Details of Award
NERC Reference : NE/K008250/1
Ultrasensitive detection of iodine species in the atmosphere
Training Grant Award
- Lead Supervisor:
- Professor GAD Ritchie, University of Oxford, Oxford Chemistry
- Grant held at:
- University of Oxford, Oxford Chemistry
- Science Area:
- Atmospheric
- Marine
- Overall Classification:
- Atmospheric
- ENRIs:
- Global Change
- Science Topics:
- None
- Abstract:
- Tropospheric chemical processes determine the atmospheric fate of many primary pollutants and govern the production of species such as ozone and secondary organic aerosol, secondary pollutants in their own right which also play a major role in the radiative balance of the climate system. This project is concerned with assessment of the impact of both iodine atoms and iodine-containing compounds, upon tropospheric chemistry and composition. Recent measurements have shown that iodine can destroy O3 and perturb HOx and NOx ratios in boundary layer environments as diverse as the equatorial Atlantic Ocean, the polar ice-caps, and mid-latitude coastlines. Higher iodine oxides have been implicated in the formation of new aerosol particles in regions of high iodine activity with potentially significant impacts upon cloud condensation nuclei populations and hence radiative transfer - depending upon the prevalence of iodine activity throughout the marine atmosphere. While these impacts have all been shown to occur at specific locations, wider quantification of the consequences of iodine chemistry is limited by gaps in our understanding regarding the distribution and behaviour of the iodine-containing compounds, related in part, to current limitations in analytical capability. Specific questions include, what are the distributions of these halogen species around hot-spots of activity - are recent satellite observations of total iodine columns over the open ocean restricted to the boundary layer - in which case the higher concentrations will lead to greater (non-linear) local O3 loss and new particle formation - or is there a significant free tropospheric component? What is the total gas-phase iodine content in specific boundary layer environments - and consequently how large is the pool of condensable iodine species which could contribute to particle formation and/or growth? Understanding of such factors is required to quantify the current impacts of iodine upon tropospheric chemistry and composition, a necessary precursor to determining their likely response to changing environmental conditions in the future. This project aims to address these uncertainties through the development and application of an entirely new instrument for measuring the mixing ratio of I atoms at the sub-parts per trillion (ppt) level over a one second period, a significant improvement on current detection methods. In addition to the ultra-high sensitivity and high time resolution afforded by this new approach, further advantages include a reliable internal calibration that returns absolute number densities within a lightweight, portable and relatively inexpensive instrument. The objectives of this proposal are therefore: (1) to develop and optimize a prototype ultra-sensitive detection system based upon diode laser absorption within a resonant optical cavity, (2) to compare the new device with a recently developed resonance fluorescence detection methodology, and (3) to deploy the system in a field campaign in order to demonstrate the viability of the method.
- NERC Reference:
- NE/K008250/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- Analytical Sci and Tech
This training grant award has a total value of £74,211
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - RTSG | Total - Student Stipend |
|---|---|---|
| £13,978 | £11,039 | £49,194 |
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