The key nutrients affecting the Danube ecosystems and leading to eutrophication processes are phosphorus and nitrogen, both of which enter the river basin from point sources such as municipal, industrial and agricultural facilities, as well as diffuse sources throughout the catchment area, where nutrients originate from erosion and surface runoff, groundwater inflow and atmospheric deposition.
A significant share of the nutrients from diffuse sources are of natural origin, but excess nutrients are also widely released due to human activities, notably farming.
What the ICPDR is doing
Modelling Nutrient Emissions: The Institute of Freshwater Ecology and Inland Fisheries of Leibniz, Germany, is compiling a harmonised inventory for point and diffuse sources of pollution. The model MONERIS (MOdelling Nutrient Emissions in RIver Systems) has been developed and applied in the Danube River Basin to estimate nutrient emissions into surface waters from point and various diffuse sources. The total nutrient input into the Danube River Basin amounts to 68,000 tP/a and 758,000 tN/a.
While point source emissions from wastewater treatment plants and industrial sources are discharged directly into the rivers, the diffuse source emissions that end up in surface waters have many different pathways.
About half of the nutrients discharged into the river are from agricultural sources, a quarter from industrial sources, and a similar proportion from settlements. The main pollution sources in addition to industrial and municipal wastewater include chemical fertilisers and manure from intensive farming operations, petrochemical processing plants, iron and metal processing plants, timber, paper and pulp plants, and municipal solid waste disposal sites.
daNUbs was a mulitnational EU research project carried out under the leadership of the Technical University of Vienna. The results from this project include estimates of nutrient inputs into the river network (MONERIS), as well as an assessment of the loads of nitrogen, phosphorus and silica transported via the river network. These results indicate that the nutrient status in the Black Sea has significantly improved since the 1980s.
ICPDR Danube Watch: The Danube-Black Sea clean-up story
ICPDR Danube Watch: A new device allows farmers to increase crop yields by providing the exact amount of fertiliser needed, while limiting the amount of nutrients that end up in rivers and water systems.