Dictionary:

nitrate

  (nī'trāt', -trĭt)

1. The univalent radical NO₃ or a compound containing it, as a salt or an ester of nitric acid.
2. Fertilizer consisting of sodium nitrate or potassium nitrate.

To treat with nitric acid or a nitrate, usually to change (an organic compound) into a nitrate.

Plant nutrients and natural constituents of plants; found in soils and included in fertilizer. The amount in crops depends on the amount in soil. Found in drinking water as a result of excessive use of fertilizers.

Health problems can arise because within a day or two of harvesting some crops nitrates are converted into nitrites which can react with the haemoglobin (especially fetal haemoglobin) in the blood to produce methaemoglobin which cannot transport oxygen. Maximum levels have been established for nitrate levels in drinking water (an upper limit of 45-50 mg nitrate/L has been recommended for infants).

Nitrates are also used, together with nitrites, for curing meat products. See also nitrosamines.

Nitrogen-containing ions (electrically charged atoms) that occur naturally in soils. Soil nitrates are essential for plant growth and levels are increased by artificial fertilizers. Unfortunately, about half the nitrate leaches out into the groundwater and, after a delay of up to 30 years, this nitrate can find its way into public water supplies. After drinking the water, the nitrate may be converted to nitrite by bacteria in the mouth. Once absorbed into the bloodstream, the nitrites can combine with haemoglobin to form a blue pigment, methaemoglobin. The presence of methaemoglobin in the blood reduces its ability to carry oxygen. This can be particularly serious in babies, causing the life threatening ‘blue baby syndrome’. In the UK, nitrate levels in drinking water are monitored. The public are advised (e.g. to give babies bottled water, low in nitrates) when safe levels are exceeded. Nitrate and nitrites are present in small amounts in living animal and plant tissue. Their concentration is significantly higher in preserved cured meats (e.g. bacon and hot dogs) in which they are used to prevent bacterial infections. Nitrates and nitrites have been found to promote cancers of the oesophagus and stomach in laboratory animals, possibly by being converted to carcinogenic nitrosamines. However, the evidence that nitrates cause human cancer is weak and inconclusive. Nevertheless, if nitrates are carcinogenic in humans, vitamin C may offer some protection by inhibiting the conversion of nitrates or nitrites to nitrosamines.

For more information on nitrate, visit Britannica.com.

Nitrate (NO₃) is a compound of the elements nitrogen and oxygen. Nitrates are important to all living systems. Plants, especially, require it to develop and produce seeds. Nitrogen, the main component of Earth's atmosphere, is a relatively inert substance. To be useful, it must be converted into active forms. Lightning and radiation create nitrates in the atmosphere, where rainstorms carry them to the ground. Bacteria on roots of crops such as alfalfa and clover fix nitrogen in the soil. Microorganisms form nitrates as they break down animal matter. Since the early twentieth century, nitrates have been produced industrially.

Nitrates are present naturally in sewage and in some mineral deposits. Chile's Atacama Desert is the world's leading supplier of the mineralized form. Approximately 86 percent of the nitrate produced in the United States is used for fertilizer, though the chemicals have other uses. Potassium nitrate (KNO 3), also known as saltpeter, is the key ingredient in gunpowder. Saltpeter is formed naturally in warm climates by bacteria decomposing accumulations of excreta and animal refuse. Contact among putrefying material, alkaline soil, plant ashes, air, and moisture causes nitrates to form and penetrate the ground. After evaporation of rainwater, saltpeter appears as white powder on the surface.

Since the temperate climates of Europe and North America did not favor the formation of saltpeter, its supply was a vital concern for American colonists. European countries obtained saltpeter from India. When the American Revolution cut off the colonies from this source, some colonial governments offered bounties and established "artificial nitrate works, " without much success. France saved the Continental Army from running out of gunpowder after having taken great pains to develop its own domestic supply. In the early nineteenth century, salt-peter was discovered in large quantities in caves in Kentucky and Tennessee. This resource helped fuel the Confederate armies during the American Civil War, though 90 percent of their powder likely came from foreign sources that managed to get through the Union blockade. After this period, the United States and Europe imported nitrate from Chile.

