Filter (0.4µm)

The leaching of aerosol particles by cloud condensation is dependent on pH and also on the weathering state of the particle. During a leaching experiment, several successive 1st order dissolution reaction can be pointed out. Also, to improve the cloud interaction simulation, a multiphase (solids + liquids) photochemical reactor was build and tested. Preliminary experiments have shown a strong influence of the irradiation on transition metals dissolution rate. Aim of the research Dissolved transition metals are potential catalysts for different processes in the liquid phase, such as the SIV oxidation or the HOx cycles. Large uncertainties arise from estimations of trace metals concentrations in tropospheric waters. The chemical composition of cloud water varies according to the incorporation of atmospheric aerosols and gaseous species, and some products of chemical reactions taking place within the droplets. Trace metals in cloud water are exclusively coming from the solid aerosols dissolution in heterogeneous multiphase chemical reactions, where photon absorption may play a role. Activities during the year Using the kinetic data accumulated last two years during dissolution experiments in the dark (CMD-APP Reports: "Trace metals dissolution affecting aqueous chemistry " (1998), "Trace metals supply and acid-base reactions in cloud and rain water " (1999)), a successive 1st order dissolution kinetic scheme was proposed, where several minerals are dissolving themselves one after one. Beside, a photochemical dissolution reactor was build and tested (Figure 1); first preliminary results are showing that irradiation of the aerosol and water mixing enhance the dissolution rate for transition metals but not for others. samplin