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LABORATORY STUDIES OF THE AQEOUS CHEMISTRY OF FREE RADICALS, TRANSITION METALS AND FORMATION OF ACIDITY IN CLOUDS

Objective

The objectives are to establish reliable kinetic and mechanistic data for key reactions controlling the aqueous chemistry of clouds and fog.
To a large measure, laboratory experiments have resolved the main features of the four principal processes which are thought to be responsible for the formation of acidity in cloud and fog water from sulphur oxidation. The present project and the former within the IVth CEC environmental R&D programme have contributed to this effort. It is timely to incorporate the reaction scheme which has been established into suitable computer models to clarify which processes are the most important in real atmospheric situations.
The laboratory work includes reactions responsible for the oxidation of sulphur species to sulphuric acid and the formation of organic acids.

Modern experimental techniques such as stopped-flow kinetics, laser flash photolysis, pulse radiolysis and advanced analytical techniques are employed to investigate:

the effects of transition metal ions on the oxidation of sulphur by strong oxidants such as hydrogen peroxide, ozone and hydrogen oxychloride.
catalysis of sulphur oxidation by transition metals, mainly by manganese and iron.
the occurrence of hydroxyl and oxy-sulphur radicals in atmospheric droplets during daylight hours.
the effects of transition metals upon free radicals.

The efforts of all participants will be combined to develop a list of key elementary reactions and the associated rate coefficients for application to atmospheric cloud and fog systems.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

MAX-PLANCK-GESELLSCHAFT ZUR FOERDERUNG DER WISSENSCHAFTEN E.V.
Address
Johann Joachim-becher-weg 27
55020 Mainz
Germany

Participants (5)

LUND UNIVERSITY
Sweden
Address
Paradisgatan 2
221 00 Lund
National Power plc
United Kingdom
Address
Kelvin Avenue
KT22 7SE Leatherhead
Private Universität Witten/Herdecke
Germany
Address
Stockumer Straße 10
58453 Witten
UNIVERSITY OF LEEDS
United Kingdom
Address
Woodhouse Lane
LS2 9JT Leeds
École Européenne des Hautes Études des Industries Chimiques de Strasbourg
France
Address
1 Rue Blaise Pascal
67008 Strasbourg