Presentation of natural water in nitrates. The effects of nitrates and nitrites on the human body

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Introduction

Everyone knows that the most valuable thing a person has is his health, which cannot be bought and which largely depends on his proper nutrition. No wonder there is a proverb: “Tell me what you eat, and I’ll tell you what you’re sick with!”

It is no longer a secret for most that to improve health it is better to eat more fruits and vegetables.

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Objective of the project

• obtain information from the study of various vegetables and fruits about the accumulation of nitrates and nitrites;
• summarize and analyze research as a result of studying popular scientific literature on this issue.

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Project objectives

• Briefly describe the actions that need to be taken to achieve the project goal;
• Justify and identify the reasons for the accumulation of nitrates in vegetables;
• Develop simple and effective methods for reducing the level of nitrates in vegetable products that are accessible to everyone, and ways to remove them from various products;
• Conduct product analysis using known methods in the analytical chemistry of nitrates;
• How to avoid nitrate poisoning and grow environmentally friendly products?

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What are the main sources of dietary nitrates?

These are practically exclusively plant products. Animal products (meat, milk) contain very little nitrates. The maximum accumulation of nitrates occurs during the period of greatest plant activity during fruit ripening. Most often, the maximum nitrate content in plants occurs before the start of harvesting. Therefore, unripe vegetables and potatoes, as well as early ripening vegetables, may contain more nitrates than those that have reached normal harvest maturity. In addition, the nitrate content in vegetables can increase sharply if nitrogenous fertilizers are used incorrectly. For example, when adding them shortly before harvesting.

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Quality of vegetables and conditions for their cultivation

The quality of vegetables depends on many factors, including the fertilizers applied and plant protection products used. Nitrates are used as fertilizers and are known as nitrates: sodium, potassium, ammonium and calcium. Nitrates are the most important component of plant nutrition, since the nitrogen they contain is the main building material of the cell.

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The first conversations about nitrates in our country began after the massive gastrointestinal poisoning of watermelons in Uzbekistan in the 70s, as a result of excessive feeding with ammonium nitrate.

It is now common knowledge that nitrates are highly toxic to humans and farm animals:

• Nitrates are especially dangerous for infants, because their enzyme base is imperfect and the reduction of methemoglobin to hemoglobin is slow.
• Nitrates contribute to the development of pathogenic intestinal microflora, which releases toxic substances into the human body - toxins, resulting in toxicity, i.e. poisoning of the body.
• Nitrates reduce the content of vitamins in food, which are part of many enzymes, stimulate the action of hormones, and through them affect all types of metabolism.
• Pregnant women experience miscarriages, and men experience decreased potency.
• The amount of iodine decreases; sharp dilatation of blood vessels; decrease in pressure.
• They influence the occurrence of cancerous tumors in the gastrointestinal tract.

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The main signs of nitrate poisoning:

• Blueness of nails, face, lips and visible mucous membranes;
• Nausea, vomiting, abdominal pain;
• Diarrhea, often with blood, enlarged liver, yellowness of the whites of the eyes;
• Headaches, increased fatigue, drowsiness, decreased performance;
• Shortness of breath, increased heart rate, up to loss of consciousness;
• In case of severe poisoning, the outcome is fatal.

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Ways nitrates enter the body:

1. Through food:
   • Plant origin;
   • Animal origin.
2. Through drinking water;
3. Through medications.

Nitrates also enter the human body through tobacco. The bulk of nitrates enters the human body with canned food and fresh vegetables, as well as with dairy products.

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Harm reduction methods

• The amount of nitrates decreases during heat treatment of vegetables (washing, boiling, frying, stewing and blanching);
• To reduce the amount of nitrates in old potato tubers, the tubers should be filled with a 1% solution of table salt;
• For pattisons, zucchini and eggplants, it is necessary to cut off the upper part, which is adjacent to the stalk;
• Because There are more nitrates in the peels of vegetables and fruits, then they must be peeled, and for herbs, their stems must be thrown away and only the leaves must be used;
• In cucumbers, beets, radishes, you also need to cut off both ends, because... here is the highest concentration of nitrates;
• Vegetables and fruits should be stored in the refrigerator, because... at a temperature of +2C it is impossible to convert nitrates into more toxic substances - nitrites.

