Understanding the changing sources of volatile organic compounds in the UK over the last two decades and implications for the future

Volatile Organic Compounds (VOCs) are emitted into the atmosphere from a wide variety of sources and can be anthropogenic (man-made) or biogenic (naturally produced) in origin. Dominant sources of hydrocarbons vary greatly on global and regional scales, depending upon the population, vegetation and industry within the surrounding environment. This variation in source strength often leads to a corresponding variation in the significance of different species. Once emitted into the atmosphere, VOC concentrations are influenced by a number of factors including meteorology, dry and wet deposition and chemical reactions. The atmospheric chemistry of VOCs is dominated by the hydroxyl radical which leads to their oxidation at a range of timescales, from hours to months, dependent upon their structure. Ultimately their oxidation leads to the formation of carbon dioxide (CO2), an important climate gas. Their greatest significance to the atmosphere, however, is the secondary pollutants produced during their oxidation which tend to be more harmful, including ozone, formaldehyde and other highly oxygenated compounds which are all implicated as key contributors to respiratory illnesses in people as well as limiting crop yields through damage to plant stomata and leaves. The efficiency with which different VOCs can produce these important secondary pollutants in the atmosphere is dependent upon their structure so it is, therefore, vitally important to make observations of individual (speciated) VOCs in the atmosphere as a bulk measurement of the total VOC concentration tells us very little about their potential for harm.

This project aims to:
1. Provide the UK with continuous quality controlled measurements of VOCs at three urban sites in order to better understand their role in the UK atmosphere. Compare between different cities to identify the significance of different localised sources and meteorology to their ambient concentrations. Provide near real-time, automated observations to yield important information regarding local air quality at these locations.

2. Place the data produced in the context of historic data collected at UK air quality sites and short-term deployments of equipment during field projects in the UK to investigate the changing composition and the contributions of individual sources to the ambient VOCs over the last thirty years.

3. Compare current and historic observations of VOCs to the National Atmospheric Emissions Inventory outputs to evaluate its effectiveness in predicting ambient levels of VOCs in the UK.

The student will develop transferable skills in quality assessment and evaluation of atmospheric observations. They will apply data analysis tools for measurement comparison and analysis of long term trends of atmospheric gases using a variety of statistical techniques. They will also gain understanding and knowledge to enable them to place their observations in the wider context of historical, regional and global composition.