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Fractional analysis of metals and prospects for its application in forensic chemistry / Krylova A.N. // Forensic-medical examination. - M., 1958. - No. 4. - S. 26-30.

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One of the features of forensic chemical analysis is that, if it is necessary to study biological material for a large group of substances of a different nature, as a rule, no more than 1-2 substances are detected at the same time. Combined poisoning with two or more substances is rare.

In this regard, there is no need for a strictly systematic course of research based on the separation and mandatory separation of one substance from another. Indeed, the study of biological material for alkaloids, barbiturates and other organic substances is carried out within certain groups, determined by the method of isolation, in any sequence, without separation from each other, i.e., in fact, it is fractional.

At the same time, research on heavy metals and arsenic is still carried out mainly according to a strictly systematic course of analysis, in which the liquid obtained after the destruction of biological material is subjected to a series of operations aimed at separating metal and arsenic cations into various subgroups and separating them from each other. from friend.

The operations of dividing into groups and separating cations from each other are laborious, require a lot of time, and do not always give the expected effect. Due to the phenomena of co-precipitation, peptization, numerous filtering, washing and dissolving operations, not only is complete separation not always achieved, but often the analysis results are confused and small amounts of cations are generally lost.

Institute staff forensic medicine and the Department of Forensic Chemistry of the Moscow Pharmaceutical Institute studied in detail the hydrogen sulfide method of systematic qualitative analysis of biological material for metals and arsenic and showed the errors that occur in this case.

So, when determining lead during the analysis, up to 42% is lost, zinc - up to 21%. Manganese is found in the systematic course of analysis only in a very small amount, since the bulk of it - up to 64% - is lost, co-precipitating with iron. When determining a number of metals in biological material by a systematic hydrogen sulfide method, there is a large scatter in the results of the determination: in the study of tin, from 33 to 76% of it is determined, in the determination of antimony - from 44 to 89%, in the determination of chromium - from 30 to 70%.

Small amounts of metal and arsenic cations, which are of particular interest to forensic chemistry, often cannot be detected at all by the hydrogen sulfide method. Mercury, cadmium, chromium, etc. can serve as an example of this. Thus, less than 1 mg of mercury by the hydrogen sulfide method is no longer detected even when the biological material is destroyed by chlorine, at which the volatility of mercury is the lowest. When destroyed by sulfuric and nitric acids, the detection limit for mercury lies even higher. The limit for determining chromium ranges from 1 to 3 mg. Iron co-precipitating with cadmium sulfide masks its color to such an extent that it is no longer possible to judge the presence of 2 mg of cadmium from this reaction. Due to the significant dissolution of copper sulfide in ammonium polysulphide, it is impossible to completely separate copper from arsenic, tin and antimony.

The need to work with foul-smelling hydrogen sulfide, which strongly pollutes laboratory air and is a poison, during research for metals and arsenic, is also one of negative sides systematic hydrogen sulfide method.

For about 100 years, the search continues for the possibility of replacing the classical hydrogen sulfide method.

In the last 25 years, a new direction in chemical analysis has been intensively developed, with the goal of finding a qualitative detection method free from the shortcomings of the hydrogen sulfide method and allowing each cation to be determined in the presence of others, i.e. fractional method.

N. A. Tananaev, I. M. Korenman, F. I. Trishin, V. N. Podchainova, and others work a lot on fractional methods. These methods find more and more supporters. In 1950, N. A. Tananaev's guide to fractional analysis appeared 1 .

The fractional analysis method avoids many of the difficulties that arise with the classical hydrogen sulfide method. Particularly attracted by its sensitivity, evidence and speed.

The use of fractional analysis in forensic chemistry in the study of cadaveric material for metal poisons is not only desirable, but greatly facilitates the study. As already mentioned, more than one substance is rarely found simultaneously in cadaveric material. Salt Exclusion heavy metals and arsenic, there are few cases when poisoning occurs with some complex compound, for example, Scheinfurt greens, which, being a copper salt of arsenic acid, contains both arsenic and copper.

The presence of metals as a natural component in the human body, it would seem, complicates the development of fractional methods. However, among the many metals that make up human tissues, only iron is contained in significant quantities, which must be considered when detecting a particular metal.

In the field of forensic chemistry, fractional methods have been developed for the detection and determination of arsenic (A. N. Krylova), mercury (N. A. Pavlovskaya, M. D. Shvaykova, and A. A. Vasilyeva), lead, barium, silver, and antimony (A. N. Krylova), cobalt (L. T. Ikramov).

The advantages of the fractional method are clearly visible from the table.

Comparative data on the detection of metals and arsenic by fractional and systematic hydrogen sulfide methods in biological material

If arsenic is detected by the fractional method, you can get an answer after 1 hour, not counting the time required for destruction organic matter. The detection of arsenic by the hydrogen sulfide method requires at least 3 working days, i.e. 20 working hours. The sensitivity of the fractional method in detecting arsenic is so great that, under some change in conditions, it makes it possible to detect even arsenic contained in the natural state.

The detection of lead by a fractional method in the sulfate precipitate obtained after the destruction of organic substances requires only 15-20 minutes, and the study of this precipitate by the fusion method generally accepted in forensic practice takes at least one working day, i.e. at least 6 hours. The study for lead by the hydrogen sulfide method after the destruction of organic substances by chlorine at the time of isolation lasts at least 2 working days.

The fractional method can detect 0.015 mg of lead in 100 g of cadaveric material, by fusion of the sulfate precipitate after destruction by sulfuric and nitric acids - 0.5 mg, and after destruction by chlorine at the time of isolation - only 30 mg of lead. Thus, the sensitivity of the fractional method for detecting lead in cadaveric material is 33 times higher in the first case, and 2000 times higher in the second case.

Fractional detection of barium also requires only 20 minutes instead of 6 hours for conventional fusion testing. This method makes it possible to detect 0.015 mg of barium per 100 g of the test object.

A study on silver by the fractional method makes it possible to obtain an answer after 2-3 hours, while in the study by the hydrogen sulfide method, the answer is obtained only after 2 days. The fractional method can detect 0.05 mg of silver in 100 g of cadaveric material.

AT recent times completed work on fractional methods for the determination of antimony and cobalt.

It is necessary to spend at least 3 working days, i.e. 20 working hours, for the detection of antimony by the systematic course of the analysis. The fractional method of detection of antimony offered by us gives the chance to receive the answer within 10 minutes. If the systematic course of the analysis can detect 1 mg of antimony in 100 g of the object, then by the fractional method it is possible to find 0.1 mg of it.

Cobalt is not included in the mandatory list of poisons subject to forensic analysis, so the development of a fractional method that allows cobalt testing regardless of the overall course of the analysis is very useful. With this method, the study is completed within 2-3 hours and 0.1 mg of cobalt can be detected in 100 g of the object.

The advantage of the fractional method is especially clearly seen on the example of mercury. Being a highly volatile metal, mercury has caused a lot of trouble for forensic chemists. Many works have been devoted to the issues of its detection in the study of cadaveric material. In the study by the hydrogen sulfide method, the detection limit is 1 mg of mercury per 100 g of cadaveric material. At the same time, mercury often remains in small amounts in the organs of those who died from mercury poisoning. In addition, due to volatility, it is lost even in the process of destruction of organic matter. When destroyed by sulfuric and nitric acids, losses can reach a total of 98%.

Attempts to increase the sensitivity of the method for detecting mercury went mainly along the path of fractional analysis. In the early 1900s, A. V. Stepanov proposed a private method for studying mercury in urine; in fact, this method is fractional. Further, A. F. Rubtsov, and then M. D. Shvaikova, A. A. Vasilyeva and N. A. Pavlovskaya studied in detail the issue of fractional detection of mercury in cadaveric material. At present, A. A. Vasilyeva has developed a method for fractional detection of mercury, which is characterized by speed and high sensitivity; it allows you to determine 0.01 mg of mercury in 100 g of cadaveric material, i.e., the sensitivity of mercury detection has increased 100 times. At the same time, the research time was reduced by a factor of three compared to the hydrogen sulfide method.

For each of the above ions, a quantitative determination method has also been developed that allows analysis to be carried out without preliminary separation. In this case, the results of the determination are quite satisfactory. Silver, lead, barium and arsenic are determined in cadaveric material in the range from 74 to 100%, and mercury according to the latter method - up to 100%.

The possibility of successful analysis if it is necessary to study an object weighing 10-25 g, as well as the speed of response, especially for private tasks, makes fractional analysis especially valuable for forensic purposes.

The evidence of fractional methods proposed for forensic research is also in many cases much higher, since, in addition to the use of specific reactions for the isolation of one or another ion, complex formation and selective extraction with organic solvents are widely used in the development of fractional reactions, which makes it possible to extremely quickly and efficiently eliminate the influence of foreign ions. And the use of the most specific microcrystalline reactions for subsequent confirmatory reactions further increases the evidence of fractional methods.

Due to the reduction in the number of operations in this analysis compared to the systematic hydrogen sulfide method, the use of the fractional method will significantly save not only time, but also reagents. In addition, it makes it possible to remove hydrogen sulfide, which is harmful to health and highly polluting the air, from use in laboratories.

The indisputable advantage of the fractional method is already clearly visible in these few examples.

