Global Gray Water Footprint and Water Pollution Levels Related to Anthropogenic Nitrogen Loads to Fresh Water

Environ Sci Technol. 2015 Nov 3;49(21):12860-8. doi: 10.1021/acs.est.5b03191. Epub 2015 Oct 22.


This is the first global assessment of nitrogen-related water pollution in river basins with a specification of the pollution by economic sector, and by crop for the agricultural sector. At a spatial resolution of 5 by 5 arc minute, we estimate anthropogenic nitrogen (N) loads to freshwater, calculate the resultant gray water footprints (GWFs), and relate the GWFs per river basin to runoff to calculate the N-related water pollution level (WPL) per catchment. The accumulated global GWF related to anthropogenic N loads in the period 2002-2010 was 13×10(12) m3/y. China contributed about 45% to the global total. Three quarters of the GWF related to N loads came from diffuse sources (agriculture), 23% from domestic point sources and 2% from industrial point sources. Among the crops, production of cereals had the largest contribution to the N-related GWF (18%), followed by vegetables (15%) and oil crops (11%). The river basins with WPL>1 (where the N load exceeds the basin's assimilation capacity), cover about 17% of the global land area, contribute about 9% of the global river discharge, and provide residence to 48% of the global population.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agriculture
  • China
  • Crops, Agricultural
  • Environmental Monitoring
  • Fresh Water / chemistry*
  • Nitrogen / analysis*
  • Rivers
  • Water Pollutants, Chemical / analysis
  • Water Pollution / analysis*


  • Water Pollutants, Chemical
  • Nitrogen