F.A.F., et al., Direct measurements of OH and other product yields from the HO2 +CH3C(O)O2 reaction. Atmospheric Chemistry and Physics, 2016. 16(6): p. 4023-4042.
  7. Onel, L., et al., An intercomparison of HO2 measurements by fluorescence assay by gas expansion and cavity ring-down spectroscopy within HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry). Atmospheric Measurement Techniques, 2017. 10(12): p. 4877-4894.