Further work on fractional methods in forensic analysis will finally leave the systematic hydrogen sulfide method, which will make it possible not only to increase the sensitivity and evidence of detection of cations, but also to significantly reduce the time of analysis for metals and arsenic (possibly up to 3 working days, including the time required to destroy organic matter). The latter circumstance is especially important, because forensic chemical studies are unacceptably long: in order to give an answer in the study of metals and arsenic, some laboratories spend at least 2 weeks. Even when using the most quick method destruction by sulfuric and nitric acids on full analysis metals takes at least 8-10 days. This not only does not meet the requirements of the investigating authorities, but also does not correspond to the possibilities provided by the modern level of development of analytical chemistry.

findings

1. The systematic method of hydrogen sulfide analysis of metal and arsenic cations currently used in forensic practice is outdated.
2. The fractional method currently being developed for the analysis of metal cations and arsenic makes it possible to reduce the time of forensic chemical analysis by 2-3 times compared to the hydrogen sulfide method, increase sensitivity in some cases by 100 and even 2000 times, increase the evidence for the detection of metals and arsenic, and also significantly reduce the consumption of reagents and abandon the use of hydrogen sulfide, which pollutes the air of laboratories.

1 Tananaev N. A. Fractional analysis. M., 1950.

In the forensic-chemical and chemical-toxicological analysis, in the study of biological material (organs of corpses, biological fluids, plants, food products, etc.), the mineralization method is used for the presence of "metallic" poisons. These poisons in the form of salts, oxides and other compounds, in most cases, enter the body orally, are absorbed into the blood and cause poisoning. "Metal" poisons will be in the body in the form of compounds with proteins, peptides, amino acids and some other substances that play an important role in life processes. The bonds of metals with most of these substances are strong (covalent). Therefore, to study biological material for the presence of "metal" poisons, it is necessary to destroy the organic substances with which metals are associated and transfer them to the ionic state. The choice of the method of mineralization of organic substances depends on the properties of the elements under study, the amount of biological material received for analysis.

Mineralization is the oxidation (burning) of organic matter (object) to release metals from their complexes with proteins and other compounds. The most widely used methods of mineralization can be divided into 2 large groups:

General methods (methods of "wet" mineralization) are used in a general study for a group of "metal poisons", suitable for isolating all metal cations. Besides mercury. For mineralization, mixtures of oxidizing acids are used: sulfuric and nitric, sulfuric, nitric and perchloric.

Private methods (methods of "dry ashing") - a method of simple combustion, a method of fusion with a mixture of nitrates and carbonates of alkali metals. Particular methods include the method of partial mineralization (destruction), which serves to isolate inorganic mercury compounds from biological materials.

1.1. Destruction of biological material by nitric and sulfuric acids

In a Kjeldahl flask with a capacity of 500-800 ml, add 100 g of crushed biological material, add 75 ml of a mixture consisting of equal volumes of concentrated nitric and sulfuric acids and purified water. The flask with the contents in a vertical position is fixed in a tripod so that its bottom is above the asbestos mesh at a distance of 1-2 cm. A separating funnel is fixed above the Kjeldahl flask in a tripod, which contains concentrated nitric acid, diluted with an equal volume of water. Next, begin to gently heat the flask. Within 30-40 minutes, destruction occurs, the destruction of the uniform elements of biological material. At the end of the destruction, a translucent liquid is obtained, colored yellow or brown.

Then the Kjeldahl flask with the contents is lowered onto an asbestos grid and heating is increased - the stage of deep liquid-phase oxidation begins. To destroy the organic substances in the flask, concentrated nitric acid diluted with an equal volume of water is added dropwise from a dropping funnel. Mineralization is considered complete when the clear liquid (mineralizate), when heated without adding nitric acid for 30 minutes, ceases to darken, and white vapors of sulfuric anhydride are released above the liquid.

The resulting mineralizate is subjected to denitration: cool, add 10-15 ml of purified water and heat to 110-130°C, and then carefully drop by drop, avoiding excess, add a formaldehyde solution. At the same time, an abundant release of brown, sometimes orange, vapors is noted. After the end of the release of these vapors, the liquid is still heated for 5-10 minutes, and then 1-2 drops of the cooled liquid (mineralizate) are applied to a glass slide or porcelain plate and a drop of diphenylamine solution in concentrated sulfuric acid is added. The effect of the reaction is a characteristic blue coloration.

The negative reaction of the mineralizate with diphenylamine to nitric, nitrous acids, and also to nitrogen oxides indicates the end of the denitration process. With a positive reaction of the mineralizate with diphenylamine, denitration is repeated.

The method of mineralization of biological material with concentrated nitric and sulfuric acids has a number of advantages. Mineralization by this method is faster, a relatively small amount of mineralizate is obtained than using other methods. However, mineralization with a mixture of sulfuric and nitric acid is unsuitable for isolating mercury from biological material, since a significant amount of it volatilizes when the biological material is heated at the stage of deep liquid-phase oxidation.

Bashurova Maria

In this paper, one of the main environmental issues of our time: environmental pollution by one of the heavy metals - lead. In recent years, poisoning with compounds of this particular metal has been most often recorded.

Here, for the first time, the amount of lead compounds emitted by road transport for the village of Novoorlovsk was calculated. As a result of qualitative reactions, lead compounds were found in the environment of Novoorlovsk.

And also identified the main sources of pollution with lead compounds in the village of Novoorlovsk.

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Scientific and practical conference "Step into the future"

Exploring content

lead compounds

In the environment p.Novoorlovsk

Completed by: Bashurova Maria Viktorovna

student of the 10th grade of the municipal educational institution "Novoorlovskaya secondary

comprehensive school».

Head: Gordeeva Valentina Sergeevna

Chemistry teacher, Novoorlovskaya secondary

comprehensive school".

the Russian Federation

Trans-Baikal Territory, Aginsky district, urban-type settlement Novoorlovsk

2010

Introduction

1.1 Characterization and use of lead and its compounds.

1.2 Sources of lead pollution.

Chapter 2. The study of the content of lead compounds in the environment p.Novoorlovsk.

2.1. Research methods.

2.3. Conclusions based on the research results.

Conclusion.

Bibliographic list.

Applications.

Bashurova Maria

Introduction.

The role of metals in the development and formation of the technical culture of mankind is exceptionally great. The historical names "Bronze Age", "Iron Age" speak of the strong influence of metals and their alloys on all areas of production development. And in our daily practice, we encounter metals every minute. And we ourselves have metals. They are used to carry out various processes in the body. But metals are not always necessary. Many of them are even dangerous for the body. For example, some metals are extremely toxic to vertebrates already in small doses (mercury, lead, cadmium, thallium), others cause toxic effects in large doses, although they are trace elements (for example, copper, zinc). In invertebrates with hard integuments, lead is most concentrated in them. In vertebrates, lead accumulates to the greatest extent in bone tissue, in fish - in the gonads, in birds - in feathers, in mammals - in the brain and liver.

Lead is a metal that, when in contact with the skin and when ingested, causes the largest number diseases, therefore, according to the degree of impact on living organisms, lead is classified as a highly hazardous substance along with arsenic, cadmium, mercury, selenium, zinc, fluorine and benzaprene (GOST 3778-98).

Cars with lead batteries have a huge impact on lead pollution. Exhaust gases are the most important source of lead. The increase in lead in the soil, as a rule, leads to its accumulation by plants. Many data indicate a sharp increase in the content of lead in plants grown along the edges of freeways. lead pollution in water wastewater enterprises containing lead salts in toxic quantities, as well as lead pipes. Toxic substances contained in the waters are very dangerous for humans, as they actively accumulate in food chains.

According to the analytical agency "AUTOSTAT" in Russia in 2009. there are approximately 41.2 million vehicles. The composition of the car park by type of fuel used is as follows: the number of cars using gas as fuel does not exceed 2%. The rest of the cars use diesel fuel - 37% or "leaded" gasoline - 61%.

One of important issues any region is the pollution of soil, water, air with heavy metals.

In conducting this study, we put forward hypothesis that lead compounds are present in the environment of Novoorlovsk.

An object research - lead pollution of the environment.

Thing research - the highway and cars passing along it; the soil; snow; plants.

Purpose of the study:study the content of lead compounds emitted into the air; accumulated in soil, plants, snow.

To achieve this goal, we solved the following tasks:

1. To study the scientific literature and Internet sites for the purpose of the study.

2. Carry out a qualitative analysis of samples of soil, snow and plants for the content of lead compounds.

3. Find out the level of pollution with lead compounds in the environment of the area.

4. Determine the amount of lead compounds emitted by vehicles.

5. Determine the main sources of lead pollution in the area.

Scientific novelty . As a result of the work, a qualitative analysis was carried out for the content of lead compounds in samples of soil, snow and plants taken from the environment of the village of Novoorlovsk. The amount of lead compounds emitted by vehicles has been determined. The main sources of pollution with lead compounds in the area have been identified.
Practical significance work.Methods for detecting the content of lead compounds in soil, snow, and plants that can be used have been studied. It has been established that lead compounds are found near the main sources of pollution. It was determined in the course of research that the main sources of pollution with lead compounds are the highway, the Central boiler house, CJSC Novoorlovsky GOK.

"Study of the content of lead compounds in the environment of Novoorlovsk"

Bashurova Maria

Russian Federation, Trans-Baikal Territory, Aginsky district, urban-type settlement Novoorlovsk

MOU "Novoorlovskaya secondary school", grade 10

Chapter 1. Pollution of the environment with lead compounds.

1.1. Characterization and application of lead and its compounds.

Lead - Pb (Plumbum), serial number 82, atomic weight 207.21. This bluish-gray metal has been known since time immemorial. The origin of the name "lead" - from the word "wine" - is associated with the use of this metal in the manufacture of vessels for storing wine. A number of experts believe that lead played a decisive role in the fall of the Roman Empire. In ancient times, water flowed from lead-covered roofs down lead gutters into lead-covered barrels. In the manufacture of wine used lead boilers. Lead was present in most ointments, cosmetics, and paints. All this may have led to a decrease in the birth rate and the emergence of mental disorders among aristocrats.

