The sum of the concentrations of all nitrogen forms in water, including ammonia (NH3), ammonium ion (NH4+), nitrite (NO2), and nitrate (NO3), and dissolved and particulate organic nitrogen expressed as elemental nitrogen.
TOTAL NITROGEN

The sum of the concentrations of all nitrogen forms in water, including ammonia (NH3), ammonium ion (NH4+), nitrite (NO2), and nitrate (NO3), and dissolved and particulate organic nitrogen expressed as elemental nitrogen.