Distribution of iron and its minerals in river sediments of Eastern Donbass

Abstract

Relevance. Within the coal-mining regions of the Eastern Donbass among the technogenic geochemical flows technogenic mine waters play a special role, they carrying about 800 tons of iron annually into the river network. As in the aquatic environment iron is also accumulates in river sediments, which performing deposition functions and at the same time, under certain hydrological conditions serving as a source of secondary pollution of the aquatic environment with iron as well as other typomorphic metals of technogenic mine waters. Aim. Study of iron and its main minerals distribution in the river sediments of the Eastern Donbass, assessment of the role of natural and technogenic factors in this distribution. Methods. When analyzing the iron content special attention was paid to the pelitic fraction of sediments with a particle size of less than 0.01 mm. The study of the authigenic iron minerals assemblage have carried out using electron probe methods on a scanning electron microscope VEGA II LMU with an energy dispersive microanalysis system. Results. Iron content in the river sediments of the Tuzlov basin exceeds those in the Seversky Donets basin, especially in the pelitic fraction. This is due to the fact that the load of highly mineralized technogenic mine waters on river systems is much higher in the Tuzlov basin. It was revealed that, in general, iron concentrations are higher in the small rivers sediments than those in the middle river sediments, both in total samples and in the pelitic fraction. A positive correlation has been established between the amount of pelitic fraction and the iron content in river sediments, regardless of the size of the river. The main occurrence form of iron in river sediments is mineral. The main iron minerals in the studied river sediments are iron hydroxides, magnetite, pyrite, siderite, and ilmenite. It has been found that content of authigenic iron minerals in small rivers sediments are almost twice as high as those in the middle rivers sediments. The influence of technogenic mine waters on river sediments appears in an increase in the content of authigenic iron minerals, which are formed under conditions of constant iron supply with mine waters in predominantly pelitic alluvium enriched in organic matter.