Occurrence and Distribution of Environmentally Hazardous Elements in the Katrishte Lignite Bed, Strouma-Mesta Province, Bulgaria

Abstract

The Katrishte lignite deposit is located in southwest Bulgaria. A new, open pit deposit, it is characterized by high concentrations of Si, Al, Fe, Ni, As, Co, Cd, and Mo. The distribution of these elements is related to the ash content in the coal seam and is divided into three categories: increasing ash content, increasing elemental concentration, and increasing ash content with decreasing elemental concentration and unequal distribution. Most of the elements correlate favorably with ash content and are encountered in the east, west, and southwest portions of an ancient peat bog. Distribution patterns suggest Ni, Co, Zn, and Ca to be derived from terrigenous materials from the southwest, whereas Cu in part, along with Fe, was derived from the southeast; however, all other elements were brought by the water flows around the peat bog. Concentrations of Cd, Ni, Cu, Pb, and Zn are high, such that they are perceived as hazardous and thus the ash should not be used for fertilizer. Deposition of this ash should be done with care, reflecting the high amount of Cd and Ni for most soils, and Cu, Pb, and Zn for soils with a pH of 3.5–5.5.