[en] Concentrations of 38 elements in brown coal, bottom ash and size fractionated ESP coal ash from the Belchatow I Power Plant were determined by INAA. Based on enrichment factors calculated relatively to iron and average crustal rock composition as a function of particle size the elements are grouped into three classes: Group I, elements that show little or no enrichment in the small particles (Na, Mg, Al, K, Sc, Ti, Mn, Co, Rb, Cs, Ba, La, Ce, Sm, Eu, Lu, and Th); Group II, elements whose enrichment increases greatly with decreasing particle size (Cl, Zn, As, Se, Br, Cd, Sb, and I); and Group III, elements whose behaviour is intermediate to those in Group I and II (Ca, V, Cr, Ni, Cu, Ga, Sr, Mo, In, W, and Au). (author)