DISSOLUTION OF TRACE-METALS FROM LAVA ASH - INFLUENCE ON THE COMPOSITION OF RAINWATER IN THE MOUNT-ETNA VOLCANIC AREA

Dissolution of trace metals from lava ash of the Mount Etna volcano in aqueous suspensions is studied as a function of solution pH and aeros ol mass loading. The sate of dissolution and the final concentration i ncrease with decreasing pH. Leaching experiments are found to be consi stent with the observations of these metals in rainwater of the volcan ic area. Elements such as Fe and Mn are important in the aqueous oxida tion of SO2 which increases the acidity of the rainwater. Leaching of Na, Ca, K, Fe and Mg may have a buffering effect in reacting with clou d and aerosol droplets. (C) 1998 Elsevier Science Ltd. All rights rese rved.