Regional Standards for the Maximum Permissible Concentrations of Metals in Lake Ilmen

Abstract— The regional concentrations of metals in Lake Ilmen were substantiated. The calculations employed the primary data of hydrochemical monitoring over the period 2000‒2020, borrowed from materials of the North-West Administration for Hydrometeorology and Environmental Monitoring. The results of the calculations of the environmentally acceptable concentrations (EACs) of seven metals (total iron, copper, lead, cadmium, manganese, cobalt, and trivalent chromium) were presented. Three different methods were used for the calculations: Patin’s method, Zamolodchikov’s method, and the method proposed by Venitsianov and co-authors. In the calculations by the Patin’s method, two indicators were used: the average concentration of a chemical element for the period under review and the standard deviation. The calculations by the Zamolodchikov’s method were based on the use of the upper and lower quartiles of the distribution. In the calculations by the method proposed by Venitsianov and co-authors, three indicators were used: the sample size, the upper quartile of the distribution, and the standard deviation for the quantile of ~0.75. Based on the principle of sanitary maximalism, the method proposed by Venitsianov and co-authors was substantiated as optimal for calculating regional maximum permissible concentrations of the metals. A very tight correlation between the EACs of the metals and their abundances in the Earth’s crust (clarkes) was revealed.