Abstract
A two-month field campaign was carried out from May to June 2010 at a remote site (Trisaia ENEA Research Centre) in the Southern Italy aiming to identify and quantify the changes of aerosol chemical composition in the presence of Saharan dust. The 24-hr PM_(10) and PM_(2.5) filter samples were analyzed by mass, carbonaceous species, inorganic ions and elemental composition. Saharan dust transport events were identified with two approaches: one recommended by EC (2011) and one based on indicators derived from measurements. Three indicators were used: PM_(2.5)/PM_(10) mass concentrations ratio, Ca/Al ratio and Al concentration. Based on these criteria, four Saharan dust transport events were identified, but only one had elevated dust concentration and leaded to an exceedance of the European short-term (24 hour) limit value of 50 μg/m^3 for PM_(10) (June 16^(th)). The comparison of chemical composition of fine and coarse aerosol fractions during dust and non-dust conditions shows that the presence of dust increases NH_4 and nssSO_4 concentrations in the fine fraction and NO_3 and nssSO_4 concentrations in the coarse fraction. OC and EC concentrations also increase in the fine fraction during dust transport. The uptake of primary and secondary species, inorganic and organic, by dust particles changes their composition and, thus, their properties and this may have implications for human health and climate change.
Highlights
Mineral dust particles originating in the Sahara desert are frequently transported over the whole Mediterranean area.An eleven years study of Saharan dust outbreaks in the whole Mediterranean basin revealed that the dust transport paths have a marked seasonal behavior (Pey et al, 2013)
This study shows the daily mineral dust concentrations in the coarse and fine aerosol fractions and identifies the related changes in chemical composition at a rural background site, located at ENEA Research Centre of Trisaia, Southern Italy
Several dust events were identified during the campaign, the highest levels of both PM10 and PM2.5 concentrations observed at ground occurred between June 14th and 18th
Summary
An eleven years study of Saharan dust outbreaks in the whole Mediterranean basin revealed that the dust transport paths have a marked seasonal behavior (Pey et al, 2013). The western Mediterranean area is more subjected to dust intrusions during the summer season while in the eastern part dust events are more frequent during the autumnspring period. Southern part of Italy is affected by Saharan dust intrusions in all seasons. These events may lead to substantial increase of aerosol mass concentrations (Perez et al, 2008; Pederzoli et al, 2010; Remoundaki et al, 2013, Marconi et al, 2014), leading to exceedances of the PM10 daily limit value (50 μg/m3)
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