He is malleable, soft. Even a fingernail leaves a mark on it. Lead melts at a temperature of 327.4 degrees. In air, it quickly becomes covered with a layer of oxide. Nowadays, lead is experiencing a “second youth”. Its main consumers are the cable and battery industries, where it is used to make sheaths and plates. It is used to make casings for towers, refrigerator coils and other equipment at sulfuric acid plants. It is indispensable in the manufacture of bearings (babbitt), printing alloy (hart) and some types of glass. Lead nitrate Pb(NO 3 ) 2 , which is used in pyrotechnics - in the manufacture of lighting, incendiary, signal and smoke compositions; lead dihydroxocarbonate - Pb 3 (OH) 2 (CO 3 ) 2 - used for the preparation of high-quality paint - white lead. True, she has a small flaw: under the influence of hydrogen sulfide, she gradually fades. That is why old oil paintings become so dark. Red lead (Pb 3 O 4 ) is a bright red substance from which ordinary oil paint is obtained. Also, for the preparation of paints, the lead pigment lead chromate PbCrO is widely used. 4 ("yellow crown"). The starting product for the production of lead compounds is lead acetate Pb 3 (CH 3 COO) 2 . Although its compound is poisonous, its 2% solution is used in medicine for lotions on inflamed surfaces of the body, as it has astringent and analgesic properties. The most highly toxic properties are alkylated compounds, in particular, tetraethyl lead (C 2 H 5 ) 4 Pb and tetramethyl lead (CH 3 ) 4 Pb are volatile poisonous liquid substances. Tetraethyl lead (TEP) is an antiknock for motor fuel, so it is added to gasoline.

1.2. Sources of lead pollution.

Lead enters water in a variety of ways. In lead pipes and other places where this metal can come into contact with water and atmospheric oxygen, oxidation processes occur: 2Pb + O 2 +2H 2 O→2Pb(OH) 2 .

In alkalized water, lead can accumulate in significant concentrations, forming plumbites: Pb(OH) 2 +2OHֿ→PbO 2 ²ֿ+2H 2 O.

If there is CO in the water 2 , then this leads to the formation of a fairly well-soluble lead bicarbonate: 2Pb + O 2 →2PbO, PbO+CO 2 →PbCO 3 , PbCO 3 +H 2 O+CO 2 →Pb(HCO 3 ) 2 .

Also, lead can get into the water from soils contaminated with it, as well as through direct discharges of waste into rivers and seas. There is a problem of contamination of drinking water in areas where smelters are located or where industrial wastes with a high lead content are stored.

The highest concentrations of lead are found in the soil along the highway, as well as where there are metallurgical enterprises or enterprises for the production of lead-containing batteries or glass.

Automobile transport that runs on liquid fuels (gasoline, diesel fuel and kerosene), combined heat and power plants (CHP) and thermal power plants (TPP) are one of the main sources of air pollution. Car exhaust emissions contain heavy metals, including lead. Higher concentrations of lead in the atmospheric air of cities with large industrial enterprises.

Most of the lead in the human body comes from food. Lead levels are highest in canned food in tins, fresh and frozen fish, wheat bran, gelatin, shellfish and crustaceans. High levels of lead are found in root crops and other plant products grown on land near industrial areas and along roads. Drinking water, atmospheric air, smoking are also sources of lead compounds entering the human body.

1.3. Consequences of the intake of lead compounds in the human body.

In 1924, in the United States, when large quantities of thermal power plants were required for the production of gasoline, accidents began at the factories where it was synthesized. 138 poisonings were registered, of which 13 were fatal. This was the first recorded lead poisoning.

Like radiation, lead is a cumulative poison. Once in the body, it accumulates in the bones, liver and kidneys. Significant symptoms of lead poisoning include: great weakness, abdominal cramps and paralysis. Asymptomatic, but also dangerous is the constant presence of lead in the blood. It affects the formation of hemoglobin and causes anemia. There may be mental disorders.

Currently, lead occupies the first place among the causes of industrial poisoning. Lead pollution of atmospheric air, soil and water in the vicinity of such industries, as well as near major highways, creates a threat of lead damage to the population living in these areas, and especially children, who are more sensitive to the effects of heavy metals.

Lead poisoning (saturnism) is an example of the most common environmental disease. In most cases we are talking about the absorption of small doses and their accumulation in the body until its concentration reaches the critical level necessary for toxic manifestations.
Target organs in lead poisoning are the hematopoietic and nervous systems, kidneys. Saturnism does less damage to the gastrointestinal tract. One of the main signs of the disease is anemia. At the level of the nervous system, damage to the brain and peripheral nerves is noted. Lead toxicity can, for the most part, be prevented, especially in children. Laws prohibit the use of lead-based paints, as well as its presence in them. Compliance with these laws can at least partially solve the problem of these “silent epidemics”. Generally accepted is the following classification of lead poisoning, approved by the Ministry of Health of the Russian Federation:

1. Carriage of lead (in the presence of lead in the urine and the absence of symptoms of poisoning).

2. Mild lead poisoning.

3. Lead poisoning of moderate severity: a) anemia (hemoglobin below 60% - up to 50%); b) unsharply expressed lead colic; c) toxic hepatitis.

4. Severe lead poisoning: a) anemia (hemoglobin below 50%); b) lead colic (pronounced form); c) lead paralysis.

In the treatment of lead poisoning, drugs such as tetacin and pentacin are used. (Appendix 1) Preventive measures are also needed. (Annex 2)

Chapter 2. Study of the content of lead compounds in the environment of Novoorlovsk

2.1. Research methods.

To calculate the amount of harmful emissions from vehicles in 1 hourwe used the methodology approved by the order of the State Committee for Ecology of Russia No. 66 dated February 16, 1999.

1. On the highway, determine a section of the road with a length of 100m.

1. Calculate the total distance (S) covered by all cars in 1 hour: S = N*100m.
2. Taking measurements of car emissions per 1 km, calculate how many emissions of lead compounds were produced by cars in 1 hour.
3. Calculate the approximate amount of lead compounds emitted in 1 hour over the total distance travelled.

To determine the content of lead compounds on the surface of the earth (in snow)we used the methodology from the school workshop.

1. To take a sample, you will need a container with a capacity of at least 250 ml.
2. The container is immersed in the snow with an open end, trying to reach its lower layer.
3. The sample is taken out and delivered to the laboratory for thawing.
4. 100 ml of liquid is poured from each sample and filtered.
5. 1 ml of melt water from each sample is poured into test tubes and 1 ml of KI solution and 1 ml of 6% HNO are added 3 .
6. Changes in test tubes are determined.

To determine the content of lead compounds in soilWe used the methodology from the school workshop:

1. Soil sampling is done.
2. The soil is dried for 5 days.
3. Each sample is weighed 10 mg and placed in test tubes.
4. 10 ml of distilled water is added to each tube.
5. Mix the contents of the test tubes for 10 minutes and leave for a day.

6. A day later, add 1 ml of KI and HNO to the test tubes 3 and note the changes.

To determine the content of lead compounds in plantsWe used the methodology from the school workshop:

1. 50 pieces of leaves or 50 g of grass are selected.
2. The plant material is dried and crushed.
3. The plant mass is placed in test tubes, filled with 20 ml of distilled water and left for a day.

4. A day later, 1 ml of KI and HNO are added 3

5. Mark changes.

2.2. Research results.

The research was carried out in the summer and autumn of 2010.

To calculate the amount of harmful emissions by vehicles for 1 hour, a highway was chosen, passing in the center of the village of Novoorlovsk. As a result of these calculations, we obtained that 0.644 g of lead compounds are emitted into the air in 1 hour (Appendix 3).

To determine the content of lead compounds in the environment, we took five samples on the soil surface (in snow), in soil, in plants in certain areas: 1. Road near the school 2. Central boiler house 3. CJSC Novoorlovsky GOK 4. Forest 5 The road along the dacha cooperative. We assessed the level of contamination with lead compounds by the degree of sediment coloration: intense yellow - a strong level of contamination; yellowish - medium level; no yellow sediment - weak level.

In the course of studying the content of lead compounds on the soil surface (in snow), it was found that the highest level of lead compounds was found on the roadside near the school, the Central Boiler House and CJSC Novoorlovsky GOK. This can be seen from the bright yellow precipitate, which was obtained during the experiment and was a qualitative indicator of the lead content. (Annex 4)

When studying the content of lead compounds in the soil, it turned out that there was a high level of pollution with lead compounds on the roadside near the school and CJSC Novoorlovsky GOK. (Annex 5)

An analysis of the plant mass showed that plants growing near the Central Boiler House, CJSC Novoorlovsky Mining and Processing Plant and the road along the dacha cooperative accumulate the largest amount of lead compounds in their tissues. (Annex 6)

We obtained the lowest level of contamination of the surface of soil (snow), soil and plants with lead compounds in samples taken in the forest.

All the results obtained by us were communicated to the population in the form of bulletins and leaflets about the danger of pollution with lead compounds. (Appendix 7.8)

2.3. Findings.

1. Experimental data confirmed that the source of lead compounds in our village is the central highway, as well as CJSC Novoorlovsky GOK and the boiler house.
2. Lead compounds have been found on the soil surface (snow), in soil and in plants.

3. As a result of calculations of the amount of harmful emissions by motor vehicles, we obtained that 0.644 g of lead compounds are emitted into the air in 1 hour.

4. Lead compounds for humans are the cause of many serious diseases.

"Study of the content of lead compounds in the environment of Novoorlovsk"

Bashurova Maria

Russian Federation, Trans-Baikal Territory, Aginsky district, urban-type settlement Novoorlovsk

MOU "Novoorlovskaya secondary school", grade 10

Conclusion.

