9 There are various of sources of waste materials with technologically enhanced concentrations of naturally occurring radioactive materials, especially those with high activities of 226 Ra, 228 U and 232 Th. These include oil and gas industry (1-3), non-uranium mining (copper mining, niobium industry, phosphate and gold industry) (4-6), coal mining (7, 8), and energy production (9-11). The purpose of this paper was to determine the chemical and radiological profile of the slag and ash produced by a coal burning thermoelectric unit of the former chemical factory Adriavinil. The factory was situated in a small Croatian town of Kaštel Suæurac, near Split, on the northeast coast of the central Adriatic (Figure 1). Since 1949, coal had been used to fuel a power unit. It was transported from several coal mines such as Raša in Istria (anthracite), Drinovci and Širitovci near Šibenik (brown coal and lignite) and the broader area of Livanjsko polje in Bosnia and Herzegovina (brown coal and lignite). All coal was the Oreš anin V, et al. COAL ASH LANDFILL IN KAŠTEL GOMILICA Arh Hig Rada Toksikol 2006;57:9-16 source of elevated uranium concentrations and its natural radionuclides. Table 1 shows the activities of 232 Th, 226 Ra and 238 U together with 238 U/ 226 Ra activity ratio of the coal cores (brown coal and lignite) of the Tušnica region in Livanjsko polje (Bosnia and Herzegovina) sampled in 1993. The content of 232 Th, 226 Ra and 238 U in slag and ash increased several times during combustion, which also depended on the inorganic portion of the coal. Slag and ash were deposited in the vicinity of the factory until 1973 and then moved to a more appropriate location a few hundred meters away, at the edge of the town of Kaštel Gomilica, where it was covered with a protective plastic foil and a layer of clay and humus. The area was then fenced in and grassed over. With time the area between the factory and the old depot had gradually been covered with waste materials, which contained slag and ash. At the turn between the 1980s and 1990s, slag and ash were dumped directly into the sea shallows in the south-western section of the facility. Original Scientific Paper CHEMICAL AND RADIOLOGICAL PROFILE OF THE COAL ASH LANDFILL IN KAŠTEL GOMILICA * Višnja OREŠÈANIN 1 , Delko BARIŠIÆ 1 , Luka MIKELIÆ 1 , Ivanka LOVRENÈIÆ 1 , Martina ROŽMARIÆ MAÈEFAT 1 , Gordana PAVLOVIÆ 2 , and Stipe LULIÆ 1 Institute Ruðer Boškoviæ 1 , Institute of Mineralogy and Petrography 2 , Zagreb, Croatia Received in May 2005 Accepted in February 2006 The objective of this study was to determine the chemical, radiological and leaching properties of slag and ash produced by a thermoelectric unit of a former factory Adriavinil and deposited in the area of Kaštel Gomilica near Split, Croatia. A total of 33 samples were analysed. The bioavailable fraction of the slag and ash was estimated using different leaching tests. The waste material was characterized by a high activity of naturally occurring radionuclides 238 U, 235 U and 226 Ra and by elevated concentrations of heavy metals. The concentrations of most heavy metals were three to four times as high as in the common soil. Uranium slag and ash concentration was almost 40 times higher than in control soil. More than 37 % of the total U could be removed from the slag and ash with the sea water. KEY WORDS: heavy metals, leaching, radionuclide, slag and ash *Preliminary report presented at the 6th Symposium of the Croatian Radiation Protection Association with international participation, Stubi ke Toplice, Croatia, 18-20 April 2005