Pollution by Nutrients in the Danube Basin

The assessment of pollution by nutrients in the Danube River has a long-term history at the basin-wide level, especially for estimating the influx of these substances to the Black Sea. The main aim of this chapter is to provide a general overview of the nutrient levels in the Danube Basin based on the data collected in the frame of long-term Trans-National Monitoring Network (TNMN) of the International Commission for the Protection of the Danube River (ICPDR) during 2001–2009. For selected monitoring sections, the dependence of the nutrient concentrations on corresponding daily discharges is also investigated. A comparative view of the surveillance TNMN data and investigative data obtained during the two monitoring programs known as Joint Danube Surveys 1 and 2 (JDS1 and JDS2) is presented. In order to get a general overview of the nutrient levels over the studied period, the temporal trends were analyzed using nonparametric Spearman correlation coefficient before and after removing the impact of the daily discharge on the measured concentration.