Soil & Water Res., 2016, 11(3):196-204 | DOI: 10.17221/15/2015-SWR

Estimated contribution of selected non-point pollution sources to the phosphorus and nitrogen loads in water bodies of the Vltava river basinOriginal Paper

Pavel ROSENDORF, Petr VYSKOČ, Hana PRCHALOVÁ, Daniel FIALA

Department of Protection of Aquatic Ecosystems, T.G. Masaryk Water Research Institute, Prague, Czech Republic

Eutrophication of inland waters by phosphorus as well as loads of coastal and marine waters by nitrogen is a major problem that impedes water bodies to meet the status defined by the Water Framework Directive. In order to reduce the nutrient load on the aquatic environment, first the significance of various pollution types should be thoroughly analyzed. The analysis of phosphorus runoff from agricultural land under normal rainfall-runoff conditions, and of nitrogen runoff associated with the application of manure on farmland shows their different impact on water body status in the Vltava river basin. The assessment of phosphorus indicates that annual specific phosphorus runoff ranges from 0.1 to 9.98 kg/km2 and in the sub-basins of the Upper Vltava, Berounka, and Lower Vltava, the average values from all water bodies reach 4.08, 2.92, and 4.02 kg/km2, respectively. Compared with the allowable capacity of water bodies for achieving a proper status, the average rate of phosphorus input on the load of water bodies comes within 20%, with a maximum value slightly exceeding 50%. This phosphorus input will not be a significant source of eutrophication of inland waters and measures will have to focus rather on other eutrophication sources. Estimating the significance of the impact of manure application on the nitrogen load of water bodies provides a completely opposite picture. The analyses showed that the load of water bodies ranges from very low values in areas without livestock to high loads in tens of kg/ha per year (max. 31.5 kg/ha/year). In the sub-basins of the Upper Vltava, Berounka, and Lower Vltava the annual specific runoff of nitrogen reaches average values for all water bodies (4.8, 3.9, and 5.7 kg/ha, respectively). The assessment of the proportion of nitrogen input on the load of water bodies showed that 25% of cases in the area of the water body may represent a critical load leading to an adverse assessment of ecological status. In many other water bodies it can, however, taking into account the load of mineral fertilizers, lead to exceeding the allowable capacity of water bodies and the risk of not achieving a right status. Nitrogen input after application of manure in soils represents an important source that threatens the right status of waters. Attention should thus be paid to all types of measures that will reduce the load of this source or restrict its transport from soil to waters.

Keywords: eutrophication; nutrients; Water Framework Directive; water quality

Published: September 30, 2016  Show citation