Abstract
Particulate matter (PM) in natural coastal environments can include sea spray aerosol (SSA), mineral dust, and particles from human activities. In a natural and uncontaminated scenario, three measurement campaigns were conducted on the island of Culuccia (Sardinia, Italy) to evaluate the PM concentration and the contribution of SSA in different seasons. The observed trend of concentrations of the various PM fractions confirmed the direct correlation with the main weather-climate parameters like temperature, relative Humidity (rH), and wind speed. Precipitation was not considered since rainfall events were too few in all three measurement campaigns. To evaluate the chemical composition of SSA particles, the collected PTFE filter was analyzed by Raman spectroscopy and SEM-EDX. The combined use of both techniques on the same PM particle represents an innovative approach that allows individual particles to be uniquely identified. The main compounds classes found are carbonaceous fraction, secondary formation salts (nitrates and sulfates), sodium chloride, silicates, and aluminosilicates. In the March and June campaigns, considerable quantities of nitrates and sodium chloride were found; in contrast, in the October campaign, considerable quantities of different types of sulfates were detected, with nitrates and sodium chloride being absent. A correlation between the PM composition and meteorological parameters was observed according to the value of the Deliquescence Relative Humidity (DRH), highlighting the influence of weather and climate conditions on the chemical composition of sea spray in natural coastal environments, especially for the relative humidity and coarse and fine PM trends.