Concentration of Nitrogen (NO3+NO2) in Rivers, Lakes and Groundwater

In water, nitrogen (N) occurs as nitrates (NO3-) and nitrites (NO2-). These are naturally occurring ions that are part of the nitrogen cycle. Nitrate is used mainly in inorganic fertilizers, and sodium nitrite is used as a food preservative, especially in cured meats. In most countries, nitrate levels in drinking-water derived from surface water do not exceed 10 mg/liter, although nitrate levels in well water often exceed 50 mg/liter; nitrite levels are normally lower, less than a few milligrams per liter (WHO 2004).