This work shows that the highway and cars passing through it can be a fairly strong source of heavy metals in the environment. Lead from gasoline enters the exhaust gases and then into the atmosphere. The level of pollution will also depend on the traffic load of the road. Since the soil and plants near the road are heavily polluted with lead, it is impossible to use the land for growing agricultural products and grazing livestock, and the plants for feeding farm animals.

As a result of the work, a qualitative analysis was carried out for the content of lead compounds in samples of soil, snow and plants taken from the environment of the village of Novoorlovsk. The amount of lead compounds emitted by vehicles has been determined.

Educational work is needed among the local population, especially the owners of summer cottages that are close to the highway.

We have developed information bulletins and leaflets in which recommendations are given to reduce the impact of the route on vegetable gardens:

1. If possible, remove your site from the source of pollution by not using the land directly adjacent to the route.
2. Do not use the land on the site to plant plants with a height of more than 1 meter (corn, dill, etc.)
3. In the future, these plants should be removed from the garden without using them.

List of sources used:

1. Vishnevsky L.D. Under the sign of carbon: Elements of group IV of the periodic system D.I. Mendeleev. M.: Enlightenment, 1983.-176s.

2. Lebedev Yu.A. The second wind of the marathon runner (About lead). M.: Metallurgy, 1984 - 120p.

3. Mansurova S.E. School workshop "We monitor the environment of our city." M.: Vlados, 2001.-111s.

4. Nekrasov B.V. Fundamentals of General Chemistry. Volume 2. M .: Publishing house "Chemistry", 1969 - 400s.

5. Nikitin M.K. Chemistry in restoration. L .: Chemistry, 1990. - 304 p.

6. Nikolaev L.A. Metals in living organisms. M.: Enlightenment, 1986. - 127p.

7. Petryakov-Sokolov I.V. Popular library of chemical elements. Volume 2. M .: Publishing house "Nauka", 1983. - 574 p.

8. Ruvinova E.I. Lead pollution and children's health. "Biology", 1998 No. 8 (February).

9. Sumakov Yu.G. Live appliances. M.: Knowledge, 1986. - 176p.

10. Sudarkina A.A. Chemistry in agriculture. M.: Enlightenment, 1986. - 144p.

11. Shalimov A.I. Nabat of our anxiety: ecological reflections. L.: Lenizdat, 1988. - 175p.

12. Shannon S. Nutrition in the atomic age, or how to protect yourself from small doses of radiation. Minsk: Publishing house "Belarus", 1991. - 170p.

Slides captions:

Bashurova Maria Grade 10 Novoorlovskaya secondary school

R&D: STUDYING THE CONTENT OF LEAD COMPOUNDS IN THE ENVIRONMENT Novoorlovsk settlement

Sources of lead compound contamination: car batteries, aircraft engine emissions, lead-based oil paints, bone meal fertilizers, ceramic coatings on porcelain, cigarette smoke, lead-lined or lead-lined pipes, the process of obtaining lead from ore, exhaust fumes, solders, plants grown near highways

Hypothesis of work: Lead compounds are present in the environment of Novoorlovsk.

The purpose of the work: to study the content of lead compounds emitted into the air, accumulated in soil, plants, snow.

Lead - Pb (Plumbum) serial number 82 atomic weight 207.21 This bluish-gray metal. He is malleable, soft. Tm = 327.4 degrees. In air, it quickly becomes covered with a layer of oxide.

Lead applications: battery and cable industry. Indispensable in the manufacture of bearings, printing alloy and some types of glass.

Lead compounds: Pb (N O3) 2 - lead nitrate, Pb 3 (OH) 2 (CO 3) 2 - lead dihydroxocarbonate (Pb 3 O 4) - minium (C2H5) 4 Pb - tetraethyl lead (TES) (CH3) 4 Pb – tetramethyl lead

Sources of lead compounds in the human body: Food (canned food in cans, fresh and frozen fish, wheat bran, gelatin, shellfish and crustaceans.) Drinking water Atmospheric air Smoking

Lead is a cumulative poison. Accumulates in the bones, liver and kidneys.

Saturnism is lead poisoning. Symptoms: severe weakness, abdominal cramps, paralysis, mental disorder

Vehicle group name Quantity per 20 min, pcs Quantity per hour (N), pcs Total distance traveled per hour by all vehicles, km Emissions per 1 km by one vehicle, g/km Emissions per 1 km by all vehicles, g/km Emissions for the total distance, g/km Passenger cars 6 1.8 0.019 0.342 0.62 Passenger diesel cars 2 6 0.6 - - - Truck carburetors with a carrying capacity of up to 3 tons 1 3 0.3 0.026 0.078 0.02 Truck carburetors with a carrying capacity of more 3 t - - - 0.033 - - Carburetor buses 1 3 0.3 0.041 0.123 0.004 Diesel trucks 2 6 0.6 - - - Diesel buses 1 3 0.3 - - - CNG-powered buses - - - - - - Total 13 39 3.9 0.119 0.543 0.644

Sampling sites: 1. Road near the school 2. Central boiler house 3. CJSC "Novoorlovsky GOK" 4. Forest 5. Road along the dacha cooperative.

The content of lead compounds on the soil surface (in snow). Test tube number Sampling area Presence of sediment Pollution level 1 Road near the school Yellow sediment Strong 2 Central boiler house Yellow sediment Strong 3 ZAO Novoorlovsky GOK Yellow sediment Strong 4 Forest No sediment Weak 5 Road along the dacha cooperative Yellowish sediment Medium

Sources of lead compounds in Novoorlovsk: Central boiler house Highway CJSC Novoorlovsky GOK

Lead is dangerous to humans!!!

Thank you for your attention!

Preview:

Appendix 1.

Treatment of lead poisoning.In acute poisoning, complexing agents are used, among which the most effective are tetacin and pentacin when administered intravenously (6 g of the drug per course of treatment in the form of a 5% solution). Also used are agents that stimulate hematopoiesis: iron preparations, campolone, cyanocobalamin, ascorbic acid. To reduce pain during colic, warm baths, a 0.1% solution of atropine sulfate, 10% sodium bromide solution, 0.5% novocaine solution, and a milk diet are recommended. To reduce vegetative-asthenic phenomena, intravenous glucose with thiamine and ascorbic acid, bromine, caffeine, coniferous baths, and a galvanic collar can be used. With encephalopathy, dehydrating agents are prescribed (25% magnesium sulfate solution, 2.4% aminophylline solution, 40% glucose solution); with polyneuropathy - thiamine, anticholinesterase agents, four-chamber baths, massage, physiotherapy exercises.

To remove lead from the depot, diathermy of the liver, intravenous administration of a 20% sodium hyposulfite solution are used.

Protective agents: B vitamins, vitamin C, vitamin D, calcium, magnesium, zinc, pectin compounds, sodium alginate, various varieties of cabbage.

Appendix 2

Prevention of lead poisoning.The main measure to prevent lead poisoning is to replace it with other, less toxic substances in those industries where it is used. For example, lead white is replaced with titanium-zinc, instead of lead gaskets for notching files, tin-zinc alloy gaskets are used, lead pastes for finishing car bodies are replaced with a paste made of plastic materials. During technological processes, as well as during the transportation of lead and lead-containing materials, it is necessary to hermetically seal sources of dust release, equipment for powerful aspiration ventilation with purification of air polluted with dust and lead vapors before it is released into the atmosphere. It is forbidden to use the labor of women and teenagers in the processes of lead smelting. It is necessary to observe such personal hygiene measures as sanitation of the oral cavity, washing hands with a 1% solution of acetic acid, the use of special clothing and respirators, therapeutic and preventive nutrition.

Appendix 3

Results of the carried out technique

determination of emissions of lead compounds by motor transport.

Vehicle group name	Quantity for 20 min, pcs	Quantity per hour (N), pcs	common path, traveled per hour by all cars, km	Emissions per 1 km by one vehicle, g/km	Emissions per 1 km by all vehicles, g/km	Emissions for the total path, g/km
Cars				0,019	0,342	0,62
Passenger diesel
Cargo carburetor with a load capacity of up to 3 tons				0,026	0,078	0,02
Cargo carburetor with a carrying capacity of more than 3 tons				0,033
Carburetor buses				0,041	0,123	0,004
Truck diesel
Diesel buses
Gas-cylinder, working on compressed natural gas
Total				0,119	0,543	0,644

Appendix 4

Sample tube number	Sampling site	Presence of sediment	Pollution level
	road near the school	yellow precipitate	Strong
	Central boiler house	yellow precipitate	Strong
	CJSC Novoorlovsky GOK	yellow precipitate	Strong
	Forest	No sediment	Weak
		Yellowish precipitate	Average

Appendix 5

Sample tube number	Sampling site	Presence of sediment	Pollution level
	road near the school	yellow precipitate	Strong
	Central boiler house	Yellowish precipitate	Average
	CJSC Novoorlovsky GOK	yellow precipitate	Strong
	Forest	Yellowish	Weak
	Road along the dacha cooperative	Yellowish precipitate	Average

Appendix 6

Sample tube number	Sampling site	Presence of sediment	Pollution level
	road near the school	Yellowish precipitate	Average
	Central boiler house	yellow precipitate	Strong
	CJSC Novoorlovsky GOK	yellow precipitate	Strong
	Forest	No sediment	Weak
	Road along the dacha cooperative	Yellow	Strong

After the mineralization of organs with sulfuric and nitric acids, lead and barium will be in the sediment in the form of BaSO 4 and PbS0 4 . The optimal conditions for quantitative precipitation

of Ba 2 + and Pb 2 + are: the concentration of H 2 SO 4 in the mineralization ~ 20% H 2 SO 4, the absence of nitrogen oxides (partial dissolution of PbSO 4 and, to a much lesser extent, BaS0 4 in nitric acid), time precipitation (~24 hours). Due to co-precipitation, Ca 2 +, Fe 3+, Al 3 +, Cr 3+, Zn 2+, Cu 2+, etc. can also be in the precipitate. When co-precipitating Cr 3 +, the precipitate is colored dirty green. To avoid loss of Cr 3+, the dirty green precipitate is treated with a solution of ammonium persulfate in 1°/o sulfuric acid solution while heated. The undissolved precipitate is analyzed for Ba 2 + and Pb 2 +, and the filtrate is left for the quantitative determination of chromium. In order to separate Ba 2+ and Pb 2+ (the presence of Pb 2 + interferes with the detection of Ba 2 +), the precipitate directly on the filter is carefully treated with 0.5-10 ml (depending on the size of the precipitate) of a hot solution of ammonium acetate 1, achieving completeness dissolving PbSO 4 ;

Qualitative detection

The filtrate is examined for lead: a) reaction with dithizone (НrDz)

Dithizone (diphenylthiocarbazone) has found wide application in inorganic analysis. Depending on the pH of the medium in solutions, dithizone can exist in two forms:

In the enol form, the reagent is slightly soluble in organic solvents (chloroform, carbon tetrachloride). In the ketonnon form, oi dissolves quite well in them, forming intensely green colored solutions. In alkaline solutions it gives an anion HDz", which is colored orange.

