nitrat

Nitrat (nitrate) is the NO3− ion, the conjugate base of nitric acid. The ion carries a −1 charge and has a trigonal planar geometry with resonance among three equivalent N–O bonds. Nitrates form a large class of compounds known as nitrates, most commonly as salts such as sodium nitrate (NaNO3), potassium nitrate (KNO3) and calcium nitrate (Ca(NO3)2).

In nature nitrates occur in soils, sediments and groundwater as part of the nitrogen cycle. They are produced by microbial oxidation of ammonia (nitrification) and can be released from mineral deposits. Human activities—especially the use of nitrogen fertilizers, animal manure, sewage and some industrial processes—introduce nitrate to ecosystems on a large scale.

Uses: Nitrates are widely used as fertilizers because they supply readily available nitrogen to plants. They are also employed in the food industry as preservatives and curing agents. Certain nitrate salts have historical or practical roles as oxidizers in explosives and other applications.

Environmental and health aspects: High levels of nitrate in drinking water can pose health risks, notably for infants, and are regulated in many countries. In the body nitrate can be reduced to nitrite, which can interfere with hemoglobin function and, under some conditions, participate in the formation of nitrosamines. Excess nitrate also promotes eutrophication and algal blooms in aquatic systems.

Regulation and management: Regulations set maximum nitrate levels in drinking water; treatment methods include ion exchange, reverse osmosis and denitrification. Agricultural practices such as controlled fertilizer application, crop rotation and vegetative buffers help reduce nitrate leaching.