As the nineteenth century progressed into the twentieth, demand for nitrate fertilizers increased dramatically. Many countries experimented with methods of converting atmospheric nitrogen. All processes seemed expensive and complex. The outbreak of World War I drove the United States to attempt its own synthetic production by 1917. In preparation, a hydroelectric dam was built at Muscle Shoals, Alabama. Soon after, the process introduced in Germany by Fritz Haber in 1912 proved its superiority and the power plant was abandoned. In the 1930s, it became the foundation of the Tennessee Valley Authority.

Nitrates have become an environmental concern. Elevated levels of nitrogen flowing down the Mississippi River enter the Gulf of Mexico and nourish algal blooms. When algae die and decompose, they consume oxygen, depleting that vital element from the water. Fish and other creatures suffocate in affected areas that can cover thousands of square miles, causing problems for commercial fishing and other coastal industries. Sources of the nitrogen include sewage treatment water, industrial wastes, and atmospheric pollutants; large loads also come from livestock operations and nitrate fertilizer runoff from farm-land. Nitrates infiltrate ground water as well as surface waters. According to the Environmental Protection Agency, when nitrates are present in quantities in excess of ten milligrams per liter, the water supply can pose a potentially fatal threat to infants under six months and to young and pregnant animals.

Bibliography

Hill, Michael J., ed. Nitrates and Nitrites in Food and Water. New York: Ellis Horwood, 1991.

Keleti, Cornelius. Nitric Acid and Fertilizer Nitrates. New York: Dekker, 1985.

Wilson, W. S., A. S. Ball, and R. H. Hinton. Managing Risks of Nitrates to Humans and the Environment. Cambridge: Royal Society of Chemists, 1999.

Any salt of nitric acid. High intakes by animals may occur when they eat large quantities of lush herbage that has been heavily fertilized with a nitrogen fertilizer such as potassium or ammonium nitrate. It can also occur after a long drought during which nitrification bacteria accumulate large amounts of nitrate in the soil and the first growth after the drought breaks may also be toxic.
Pigs fed on food residues may ingest potassium nitrate used in meat curing when their swill contains butcher's residues.

• n. explosives — nitroglycerin and others used to blast out water holes and left in the hole may cause subsequent nitrate poisoning.
• n. poisoning — unusual unless animals get access to unguarded fertilizer or butcher shop residue containing potassium nitrate. Causes gastroenteritis with diarrhea and vomiting. Long-term, low level intake thought to cause abortion in cattle. Chief importance is as a constituent of ruminant diet and its conversion in the rumen to nitrite causing nitrite poisoning.
• n. reduction test — a biochemical reaction used in the identification of bacteria, particularly mycobacteria. It is based on the reduction of nitrate to nitrite and/or the release of nitrogen gas.

Trinitrate redirects here. See also glyceryl trinitrate.

An electrostatic potential map of the nitrate ion. Areas coloured red are lower in energy than areas coloured yellow. The oxygen atoms carry the majority of the negative charge.

The structure and bonding of the nitrate ion. The N−O bonds are intermediate in length and strength between a single bond and a double bond.

In inorganic chemistry, a nitrate is a salt of nitric acid with an ion composed of one nitrogen and three oxygen atoms (NO₃⁻). In organic chemistry the esters of nitric acid and various alcohols are called nitrates. Nitrate from food, especially vegetables, is converted in the human digestive tract to nitrite which reacts with amines to form carcinogenic nitrosamines.

Chemical properties

The nitrate ion is a polyatomic ion with the empirical formula NO₃⁻ and a molecular mass of 62.0049. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identical oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a formal charge of negative one, where each oxygen carries a -2/3 charge while the nitrogen carries a +1 charge, and is commonly used as an example of resonance. The three canonical structures of the nitrate ion are shown resonating below:

Almost all inorganic nitrate salts are soluble in water at standard temperature and pressure.

In organic chemistry a nitrate is a functional group with general chemical formula RONO₂ where R stands for any organic residue. They are the esters of nitric acid and alcohols formed by nitroxylation. Examples are methyl nitrate formed by reaction of methanol and nitric acid,^[1] the nitrate of tartaric acid,^[2] and the inappropriately named nitroglycerin.

