Chemical and isotopic characterisation of bulk deposition in the Louros basin (Epirus, Greece)

Abstract

About 120 rainwater samples were collected through a network of five bulk collectors in the area of the Louros basin (Epirus, Greece) during the wet season from October 2008 to August 2009. They were analysed for their isotopic (δD and δ18O) and chemical (H+, Na+, K+, Mg2+, Ca2+, NH4 +, F−, Cl−, Br−, NO3 −, SO4 2 −) composition. A local meteoric water line (δD‰ = 5.80 ± 0.02 δ18O‰ + 0.02 ± 0.12) and a local isotopic lapse rate (−0.18 δ18O‰/100 m) were obtained considering the volume-weighted means of the five sampling sites. These results agree well with those obtained in nearby areas. The chemical composition of the samples allows to identify an almost entirely marine origin for chloride and sodium with decreasing deposition values at increasing distance from the coast. Nitrate and ammonium are almost completely of anthropogenic origin, calcium and potassium are overwhelmingly geogenic, sulphate has a prevailingly anthropogenic origin with a significant marine contribution and magnesium has a mixedmarine and soil dust origin. Finally, as for most of the Mediterranean area, rainwater acidity is buffered by the dissolution of the abundant geogenic carbonate aerosol.