Quantitative determination of minerals and anthropogenic particles in some Polish peat occurrences using a novel SEM point-counting method

Abstract

A method is proposed for determining the mineral composition of peat using scanning electron microscope. In an illustrative example, five groups of particles occurring in amounts of >0.05 % are distinguished in peat from Puścizna Mała bog in the Carpathian foreland, Poland. These are spheroidal aluminosilicate particles (SAP), feldspars, nondescript aluminosilicates (mainly clays), silica (quartz and opaline silica), and Fe(hydro)oxides. Two more site-specific groups (barite and ZnS) are distinguished in highly polluted fens (Bagno Bruch and Bagno Mikołeska) near a zinc smelter in Upper Silesia. At Bagno Bruch, peat contents of predominantly authigenic ZnS microspheroids range up to 1.1 %. SAP originating from coal-burning power stations account for maximum concentrations of <21–39 % of the inorganic fraction in the studied mires. SAP concentrations vary with depth, and mean spheroid diameters with distance from emission sources. A distinct feature of SAP is their common enrichment in Ti what questions the use of Ti as a proxy for soil dust in fly ash polluted bogs. As amounts of anthropogenic magnetic spherules, less abundant than SAP in all mires, relate to water table level position, they are unsuitable as tracers of air pollution. The proposed method is recommended for application with peats having ash contents > ~4 %.