Fig. 9.
Long term mean annual nitrogen (a) and phosphorus (b) fluxes (kg/ha/year) in the Danube River Basin according to SWAT model results in the period 1995–2009. In (a): the diffuse sources are represented by the sum of nitrogen input via fixation (NFIX), nitrogen transported to the soil with the precipitation (NRAIN) and the nitrogen applied as fertilizer (NAPP); NPS is the nitrogen loading to the reach from point sources; the diffuse emissions are the nitrates loading to reach in tile drainage system (NTILE), in lateral flow (LFN), in surface runoff (SRN), in baseflow (BFN) and the organic nitrogen transported with the water yield (ORGN); ORGNRF and SRRF are respectively the organic nitrogen and nitrates reduced by riparian filtering; NLEACH is the nitrogen leached to aquifer; NPYR, NsoilR, Naq, NRF and NriverR are respectively the reduction of nitrogen applied by plant, soil, aquifer, riparian filter strip and river; NLoad is the total nitrogen load at the outlet of the Basin. In (b): the diffuse sources are represented by phosphorus applied as fertilizer (PAPP); PPS is the phosphorus loading to the reach from point sources; the diffuse emissions are the soluble phosphorus (phosphate) transported in tile drainage system (PTILE) and water yield (SOLP), the organic phosphorus loading to the reach (ORGP) and the mineral phosphorus adsorbed to sediment and transported into the reach (SEDPRF); SOLPRF, ORGNRF and SEDPRF are respectively the soluble, organic and mineral phosphorus reduced by riparian filtering; PPYR, PsoilR, PRF and PriverR are respectively the reduction of phosphorus applied by plant, soil, riparian filter strip and river; PLoad is the total nitrogen loads at the outlet of the Basin.