Water quality research. Examination of mineralizates for the presence of lead Qualitative determination of lead in biological material

LEAD COMPOUNDS

Lead ions that enter the body combine with sulfhydryl and other functional groups of enzymes and some other vital protein compounds. Lead compounds inhibit the synthesis of porphyrin, cause dysfunction of the central and peripheral nervous system. About 90% of lead ions entering the blood are bound by erythrocytes.

Lead compounds are excreted from the body mainly with feces. Smaller amounts of these compounds are excreted in the bile, and traces are excreted in the urine. Lead compounds are partially deposited in bone tissue in the form of trisubstituted phosphate. It should be borne in mind that small amounts of lead are contained in the body as a normal component of cells and tissues.

Examination of mineralizates for the presence of lead

To detect lead in the organs of corpses, blood, urine and other objects of biological origin, a precipitate is used, which is formed in mineralizates after the destruction of biological material by a mixture of sulfuric and nitric acids.

After the destruction of biological material by a mixture of sulfuric and nitric acids, lead precipitates in the mineralizate in the form of a white precipitate of lead sulfate. The same color precipitate of barium sulfate is formed during poisoning with barium compounds. As a result of co-precipitation, precipitates of lead and barium sulfates can be contaminated with calcium, chromium, iron, etc. ions. If chromium is present in the precipitate, it has a dirty green color. To free precipitates of lead and barium sulfates from impurities, these precipitates are washed with sulfuric acid and water, and then the lead sulfate precipitate is dissolved in an acidified ammonium acetate solution:

The course of analysis for the presence of lead depends on the amount of precipitation in the mineralizates.

Investigation of relatively large precipitates of lead sulfate

Reaction with potassium iodide. In the presence of lead ions, a yellow precipitate of PbI 2 precipitates, which dissolves when heated and reappears as yellow plates when the solution is cooled.

Reaction with potassium chromate. The formation of an orange-yellow precipitate of barium chromate indicates the presence of lead ions in solution. Limit of detection: 2 µg of lead per sample.

Reaction with hydrogen sulfide water. The appearance of a black precipitate of lead sulfide (or turbidity) indicates the presence of lead ions in solution. Limit of detection: 6 µg of lead per sample.

reaction with sulfuric acid. The appearance of a white precipitate indicates the presence of lead ions in the solution. Limit of detection: 0.2 mg lead ions per sample.

TETRAETHYLlead

TES is a clear, colorless liquid with an unpleasant, irritating odor (in negligible concentrations it has a pleasant fruity odor). It is almost insoluble in water, easily soluble in kerosene, gasoline, chloroform.

The isolation of tetraethyl lead is carried out by various methods, depending on the nature of the object.

a) When examining the internal organs of a corpse, isolation is carried out by distillation with water vapor. The distillate in the amount of 50-100 ml is collected in a receiver containing 30 ml of a saturated alcoholic solution of iodine; the receiver is connected to a trap containing also a saturated alcohol solution of iodine.

After distillation, the contents of the trap and the distillate are combined, covered with a watch glass and left for 30 minutes at room temperature, then evaporated to dryness in a porcelain cup on a water bath. The residue is treated with nitric acid (1:2) and again evaporated on a water bath. The crystalline residue is dissolved in a small amount of distilled water and subjected to a qualitative and quantitative study on the lead ion according to the method described above. For the purposes of chemical-toxicological analysis, the method was developed by A. N. Krylova.

Research at TPP should be carried out immediately upon receipt of the object. A positive result is obtained with a content of 0.3 mg of TES in 100 g of the test object.