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Performer: Tatyana Yakovleva, 11a grade, tel. house. 73514 91 tel. mob. 8911 190 43 98 Address: 198334 St. Petersburg, Dobrovoltsev st., 40, building 2, apt. 95 Head: Elena Petrovna Efimova, ecology teacher, tel. house. 7503632, tel. mob. 8921 920 6162 website

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The problem of food contamination with nitrates is relevant for assessing the quality of vegetables, fruits, and various juices. The study of this issue is associated with the development of knowledge about the causes of cancer, diseases of the nervous system and the musculoskeletal system.

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Goals and objectives of the work

Purpose of the work: to determine the dependence of the quality of vegetable products in terms of nitrate content on the amount of nitrogen-containing fertilizers used in household farming. Objectives of the work: 1. Studying the literature on the transformation of nitrogen in soils of agroecosystems. 2. Mastering the techniques necessary to perform the work: soil sampling and preparation of salt soil extract; determination of soil acidity; determination of the amount of nitrates in soil extract; determination of nitrates as the main nitrogen-containing pollutant of vegetable products in various types of vegetables. 3. Conducting research on the effect of the amount of nitrogen-containing fertilizers used on the quality of the products selected for research: lettuce and radishes. 4. Development of recommendations for feeding agricultural crops with nitrogen fertilizers and for the use of products with a possible excess of nitrate content.

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The role of nitrogen in the environment

Nitrogen is an essential nutrient necessary for the normal development of plants. It is part of proteins (up to 16–18% of their mass), nucleic acids, nucleoproteins, chlorophyll, hemoglobin, phosphatides, and alkaloids. Nitrogen compounds play an important role in the process of photosynthesis, metabolism, and the formation of new cells. Nitrogen is as indispensable as carbon in the formation of soil cover and ecosystem fertility, in increasing agricultural productivity and improving protein nutrition for humans.

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Diagram of the nitrogen cycle in nature

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Nitrogen is the most important nutrient that determines the size of the crop. It is nitrogen fertilizers that play a decisive role in increasing yield, especially if the plants are provided with water. Nitrogen fertilizers account for about 60% of the total increase in yield obtained through the application of mineral fertilizers. A low supply of nitrogen to plants not only leads to a shortage of crops, but also worsens its quality: the content of protein and essential amino acids (lysine, methionine, tryptophan, etc.) in the products decreases. In addition, the content of vitamins in the products decreases.

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The main reason for the excessive accumulation of nitrates in plants is the intensive supply of mineral nitrogen in the form of nitrates and their incomplete involvement in metabolism. Unused nitrates accumulate in various vegetative organs, causing a significant excess of their supply over consumption. One of the main sources of excess nitrates in crop products is the use of excessively high doses of nitrogen and organic fertilizers or late fertilizing with nitrogen. With excessive absorption of nitrates, one part of them is reduced to ammonia and included in organic matter, while the other accumulates in stems, petioles, leaves and other vegetative organs.

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The influence of soil acidity on the nitrate content in plants

The effect of increased soil acidity on plants can be manifested directly or indirectly. Its direct effect is expressed in disruption of the permeability of root cell membranes, acidification of cell content, deterioration in the supply of nutrients to plants and their absorption of mineral fertilizers. The indirect effect of low acidity on plants is manifested in disruption of the structure, aeration and water absorption of the soil, increased mobility of toxic ions (aluminum, iron, manganese) and suppression of the activity of beneficial microflora. The acidic reaction of the soil promotes the accumulation of nitrates in plants. This is due to the inhibition of the supply of a number of mineral elements to them, especially molybdenum, which participate in the conversion of nitrates.

