Emission of nitrogen and phosphorus in polish rivers: Past, present, and future trends in the Vistula River catchment

The aim of this research was to describe possible actions able to reduce nitrogen and phosphorus Polish river loads with their spatial differentiation. Spatial modeling has been applied for the estimation of potential, application, and effects of such actions at different geographical scales. A GIS oriented model-MONERIS has been validated and applied to calculate possible nutrient reduction. The investigations show that WWTPs are the major source of phosphorus emission. The efficient reduction of P-emission is possible by combining two actions: full implementation of the National Programme of Municipal Wastewater Treatment with the application of nonphosphate detergents. The possible reduction of total phosphorus emission can be as high as 30-50% in 2015 for whole Vistula catchment (compared with the present state). The reduction of nitrogen emission is much more complex, as N-emission is arises mainly from diffuse sources-principally agriculture. The most important sources for emissions are via tile drainage and ground-water. In these cases the most promising actions are to increase the efficiency of fertilizer consumption and decrease the soil erosion. These goals can be achieved by widespread implementation of Usual Good Farming Practice and promotion of additional good practices described in the Code of Good Agriculture Practice.