Atmospheric aerosol episodes over Lithuania after the May 2011 volcano eruption at Grimsvötn, Iceland

Abstract

During the eruption of the volcano at Grimsvötn in Iceland (21 May 2011), an inflow of volcanic pollutants to the atmospheric surface layer of Vilnius, Lithuania from 0700 UTC 24 May until the end of 29 May 2011 was observed. A cloud of volcanic plume rose up from Grimsvötn and reached an altitude of 19km. The analysis of possible volcanic origin PM1 aerosol sources was supplemented with forward and backward air mass trajectories, concentration and composition measurements and size distribution calculations of aerosol particles. According to the forward air mass trajectories from the volcano at Grimsvötn, the plume from the layer of 3000-4500m was advected southeastward from Iceland towards the British Isles and the Baltic Sea. The plume reached Vilnius and descended from the troposphere to the surface after about 86h. After data analysis, four episodes selected in the time series of the atmospheric submicron aerosol particle (PM1) concentration of chemical components (sulfate, ammonium, nitrate and organics) were analyzed with the Aerodyne Quadrupole Aerosol Mass Spectrometer, and calculations of the size-resolved distribution spectra were made. Two clear episodes were detected when the main source of aerosols was the volcano, with well-defined size distribution spectra of PM1 chemical components in the accumulation mode. The ammonium to sulfate molar ratio (ASR) during Episodes 1 and 2 is 0.81, suggesting that sulfate particles were partially neutralized by ammonium and determined by volcanic eruptions. However, during Episodes 3 and 4 the ASR was higher (1.0) and determined by both volcanic and non-volcanic origin components. This study shows that the sulfate emissions from the volcano at Grimsvötn in Iceland reached distances farther than 3000km, and they can have an influence on the local concentration and size distribution spectra of PM1 chemical components. Over the period of the volcanic eruption (Episode 1) the sulfate concentrations increased by a factor of 3 and reached 90% of PM1, while the nitrate and organic levels remained low and unchanged. The volcanic sulfate contribution made up about 250% of the average concentration of anthropogenic sulfate in Vilnius. © 2012 Elsevier B.V.