Eyjafjallajoekull volcanic ash in southern Italy

摘要

PM2.5 in situ measurements were performed at the lstituto di Metodologie per l'Analisi Ambientale of the National Research Council of Italy (CNR-IMAA, Tito Scalo - Southern Italy) beginning 20 April 2010, the date when the Eyjafjallajokull volcanic ash plume first arrived over Southern Italy. The PM2.5 particles collected during the passage of the volcanic ash were analyzed for concentration, chemical composition, and mineralogical and morphological features. PM2.5 and Al, Ca, Fe, K, Mg, Mn, and Ti daily concentrations increased during the first days of sampling and reached their highest value on 22 April. On that day, ground-based remote sensing observations performed at the CNR-IMAA Atmospheric Observatory (CIAO) showed the volcanic ash mixing with the underlying local aerosol layer. A Field Emission Scanning Electron Microscope and Energy-Dispersive X-ray Spectroscopy (FESEM-EDS) analysis performed on the PM2.5 samples collected during the period under study revealed the falling of the volcanic ash particles onto the ground. Ash particles were distinguished from background particles in both the fine and coarse size fractions. In particular, complex secondary aerosols (mainly sulphates and nitrates), likely related to the Eyjafjallajokull volcanic emissions, were found in the fine fraction. The coarser volcanic particles were mainly composed of minerals associated with basaltic-to-andesitic magmas. SEM observations conducted on volcanic particles showed that the surfaces of the smallest particles contained condensate phases of soluble components, mainly derived from the oxidation and hydration of SO_2 released during the eruptions. The volcanic ash particles were mainly concentrated in the samples collected on 21-22 April. This agreed with the increase in the concentration of PM2.5 and the volcanic ash-related chemical elements measured in the PM2.5 samples.