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Concentrations of atmospheric halocarbons are very low and difficult to measure; nevertheless, they are of high environmental importance and contribute more than 20 % to the anthropogenic greenhouse effect. Moreover, the chlorine and bromine atoms released during the breakdown of halocarbons in the stratosphere lead to ozone loss. In higher concentrations, many halocarbons are toxic and cause adverse health effects in humans and wildlife such as endocrine disruption. The lowest halocarbon mixing ratios can only be detected using the most sensitive analytical techniques, usually involving mass spectrometers (MS). UEA has been at the forefront of discovering many previously undetected halocarbons, not least thanks to unique analytical capabilities in the form of a high-resolution MS dedicated to atmospheric measurements (Autospec). Recently, we showed that this MS can also be used for isotope measurements in (Laube et al., 2010). Stable isotope measurements in volatile organic compounds (VOCs) are a unique tool to study their sources and sinks, which can often be distinguished by the isotopic fingerprints of natural or anthropogenic production and loss pathways. This project will focus on the development of analytical methods for isotope analysis using the Autospec as well as an additional purpose-built MS for chloromethane (CH3Cl) isotope analysis. CH3Cl is the most important natural gas that leads to chlorine-catalysed ozone destruction in the stratosphere. The project will provide training for the student in recent methodological and instrument advances in stable isotope ratio mass spectrometry and GC-MS coupled techniques. In addition, the student will learn about the environmental and atmospheric chemical background. Good experimental and quantitative-analytical skills are required for this challenging project. The student will be actively encouraged to network through attendance at conferences, workshops and meetings at institutional, national and international levels.
This project is available for a 1 January 2013 start.
Funding Notes:
Funding is available for UK students and will cover tuition fees and provide a stipend. European Union (EU) citizens may apply but you will be eligible for a fees-only award. Please refer to the full NERC eligibility criteria at http://www.nerc.ac.uk/funding/available/postgrad/eligibility.asp
References:
Ref1: Aeppli, C., Holmstrand, H., Andersson, P., and Gustafsson, O. (2010) Direct Compound-Specific Stable Chlorine Isotope Analysis of Organic Compounds with Quadrupole GC/MS Using Standard Isotope Bracketing. Anal. Chem. 82, 420-426
Ref2: Kaiser, J., Engel, A., Borchers, R., and Röckmann, T. (2006) Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N2O isotope distribution. Atmos. Chem. Phys. 6, 3535-3556
Ref3: Laube, J., Kaiser, J., Sturges, W. T., Bönisch, H., and Engel, A. (2010) Chlorine isotope fractionation in the stratosphere. Science 329 1167.