REV. CHIM. (Bucharest) ♦ 63♦ No. 8 ♦ 2012 http://www.revistadechimie.ro 846 Research Regarding Aerosol Properties of the Grimsvötn Ash by Applying Sun Photometry DELIA CALINOIU*, IOANA IONEL*, GAVRILA TRIF-TORDAI Politehnica” University of Timisoara, Faculty of Mechanical Engineering, 1 Mihai Viteazu Blv., 300222, Timisoara, Romania This paper gives the aerosol columnar properties above Timisoara, Romania, informing about the possibility to detect particles dispersion originated from thousands of kilometers distance. Volcanic ash has a peculiar chemical composition and it affects, as demonstrated by this article, much extended areas, far away from the source of origin. The novelty brought by the article addresses a specific episode, over Romania, due to a phenomenon that occurs at major distance, over which until now, one could not suppose normal dispersion of pollutants, and still it exists and is active and out of human control. The study was achieved by end of May 2011, when the Grímsvötn volcano erupted in Iceland, by means of photometry. The sun photometer observation s results, consisting of aerosol optical depth (AOD), Angstrom coefficients, fine and coarse mode concentration and size distribution, allow identifying the volcanic aerosols. The single scattering albedo was detected to be between 0.75 and 0.85, at 440 nm. Keywords: volcanic ash, aerosol, sun photometer, aerosol optical depth (AOD) It is known that volcanic eruption may eject large amounts of ash (aerosols – in function of the types of magma, in special SiO 2 ) and trace gases such as sulphur dioxide (SO 2 ) into the atmosphere. The principal gases released during volcanic eruption are H 2 O, CO 2 , SO 2 , H, CO, HCl, NH 3 , H 2 S, and HF [1]. These ejects can have considerable impact on the visibility and human health [2], and also reduce solar radiation reaching the surface. The effects of volcanic ash depend on the grain size, mineralogical composition and chemical coatings on the surface of the ash particles [3]. The eruption of the Grímsvötn volcano in South - East Iceland (64.41 N, 17.33 W) began on 21th May 2011 at 19:25 GMT [4]. Disruption of the air travel commenced on 22 May starting from Iceland, and reached other locations such as Greenland, Scotland, Norway, Svalbard and a small part of Denmark, on subsequent days. On 24 th May the disruption spread already to Northern Ireland and to airports in northern England. On 25 th May the disruption arrived to Northern Germany, as consequence airports at Hamburg and Bremen were closed for a few hours. On 27 th May Greenlandic airspace was closed due to a concentration of ash over Greenland and the North Atlantic. Ash chemical composition from Grimsvötn eruption on 22 th May is presented in table 1. Sample GR11-01 from Kirkjubaejarklaustur, was collected during the onset of fallout just after midnight 22 th May, 00:58 GMT. Sample GR11-02 was collected in the morning of 22 th May, 08:45 GTM from Horgsland / Sida. Based on chemical composition, the ash classifies as tholeiite-basalt, with no significant difference between samples GR11-01 and GR11-02 [5]. More information on the Grímsvötn eruption, such as description of the eruptive phases, plume heights, size distribution analysis, etc. can be found in the website of the Institute of Earth Sciences (http://earthice.hi.is). The aim of this paper is to investigate the optical, chemical and microphysical properties of the volcanic aerosols based on the AERONET sun photometer * email: delia.calinoiu@yahoo.com; ionel_monica@hotmail.com observations in the Timisoara city from Romania during 26 – 29 May 2011. Timisoara is located in the Western part of Romania, thus it is one of the first areas where the result of the eruption consequences from Iceland were observed. Experimental part The sun photometer is located on the roof of the Mechanical Engineering Faculty of “Politehnica” University of Timisoara (fig. 1, right), with coordinates: 45.74 N; 21.22 E and 122 m altitude. The sun photometer from Timisoara is connected at AERONET site [6], position 645. Figure 1 presents the sun photometer components. This is composed from an optical head, electronic box and a robot [6]. Table 1 ASH CHEMICAL COMPOSITION FROM GRÍMSVÖTN 2011 ERUPTION, Wt [% ] [5]