Establishing Regional Maximum Permissible Metal Concentrations in Lake Imandra

This study aims to substantiate regional maximum permissible concentrations (MPC) of metals in the water of Lake Imandra. Primary hydrochemical monitoring data from 1991 to 2018 were used for the calculations. The regional MPCs of six metals – total iron, copper, manganese, zinc, nickel, and aluminum – were determined. Three calculation methods were applied: the S.A. Patin method, the D.G. Zamolodchikov method, and the method developed by E.V. Venitsianov and co-authors. The S.A. Patin method uses two parameters: the average concentration (C_avg) of the chemical element during the study period and its standard deviation (σ). The D.G. Zamolodchikov method relied on the upper and lower quartiles (UQ and LQ) of the distribution. The E.V. Venitsianov method employed three parameters: sample size, the upper quartile of the distribution, and the standard deviation for a quantile of approximately 0.75. The principle of sanitary maximalism was used to identify the optimal method for calculating regional MPCs. The E.V. Venitsianov method was found to be the most suitable. A strong correlation was observed between the natural logarithms of regional MPCs and the natural clarkes of metals in the Earth’s crust.