Details of Award
NERC Reference : NE/J017868/1
Novel mass spectrometric techniques for stable isotope measurements in atmospheric halocarbons
Training Grant Award
- Lead Supervisor:
- Professor J Kaiser, University of East Anglia, Environmental Sciences
- Grant held at:
- University of East Anglia, Environmental Sciences
- Science Area:
- Atmospheric
- Freshwater
- Marine
- Terrestrial
- Overall Classification:
- Atmospheric
- ENRIs:
- Global Change
- Pollution and Waste
- Science Topics:
- None
- Abstract:
- Atmospheric halocarbons are present at mixing ratios from 500 to 600 parts per trillion in case of chloromethane (CH3Cl) and dichlorodifluoromethane (CF2Cl2) down to parts per quadrillion for the least abundant measurable gases. In spite of these low abundances, halocarbons are of high environmental importance: They contribute more than 20 % to the anthropogenic greenhouse effect and the chlorine and bromine atoms released during their breakdown 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 breakdown products of some halocarbons are also toxic to ecosystems, e.g. trifluoroacetic acid produced from chlorofluorocarbons (CFCs) and hydrofluorocarbons is a persistent water pollutant with acute algal toxicity. Emissions of ozone-depleting halocarbons are regulated under the Montreal protocol and its amendments and levels of anthropogenic CFCs decline. However, the observed decline is not always in agreement with reported production and emissions, which may be due to leaks from product banks or reporting errors. Detection, monitoring and verification are therefore important. Moreover, some halocarbons are also emitted naturally, e.g., natural CH3Cl sources are thought to contribute about 15 to 20 % chlorine-catalysed ozone destruction in the stratosphere. 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 chlorine isotope measurements in stratospheric CF2Cl2. 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 provides insight into trace gas budgets, biosphere-atmosphere interactions and atmospheric chemistry and transport. In the past, stable isotope measurements in VOCs have focussed on carbon isotope ratios, after oxidation to CO2. However, last year UEA acquired a special isotope ratio MS with a dedicated detector that can analyse CH3Cl and its isotopic analogues directly. This instrument together with the Autospec will be at the centre of this PhD project. The student will * build a trace gas pre-concentration and gas chromatographic front-end for the isotope ratio MS * develop an analytical method for multi-collector isotope measurements in CH3Cl * develop numerical techniques for data reduction of CH3Cl isotopologue ratio measurements to 37Cl/35Cl, 13C/12C and 2H/1H isotope ratios and possibly clumped isotopes (13CH337Cl) * develop new approaches to peak integration for isotope ratio analysis * develop GC-MS methods for the measurement of chlorine, carbon and bromine isotope ratios in atmospheric trace gases with mixing ratios at the lower ppt level using the Autospec * analyse isotope ratios in halocarbons from a meridional section of upper tropospheric/lower stratospheric samples and ground level samples from coastal sites in the UK and Malaysia * use statistical methods and ancillary data to interpret the variability in the isotopic composition of the samples The project will provide training for the student in the most 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. The student will be actively encouraged to network through attendance at conferences, workshops and meetings at departmental, institutional, regional, national and international levels.
- NERC Reference:
- NE/J017868/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- Analytical Sci and Tech
This training grant award has a total value of £73,055
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - RTSG | Total - Student Stipend |
|---|---|---|
| £13,812 | £10,959 | £48,285 |
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