Composition of individual aerosol particles above the Israelian Mediterranean coast during the summer time

Abstract

Aerosol particles were collected aboard a ship in Haifa Bay and Tel Aviv, Israel, during the summer time. The aerosol particles (6170) were analyzed as individual particles and classified according to their chemical composition, size, number concentration per cubic centimeter and morphology. Most of the aerosol particles could be classified into four groups. The first contains gypsum from the sea and from industrial sources brought in by land breezes. A second group is characterized by continental aluminosilicate and quartz. A third group consists of sea salt mixed with sulfate particles. The fourth group is characterized by an abundance of sulfate particles, some of which are ammonium sulfate brought by the land breezes. The particles were identified as marine and mineral aerosols which originated in Eastern Europe and the Mediterranean sea, while local aerosols brought by land breeze characterized by phosphate, fly ash and soil particles originated in the Haifa industrial zone. In addition, the aerosols were analyzed for sulfates and nitrates. Aerosols of sea and land breezes differed as follows: 1. (1) Sulfate and nitrate concentrations in the aerosols were 5–10 times higher during land breeze than during sea breeze, and the total content of suspended particles was, respectively, 6–12 times higher. 2. (2) Particle size spectra during land breeze were broader than during sea breeze and their concentrations were about 20 times greater. Analyses of individual particles by electron microscopy revealed that during the sea breeze the aerosols contained calcium sulfate, sodium sulfate and sulfuric acid. The sulfuric acid, of pH 2.5, is due to the long-range transport as previously reported ( Ganor et al., 1993) while the other sulfates are from the sea. This explains the high concentration of sulfates in the atmospheric sea breeze above the Israelian Mediterranean coast during the summertime.