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Investigating the impact of combustion sources to air pollution in Delhi, India.

Dr Jacqui Hamilton (WACL, University of York), Prof James Lee (WACL, University of York)

Contact email: jacqui.hamilton@york.ac.uk

Introduction

Exposure to poor air quality is the top environmental risk factor of premature mortality across the globe. Heart disease and strokes are the most common reasons for premature deaths due to air pollution, with less serious impacts including increases in respiratory and cardiovascular disease and cancer.  A recent study (WHO, 2014) identified Delhi as the most polluted city in the world, causing an estimated 20,000 premature deaths annually.  This figure is anticipated to rise to ~30,000 by 2025 (Lelieveld et al., 2015). In the face of continuing rapid growth in population, city authorities in Delhi have initiated a range of measures to control air quality, including use of compressed natural gas in public transport, relocation of industries and introduction of Metro transport. Despite this, air quality continues to deteriorate.

Volatile organic compounds (VOCs) are emitted from a huge variety of natural and man-made sources. In the urban atmosphere VOCs lead to the formation of ozone and particulate matter (PM), two of the most important pollutants for health impacts. For policy development it is useful to have speciation of the VOCs present as different molecular structures lead to different yields of ozone and PM. Emissions of VOCs in Delhi, as with other developing megacities in India and beyond, are complex, as the contributions from diffuse sources such as traffic, biomass burning for cooking and heating and small industrial sources are large compared with emissions from large plants. Measurement data on India-specific emission factors are sparse. Recent evidence suggests that real-world vehicle emission factors are poorly understood for the vehicle fleet in developed countries, but uncertainties are much larger for the Delhi fleet and no independent measurements appear to exist.  Accurate estimation of emissions from all types of burning processes is essential to assess its potential impact.

Figure 1:  Burning of plantation waste in India (left), Traffic congestion in Dehli (right).

Project Description

This project, based in the world leading Wolfson Atmospheric Chemistry Laboratories, will combine state of the art instrument development with both laboratory simulations and field measurements to characterise the complex mix of volatile organic compounds in Delhi and estimate their emission fluxes. This project will be integrated into the NERC funded DELHI-FLUX project involving scientists from the UK (CEH, Lancaster, Manchester) and India (Indian Institute of Technology, CSIR National Physics Laboratory).  Laboratory simulations will involve burning under controlled conditions using fuel samples from different locations in Delhi, with examples including the various residential bio-fuels (dung cakes, different fire wood types and crop residues) used in both heating and cooking situations, wood burning in Dhaba (small-scale roadside restaurants) and diesel use in generators for market stalls. Two intensive measurement periods will take place in Delhi to obtain information about the sources of VOCs and the factors that control their emission.

In this project, the student will develop and optimise a high-resolution method to measure emissions and fluxes of volatile organic compounds  (VOC) based on two-dimensional gas chromatography (GCXGC).  This technique targets intermediate chain (up to C14), low volatility hydrocarbons and oxygenated VOCs. These compounds (that are not detected by the standard instrumentation), are often overlooked as there are many isomers with relatively low concentrations.  A recent study from our group has shown that these species, can however dominate the reactive carbon in a megacity. For instance, VOC emissions from diesel vehicles were significantly underestimated in London. (Dunmore et al., 2015. BBC, 2015).  The GCXGC will be coupled to a relaxed eddy accumulation sampler, allowing the fluxes of higher molecular weight VOCs to be measured for the first time.  This technique will be used to;

  • Characterise the chemical composition of VOCs from a range of burning emissions in controlled laboratory studies.  This data will be used to determine emission factors for VOCs for different fuel sources and burning conditions.

  • Deploy the instrumentation during the DELHI-FLUX field experiments during two 5-week intensive measurement periods.

  •  Analysis of field data to determine the impact of combustion sources on VOC composition in Delhi.

Potential for high impact outcome

Developing economies such as India must maximise air quality improvements in the shortest time possible but with acceptable economic costs. In order to achieve this there is a need for policy informed by scientific understanding. This work will contribute to one of the aims of DEHLI-FLUX project:  to improve the emission factor database for key source types and compounds in Delhi through a combination of lab and field based emission factor measurements, using harmonised instrumentation. This project addresses the primary pollutants directly affecting human health and the key precursors (i.e. VOCs) for secondary pollution, as well as combustion tracers required to interpret and scale the results. The outcomes of the project are designed to be directly useful to practitioners tasked with managing air pollution in Delhi. The research should also provide high quality research papers.

Training

The student will work under the supervision of Dr. Jacqui Hamilton and Prof. James Lee at the Wolfson Atmospheric Chemistry Laboratories (WACL), part of the University of York’s Department of Chemistry.  

The successful PhD student will have access to a broad range of training workshops put on by the University of York as part of its Innovative Doctoral Training Program (iDTP). The studentship is offered as part of the SPHERES Doctoral Training Program which will provide additional training. Through the Department of Chemistry, University of York and SPHERES training there are a wide range of activities including courses aimed at specific scientific objectives, improving your transferrable skills, completing your PhD and putting your work into a wider scientific context.

Drs Hamilton and Moller will provide comprehensive training in the technical aspects of the analytical instrumentation, data analysis and interpretation.

Student profile

The student should have an interest in global environmental problems and a strong science background (e.g. chemistry, physics, environmental sciences, forensic science). Interest in and experience of analytical science would be beneficial but training will be given to enable the successful student to carry out the work involved in this project. The student must be willing to travel outside the UK.

References

BBC, 2015. http://www.bbc.co.uk/news/science-environment-34347873

Dunmore et al., Atmospheric Chemistry and Physics, 15, 9983-9996, 2015.

Lelieveld, J. et al., Nature 525, 367–371, 2015.

WHO, 2014. http://www.who.int/phe/health_topics/outdoorair/databases/cities/en/

Photo credits.  https://commons.wikimedia.org/w/index.php?curid=16720232, https://commons.wikimedia.org/w/index.php?curid=4783150.

Related undergraduate subjects:

  • Chemistry