Evaluation of concentrations of nitrogen and phosphorus compounds in the middle basin of Biebrza River

The paper presents the assessment of concentrations of nitrogen and phosphorus compounds. The results was compared with surface water Polish norms. Samples of water were taken from 7 sampling points in November 2014 and January – June 2015. The concentrations of nitrate(III) and (V) nitrogen, ammonium nitrogen, phosphate phosphorus(V) were tested in the samples. Research indicates that concentrations of nitrate nitrogen(V) were in class II, while concentrations of nitrate nitrogen(III), ammonium nitrogen and phosphate phosphate(V) exceeded limit values of water quality class II. The results of the analysis show that the forms of land use development near the river is influencing on water quality.