In case of a negative result in the study at TPP, it is necessary to analyze the decomposition products of tetraethyl lead - non-volatile lead compounds, for which the contents of the flask, after distillation of the TPP, are placed in a large porcelain cup and evaporated in a water bath. The residue is subjected to mineralization with sulfuric and nitric acids and examined as described above. A positive result is observed even in the presence of 0.3 mg of inorganic lead in 100 g of cadaveric material.

b) Isolation from plant objects.
In the study of animal products (meat, meatballs, etc.), thermal power plants are isolated according to the method described above. If the products are flour, cereals, bread and other substances of vegetable origin, the isolation of the thermal power plant is
it is more respectful to produce by extraction with an organic solvent. In this case, 50-100 g of the object is poured, for example, with chloroform and left at room temperature for 2 hours in a flask with a ground stopper. The chloroform extract is filtered into a beaker, on the bottom of which about 1 g of dry
crystalline iodine. Stir the contents of the beaker periodically. rotational movement in order to accelerate the dissolution of iodine. The object on the filter is washed 1-2 times with chloroform, and the washing liquid is collected in the same beaker. After 15-30 minutes, the contents of the glass are transferred to a porcelain
cup and evaporated to dryness on a water bath. Dry residue
destroy with sulfuric and nitric acids, remove nitrogen oxides
and examine for Pb 2+ .

When examining clothing for the presence of TES, it is subjected to extraction with an organic solvent with further transfer of TES to inorganic lead compounds, detection and quantitative determination of it.

c) Insulation from gasolines. All methods for isolating TES from gasoline are reduced to the destruction of the tetraethyl lead molecule and the detection and determination of Pb 2 +. Let's take one of the ways as an example. Mix 20 ml
of gasoline with 20 ml of a 4% alcohol solution of iodine. After some time, the aqueous phase is poured into a porcelain dish and evaporated to dryness on a water bath. The resulting residue is examined for Pb 2 +

Qualitative detection and quantification. After the destruction of the TES molecule, the detection and determination of Pb 2+ does not present any special features. All reactions and methods described above are suitable.

Iodometrically, it is possible to determine up to 1 mg of TES in the test sample (A.N. Krylova).

BARIUM COMPOUNDS

Soluble barium compounds that enter the body through the alimentary canal are absorbed in the stomach and cause poisoning.

Barium compounds are excreted from the body mainly through the intestines. Traces of these compounds are excreted through the kidneys and partially deposited in the bones. Information about the content of barium as a normal component of the cells and tissues of the body is not available in the literature.

MANGANESE COMPOUNDS

Manganese compounds are among the strongest protoplasmic poisons. They act on the central nervous system, causing organic changes in it, affecting the kidneys, lungs, circulatory organs, etc. When using concentrated solutions of potassium permanganate for gargling, swelling of the mucous membranes of the mouth and pharynx may occur.

Manganese compounds accumulate in the liver. They are excreted from the body through the alimentary canal and in the urine. During the pathological and anatomical autopsy of the corpses of persons who died as a result of poisoning with manganese compounds, burns of the mucous membranes in various parts of the alimentary canal are noted, resembling burns caused by caustic alkalis. Degenerative changes are found in some parenchymal organs.

CHROMIUM COMPOUNDS

In acute poisoning with chromium compounds, they accumulate in the liver, kidneys and endocrine glands. Chromium compounds are excreted from the body mainly through the kidneys. In this regard, when poisoning with these compounds, the kidneys and mucous membranes of the urinary tract are affected.

SILVER COMPOUNDS

Silver compounds that enter the stomach are absorbed into the blood in small quantities. Some of these compounds interact with the hydrochloric acid of the contents of the stomach and turn into chloride, which is insoluble in water. Silver nitrate acts on the skin and mucous membranes. As a result, "chemical" burns can occur. When dust containing silver or its compounds enters the body through the respiratory tract, there is a danger of damage to the capillaries. Long-term intake of silver compounds inside can cause argyria (deposits of silver in the tissues), in which the skin becomes gray-green or brownish in color.

Silver compounds are excreted from the body mainly through the intestines.

