Nitrogen as a chemical element was discovered by the French chemist Lavoisier in the second half of the 18th century. This gas, which makes up 78.08% of atmospheric air, was called nitrogen, which means “non-life”, i.e. does not support combustion and breathing. Subsequent studies showed that it is nitrogen that plays the most important role in the life of not only plants, but also the entire organic world. The main sources of nitrogen for plant nutrition are nitric acid and ammonium salts. Ammonium Nitric Acid

Nitrogen cycle in nature Nitrates are a necessary part of the nitrogen nutrition of plants, without which complex biological processes of protein synthesis are impossible. Nitrates in plants are reduced to nitrites, which, undergoing further transformations, produce ammonia, the basis of plant nutrition.

Up to 70–80% of nitrates enter the human body with vegetables and fruits. By themselves, they do not pose a health hazard, especially since most of these compounds are excreted in the urine (65–90% per day). However, part of the nitrates (5-7%) when they are found in excess in vegetables, in the gastrointestinal tract can turn into nitrites (nitrous acid salts), which have a harmful effect on the body.

The harmful effects of nitrates and nitrites on the body are manifested in the following: 1) Once in the blood, nitrites oxidize divalent iron into ferric iron. In this case, methemoglobin is formed, which is unable to transport oxygen to tissues and organs, which can result in suffocation. Nitrates Young children are especially sensitive to the effects of nitrites and nitrates, which is due to the poor functioning of their enzymatic system. In addition to children, the group at increased risk of damage to the body by nitrate compounds also includes people suffering from diseases of the cardiovascular and respiratory systems, pregnant women, and elderly people who, even without exposure to salts of nitric or nitrous acid, have an insufficient supply of oxygen to organs and tissues. 2) The danger of nitrates and nitrites entering the body in increased quantities is associated with their pronounced carcinogenic effect. Hb (Fe +2 Fe +3) nitrate reductase methemoglobin (O 2)

Ways of nitrates entering the human body: - The bulk of nitrates enter the human body with canned and fresh vegetables; - Nitrates are also found in animal foods. Fish and meat products in their natural form contain some nitrates (5-25 mg/kg in meat, and 2-15 mg/kg in fish). But nitrates and nitrites are added to finished meat and fish products in order to improve their consumer properties and for longer storage; - Some nitrates can be formed in the human body itself during metabolism. - Nitrates enter the body with water. Typically, city residents drink water that contains up to 20 mg/l of nitrates, while residents of rural areas drink water containing up to 20 mg/l of nitrates;

The Food and Agriculture Commission of the UN FAO has established the maximum permissible amount of nitrates per day for humans to consume - 500 mg. In the CIS countries, the permissible daily dose of nitrates for an adult is taken to be equal to mg (average 312.5 mg), for children it is calculated based on 5 mg of nitrates per 1 kg of body weight. A dose of 600 mg of nitrates is toxic for an adult weighing 60 kg. To receive such a dose, a person must eat 1165 g of cabbage, 1750 g of greenhouse cucumbers, 1750 g of carrots, 700 g of beets, 875 g of radishes or 1000 g of lettuce (at the maximum level) in one sitting. Since these vegetables are not consumed in such quantities, it reduces the risk of nitrate poisoning when included in the diet. During spring periods, a person's intake of nitrates reaches up to 700 mg, regardless of how much food he takes.

There are 3 groups of vegetables and fruits according to the accumulation of nitrates: Groups with a high content of nitrates (up to 5000 mg/kg wet weight): dill, lettuce, spinach, beets, radishes, green onions, melons, watermelons. With an average nitrate content (300 – 600 mg/kg wet weight): zucchini, pumpkin, carrots, turnips, radishes, cucumbers, white cabbage and cauliflower. Low in nitrates (10 – 80 mg/kg wet weight): peas, fruits and berries, beans, potatoes, tomatoes, onions, sorrel.

Accumulation of nitrates in vegetables products The amount of nitrates per mg/kg minimum watermelon 3896 eggplant green peas 4112 cabbage white kohlrabi potatoes onions onion cucumber pepper peppers Sweet Rudish beetroot stuks table celery 9136 pale

Nitrates accumulate in different parts of plants depending on the species and even variety. The largest amount of nitrates, as a rule, accumulates in: - leaf veins, - leaf petioles, - stems, - stalks and covering leaves of cabbage, - skin and surface layers, - root greens, - upper and lower parts of the root crop. More intensely colored fruits and vegetables contain less nitrates than those with an "unripe" appearance, even if this is a feature of the particular variety. For example, green beans contain more nitrates than yellow beans; carrots of more intensely colored varieties accumulate less nitrates than palely colored varieties.

