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.
An assessment was made of the effectiveness of reclamation using sewage sludge for the accelerated formation of a stable erosion-proof vegetation cover on the unproductive anthropogenic soil of a sand quarry in the context of the Kola North. The experiment, launched in 2017, included three treatments: control – no treatment, experiment 1 – fragmentary (50 %) application of sewage sludge, experiment 2 – continuous application. In the sixth growing season, anthropogenic soil samples were examined, and measurements of CO2 emissions were carried out. It was shown that the application of sewage sludge had a positive effect on the physicochemical and agrochemical properties of the soils: in situ pH and density decreased, hygroscopicity increased, available phosphorus and potassium increased. Significant differences (p < 0.05) were found between CO2 emissions in the control and experimental treatments. The content of organic carbon in the control treatment was lower than in the experimental ones; under fragmentary application of sewage sludge, it was three times lower, and under continuous application, it was nine times lower. Significant (p < 0.05) differences in the content of carbon and nitrogen in cold and hot water extracts between control and treatment samples were found under continuous application of sewage sludge. At the same time, by calculating the C/N ratio, a very low level of nitrogen was found in the humus. The main factors behind the variability of the estimated parameters were identified – the treatment itself and the method of its application, the contribution of the treatment alone was 60 %, the contribution of the application method was 14 %. Taking into account the economic factors, fragmentary application of sewage sludge onto the anthropogenic sand quarry soil is recommended to support the establishment of a stable erosion-proof phytocenosis.
