The aim was to assess the importance of a new atmospheric reaction, recently discovered by the UK team through a current NERC research grant, using the unique simulation chamber facility available in Guangzhou.

The overall science aim of this IOF pump-priming project is to assess the importance of a newly discovered atmospheric chemical process (the SCI + DMS reaction, see Summary text below) through a new international collaboration which brings together leading UK and Chinese expertise and facilities. Our specific objectives are : 1. To develop a new partnership with researchers from the State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIG-CAS), whose expertise and unique atmospheric simulation chamber complements UK capability, through research staff exchanges and a programme of experiments at the GIG-CAS chamber. 2. To perform a series of experiments in the new GIG-CAS atmospheric simulation chamber to assess the impacts of SCI + DMS chemistry upon atmospheric sulphur oxidation, allowing the importance of this new chemistry, discovered through a current NERC research grant, to be assessed.

The wider project context involved atmospheric processing of sulphur species. Well understood atmospheric chemical processes break down the sulphur species - molecules such as dimethylsulphide (DMS) or SO2 - these reactions are driven by OH radicals in the gas phase, and form sulphate aerosol particles, which scatter sunlight and can catalyse the formation of cloud droplets - so the processing of sulphur species exerts a major influence upon climate. Sulphur processing leading to sulphuric acid also contributes to rainwater acidity.

This project used the newly developed chamber in Guangzhou to resolve uncertainties - the GIG chamber instrumentation can detect the gas- and condensed-phase DMS oxidation products, and has recently been used for a study of SCI chemistry in vehicle exhausts. The project consisted of PI / research staff exchanges to plan and model the chamber experiments in detail, followed by simulation chamber measurements to probe the SCI - DMS system in Guangzhou. These experiments determined the importance of this new reaction, under realistic atmospheric boundary layer conditions. This proposal has developed following discussions between Bloss and Wang at meetings in Beijing, and a visit by Bloss to the GIG facility in March 2015. In addition to the specific science goals, it nurtured a developing collaboration between UK groups (with substantial expertise in the conduct of simulation chamber experiments) and leading Chinese researchers at GIG (with unique chamber facilities) in atmospheric chemistry, with potential for future links, for example in the context of forthcoming NERC-Newton-NSFC "Urban Air Pollution in a Chinese Megacity" projects. China is rapidly emerging as a research-leading nation, and this engagement links to top scientists (i.e., within the Chinese Academy of Sciences) thereby supporting the UK's international reputation in atmos