Scientific publications

The quality characteristics of the transboundary flow of the Lenderka River across the border to Finland were calculated using an automated software complex (APC) with the input of data obtained during regime observations of the North-Western Administration for Hydrometeorology and Environmental Monitoring for the period from 2003 to 2012. The main characteristics of the river flow quality were, firstly, volume shares of the water flow contaminated with individual chemical components and, secondly, volume shares of the water flow differing in total pollution (Vpoll%). In the first case, the average values of Vpoll% in the series Fetotal, pH, Cu2+, O2 %, BOD5, and oil products decreased over the study period from 100 to 2.4 %. In the second case, the calculations showed that the river flow averaged over the entire period in accordance with the Guideline 52.24.643-2002 consists of 73.91 % “relatively clean” 1st class water and 26.09 % “slightly polluted”2nd class water. Factor analysis showed that factor 1, which accounted for more than 48 % of the total variance, was of primary significance for the interannual variation of the water flow quality. It depends on interannual fluctuations in the water discharge. Factor 2 (contributing more than 21 %) depends on the water temperature in the cold period, and factor 3 (explaining more than 14 %) depends on the water temperature in the warm period. The mechanism of the water temperature influence on the flow quality is not yet clear; it is possible that its values depend on the ratio of snow and rain input to the river.