Objective
Dimethyl sulphide (DMS) is the major biogenic sulphur gas emitted to the atmosphere and it has been recently estimated to contribute as much as 40 % to the global column of atmospheric sulphate (SO4 2-). DMS, emitted by the oceans, has tentatively been identified as the major precursor of initially condensation nuclei (CN) and eventually cloud condensation nuclei (CCN) in remote marine regions.
Thus, it has been postulated that DMS may have a significant influence on the Earth's radiation budget and possibly in climate regulation. This influence might be even larger than anticipated if the recent suggestion that substantial amounts of DMS may reach the upper troposphere over convective regions is validated. The exact nature and extend of the interaction between DMS and climate cannot presently be assessed with a high degree of reliability due largely to uncertainties in the product distributions from the oxidation of DMS.
The present research project proposes to concentrate on investigating the reaction pathways in the oxidation of DMS which have been designated in previous research projects as being those most likely to produce H2S04 and MSA aerosols, the principal precursors of marine atmospheric aerosol and eventually CCN. The issues to be addressed, which are currently thought to be most crucial for an understanding of the tropospheric DMS chemistry and assessing the magnitude of its regulatory influence on climate, will include:
1. The mechanism of CN generation via the DMS-SO2-H2SO4 pathway or alternatively via DMS-SO3-H2S04 without the intermediacy of SO2 formation.
2. The relative contribution of MSA and H2SO4 to CN formation (MSA/nss-SO4 2- ratio) in the marine troposphere but also in the upper troposphere (a new issue). What are the factors controlling its seasonal and latitudinal variation: temperature, NOx or the nature of the oxidant (mainly OH and NO3, eventually also Cl or BrO).
3. The formation yield of DMSO under different atmospheric conditions ; its heterogeneous loss and kinetics and products of its further gas phase oxidation; relative yields of SO2, MSA and DMSO2
4. The influence of heterogeneous oxidation of SO2 (e.g. on sea salt) on the H2SO4/SO2 yield.
5. The aqueous phase oxidation of DMSO and DMSO2 and its relative importance compared to gas phase oxidation
The project will consist principally of laboratory studies combining state-of-the-art laboratory methods to investigate individual reaction steps and overall mechanisms under realistic atmospheric conditions. A chemical module for DMS oxidation will be made available for integration in chemistry-transport models.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques.
- natural scienceschemical scienceselectrochemistryelectrolysis
- natural sciencesearth and related environmental sciencesatmospheric sciencesmeteorologytroposphere
You need to log in or register to use this function
Call for proposal
Data not availableFunding Scheme
CSC - Cost-sharing contractsCoordinator
45071 ORLEANS
France