Environmental toxicants evaluation in a modern monitoring system - Romanian monitox network area

In this paper a class consisting of 8 environmental toxicants were selected to assess Danube River water quality between Calarasi-Silistra sector until the river flow into the Black Sea, the Romanian Monitox Network Area. A comprehnsive comparison between 2 years of investigations in terms of nutrients contribution, such as different forms of nitrogen (ammonium nitrogen (N-NH4+), nitrite nitrogen (N-NO2-), nitrate nitrogen (N-NO3-), organic nitrogen, total nitrogen (TN)) and phosphorus (orthophosphate phosphorus (P-PO4 -3), total phosphorus (TP)), was made in order to provide information on the spatial and temporal variations of this river water quality. Sampling was performed according to European standards and quantitatively analysed using molecular spectrophotometry using UV VIS spectrophotometer Perkin Elmer Lambda 650S. The obtained results showed differences in nitrite nitrogen loads in surface water samples with higher values in the samples collected from the sampling points situated at the mouths of the Danube River into the Black Sea in 2020. Regarding quality classes, the surface waters were generally framed, in good quality class. The nutrients concentrations, combined in CCME WQI index, give an overview on surface water quality assessement in Romanian Monitox Network Area, with a good quality of Lower Danube (Constanta in 2019 and 2020) and fair quality of Danube Delta in 2020, but very closed to good quality.