ACID-RAIN ON MT CARMEL, ISRAEL

Wetfall and bulkfall were collected on Mt Carmel, Israel, for three hydrological years, 1989-1992, using an acid precipitation sampler equipped with a moving cover. The analysis of 40 rain events indicated that in more than 65% of the events the pH was acid (< 5-6) and in nearly 40% of the events strongly acid. Only in 12% of the events was the pH distinctly alkaline. Bulkfall collected on the same site had a higher pH, due to much higher Ca2+ and K+ concentrations, suggesting the effects of local aerosols emanating from calcareous soils. The relatively high Na+ and Cl- levels and their Na+/Cl- ratio of 0.866 indicated the marine origin of the major portion of dissolved salts. Alkaline wetfall, strongly enriched in K+, Cl- and Na+, was associated with duststorms. X-ray and chemical analysis of the dryfall (dust) showed the presence of quartz, carbonates, clay minerals, feldspar, halite and gypsum. SO42-, responsible for the acidity of the wetfall, appears to be imported from Central or Eastern Europe, via the Mediterranean Sea, as suggested by back-trajectories of 26 rain events.