Grey water footprint as an indicator for diffuse nitrogen pollution: The case of Navarra, Spain.

Nitrogen is an essential element for plant growth, while its application and associated pollution is a worldwide concern. Generally, diffuse source pollution and its impacts on ecosystem health are difficult to monitor and regulate. Here we used the grey water footprint (GWF) and water pollution level (WPL) indicators, based on a soil nitrogen balance approach to differentiate between surface and groundwater, in order to better understand and quantify the pressure that nitrogen fertilisation generates on freshwater.