With many metal cations [Mn, Cr, Co, Ni, Zn, Fe(III), Tl, Cu, Cd, Ag, Pb, Bi, Hg], dithizone gives intracomplex salts (ditizonates), which are usually soluble in nonpolar organic compounds. sk solvents (CHC1 3, CC1 4). Many of the intracomplex compounds are brightly colored.

and secondary dithizonates:

There are primary dithizonates:

Primary dithizonates form with all cations. Secondary dithizonates are formed with only a few metals (HgDz, Ag 2 Dz, CuDz, etc.). Fischer, who introduced dithizone into analytical practice (1957), attributes the following structure to them:

Where a metal can give both primary and secondary dithizonate, everything depends on the pH reaction of the medium: in an acidic medium, primary dithizonate is formed, in an alkaline medium and with a lack of a reagent, secondary dithizonate is formed.

Both the formation and extraction of dithizonates depend primarily on the pH of the medium.

To detect lead, the solution obtained by treating the precipitate of PbS0 4 and BaS0 4 with ammonium acetate is shaken with a solution of dithizone in chloroform (CC1 4): in the presence of Pb 2 +, it is observed (at pH 7.0-10.0) "appearance purplish red color

The reaction is highly sensitive - 0.05 μg R 2+ in 1 ml. The limit of detection of Pb 2+ by this reaction in the organs is 0.02 mg.

Under the described conditions of chemical-toxicological analysis, the reaction is almost absolutely specific, since the preparation of Pb(HDz) 2 is preceded by the conversion of Pb 2+ to PbSO 4, i.e., the separation of Pb 2+ from most other elements. With PbSO 4, mainly Fe 3 + and Cr 3 + can coprecipitate. At the same time, Fe 3+ has a low affinity for dithizone, and Cr 3 + forms uncolored compounds with dithizone.

One of the advantages of the reaction is the ability to combine with its help a qualitative analysis for Pb 2+ with a quantitative determination. In this case, in the presence of a purple-red color of the chloroform layer, first

quantitative determination (see p. 302). Then, after measuring the color density of Pb (HDz) 2 on a photoelectrocolorimeter, lead dithizonate for further qualitative reactions is vigorously shaken for 60 seconds with 0.5-2 ml (depending on the volume and color intensity of the extract) 1 n. HNO 3 solution (or HC1):

Pb(HDz) 2 >- Pb(N0 8) 2 + 2H 2 Dz

(organic layer (water (organic layer)

calcic solution layer) calcic

bearer) creator)

Depending on the volume of the aqueous layer, the solution is further investigated by microcrystalline or macrochemical reactions.

I. With a small volume of the aqueous layer (0.5 ml), the entire volume is divided into 2 parts, carefully evaporated and reactions are carried out: a) a double salt of cesium iodide and c in and n c a - CsPbl 3 are obtained. Acidify 1/2 part of the residue with 30% acetic acid and mix with several crystals of potassium iodide:

1-2 crystals of cesium chloride are added to the solution - after some time a greenish-yellow precipitate of cesium iodide and lead precipitates. When viewed under a microscope, one can observe needle-shaped crystals, often collected in beams and spheroids.

Optimal conditions: 30°/v acetic acid solution, no mineral acids, little CsCl and excess KI.

The sensitivity of the reaction is 0.01 μg. The reaction makes it possible to detect (detection limit) 0.015 mg Pb 2+ per 100 g of the object of study;

b) formation of potassium, copper and lead hexanitrite КrСuРb(NO 2) 6 . The second part of the residue is mixed with 1-2 drops saturated solution copper acetate and carefully evaporated to dryness. The residue is dissolved in 2-3 drops of a 30% solution of acetic acid and a few crystals of potassium nitrite are added. In the presence of Pb 2+, after 5-10 minutes, KrCu Pb(NO 2) 6 crystals appear in the form of black or brown (with small amounts of Pb 2 +) cubes over the entire field of view. Optimal conditions: 30% solution of CH 3 COOH, absence of mineral acids, excess of potassium nitrite. The sensitivity of the reaction is 0.03 μg. The detection limit for Pb 2+ in biological material is 0.015 mg per 100 g of the organ.

P. With a large volume of the aqueous layer (2 ml or more), it is neutralized to pH 5.0 according to universal indicator paper, divided into 4 parts and examined by the reactions:

a) formation of PbS:

Pb(N0 3) 2 + H 2 S = PbSJ + 2HN0 3 .

The precipitate does not dissolve in dilute sulfuric and hydrochloric acids, but dissolves in dilute nitric acid with the release of nitrogen oxides and elemental sulfur:

3PbS + 8HNO 3 \u003d 3Pb (NO 3) 2 + 2NO + 3S + 4H 2 O;

b) formation of PbS0 4:

Pb(OCOCH 3) 2 + H 2 SO 4 = PbSO 4 | + 2CH 3 COOH

Lead sulfate is slightly soluble in water (1:22,800 at 15°); in dilute sulfuric acid, its solubility is even less; it is practically insoluble in alcohol; dissolves significantly in nitric acid, even better - in hydrochloric acid, especially when heated:

When water is added, lead sulfate precipitates again.

The precipitate of lead sulfate dissolves in solutions of caustic soda, caustic potash, acetate and ammonium tartrate (difference from barium sulfate and strontium sulfate):

When dissolved in ammonium tartrate, Pb 2 0 (C 4 H 4 0 6) 2 is formed.

c) formation of PbCr0 4 ; insoluble in acetic acid, but
soluble in mineral acids and caustic alkalis:

2Pb (OSOCH 3) 3 + K 2 Cr 2 0 7 + HOH - 2CH 3 COOK + 2PSYU 4 + 2CH 3 COOH.

d) the fourth part is examined by microchemical reactions
obtaining CsPbl 3 and K2CuPb(N0 2)e.

Quantitative determination of Pb 2+ after its isolation in the form of lead sulfate is possible by several methods:

a) bichromate o-th odometric in excess of bichromate that did not react with Pb 2+. The definition is based on the following reactions:

The bichromate-iodometric method of determination gives good results (93% with an average relative error of 1.4 ° / o) with a content of 2 to 100 mg of lead per 100 g of the organ. With lead amounts less than 2 mg (determination limit), the method is unreliable. For example, in the presence of 1 mg of Pb 2 + in 100 g of an organ, only 37% is determined on average;

b) extraction-photometric metric and under lead diti-zonate. The method is based on the above sensitive and rather specific reaction:

Pb (OSOCH 3) 2 4- 2H a Dz (at pY 7-10) - Pb (HDz) a + 2CH 3 COOH.

The resulting dithizonate is extracted with chloroform at a pH above 7.0 until the extraction of Pb 2+ is complete. The extracts are combined, washed with a KCN solution in the presence of NH 4 OH, settled, the volume is measured, and then the color density of the chloroform extract is determined on FEC at a full length of 520 nm in a cuvette with an absorbing layer thickness of 1 cm. Chloroform serves as a reference solution. Beer's law is observed within 0.0001 - 0.005 mg / ml.

c) complexometric, which is common to many divalent and some trivalent cations.

The principle of complexometric titration is as follows: a small amount of the corresponding indicator is added to the test solution containing a certain cation at a strictly defined pH value - a colored complex compound of the indicator with the cation is formed that is highly soluble in water. When titrated with trilon B (complete III) - disodium salt of ethylenediaminetetraacetic acid, the complex of the cation with the indicator is destroyed, since trilon B forms a more stable complex with the cation being determined. At the equivalent point, a free indicator is released, coloring the solution in the color inherent in the indicator at a given pH value of the medium.

Most cations are determined in an alkaline medium, for which an ammonia buffer (a mixture of ammonia and ammonium chloride) is introduced into the titrated solution.

The determination of Pb 2+ (or another divalent cation) is based on the following reactions:

A. N. Krylova for the determination of Pb 2+ recommends back titration of Trilon B (used to determine cations that react with a solution of NH 4 OH). The essence of the technique is as follows: the test solution is diluted with water to 100-150 ml and mixed with an excess of 0.01 N. solution of Trilon B. 10 ml of ammonia-chloride buffer 2 and 0.1 - 0.2 g of dry Zriochrome black T (mixture with NaCl 1:200). An excess of Trilon B is titrated with 0.01 N. ZnCl 2 solution until the blue-blue color changes to red-violet. 96% is determined with an average relative error of 6.2% at 1 mg Pb 2 + per 100 g of the organ; 97% with an average relative error of 27% at 10 mg. The limit of determination is 0.5 mg Pb 2 + per 100 g of the organ.

toxicological significance. The toxicological significance of lead is determined by the toxic properties of metallic lead, its salts and some derivatives, their wide and varied use in industry and everyday life.

