Past and future trends in grey water footprints of anthropogenic nitrogen and phosphorus inputs to major world rivers
The grey water footprint (GWF) is an indicator of aquatic pollution. We calculate past and future trends
in GWFs related to anthropogenic nitrogen (N) and phosphorus (P) inputs into major rivers around the
world. GWFs were calculated from past, current and future nutrient loads in river basins using the Global
NEWS model. We present water pollution levels (WPLs), deduced from GWFs for more than 1000 rivers.
The calculated GWFs andWPLs ofthe different river basins showa large variationamong different periods.
WPL values generally increased between 1970 and 2000. For the year 2000 about two-thirds of the basins
have WPL values exceeding 1 for N or P, indicating that the pollution assimilation capacity has been fully
consumed. Even though the other rivers have aWPL < 1, this does not guarantee that at sub-basin level or
within particular periods of the year no eutrophication exists. High WPLs are generally found in rivers in tropical–subtropical areas.