Применение материала из бедных вермикулит-серпентиновых руд для рекультивации городских почв и агропочв в Арктической зоне России

The problem of waste disposal in the mining industry is urgent for the Arctic zone of Russia. Significant volumes of overburden rocks from the Kovdor phlogopite deposit, represented by poor vermiculite-sungulite ores, require the development of environmentally safe methods for their integration into economic circulation. The aim of the study is to assess the potential of vermiculite-serpentine concentrate (VSC) obtained from overburden rocks for the remediation of anthropogenically disturbed soils. The prospect of using VSC for improving soil properties is due to its favourable mineral composition (serpentine 30-35, vermiculite 28-31 wt.%). Laboratory experiments prepared mixtures of VSC with agrosoil (10-60 wt.%) and samples of urban soils from three cities in the Murmansk Region (Apatity, Kirovsk, and Monchegorsk) (20 wt.%), differing in the level of anthropogenic impact. The content of chemical elements in two mobile fractions was studied, phytotesting was carried out with French marigolds (Tagetes patula). VSC has an alkaline reaction (рНН2О 8.9) due to the presence of minerals in the composition capable of concentrating Ni; the gross content of this component is 730 mg/kg. It was found that the introduction of VSC increases the alkalinity of soil mixtures and the content of mobile forms of Ca and Mg. In slightly contaminated agrosoil, the content of mobile nickel when adding 10-50 % VSC increases from 1.5 to 2.5 mg/kg, with a content of more than 60 % it decreases below background values. Phytotesting showed that in the range of 10-60 % VSC, the root mass increased from 0.09-0.1 to 0.13-0.18 g/plant, there were no signs of phytotoxicity. For soils of Monchegorsk, characterized by a high level of anthropogenic contamination with nickel and copper, the introduction of concentrate, on the contrary, led to a steady decrease in the content of mobile forms of both metals. Vermiculite-serpentine concentrate can be recommended as a meliorant for soil remediation, poor in macroelements and contaminated with heavy metals.