Nitrite is a naturally occurring inorganic form of nitrogen. It is relatively unstable as it is the intermediate species between ammonia and nitrate. Hence, it is usually found in very low concentrations in the environment, less than 0.1 mg/L, and its concentration does not normally exceed 1 mg/L in municipal wastewater.
WHY IS IT IMPORTANT?
Nitrite is the intermediate oxidation state of nitrogen in the oxidation of ammonia to nitrate, and in the reduction of nitrate. Therefore, although it is generally a short-lived compound it provides important information on the kinetics of nitrification and denitrification processes. Due to its high toxicity, a limit of 1 mg/L has been imposed on drinking water.