Source and pathway apportionment of nitrogen and phosphorus emission...
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Fig. 8.9 Annual source apportioned nitrogen and phosphorus emission into the Vistula and Oder basins in 1995-2002 and 2003-2008 (please note different scales) (source: Kowalkowski et al., 2012)
In both basins the tile drainage and groundwater were the main pathways of N, while overland ow, erosion, WWTPs, and urban systems played a key role in P emission. Between 1995-2002 and 2003-2008 sub-periods N emission via groundwater dropped by 30% and 37%, while N emission from WWTPs dropped by 15% and 40% in the Vistula and Oder basin (Fig. 8.9). A signiďŹ cant decline in N and P emission via groundwater is an indication of reduced nutrient leaching which in turn could have been connected with reduced pressure in agricultural sector (see to sub-chapter 8.5). More effective N removal from WWTPs in the Oder basin is a result of more advanced measures in nutrient mitigation from point sources in that