SOLUBILITY OF MAJOR SPECIES IN PRECIPITATION - FACTORS OF VARIATION

The soluble and insoluble fractions of Cl, S, K, Ca, Zn, Al and Fe have been analyzed in six and 29 precipitation events collected in two rural sites in France, in Brittany and in the Vosges, respectively. The results are compatible with those of previous studies: Cl and S are soluble to the extent of more than 97%; K, Ca and Zn are more variable, with insoluble fractions up to 13%; Al and Fe are present in insoluble forms to the extent of about 80%. Large solubility variations are found for K, Zn and Al, with significant correlation with the pH for the latter. In the same way, the soluble percentages of K and Al are greater in the Vosges for precipitation events associated with air masses originating from the north and east sectors with high anthropogenic activities and high acidities. Finally, for a sequentially collected snow event, it is shown that although the pH is stable, the soluble and insoluble Al forms evolve differently, indicating differentiated enrichments and/or scavenging phenomena. © 1990.