Especially dangerous in relation to lead poisoning are the extraction of lead ores, lead smelting, the production of batteries, lead paints [white lead 2PbCO 3 .Pb (OH) 2 and red lead Pb 3 O 4], the use of which in the USSR is limited only to painting ships and bridges , tinning, soldering, the use of lead glaze PbSi0 3, etc. With insufficient labor protection, industrial poisoning is possible.

Sources of domestic poisoning were, in a number of cases, poor-quality tinned, enameled, porcelain-faience and glazed earthenware.

Cases of lead poisoning through drinking water (lead pipes), snuff wrapped in lead paper, after a gunshot wound, etc. are described. Cases of poisoning with lead salts and tetraethyl lead are also known.

Lead is a protoplasmic poison, causing changes mainly in the nervous tissue, blood and blood vessels. The toxicity of lead compounds is largely related to their solubility in gastric juice and other body fluids. Chronic lead poisoning produces a characteristic clinical picture. The lethal dose of various lead compounds is not the same. Children are especially sensitive to it. Lead is not a biological element, but is usually present in water and food, from where it enters the body. A person who is not working with lead absorbs, as N.V. Lazarev points out, 0.05-2 g of lead per day (an average of 0.3 mg). Lead compounds can accumulate in bone tissue, liver, and kidneys. About 10% of it is absorbed by the body, the rest is excreted in the feces. Lead is deposited in the liver and in tubular, somewhat less - in flat bones. In other organs, it is deposited in a small amount. Hence the possibility of detecting lead in the internal organs of the corpses of people who died from other causes, and the need to quantify it with positive results of a qualitative analysis.

The natural content of lead (according to A. O. Voinar, in milligrams per 100 g of the organ) in the liver is 0.130; in the kidney 0.027; in tubular bones 1.88; in the stomach and intestines 0.022 and 0.023, respectively.

Plants growing on the territory of the school yard and the territory adjacent to it are noticeably oppressed and have a deplorable appearance.

We assume that one of the reasons for these phenomena can be considered the accumulation of heavy metal ions and acid anions in the soil of the schoolyard. Pollution occurs mainly through the atmosphere, aerosols, vapors, dust, soot, soluble substances brought with rain and snow settle on the soil surface. Pollutants come from the chimneys of diesel locomotives and cars. All soil pollutants enter the food chain and enter the human gastrointestinal tract with food or water. The human body is influenced by environmental factors. Close to boiler houses railway networks, serviced by diesel locomotives running on fuel oil, a large flow of vehicles running on diesel sulfur-containing fuel, an increased content of heavy metal compounds should be expected.

In big Soviet Encyclopedia the following definition is given:

Heavy metals are groups of metals including Cu, Ni, Co, Pb, Sn, Zn, Cd, Bi, Sb, Hg. Heavy metals are used both in the elemental state and in the form of various alloys with other metals.

In Dahl's dictionary:

Heavy metals - metals that have a high specific gravity, for example: copper, lead, zinc, tin.

Therefore, I devote my work to determining the content of heavy metals and acid anions in the soil and snow of the schoolyard, as well as to elucidating the effect of heavy metal ions on the growth and development of plants.

Theoretical part

Lead enters the environment from natural sources. These are wind erosion of the soil, volcanic activity, forest fires. But the main income comes from anthropogenic sources: household and industrial waste, vehicles, aviation, rocket and space technology, as well as hunting, as a result of which up to 1,400 tons of lead shot are released into the environment annually.

Lead easily penetrates the soil and accumulates in plants. These plants are included in the trophic chain, which leads to an increase in the concentration of this element. Man, as the final link in the food chain, experiences the greatest danger of the toxic effects of lead. In the literature, we did not find a description of the effect of lead on the growth and development of plants.

Sources of lead in the human body

Organic lead compounds enter the human body through the skin and mucous membranes with food and water, inorganic (for example, contained in exhaust gases) - through the respiratory tract and digestive tract.

1. More than half of all lead in the body comes from the air. Every day, a city dweller inhales 20 m3 of air with a lead content of 2 * 10 "mg/mg.

Vehicles do a lot of harm. The rapid growth in the number of cars in last years led to the fact that in some cities, where there are no enrichment plants or metallurgical plants, up to 8 thousand tons of lead are emitted into the air per year, which exceeds the permissible level.

With a daily meal, 0.06-0.5 mg of lead enters the body. In products of plant and animal origin, the natural content of lead does not exceed 0.5-1.0 mg/kg. It is found in large quantities in predatory fish, such as tuna (up to 2.0 mg/kg), mollusks and crustaceans (up to 10 mg/kg). The toxic dose of lead is -1 mg, the lethal dose is -10 g.

Lots of lead in food grown along highways. Lead is produced by the combustion of leaded gasoline (gasoline containing tetraethyl lead) and easily permeates soil. Lead compounds are added to gasoline to improve engine performance.

Absorbed lead penetrates into the blood, is distributed in bone (up to 90%) and soft (liver, kidney, brain) tissues, as well as in hair, nails and teeth. Lead is absorbed more actively with a deficiency in the body of iron, calcium, zinc compounds and with an increased intake of vitamin D.

The main mechanism of action of lead on the body is that it blocks the enzymes involved in the synthesis of hemoglobin, as a result of which red blood cells cannot carry oxygen, anemia and chronic oxygen deficiency develop.

Lead poisoning is very variable in manifestations and includes mental agitation, anxiety, nightmares, hallucinations, impaired memory and intelligence with symptoms of personality disintegration. Neurological disorders in children are very dangerous - hyperactivity, deterioration in mental development, and a decrease in working capacity for learning. Poisoning with lead and its salts causes damage to the gums, intestinal upset, kidney disease. Lead compounds are carcinogenic and genotoxic - they can cause mutations, disrupting the tertiary structure and functions of DNA synthesis and repair enzymes.

According to the results of official statistics, among occupational intoxications, lead ranks first.

It is almost impossible to determine the amount of lead emissions into the atmosphere by car engines more precisely, since the amount of emissions depends on many factors that are difficult to take into account.

In order to reduce lead pollution, it is necessary to reduce the use of leaded gasoline, since this gasoline is the source of lead emissions into the atmosphere. It is also necessary to create a number of installations that would retain lead, that is, the amount of lead settled in these installations. Natural such installation are any kinds of vegetation.

The creation of even minor barriers would not greatly, but would reduce the degree of lead poisoning of the population of our planet.

At present, it is difficult to find an industry where copper, its alloys or compounds are used. Heat exchangers, vacuum apparatuses, pipelines, electrical wires are made from copper. Bronze, brass, copper-nickel and other copper alloys are used as a structural material, anti-friction, corrosion-resistant, highly thermally and electrically conductive materials in mechanical engineering, shipbuilding, and the aviation industry. Copper oxides are used in the production of glass and enamel, copper (II) sulfate is used in electroplating, in wood conservation, in the manufacture of paints, and in ore dressing. Oxide-copper catalysts are used for gas purification, chloride and copper (II) nitrate - in pyrotechnics. Many copper compounds are pesticides or fertilizers, so they are widely used in agriculture.

The extent of the use of copper and its compounds must be taken into account when analyzing the impact of copper content in the environment on living organisms. The effect of copper on living organisms is ambiguous, since, on the one hand, it is an important trace element involved in metabolic processes, and on the other hand, its compounds are toxic (in high concentrations). A pronounced ability to complex formation, interaction with oxygen, susceptibility to reversible reduction - these are the features of copper that determine its biological role in living cells.

Excess copper is also toxic to plants. With copper intoxication, the color of the leaves changes to red and brown-brown, which indicates the destruction of chlorophyll. In addition, there is growth inhibition, developmental delay.

Biological functions of copper

It is a component of 11 enzymes.

Necessary for the formation of hemoglobin, since it activates iron, which accumulates in the liver, otherwise it cannot participate in the formation of hemoglobin. Stimulates the hematopoietic function of the bone marrow.

Necessary for the correct exchange of vitamins of groups B, A, C, E, P

It has an insulin-like effect and affects energy metabolism.

Necessary for the processes of growth and development, a significant part of it is captured from the mother's body by the fetus during fetal development.

The reaction of the body to a lack and excess of copper

The lack of copper leads to the destruction of blood vessels, disease of the skeletal system, the occurrence of tumor diseases. Removal of copper from the connective tissue causes the disease "lupus erythematosus".

Excess copper in various tissues leads to severe and often irreversible diseases. The accumulation of copper in the liver and brain leads to Wilson's disease (hepatocerebral dystrophy).

Impact on the body: with a lack of iron, a person begins to tire quickly, headaches occur, and a bad mood appears.

IMPACT OF ACID RAIN ON LIVING NATURE.

Rainwater, which is formed during the condensation of water vapor, must have a neutral reaction, i.e. pH \u003d 7 (pH is an indicator that characterizes acidity). Rainwater, dissolving carbon dioxide, is slightly acidified (pH = 5.6-5.7). And having absorbed the acid formed from sulfur dioxide and nitrogen, the rain becomes noticeably acidic.

