nitrát

Nitrate, or nitrát, is the polyatomic anion NO3− and the conjugate base of nitric acid. It forms salts with many cations, such as sodium, potassium, and ammonium, and is a common component of soils, water, and minerals. In nature, nitrates arise from microbial oxidation of ammonia and from the weathering of nitrate-bearing rocks, and they accumulate in agricultural soils and groundwater.

Nitrates occur widely in the environment due to natural processes and human activities. They are released from soil and manure, and their concentrations are influenced by rainfall, irrigation, and crop uptake. Industrially, nitrates are produced by neutralizing nitric acid with bases. The most important commercially used nitrates include sodium nitrate (NaNO3), potassium nitrate (KNO3, saltpeter), and ammonium nitrate (NH4NO3). They serve as fertilizers, oxidizers, and raw materials for various chemical processes.

Uses and applications of nitrates are diverse. The primary use is as agricultural fertilizers to supply nitrogen for plant growth. Nitrates also play a role as oxidizers in explosives and propellants. In food production, nitrates can be converted to nitrites, which have historically been used as curing agents; nitrites are more directly involved in meat preservation, while nitrates act as reservoirs that can be reduced to nitrites in the body or in foods.

Health and environmental considerations are central to nitrate management. Elevated nitrate levels in drinking water can pose health risks, particularly for infants, through methemoglobinemia. Nitrates and nitrites can also form nitrosamines under certain conditions. Environmentally, runoff and leaching from agricultural land can cause eutrophication of water bodies and groundwater contamination, affecting aquatic ecosystems and water quality.

Detection and regulation of nitrates rely on analytical methods such as ion chromatography and colorimetric or spectrophotometric assays, often reported as nitrate or nitrate-nitrogen. Regulations vary by country and are designed to protect drinking water and environmental health.