BACKGROUND LEVELS OF ATMOSPHERIC HYDROCARBONS, SULFATE AND NITRATE OVER THE WESTERN MEDITERRANEAN

Aerosols collected on top of Alfabia ridge (approximately 1100 m; Mallorca Island) have been analysed for chloride, nitrate, sulphate, aliphatic, and polycyclic aromatic hydrocarbons. The results exhibit concentrations in the level of the lowest previously reported for the western Mediterranean atmosphere. However, they are significantly higher than those described for very remote sites, thus defining a background level of particulate atmospheric compounds in this region. Two natural and anthropogenic sources, namely higher plant waxes and coal combustion particles, have been recognized as the main organic inputs to these background aerosols. The former is represented by the major n-alkanes and the latter by the polycyclic aromatic hydrocarbons.