Variability in regional background aerosols within the Mediterranean 1Institute of Environmental Assessment and Water Research (IDǼA), Dept. of Geosciences CSIC, LLuis Solé i Sabarís S/N, 08028 Barcelona, Spain
2Environmental Chemical Processes Laboratory, Dept. of Chemistry, University of Crete, P.O. Box 1470, 71409 Heraklion, Greece
3Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Metaxa & V. Pavlou, 15236, Athens, Greece
4Institute of Marine Sciences, Middle East Technical University, P.O. Box 38, 33731, Erdemli-Mersin, Turkey
Received: 05 March 2009 – Published in Atmos. Chem. Phys. Discuss.: 23 April 2009 Abstract. The main objective of this study is the identification of major factors
controlling levels and chemical composition of aerosols in the regional
background (RB) along the Mediterranean Basin (MB). To this end, data on PM
levels and speciation from Montseny (MSY, NE Spain), Finokalia (FKL, Southern
Greece) and Erdemli (ERL, Southern Turkey) for the period 2001 to 2008 are
evaluated. Important differences on PM levels and composition are evident
when comparing the Western and Eastern MBs. The results manifest W-E and N-S
PM10 and PM2.5 gradients along the MB, attributed to the higher
frequency and intensity of African dust outbreaks in the EMB, while for
PM1 very similar levels are encountered.
Revised: 19 June 2009 – Accepted: 23 June 2009 – Published: 16 July 2009
PM in the EMB is characterized by higher levels of crustal material and
sulphate as compared to WMB (and central European sites), however, RB nitrate
and OC + EC levels are relatively constant across the Mediterranean and
lower than other European sites. Marked seasonal trends are evidenced for PM
levels, nitrate (WMB), ammonium and sulphate. Also relatively higher levels
of V and Ni (WMB) are measured in the Mediterranean basin, probably as a
consequence of high emissions from fuel-oil combustion (power generation,
industrial and shipping emissions).
Enhanced sulphate levels in EMB compared to WMB were measured. The high
levels of sulphate in the EMB may deplete the available gas-phase NH3 so
that little ammonium nitrate can form due to the low NH3 levels.
This study illustrates the existence of three very important features within
the Mediterranean that need to be accounted for when modeling climate
effects of aerosols in the area, namely: a) the increasing gradient of dust
from WMB to EMB; b) the change of hygroscopic behavior of mineral aerosols
(dust) via nitration and sulfation; and c) the abundance of highly
hygroscopic aerosols during high insolation (low cloud formation) periods.
Citation: Querol, X., Alastuey, A., Pey, J., Cusack, M., Pérez, N., Mihalopoulos, N., Theodosi, C., Gerasopoulos, E., Kubilay, N., and Koçak, M.: Variability in regional background aerosols within the Mediterranean, Atmos. Chem. Phys., 9, 4575-4591, doi:10.5194/acp-9-4575-2009, 2009.