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Distribution of nitrates in different parts of vegetables

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As a result of the studied material, the need for preliminary assessment of the quality of vegetable products for nitrate content for safe use in nutrition was proven

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Practical part

The practical part of this work consisted of two main stages: Preparation of soil plots for growing experimental plants in different conditions and assessment of the environmental indicators of these soils. Monitoring the nitrate content in vegetable products over time throughout the growing season. The purpose of the experiment was to identify the source of excess accumulation of nitrates in two types of crops receiving different nitrogen nutrition. The objective of the experiment is to determine to what extent the excess amount of nitrogen fertilizers affects the quality of vegetable products.

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Description of the experimental conditions

To conduct this study, three plots were prepared (No. 1, No. 2, No. 3), each of which was divided in half for growing experimental samples of two crops: lettuce and radish. All samples were grown under the same natural conditions: the soil conditions at the beginning of the experiment were the same: podzolic soil type with moderate moisture; northwest side relative to the buildings on the site; sufficient natural light; protection from the wind by bushes.

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Objects of research

Conclusions:

1. An increase in the amount of nitrates in vegetables directly affects the quality of agricultural products: there is an improvement in the external characteristics of the product, but at the same time there is an increase in the negative impact of the composition of the product on human health; reducing the shelf life of vegetables with a high content of nitrates. 2. Excess nitrogen fertilizers leads to exceeding the maximum permissible concentration for nitrates in finished agricultural products. 3. When adding nitrogen fertilizers to the soil, you must be able to calculate the concentration of the solution of this fertilizer in accordance with the instructions for it. Particular attention is drawn to the fact that external positive signs of grown products do not reveal an excess of the maximum permissible concentration for nitrates in those product samples that received excess nitrogen. Without additional testing of plants for nitrate content, it is impossible to identify the danger of using these products for food.

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• 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 contains 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.

• Two main human assets
• nature is mind and reasoning.
• Plutarch.

• Chemistry 9th grade (UMK O.S. Gabrielyan)

• Systematize knowledge about salts, get acquainted with the oxidative properties of nitrates, learn to recognize them.
• Strengthen the ability to compare, contrast, analyze, and form an idea of ​​the cause-and-effect relationships of phenomena.

• Exercise 1
• Complete the reaction schemes and create equations using the electron balance method:
• 1)Hg + НNO3(conc.) →
• 2)Zn + НNO3 →
• 3)Сu + НNO3(conc.) →
• 4)Ag + НNO3(dil.) →
• Task 2
• Complete the equations of practically feasible reactions that characterize the properties of nitric acid. Write them in molecular and ionic form:
• with barium sulfate
• with copper(II) oxide
• with carbon monoxide (IV)
• with magnesium carbonate
• Task 3
• Write the reaction equations that can be used to carry out transformations:
• ammonia → nitric oxide (II) → nitric oxide (IV) → nitric acid → nitric oxide (IV)

• All nitrates are solid, highly soluble in water, and can be colored if the metal cation in their composition is colored. Nitrates of alkali metals, calcium and ammonium are called nitrates. They are used as soil fertilizers.
• KNO3 - potassium nitrate
• NaNO3 - sodium (Chilean) nitrate
• Ca(NO3)2 - calcium nitrate
• NH4NO3 - ammonium nitrate.

• 1. Metal + nitric acid
• 5 Mg + 12 HNO3 =>
• 5 Mg(NO3)2 + N2 + 6 H2O
• 2. Metal oxide + nitric acid
• 2HNO3 + MgO => Mg(NO3)2 +
• 3.Base + nitric acid
• Al(OH)3 + 3 HNO3 => Al(NO3)3 + 3H2O
• 4. Salts of weak acids + nitric acid
• CaCO3 + 2HNO3 => Ca(NO3)2 + H2O + CO2

• 5. Ammonia + nitric acid
• NH3 + HNO3 => NH4NO3
• 6. Alkali + nitrogen dioxide
• 2 KOH + 2NO2 => KNO3 + KNO3 + H2O
• 7. Active metal carbonates + nitrogen dioxide
• Na2CO3 + 3NO2 => 2NaNO3 + CO2 + NO

