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Applications are now open for PhD studentships starting in October 2018. 

Please read the recruitment introduction for more information about eligibility, how to apply, and possibilities for further funding.

The deadline for applications is 8 January 2018.

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KAISER_UENV18EE

KAISER_UENV18EE - Isotopic fingerprints of carbonyl sulfide (COS) in atmosphere and biosphere

Project description

Fig. 1 Stratospheric aerosol layer (STS43-22-12; NASA JSC Earth Observations Lab)

Selected other project supervisors
Dr Alina Marca (UEA)
Prof Thomas Röckmann (Utrecht University)

Background
Carbonyl sulfide (COS) is a sulfur-analogue of CO2. It is the most abundant atmospheric sulfur compound and has a lifetime of 2 to 4 years. COS has industrial and natural sources, mostly the oceans. Its main sinks are plant and soil uptake, but due to its long lifetime, some COS reaches the stratosphere where it undergoes photolysis and oxidation to sulfate and forms the stratospheric aerosol layer (Fig. 1). This layer is of key importance for ozone chemistry, the radiation balance and Earth’s climate. Like CO2, COS is taken up during photosynthesis, but not released during respiration, making it a tracer for gross primary productivity (Asaf et al. 2013). However, overlap of plant and soil uptake limit the use of COS concentration alone for this purpose. Isotope measurements have recently found applications in fingerprinting COS sources and sinks including atmospheric oxidation pathways, and can potentially distinguish between plant and soil uptake.

Methodology

  1. A novel online method for isotope analysis of COS will be used for 13C and 34S measurements (Hattori et al. 2015) and further extended to polyisotopologues (13C16O34S) on mass-spectrometers with worldwide unique analyser and detector configurations.
  2. The isotope fractionation during COS uptake by soils and vegetation will be determined using COS-enriched atmospheres, in order to provide constraints on the relative contributions of different COS sinks. Isotope fractionation during COS photolysis under realistic light conditions will be measured and used to verify the stratospheric sulfate aerosol budget.
  3. Finally, the new method will be deployed on archived tropospheric and stratospheric samples to improve the global budget of COS for the quantification of gross photosynthesis rates.

Person specification and training
This project requires good quantitative-analytical and experimental skills. A good Honours degree in science or engineering is required; an MSc is desirable. Training will be provided in isotope mass spectrometry, gas and vacuum systems, instrument control and numerical data analysis. Any scientific knowledge gaps can be filled by attending taught courses, e.g. in biogeochemical cycles and atmospheric chemistry. The project includes visits to international collaborators in the Netherlands.

Funding
This project has been shortlisted for funding by the EnvEast NERC Doctoral Training Partnership, comprising the Universities of East Anglia, Essex and Kent, with over twenty other research partners. Undertaking a PhD with the EnvEast DTP will involve attendance at mandatory training events throughout the course of the PhD.

Shortlisted applicants will be interviewed by EnvEast on 12/13 February 2018.

Selected candidates who meet RCUK’s eligibility criteria will be awarded a NERC studentship - in 2017/18, the stipend is £14,553. Ordinarily, EnvEast studentships are for 3.5 years, although longer awards may be made to applicants from quantitative disciplines who have limited experience in the environmental sciences, to allow them to take appropriate advanced-level courses in the subject area.

In most cases, UK and EU nationals who have been resident in the UK for 3 years are eligible for a stipend. For non-UK EU-resident applicants NERC funding can be used to cover tuition fees, RTSG and training costs, but not any part of the stipend. Individual institutes may, however, elect to provide a stipend from their own resources.

This PhD studentship is expected to begin in September/October 2018. Both full-time and part-time study are possible (those planning to study part-time may wish to discuss this with the supervisor before applying).

References

  1. Asaf D, Rotenberg E, Tatarinov F, Dicken U, Montzka SA, Yakir D (2013) Ecosystem photosynthesis inferred from measurements of carbonyl sulphide flux Nature Geosci 6:186 10.1038/ngeo1730
  2. Hattori S, Toyoda A, Toyoda S, Ishino S, Ueno Y, Yoshida N (2015) Determination of the sulfur isotope ratio in carbonyl sulfide using gas chromatography/isotope ratio mass spectrometry on fragment ions 32S+, 33S+, and 34S+ Anal Chem 87:477 10.1021/ac502704d
  3. Wang Y, Deutscher NM, Palm M, Warneke T, Notholt J, Baker I, Berry J, Suntharalingam P, Jones N, Mahieu E, Lejeune B, Hannigan J, Conway S, Mendonca J, Strong K, Campbell JE, Wolf A, Kremser S (2016) Towards understanding the variability in biospheric CO2 fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO2 Atmos Chem Phys 16:2123 10.5194/acp-16-2123-2016
  4. Barkley MP, Palmer PI, Boone CD, Bernath PF, Suntharalingam P (2008) Global distributions of carbonyl sulfide in the upper troposphere and stratosphere Geophys Res Lett 35:L14810 10.1029/2008GL034270
  5. Kaiser J, Röckmann T, Brenninkmeijer CAM, Crutzen PJ (2003) Wavelength dependence of isotope fractionation in N2O photolysis Atmos Chem Phys 3:303 10.5194/acp-3-303-2003