Nitrate

Nitrate is the polyatomic anion NO3− and a family of salts commonly encountered in chemistry and agriculture. It occurs in many inorganic compounds used as fertilizers, including sodium nitrate, potassium nitrate, calcium nitrate, and ammonium nitrate. Nitrates are highly soluble in water and are widespread in soil and groundwater. In plants, nitrate is a key nitrogen source for growth and metabolism.

In nature, nitrate forms by microbial oxidation of ammonium in a process called nitrification, carried out by bacteria such as Nitrosomonas and Nitrobacter. Plants assimilate nitrate through roots, converting it to amino acids. In oxygenated environments nitrate is relatively stable; under reducing conditions, it can be reduced to nitrite, nitric oxide, nitrous oxide, or nitrogen gas.

Industrial uses of nitrates include their role as essential fertilizers, supplying nitrogen for crop production. Nitrates are also used in the manufacture of explosives and propellants. In food processing, nitrate or nitrite salts are used for curing meats and preserving color.

Health and environmental aspects: high nitrate levels in drinking water can cause methemoglobinemia in infants and are studied for potential cancer risk. Regulatory limits exist for drinking water, typically expressed as nitrate-nitrogen or nitrate concentration. Nitrate contamination can result from agricultural runoff, leakage from storage facilities, and septic systems. Analytical methods for measuring nitrate include ion chromatography and colorimetric assays.