Related materials

Nitrates should not be confused with nitrites (NO₂^-) the salts of nitrous acid. Organic compounds containing the nitro functional group (which has the same formula and structure as the nitrate ion save that one of the O⁻ atoms is replaced by the R group) are known as nitro compounds.

Effects on aquatic life

In freshwater or estuarine systems close to land, nitrate can reach high levels that can potentially cause the death of fish. While nitrate is much less toxic than ammonia or nitrite,^[3] levels over 30 ppm of nitrate can inhibit growth, impair the immune system and cause stress in some aquatic species.^{[citation needed]} In most cases of excess nitrate concentrations, the principle pathway of entering aquatic systems is through surface runoff from agricultural or landscaped areas which have received excess nitrate fertilizer. These levels of nitrate can also lead to algae blooms, and when nutrients become limiting (such as potassium, phosphate or nitrate) then eutrophication can occur. As well as leading to water anoxia, these blooms may cause other changes to ecosystem function, favouring some groups of organisms over others. Consequently, as nitrates form a component of total dissolved solids, they are widely used as an indicator of water quality.

Nitrates are also a by product of septic systems. Specifically, they are a naturally occurring chemical that is left after the break down or decomposition of animal or human waste. Water quality may also be affected through ground water resources that have a high number of septic systems in a watershed. Septics leach down into ground water resources or aquifers and supply near by bodies of water. Lakes that rely on ground water are often affected by nitrification through this process.

See also

• Ammonium
• f-ratio
• Nitrification

External links

• Case Studies in Environmental Medicine - Nitrate/Nitrite Toxic
• Computational Chemistry Wiki Nitrate

Wikimedia Commons has media related to:

nitrates

References

1. ^ Organic Syntheses, Coll. Vol. 2, p.412 (1943); Vol. 19, p.64 (1939) Link
2. ^ Organic Syntheses, Coll. Vol. 3, p.471 (1955); Vol. 22, p.65 (1942) Link
3. ^ Romano, N, Zeng, C., 2007. Acute toxicity of sodium nitrate, potassium nitrate and potassium chloride and their effects on the hemolymph composition and gill structure of early juvenile blue swimmer crabs (Portunus pelagicus, Linneaus 1758) (Decapoda, Brachyura, Portunidae). Environmental Toxicology and Chemistry 26, 1955-1962.

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Dansk (Danish)
n. - nitrat
v. tr. - nitrere

Nederlands (Dutch)
nitraat (o.a. meststof), nitreren

Français (French)
n. - (Chim) nitrate, engrais azoté
v. tr. - fertiliser, répandre de l'engrais

Deutsch (German)
n. - Nitrat, Nitratdünger
v. - nitrieren, mit Salpetersäure behandeln

Ελληνική (Greek)
n. - αζωτούχο λίπασμα, (χημ.) νιτρικό άλας
v. - προκαλώ νιτροποίηση

Italiano (Italian)
nitrato, nitratare

Português (Portuguese)
n. - nitrato (m) (Quím.)
v. - nitrificar

Русский (Russian)
нитрат, нитровать

Español (Spanish)
n. - nitrato
v. tr. - nitritar, agregar nitrato

Svenska (Swedish)
n. - nitrat
v. - nitrera

中文（简体） (Chinese (Simplified))
硝酸盐, 硝酸钾, 用硝酸处理, 硝化

中文（繁體） (Chinese (Traditional))
n. - 硝酸鹽, 硝酸鉀
v. tr. - 用硝酸處理, 硝化

한국어 (Korean)
n. - 질산염, 질산비료
v. tr. - 질산염으로 포화처리하다, 질산염으로 바꾸다

日本語 (Japanese)
n. - 硝酸塩, ニトロセルロース, 硝酸肥料
v. - 硝酸で処理する, 硝化する

العربيه (Arabic)
‏(الاسم) النترات (فعل) ينترت : يعالج بحامض النتريك‏

עברית (Hebrew)
n. - ‮חנקה, מלח של חומצה חנקנית, חנקת אשלגן או נתרן המשמשת כדשן‬
v. tr. - ‮הוסיף חומצה חנקנית ל-‬

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