• . Nitrates participate in all metabolic reactions characteristic of salts.
• Ba(NO3)2 + CuSO4 => Cu(NO3)2 + BaSO4
• 2. When heated, nitrates decompose releasing oxygen. The nature of the decomposition of nitrate depends on the activity of the metal in its composition (we look at the activity series of metals):
• K, Na, Li: MeNO3 => MeNO2 + O2
• from Ca to Cu: MeNO3 => MeO + NO2 + O2
• Ag, Hg: MeNO3 => Me + NO2 + O2
• The exceptions are manganese and ammonium nitrates:
• Mn(NO3)2 => MnO2 + 2NO2
• NH4NO3 => N2O + 2H2O
• There are other ways of decomposition - depending on the temperature.
• The released oxygen actively supports combustion, which is why saltpeter is included in gunpowder and pyrotechnic mixtures.

• Nitrates are excellent nitrogen fertilizers. They are necessary for normal plant nutrition. When there is a lack of nitrogen in the soil, plants experience nitrogen starvation. It is characterized by a change in the green color of the leaves, as the formation of chlorophyll is delayed. The leaves take on a pale green color. Another sign of nitrogen starvation in plants is severe growth retardation due to limited production of proteins necessary for the formation of young cells.

• Of all mineral fertilizers, nitrates are particularly polluting the environment, as they are characterized by higher mobility in the soil than potassium and phosphorus fertilizers, and better solubility. To prevent environmental pollution by fertilizers, it is necessary to follow the basic rules for their use, storage and transportation.
• A person who has been poisoned by nitrogen monoxide, nitrates, or nitrites must be provided with complete rest, inhaling pure oxygen, and drinking milk in large quantities.

• It is not recommended to apply fertilizers in late autumn or early spring, when the soil is covered with a crust of ice or frozen, since melt water washes away up to half of the fertilizers. The timing of nitrogen fertilizer application should be close to the period of maximum use by plants. In addition, fertilizers should not be plowed into the soil.

• Excess nitrates in the soil worsens the quality of grown vegetables, fruits, grain crops, etc. The consequences of consuming low-quality products can be as follows:
• cancer develops;
• a disease appears in which the blood is unable to retain oxygen - methemoglobinemia (oxygen starvation);
• the activity of the thyroid gland is disrupted, etc.

• The Mikon-2 analyzer is designed to determine the concentration of nitrites and nitrates in various objects using the ionometric method according to existing GOSTs and approved methods.

• The presence of excess nitrates in plants can be determined by various methods. Indicator paper “Indam-2” and others are produced, with the help of which you can instantly determine the excess of nitrates in plant products.

• Property #1: dissociation of nitrates.
• Me(NO3)x ↔ Mech+ + xNO3-
• Property #2: interaction of a nitrate solution with metals that are in the series of standard electrode potentials to the left of the metal that is part of the salt.
• Property No. 3: interaction with acids. AgNO3 + HCl → AgCl + HNO3
• Аg+ + NO3- + Н+ + Сl- → АgСl↓ + Н+ + NO3-
• Аg+ + Сl- → АgСl↓

• Property #4: interaction with alkalis.
• Сu(NO3)2 + 2NаОН -> Сu(ОН)2↓ + 2NаNO3
• Cu2+ + 2NO3- +2Na+ + 2NO3- → 2Na+ + 2OH- + Cu(OH)2|
• Property #5: interaction with salts
• АgNO3 + NaСl → АgСl↓ + NaNO3
• Аg+ + Сl- → АgСl↓

• Substances themselves cannot be good or bad. It all depends on how competently a person uses them and what goals he pursues.

• Gabrielyan O.S. Chemistry. 9th grade. M.: Bustard, 2001.
• Khomchenko I.G. Collection of problems and exercises in chemistry for high school. M.: Novaya Volna Publishing House LLC, 1998.
• Workshop on inorganic chemistry / L.V. Babich et al. M.: Education, 1991.
• Surin Yu.V. Methodology for conducting problem experiments in chemistry: Developmental experiment. M.: Shkola-Press, 1998,
• Pak M. Algorithms in teaching chemistry: Book. for the teacher. M.: Education, 1993.