The Holocene sediments in north-eastern Poland are represented by mineral (alluvial and deluvial) and mineral-organic, as well as organic soil formations - peat, mursh and gyttja. The aim of the research was to determine the total content of selected elements and to investigate the mineralogical composition of the clay fraction of various Holocene sediments in north-eastern Poland. For the study, 288 soil samples were collected and total concentrations of Ca, Mg, Na, K, P, Fe, Mn, Zn, Cu after digestion in a mixture of HClO4 and HNO3 were analysed. Mineralogical composition of the clay fraction was analysed by the X-ray diffraction method. The highest average content of Fe, Mn and Zn was found in alluvial sediments in river valleys. The lowest average Mg, K, P, Fe, Mn, and Cu content was determined in mineral sediments in the moraine landscape. The content of the elements in sediments of alluvial river valleys was positively correlated with the amount of clay fraction and, except Mn, with the amount of TOC, whereas in deluvial sediments, only the Fe content correlated with the amount of clay fraction. The highest accumulation of Mg, K, Zn and Cu was found in mineral-organic sediments, while the highest Ca was in peat and gyttja. In alluvial formations in the riverine landscape, minerals from the group of mixed-packet minerals of illite-smectite dominated, with the content of smectite packages being in the range of 60-90% S. There were also small amounts of minerals from the group of illite and kaolinite. In the moraine landscape and in the landscape of ice-dammed lake origin, illite minerals dominated in the clay fraction of deluvial sediments. The presence of smectites, illite-smectite mixed-packet minerals and pedogenic chlorites was also stated. The mineralogical composition of the clay fraction of the Holocene deluvial sediments was similar to the composition of the Pleistocene accumulation sediments.  

25.2.2020