Use of a Macrokinetic Dose–Response Model for Assessing Permissible Levels of Cu(II) and Ni(II) in Soils of the Norilsk Industrial Region

Abstract— The results of a pot experiment aimed at establishing soil quality standards for the contents of Cu(II) and Ni(II) in different soil types of the southwestern part of Taimyr: podbur, cryoturbated peat gleyzem, raw-humus cryozem, and cryometamorphic gleyzem (Spodic Cryosol, Histic Gleyic Cryosol, Turbic Cryosol, and Gleyic Cryosol). The experiments were carried out under conditions of artificial pollution, which was created by the combined application of CuSO4 and NiSO4 at doses of up to 500 mg/kg. Red fescue (Festuca rubra L.) was used as a test plant. The dependence of plant growth indicators (germination, shoot length, biomass) on the concentrations of mobile and water-soluble forms of metals in the soil was studied. It was established that phytotoxicity is determined not by the total content of metals in the soil, but by their bioavailability, which is controlled by key soil properties: acidity, cation exchange capacity, and organic matter content. Using the Gendugov–Glazunov macrokinetic model, the critical content of Cu(II) and Ni(II) in the soil was calculated, the excess of which causes plant suppression. For metal forms extracted by an ammonium acetate buffer, this value varied from 14.6 to 299.5 mg/kg for Cu (II) and from 12.0 to 228.0 mg/kg for Ni (II) and depended on the soil type and sampling depth. For water-soluble metal forms, the range was several orders of magnitude lower and varied from 0.2 to 2.6 mg/kg for Cu(II) and from 0.1 to 1.1 mg/kg for Ni(II). Peat gley soil had the highest buffer capacity and, consequently, plant resistance to pollution, while podbur and cryometamorphic gleyzem were the most vulnerable. The results of this study are proposed for use in the development of regional soil quality standards for the Norilsk industrial region.