Negative phenomena occur when plants absorb an excess amount of nitrogen, which, due to their genetic characteristics or other reasons, they are not able to use in the usual physiological way. In connection with this, it is necessary to systematically monitor the nitrogen content in the soil and maintain it at the proper level. Nitrogen fertilizers The accumulation of nitrates in plants is a consequence of excessive nitrogen content in the soil. The introduction of large amounts of nitrogen fertilizers, which often occurs, no longer contributes to a corresponding increase in yield, but it significantly worsens the nutritional, technological and hygienic value of the products, and complicates their post-harvest processing and storage.

1) The most effective way to neutralize nitrates is through cooking. Processing vegetables at home (cooking, stewing, frying) helps reduce the nitrate content in products; 2) Vegetables and fruits should be stored in the refrigerator, because at a temperature of +2 °C it is impossible to convert nitrates into more toxic substances nitrites. 3) Washing and peeling vegetables reduces the nitrate content by 10 - 15%, and after cleaning the tubers - by 43 - 66%; 4) Use vitamin C (ascorbic acid) and vitamin E in food, as they reduce the harmful effects of nitrates and nitrites; 5) When canning, the nitrate content in vegetables decreases by 20–25%, especially when canning cucumbers and cabbage, since nitrates go into the brine and marinade, which must be poured out; 6) Before eating, soak vegetables in cold water for 1-1.5 hours, which reduces the nitrate content by 20-30%; Ways to reduce nitrate levels:

Methods for determining nitrates Nitratomer is intended for express analysis of the quantitative content of nitrates in vegetables and fruits (30 items), as well as in fresh meat. The tester, like a mobile phone, fits easily and comfortably in your hand, weighs only 105 g and has intuitive controls.

• What are nitrates?
• Scheme of nitrate decomposition.
• Nitrates in agriculture.
• Conclusion.

What are nitrates?

Nitrates are salts of nitrogen

Nitrates of sodium, potassium, calcium and ammonium are called nitrates.

Scheme of nitrate decomposition.

A special chemical property is nitrates when

when heated, they decompose to release

oxygen.

• NaNO 3 - sodium nitrate, sodium nitrate, soda nitrate, sodium nitrate, Chilean nitrate.

• For the first time, the first batch of saltpeter arrived in Europe in 1825, brought from Chile. However, no buyers were found for the product, and therefore it was dumped into the sea. After some time, saltpeter mining turned into a very profitable business. As a result of the Pacific War, Chile captured the richest deposits.

• Sodium nitrate is known in the food industry as additive no. E251. It is used for the production of frozen semi-finished products, as well as canned meat products. Sodium nitrate is used in sausages, sausages, etc. The additive has the ability to restore the color of processed meat. We can say that thanks to sodium nitrate, sausage and other meat products have a characteristic meat color.

• Typically a dietary supplement E251 used as a preservative, dye, color stabilizer. But sodium nitrate can also help prevent the development and formation of anaerobic microorganisms. And this is where all the beneficial properties of the compound end.
• This additive can be found not only in sausages, but also in sprats, smoked fish, and canned herring. In cheeses, nitrate is able to inhibit the activity of certain types of bacteria, thus preventing late swelling, that is, ruptures and cracks in hard cheese circles.

• Despite the proven adverse effects on the human body, the food additive numbered E251 continues to be actively used in the food production sector.
• Nitrate can cause the biggest problems for those who suffer from liver disease, hypertension, diseases of the vegetative-vascular system, and intestines. Food preservative E251 can cause cholecystitis, dysbacteriosis, and severe manifestations of allergies.
• In case of an overdose of sodium nitrate, symptoms such as fainting, loss of coordination of movements, convulsions, abdominal pain, general weakness, and dizziness are observed. Symptoms of poisoning with this compound also include blue nails or lips, abdominal pain, blue skin, diarrhea, difficulty breathing, and headache.

• KNO 3 - potassium nitrate, potassium nitrate,

potassium nitrate, Indian nitrate.

Since the East Indies contains one of the

its largest deposits,

This is where the name “Indian” comes from.

saltpeter."

• Potassium nitrate in the food industry is known as additive no. E252 .

• E252 widely used in cheeses and meat products. Various types of sausages and frankfurters, as well as canned meat, contain potassium nitrate everywhere. High nitrate content may cause discoloration of foods. Potassium nitrate has little antimicrobial effect.

