Understanding the atmospheric chemistry of biomass burning emissions and their impact on air quality and climate

Large scale biomass burning events, including wildfires, agricultural burn-off and residential fuel combustion, release large quantities of organic carbon to the atmosphere. These emissions can then undergo chemical transformations leading to a wide range of secondary gas and particulate products which can have a significant impact upon climate and air quality.

Air quality and climate change are two of the most important environmental issues of our time, impacting human health, ecosystems, and the economy. The World Health Organisation has estimated that globally 8.8 million people die each year as a direct result of exposure to air pollution. Exposure to poor air quality has a range of short and long term impacts on health including a wide range of cardiovascular and respiratory diseases, cancer, diabetes and links to dementia.

The frequency and intensity of wildfires in the US, Brazil and Australia have notably increased over the last decade, and this trend is likely to continue owing to fire/land management practises and climate change. Therefore, it is becoming increasingly important to understand the formation of gas and aerosol phase products from these emissions in order to quantify their impacts and limit their detrimental effects.

In this project we will design a series of experiments to be carried out in a flow reactor built in York to study atmospheric chemistry, in order to understand the most important formation pathways of gas and aerosol phase products from a range of biomass-burning emissions. These will focus on oxygenated aromatic volatile organic compounds (VOC), such as furans and phenolic compounds.

First, the flow reactor will be characterised through a set of experiments carried out on aromatic systems whose chemical mechanisms are already available in the Master Chemical Mechanism (MCM: mcm.york.ac.uk). The loss of the precursor species and the formation of wide range of gas and aerosol phase products will be measured using on and off-line mass spectrometric techniques including PTR-MS (Proton Transfer Reaction mass spectrometry) and SIFT-MS (Selected Ion Flow Tube mass spectrometry) for gas phase species, and UPLC (ultra-high pressure liquid chromatography) coupled to Orbitrap mass spectrometry for investigating secondary organic aerosol composition.

Experiments will be designed using box models based around the detailed chemistry available in the MCM, optimised for the conditions of the flow reactor. Newly developed and evaluated chemical mechanisms for emitted biomass burning compounds will subsequently be incorporated into the MCM.