Details of Award
NERC Reference : NE/C511599/1
Measurements of nitrogen and iodine species using a novel light emitting diode-based cavity enhanced absorption spectrometer.
Grant Award
- Principal Investigator:
- Professor R Jones, University of Cambridge, Chemistry
- Grant held at:
- University of Cambridge, Chemistry
- Science Area:
- Atmospheric
- Overall Classification:
- Atmospheric
- ENRIs:
- Pollution and Waste
- Global Change
- Environmental Risks and Hazards
- Science Topics:
- Pollution
- Tropospheric Processes
- Ocean - Atmosphere Interact.
- Abstract:
- The overall aim of this project is to use a new development of an ultra-sensitive spectroscopic detection method to study two different aspects of atmospheric science, namely, the chemistry of the marine air-sea interface and the chemistry of the night time urban atmosphere. The results from the experiments in the marine environment will allow us to improve our understanding of ozone photochemistry and aerosol particle formation. Both of these are important for the chemistry of the global atmosphere, the ability of the atmosphere to remove unwanted pollutants, and the formation of clouds which have important impacts on climate change. The measurements in the urban environment focus on the night time chemistry, in particular the removal of nitrogen oxides which are a major component of pollution. A particularly reactive compound of nitrogen - the NO3 radical - helps the atmosphere cleanse itself of hydrocarbons emitted from the surface. However this type of chemistry also leads to the formation of compounds that can then be transported long distances, potentially affecting the regional and global atmosphere far away from the source of the pollution. The first step will be to construct a novel spectrometer based on an approach known as 'cavity ringdown spectroscopy' or CRDS. Conventionally this method uses laser lighted trapped between two highly reflective mirrors in an optical cavity about 1 metre long. Using currently available mirrors, it is possible to trap the laser light for many tens of microseconds, over which time light will have travelled 10 kilometres or more - effectively producing an absorption cell of this length. Over these long distances, any gases in the cavity which absorb light even weakly can therefore reduce the trapped light intensity significantly, giving a highly sensitive detector. In this project we use an analogous method (CEAS), but also use multi wavelength light emitting diodes (LEDs) rather than laser radiation. This brings two benefits (1) using different wavelengths allows us to discriminate between the gases we wish to detect and exclude other interferences, and (2) we can build a much more compact, eyesafe instrument. The instrument we propose building will measure N2O5, OIO, IO and I2. First, the instrument will be used to detect compounds of iodine emitted by seaweed under controlled conditions in the laboratory. It is known that these emissions lead to the formation of aerosol particles in the marine environment, but the mechanism by which the gases actually condense to form particles remains unknown. Particles are important because they can affect visibility, the transport of iodine compounds inland from the coast and the chemical balance of the atmosphere by providing additional chemical reactions to those between gas phase molecules. This study will help to produce a model describing how the aerosol particles are formed and thus quantify their effects on the wider atmosphere. The instrument will then be placed in a mobile laboratory ( a 'lab-in-a-van') along with other commercial instruments to measure NO, NO2, O3, and hydrocarbons and will be used to map the distributions of these species in and around Cambridge during a 2 week field campaign. This is the first time such measurements have been made in the UK, and the first time N2O5 will have been mapped anywhere in such a manner. The importance rests on the notion that N2O5 is expected to be present in extremely high concentrations, with impacts on both local composition in the city and air downstream of local pollution sources. The results from this campaign will then be used with computer simulations of the atmosphere to assess their wider implications and will be made available to other researchers for their research.
- NERC Reference:
- NE/C511599/1
- Grant Stage:
- Completed
- Scheme:
- Standard Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Standard Grant
This grant award has a total value of £181,295
FDAB - Financial Details (Award breakdown by headings)
| Total - Staff | Total - T&S | Total - Other Costs | Total - Equipment | Total - Indirect Costs |
|---|---|---|---|---|
| £73,356 | £3,418 | £43,416 | £27,360 | £33,744 |
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