The production of electrolytic nickel includes the stage of leaching of captured firing nickel matte dust. The solutions formed during this process contain considerable amounts of Pb, which is difficult to extraction due to its low concentration upon the high-salt background. The sorption of lead from model solutions with various compositions by synthetic and natural titanosilicate sorbents (synthetic ivanyukite-Na-T (SIV), ivanyukite-Na-T, and AM-4) have been investigated. The maximal sorption capacity of Pb is up to 400 mg/g and was demonstrated by synthetic ivanyukite In solutions with the high content of Cl⁻ (20 g/L), extraction was observed only with a high amount of Na (150 g/L). Molecular mechanisms and kinetics of lead incorporation into ivanyukite were studied by the combination of single-crystal and powder X-ray diffraction, microprobe analysis, and Raman spectroscopy. Incorporation of lead into natural ivanyukite-Na-T with the R3m symmetry by the substitution 2Na⁺ + 2O²⁻ ↔ Pb²⁺ + □ + 2OH⁻ leds to its transformation into the cubic P−43m Pb-exchanged form with the empirical formulae Pb_1.26[Ti₄O_2.52(OH)_1.48(SiO₄)₃]·3.32(H₂O).

This article presents the results of the analysis and estimation of the seasonal variation of heavy metals in the water of urban lakes and the assessment of their environmental state based on the chemical data. The research covered seven lakes in Murmansk, subject to various levels of anthropogenic load. Field studies were conducted in 2019–2020. Water samples were taken both in summer and in winter/spring seasons. The most polluted lake was Lake Ledovoe, where the highest concentrations of V, Cr, Co, Ni, Cu, W, and Mn were found. Lake Yuzhnoe, which is characterized by the lowest concentrations of studied heavy metals, was the least subject to anthropogenic load. In total, V, Ni, Zn, Fe, and Mn were above the background levels in the lakes of Murmansk. The analysis of the seasonal variation showed that the highest concentrations of heavy metals were found in winter/spring season and reached their maximum during the period of melt water intake from the catchment area. The research showed the impact of the urban environment on the chemical composition of the Murmansk lakes.