Earth and plants suffer from acid rain: soil productivity decreases, nutrient supply decreases, the composition of soil microorganisms changes. Acid rain causes great damage to forests. As the pH of the water decreases, the process of swamping of water bodies occurs. At first, the main reaction (pH natural water about 8) due to its natural buffer properties - the ability to neutralize incoming acid. However, the possibilities of buffer systems are not unlimited. Gradually, the water in the reservoir begins to acidify, which leads to irreversible processes in it: plankton, mollusks, fish die, some types of algae disappear, acid-loving mosses, mushrooms and filamentous algae rapidly develop, land sphagnum moss appears, and the reservoir becomes swampy. The death of the inhabitants of the reservoir is due not so much to acidification as to the processes that it causes: a drop in the content of calcium ions, leaching (extraction) of toxic heavy metal ions from bottom sediments, oxygen deficiency, deficiency of anaerobic processes, the formation of methane, hydrogen sulfide, carbon dioxide.

Research objectives:

1. Determine the content of heavy metals in the soil and snow in the school yard.

2. Determine the content of anions in the soil and snow in the school yard.

Research tasks:

Conduct a qualitative determination of chemical elements in soil and snow;

2) Determine the content of heavy metals in snow and soil by thin layer chromatography.

3) Determine the content of acid anions in soil and snow.

Ways to solve these problems:

Snow and soil samples were studied throughout the year: soil samples in September, and snow samples in January 2007 and January 2008.

Stages of research work:

1. Qualitative Definition heavy metals in snow and soil.

2. Determination of heavy metals in snow and soil by chromatography.

3. Determination of acid anions in soil and snow.

4. Study of the effect of heavy metal ions on the growth and development of plants.

Study areas:

Sports field in the school yard.

Strip of land along the highway.

The area of ​​the new elevator in the steppe zone

Experimental stage #1.

Topic: Qualitative determination of heavy metal ions in snow and soil.

Purpose: to carry out qualitative reactions for ions: Pb2+, Fe3+, Cr +6, Cu2+, Mn2+.

Heavy metals enter the soil mainly from the atmosphere with emissions from industrial enterprises, and lead - from car exhaust gases. The most typical heavy metals are lead, cadmium, mercury, zinc, molybdenum, nickel, cobalt, tin, titanium, copper, vanadium. From the atmosphere into the soil, heavy metals "fall" most often in the form of oxides, where they gradually dissolve, turning into hydroxides, carbonates, or into the form of exchange cations.

On the degree of environmental hazard chemical substances, falling into the soil in various ways, are divided into 3 classes:

1- cadmium, mercury, lead, zinc, fluorine, arsenic, selenium;

2- cobalt, molybdenum, boron, copper, nickel, antimony;

3 - tungsten, manganese, vanadium, strontium.

Definition chemical composition soils most often begin with the analysis of water soil extract, since highly soluble soil compounds are first absorbed by plants. Excess amounts of soluble salts (more than 0.2% of the mass of dry soil) create an increased concentration of ions in the soil solution, and this reduces soil fertility and its ecological state.

Stages of work:

Soil preparation for analysis;

Water extract preparation; qualitative determination of chemical elements in soil, in water.

Soil preparation for analysis consists in grinding the material, removing impurities, sifting through a sieve with a hole diameter of 1 mm and reducing to a small mass. Various methods are used to reduce the sample. One of them is the quartering method. The crushed material was thoroughly mixed, scattered in an even thin layer in the form of a square or circle, divided into four sectors. The contents of the two opposite sectors were discarded, and the other two were connected together.

An aqueous soil extract is most often used to determine water-soluble compounds, as well as to determine the actual soil acidity.

For its preparation, 20 g of air-dry sifted its ecological state, the soil was placed in a 100 ml flask, 50 ml of distilled water was added, shaken for 5-10 minutes and filtered. The results of the work showed that the water extract of the soil contains heavy metal cations.

Lead ion detection

Qualitative determination with sodium rhodisonate.

Place a few drops of the test solution on a sheet of filter paper and add 1 drop of freshly prepared 0.2% sodium rhodisonate solution. In the presence of lead ions, a blue spot or ring is formed. When 1 drop of buffer solution is added, the blue color turns to red. The reaction is very sensitive: detectable minimum 0.1 μg

Quantification with potassium dichromate.

Dichromate and chromate ions form poorly soluble lead chromate with lead ions yellow color. Evaporate 0.5-1 l of analyzed water to a volume of 10 ml. Add 5 ml of nitric acid solution (1:2) to the obtained sample. Heat in a water bath for 15 min. , filter and evaporate in a porcelain cup. Add 2 ml of 0.5% sodium acetate solution and 8 ml of distilled water to the dry residue. Mix the solution and filter into a test tube. Prepare a standard scale.

Detection of iron ions.

The maximum permissible concentration of total iron in the water of reservoirs and drinking water 0.3 mg/l, organoleptic limiting indicator of harmfulness.

General iron.

Place 10 ml of test water into a test tube, add 1 drop of concentrated nitric acid, a few drops of hydrogen peroxide solution and approximately 0.5 ml of potassium thiocyanate solution. At an iron content of 0.1 mg / l, a pink color appears, and at a higher one, red.

Iron(II).

Potassium hexacyanoferrate (III) in an acidic environment (pH ~ 3) forms a dark blue turnbull blue precipitate with the Fe~ cation:

Add 2-3 drops of sulfuric acid solution and 2-3 drops of reagent solution to 1 ml of test water.

Iron(III).

1. Potassium hexacyanoferrate (II) in a slightly acidic medium with a cation

Fe forms a dark blue precipitate of Prussian blue:

Add 1-2 drops of the solution to 1 ml of the test water of hydrochloric acid and 2 drops of reagent solution.

2. Ammonium or potassium thiocyanate KSCN is formed in an acid medium with blood-red iron thiocyanate. Depending on the concentration of the rhodanide ion, complexes of various compositions can be formed:

To 1 ml of test water add 2-3 drops of hydrochloric acid solution and 2-3 drops of reagent solution.

Detection of manganese ions

The MPC of manganese in the water of reservoirs is 0.1 mg/l, the limiting indicator of harmfulness is organoleptic.

quality detection.

Place 25 ml of the test water into the flask, acidify with a few drops of 25% nitric acid, add 2% silver nitrate solution dropwise until cloudiness continues. Then 0.5 g of ammonium persulfate or a few crystals of lead dioxide are introduced, heated to a boil. In the presence of manganese at a concentration of 0.1 mg / l and above, a pale pink color appears:

2 Mn2++5 PbO2+4H MnO4+5 Pb2++2H2O

Copper ion detection

MPC of copper in water is 0.1 mg/l, limiting indicator of harmfulness is organoleptic.

Qualitative detection

First way.

Place 3-5 ml of the test water in a porcelain cup, carefully evaporate to dryness and apply a drop of concentrated ammonia solution to the peripheral part of the stain. The appearance of an intense blue or violet color indicates the presence of Cu +:

The second way.

Shake 5-10 ml of the test water in a cylinder with a small amount (10-20 mg) of the adsorbent - calcium fluoride or talc. Copper ions (11) in water are adsorbed on its surface. Separate the precipitate by carefully draining the water, place on a watch glass or in a recess on a porcelain plate. Nearby, for comparison, apply a drop of distilled water (“blank experiment”). To the test sediment and water, simultaneously add a drop of iron (III) chloride solution and a drop of 0.2 M sodium thiosulfate solution, mix with a glass rod and compare the discoloration rate of both samples.

In the “blank experiment”, a slow decolorization of the complex anion intensely colored in purple is observed in the presence of copper ions, which play the role of a catalyst, the purple solution decolorizes instantly. The results of the work showed that the water extract of the soil contains metal ions.

Experimental stage #2.

Topic: Determination of heavy metals in snow and soil by chromatography.

Purpose: To confirm the content of heavy metals by chromatography.

These studies were carried out by thin layer chromatography. In January, she carried out a qualitative analysis of the snow cover, the composition of which, in terms of the content of heavy metal ions, corresponds to the water extract of the soil.

Because the snow cover accumulates in its composition almost all substances entering the atmosphere. In this regard, snow can be considered as a kind of indicator of air purity. Snow is one of the most informative and convenient indicators of air pollution. Its dust content is influenced by natural factors and a special wind regime. Snow should be taken over the entire depth of its deposits in glass jars (more conveniently three-liter ones). Immediately after the sample has melted, when the temperature of the melt water is equal to room temperature, it is analyzed.

Experimental technique

Snow samples for research are taken from the entire depth of the snow cover. Melt the snow, acidify with nitric acid and evaporate from 1 liter to 5 ml. Soil samples are taken to a depth of up to 10 cm, since it is in the upper soil horizon that heavy metals accumulate. Dry crushed soil weighing 10 g is poured with 50 ml of 1 M nitric acid solution and left for a day, then the mixture is filtered and the filtrate is evaporated to 3 ml. The essence of the TLC method is the separation of complex mixtures of substances into individual compounds due to differences in sorbability in a thin layer of sorbent. To do this, we use Silufol plates, which are a fixed layer of silica gel with starch applied to aluminum foil. On a cut out plate measuring 3 x 7 cm, we mark the start line, on which, using capillaries, we apply the analyzed mixture and the witness ( water solution salts of the corresponding metal). Then this plate is placed in a glass with a solvent (n-butanol, distilled water with the addition of acetic acid until pH is established in the system). Under the action of capillary forces, the solvent rises in the sorbent layer, carrying the analyzed substances with it, while they move at different speeds and they are separated in the sorbent layer. After 15 - 20 minutes, when the solvent reaches the finish line, we take out the chromatogram.

To detect metal ions, we spray the chromatogram from a spray gun with solutions of reagents that give color reactions; to detect ions, we carry out a reaction with a solution of potassium iodide; ions - with a solution of potassium hexacyanoferrate (II); ions - with a solution of 1,5-diphenylcarbazide. In this case, colored spots appear (yellow, Prussian blue, pink, respectively). According to the height of the spot on the chromatogram, we carry out a quantitative comparison of the analyzed heavy metal ions.

