Throughfall deposition of sulfur to a mixed oak and pine forest in

Abstract

The deposition of sulfur in a forest site on Mt. Carmel was monitored during the years 1989–1992. Wet deposition, bulk deposition and dry deposition were monitored on an open site. Through-fall and stemflow were sampled in a natural, mixed pine ( Pinus halepensis) and oak ( Quercus calliprinos) forest. In more than 65% of the rain events, the pH of wet deposition was acidic (⩽ 5.6) and in nearly 40% of the events it was strongly acidic. The average wet deposition was 12.5 kg ha −1 yr −1 SO 4S. This suggested that the wet deposition of SO 4S on the Carmel was in the upper range of unpolluted areas. Bulk deposition contributed 14.3 kg ha −1 yr −1 SO4S. Coarse-grained dry deposition averaged to 58 kg ha −1 yr −1 and the average deposition rate of gypsum was4.9 kg ha −1 yr −1containing 0.92 kg ha −1 yr −1 sulfur. Pine throughfall contained 38 kg ha −1 yr −1 S and oak throughfall contained 18 kg ha −1 yr −1. Pine throughfall thus contained approximately twice as much S than oak throughfall, probably as a result of the much larger specific surface area of pine. Stemflow was negligible. The total S deposition on Mt. Carmel was considerably larger than in unpolluted forests of U.S. and Canada, but smaller than in polluted forests of Germany. The pine forests on the western slopes of the central mountain range seemed to have the important function of “filtering” the air masses that come from the western coastal area, thus preventing S pollution advancing inland.