The South Asian rivers show a discharge weighted average NO3-N of 2 mg/l and average sediment-bound N, that is mostly organic, of 0.2%. The reported global average for the uncontaminated river system is of the order of about 0.028 mg/l (NO3-N). Hence, our freshwater aquatic systems can no longer be considered natural, at least with respect to nitrogen transport.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/nitrogen-transport-rivers-south-asia
[2] http://admin.indiaenvironmentportal.org.in/category/author/v-subramanian
[3] http://admin.indiaenvironmentportal.org.in/category/journal/current-science
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/river-pollution
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rivers
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sedimentation
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sediment-transport
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/oxides-nitrogen-nox
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/bangladesh
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/south-asia