Pb2+ Fe3+ Cr2O72- Cu2+ Mn2+

Snow (sports ground) 2.0 1.6 2.1 1.4 0.4

Snow (along the road) 1.7 2.4 0.01 1.2 0.31

Snow (steppe zone) 0.5 0.7 - 0.2 0.2

Object of study The height of the spot of the analyte on the chromatogram, cm

Fe3+ Cr2O72 Cu2+ Mn2+

Soil (sports ground) 2.2 2 2.2 1.1 0.6

Soil (along the road) 1.8 1.6 1.3 1.1 0.6

Soil (steppe zone) 0.4 0.7 0.2 0.4

Analysis of snow and soil samples from a sports ground located in the immediate vicinity railway, showed the presence of lead ions in them, and the concentration of lead in the soil turned out to be higher than in the snow. This is logically explained by the fact that snow accumulates pollutants during the season, and soil from year to year. The content of lead in the soil depends on the intensity of traffic, emissions from boilers.

Soil samples taken from the road also showed a significant lead content.

In soil samples taken near the road and from the sports ground, a significant content of chromate ions and iron ions was found. Iron compounds may be present in the soil for natural reasons:

(weathering of rocks and their erosion by water). However, the presence of iron ions in the snow indicates technogenic contamination of the soil with this element.

Having come to these results, I was interested in the question: “What effect do heavy metals have on the human body and plants?”

Experimental Stage #3

Topic: Qualitative determination of anions in soil

Purpose: to carry out qualitative reactions for the presence of carbonate, sulfate, chloride, nitrate ions in the soil

1. Preparation of water extract.

Thoroughly grind the soil sample in a porcelain mortar. Take 25 g of soil, place it in a 200 ml flask and add 50 ml of distilled water. Shake the contents of the flask thoroughly and let stand for 5-10 minutes. and then filter into a 100 ml flask.

2. Preparation of hydrochloric acid extract.

Transfer the soil remaining after filtering the water extract into a flask where the initial mass is located, pour 50 mg of a 10% hydrochloric acid solution into the flask and shake the contents for 30 minutes, and then let it stand for 5 minutes.

3. Qualitative determination of the content of carbonate ions in the soil sample.

Place a small amount of dry soil in a porcelain cup and add a few drops of 10% hydrochloric acid solution with a pipette. If the soil is a salt of carbonic acid, then a characteristic “hiss” is observed - the release of carbon monoxide during the reaction (4). According to the intensity of gas release, a more or less significant content of carbonates in the soil is judged.

4. Qualitative determination of the content of chloride ions.

Pour 5 ml of an aqueous extract into a test tube and add a few drops of a 10% solution of nitric acid to it and, using a pipette, 1-2 drops of a 0.1 N solution of silver nitrate. In the presence of chloride ions in the soil extract in the amount of tenths of a percent or more, a white flocculent precipitate is formed. When the content of chloride ions is in the amount of hundredths and thousandths of a percent, no precipitation occurs, but the solution becomes cloudy.

5. Qualitative determination of the content of sulfate ions.

Pour 5 ml of an aqueous extract into a test tube, add a few drops of concentrated hydrochloric acid to it and add 3-3 ml of a 20% barium chloride solution using a pipette. In the presence of sulfates in the water extract in the amount of several tenths of a percent or more, a white fine crystalline precipitate precipitates. Hundredths and thousandths of a percent of sulfates in a solution are determined by the turbidity of the solution.

6. Qualitative determination of nitrate - ions.

Pour 5 ml of the filtrate of aqueous soil extract into a test tube and add dropwise a solution of diphenylamine in sulfuric acid. In the presence of nitrates, the solution turns blue.

Fe3+ CO32- Cl- SO42- NO3-

Sports ground + + + + +

By the road + + + + +

Steppe zone + + + - -

Qualitative chemical analysis of the samples showed the presence of various anions in the soil extract: chloride-, sulfate ions. Acting on dry soil with a solution of hydrochloric acid, we determined the presence of carbonate ions in each soil sample. During the preparation of hydrochloric acid extract, hydrogen sulfide was detected, which indicates the presence of sulfide ions in the soil. The content of iron salts is observed in the hydrochloric acid extract of all soil samples (2 and 3).

There is no visual difference in the quantitative content of the above anions in soil samples.

2. Qualitative composition of waters.

To determine the ways of penetration into the soil of the detected cations and anions, an attempt was made to carry out a qualitative analysis of melted snow water for the content of the same ions.

To determine the qualitative composition of water samples, the same methods were used as for determining the content of ions in soil. The presence of ions in melt water can be summarized in a table that reflects the presence of certain cations and anions in the studied samples.

Sample number Presence of ions chloride ions sulfate ions iron ions (2,3)

1 sports ground + - +

2 near the highway + - +

3 steppe zone + + +

Practically in all melt waters, except for the control sample, the presence of a small amount of chloride ions was noted. It is obvious that the entry of chloride ions into the snow waters is associated with "surface" pollution: soil chlorides "dissolve" in the snow masses and are detected during the study. This suggests that the content of chlorides in the soil is quite high.

Experimental stage #4.

Topic: Effect of heavy metal ions and acid anions on plants.

Purpose: To find out the effect of heavy metal ions on the growth and development of plants.

EXPERIMENTAL TECHNIQUE

1. Preparation of material for research.

The grains of a cereal plant are germinated to a juvenile state in a complete Pryanishnikov nutrient mixture.

2. Preparation of solutions.

243 mg of NH4NO3, 23 MgMgSO4 7H2O, 160 mg of KC1, 25 mg of FeC136H20, 172 mg of CaHPO4 and 344 mg of CaSO4 2H2O are placed in 5 liter jars (the complete nutrient mixture of Pryanishnikov - PPSP). Then, 10 mg of copper sulfate (II) are added to the 2nd and 4th banks, and 8 mg of lead acetate (P) are added to the 3rd and 5th. Water is poured into the jars (tap, which contains trace elements), bringing the volumes of solutions to 1 liter. The solutions in the 4th and 5th banks are acidified.

3. Conducting an experiment. 13.10.04 - soaked wheat and beans; 14.10.04 - wheat swollen;

15.10.04 - wheat was placed in test tubes; swollen beans;

18.10.04 - placed the beans in test tubes.

Wheat and beans were germinated to juvenile state.

Juvenile plants were placed in test tubes with prepared solutions: 1 - PPSP (control); 2 - PPSP + excess copper ions; 3 - PPSP + excess lead ions; 4 - acidified PPSP

Excess copper ions; 5 - acidified PPSP + excess lead ions.

Experiment results

Flask number General form plants Stem length Root length Leaf length Leaf blade width

No. 1 control Well-developed plant, 32.5 2 9 2.5

the stem is thick, the root is well developed

№2 PPSP+ excess of ions Depressed plant, leaves 37 0.1 6 2

copper pale, stem thin

№3 PPSP+ excess of ions Well-developed plant, 30 7 8 2.3

lead stem is thick, the root is well developed

No. 4 acidified PPSP+ Stunted plant 24 - 5.5 2

excess copper ions

No. 5 acidified PPSP+ Oppressed plant, live 27 4 7.5 2.2

excess lead ions

The conducted experiment showed that:

1. Plants grown in complete nutrient mixture develop normally.

2. Plants grown in nutrient solutions containing an excess of heavy metal ions (copper and lead) lag behind in development from plants grown in PPSS, according to the data in Table. 1,4,5. But some studies have led to unexpected results. There is an advance in the growth of wheat stalks in the presence of lead ions in comparison with PPSP

3. Plants grown in acidified solutions lag far behind in development, and some of them die. In plants, the growth of the aerial part is significantly inhibited, the formation of lateral roots is delayed, root hairs are not formed, chlorosis is observed (in a jar with an acidified mixture of PPSP and an excess of copper ions): leaves die, loss of turgor is observed, growth of roots in length and the formation of root hairs are inhibited (in a jar with an acidified mixture of PPSP and an excess of lead ions).

Conclusion

This work is of an exploratory nature, since studies of snow and soil samples were carried out during the year. The work clearly sets goals, objectives, ways of solving problems, stages of research work. In order to get the most reliable results on the content of heavy metal ions, I carried out comparative analyzes: 1) qualitative determination, 2) determination by thin layer chromatography. Both methods confirmed the content of heavy metal ions and acid anions in snow and soil. An experiment was modeled to reveal the effect of heavy metal ions on the growth and development of plants.

Based on the conducted research, the following conclusions can be drawn:

1. In the course of the experiment, it was found that salts of heavy metals, namely lead and copper, as well as an acidic environment, inhibit the growth and development of both aboveground (stems) and underground (roots) parts of wheat and other plants. This occurs as a result of increased absorption of heavy metal ions by plants when the nutrient solution is acidified. Ions of heavy metals in high concentrations have a toxic effect and cause the death of plants.

2. Qualitative Analysis Soil and water samples taken in the school area and from adjacent territories showed the presence in them of a fairly large number of various ions: chloride, sulfate, carbonate, sulfide ions, iron cations (2 and 3).

4. Excessive content of chloride ions in the soil and groundwater also adversely affects the life of plants, as the process of starch accumulation is disrupted.

The entry of mineral salts into soil and water is due to a number of anthropogenic and natural factors. To reduce soil and water pollution, a switch to another type of fuel should be made.

5. We have seen that the presence of heavy metals in the body is one of the negative factors affecting health.

6. To absorb sulfur compounds from the atmosphere, and heavy metal salts from the soil, it makes sense to grow plants that capture them on the territory of the school yard. Few trees and shrubs have such abilities. We propose to include poplar and pine in the list of the schoolyard greening project.