EFFECT OF NITROGEN TRANSFORMATIONS ON WATER QUALITY IMPROVEMENT

Abstract

The issue of water quantity and quality is relevant worldwide. The research aimed to determine the quality of water of the Marvelė stream in the area and its pollution by nitrogen compounds entering with drainage water from the adjacent farmland was carried out in the practical training base (Alšėnai eldership) of Kaunas University of Applied Sciences. The research revealed that the concentrations of nitrogen compounds in the stream (during the spring, when the average water temperature is about 120 C) are not high, fixed average NO3-N = 9.58 mgL-1 , and is mean – poor water quality by assessment of classes of ecological potential. The amount of dissolved oxygen, dissolved mineral salt concentrations, and changes in water pH indicate that there are intensive biochemical processes and transformations of nitrogen compounds in the water. Under the investigated conditions, chemical changes in water composition were determine due to suitable conditions in the water: optimal temperature and oxygen content (R2 = 0.69; p = 0.05) for nitrification processes to occur. The denitrification process takes place in the water, during which nitrogen is transformed into gaseous form. Was recorded during 11th -12th sampling (when O2 < 3.5 mgL-1 ). It can be assumed that active microbiological processes take place at higher temperatures, which is also confirmed by the statistical dependence of dissolved oxygen consumption and nitrate nitrogen concentration (n = 12, p = 0.02), as well as TDS, dynamics of mgL-1 values (n = 12, p = 0.04).