When using potassium nitrate in food production, it is important to note that this nitrate is almost uncontrollably converted into nitrites, which can be harmful to health. Especially long-term and excessive consumption of products containing potassium nitrate can cause the following ailments: anemia and kidney disease. If a large amount of potassium nitrate is ingested, acute abdominal pain, vomiting, impaired coordination of movements and muscle weakness will inevitably occur, and pulse irregularities and arrhythmia may also occur. Food supplement E252 disrupts the balance of oxygen in the blood, which is dangerous due to the occurrence of asthma attacks for patients with asthma and exacerbation of kidney diseases. This preservative belongs to the class of carcinogens and is a risk factor and provoking substance in the formation of various types of tumor formations. The use of the supplement is strictly contraindicated E252 children.

Nitrates in agriculture.

• Nitrogen fertilizers They are used mainly during spring tillage until the first days of July, but not later, otherwise the frost resistance of trees and shrubs, as well as the shelf life of fruits and vegetables, will decrease.

• Nitrogen fertilizers include: urea, or carbamide(45-46% nitrogen), ammonia-

saltpeter(34-35.5% nitrogen),

ammonium sulfate(20.5-21.0% nitrogen), sodium nitrate (16%

nitrogen), calcium nitrate(24% nitrogen).

• Nitrates accumulate unevenly in different parts of vegetables.
• According to the conclusion of the World Health Organization, the amount of nitrates per 1 kg of human body is considered safe. That is, an adult can receive about 350 mg of nitrates without any harm to his health. Of the nitrates that enter the adult body every day, 70% comes from vegetables, 20% - with water and 6% - with meat and canned foods.
• Nitrates themselves are low toxic. But when they enter the intestines, they are converted there under the influence of microflora into nitrites, and then converted into nitrosamines, a carcinogen. The toxic effect is based on “hypoxia” - tissue suffocation due to lack of oxygen. Nitrites disrupt the transport function of the blood, which carries oxygen throughout the body, and also reduce the activity of some enzyme systems involved in the process of tissue metabolism.

• Early vegetables always attract us. In early spring, the shelves of shops and markets are bursting with an abundance of all kinds of early vegetables, grown in local greenhouses or brought from abroad. But such a hasty replenishment of vitamins to your body is not always healthy. After all, not everything that is done in a hurry under greenhouse conditions is useful.
• Plants grown in a matter of days in greenhouse conditions contain much more nitrates than vegetables grown in an open garden. All nitrates are dangerous to our health, and it is necessary to neutralize them, while maintaining maximum vitamins.

Nitrate separation:

• most– lettuce, kale, beets, dill, spinach, green onions, radishes;
• In second place– cauliflower, zucchini, pumpkin, turnips, radishes, cabbage, horseradish, carrots, cucumbers;
• least of all– Brussels sprouts, peas, beans, sweet peppers, potatoes, tomatoes, onions.

How to reduce nitrates:

• thoroughly rinse vegetables and fruits – reduces by 10%;
• mechanical cleaning – by 15-20%;
• cooking vegetables, especially peeled and chopped - by 50%;
• It is recommended to soak greens before use in cold water for 1-1.5 hours - 20-30%;
• The nitrate content decreases during fermentation, salting, and pickling.
• To reduce the nitrate content, it is better to feed vegetables with organic fertilizers.

• A sign of excess nitrates in fresh vegetables can be their rapid spoilage; for example, young potatoes rich in nitrates often begin to deteriorate while still on sale - rotten areas appear on them. Any vegetables that have begun to spoil ahead of time (faster than usual) should be taken as a dangerous signal.

• Determination of nitrates in the laboratory.

• With the help of diphenylamine, you can carry out a reaction on freshly squeezed colorless juice of vegetable or fruit products. When nitrates are present, a blue color of varying intensity appears depending on the amount of nitrates. Blue color indicates an insignificant (acceptable) nitrate content. The dark blue color warns of an unacceptable dose of nitrates in the product.

• Nitrate tester, this is a household portable nitrate measuring device in fresh vegetables and fruits. It is not difficult to use - a puncture is made with a special probe in the product being tested, and the measurement data is displayed on the color display. The device’s memory stores data on the nitrate content standards in 30 types of vegetables and fruits.

To 100% secure

yourself from entering

organism dangerous nitrates ,

best to eat

fruits and vegetables ,

grown on your own

garden plot.

Or buy them from people

leading natural

farming without use

chemical fertilizers in it.

Scientific supervisor: teacher of school No. 1120
Chemistry teacher – Dolgova O.A.

Slide 2

• Introduction
• Objective of the project
• Project objectives
• main sources