COPPER COMPOUNDS

The absorption of copper compounds from the stomach into the blood is slow. Since copper salts that enter the stomach cause vomiting, they can be excreted from the stomach with vomit. Therefore, only small amounts of copper enter the blood from the stomach. When copper compounds enter the stomach, its functions may be disturbed and diarrhea may appear. After the absorption of copper compounds into the blood, they act on the capillaries, cause hemolysis, damage to the liver and kidneys. With the introduction of concentrated solutions of copper salts into the eyes in the form of drops, conjunctivitis may develop and damage to the cornea may occur.

Copper ions are excreted from the body mainly through the intestines and kidneys.

ANTIMONY COMPOUNDS

The antimony compounds that enter the blood act as a "capillary poison". In case of poisoning with organic compounds of antimony, the functions of the heart muscle and liver are disturbed.

In the pathoanatomical examination of the corpses of persons poisoned with antimony compounds, there is hyperemia of the lung tissue, hemorrhage in the lungs and in the alimentary canal.

Antimony is excreted from the body mainly through the kidneys. Therefore, with antimony poisoning, nephritis can develop.

ARSENIC COMPOUNDS

Arsenic can accumulate in the body. In acute poisoning with arsenic compounds, they accumulate mainly in parenchymal organs, and in chronic poisoning - in bones and keratinized tissues (skin, nails, hair, etc.).

Arsenic is excreted from the body through the kidneys with urine, intestines and through some glands. The release of arsenic from the body is slow, which is the reason for the possibility of its accumulation. In excrement, arsenic can still be detected a few weeks later, and in cadaveric material - even a few years after death.

BISMUTH COMPOUNDS

Bismuth ions, absorbed into the blood, are retained in the body for a long time (in the liver, kidneys, spleen, lungs and brain tissue).

Bismuth is excreted from the body through the kidneys, intestines, sweat glands, etc. As a result of the accumulation of bismuth in the kidneys, they may be damaged. When bismuth is excreted from the body by the sweat glands, itching of the skin and the appearance of dermatoses can occur.

Data on the presence of bismuth as a normal component of the cells and tissues of the body are not given in the literature.

CADMIUM COMPOUNDS

Absorption of cadmium compounds occurs through the alimentary canal, and vapors through the respiratory tract. Soluble cadmium compounds denature the proteins contained in the walls of the alimentary canal. The cadmium ions that enter the blood combine with the sulfhydryl groups of enzymes, disrupting their functions. Cadmium compounds accumulate mainly in the liver and kidneys. They can cause fatty degeneration of the liver. Cadmium compounds are excreted from the body mainly through the kidneys with urine and intestinal walls. In a number of cases, in case of poisoning with cadmium compounds, intestinal bleeding is noted.

ZINC COMPOUNDS

Zinc and its compounds can enter the body through the food canal, as well as through the respiratory system in the form of dust generated during the extraction and processing of zinc ores. Zinc can enter the body with inhaled air in the form of vapors released during zinc smelting and alloy production. After zinc enters the body in the form of dust and vapors, its compounds with proteins are formed, causing bouts of fever, starting with chills (the so-called caster's fever, or brass fever). Inhalation of dust and zinc fumes may cause nausea, vomiting and muscle pain. Cases of poisoning by food prepared and stored in galvanized utensils, from products containing acids (fruits rich in acids, tomato, etc.) are described. Zinc compounds that enter the stomach can cause acute poisoning, in which vomiting, diarrhea, convulsions, etc. occur.

In case of poisoning with zinc compounds, they accumulate in the liver and pancreas.

MERCURY COMPOUNDS

Vapors of metallic mercury and dust containing compounds of this metal can enter the body with inhaled air. This affects the central nervous system (primarily the cerebral cortex). Entered into the body, metallic mercury and its compounds bind to sulfhydryl groups of enzymes and other vital proteins. As a result, the physiological functions of some cells and tissues of the body are disturbed. Mercury compounds that enter the body through the alimentary canal affect the stomach, liver, kidneys, and glands through which mercury is excreted from the body. At the same time, pain in the esophagus and stomach is felt, vomiting and bloody diarrhea appear. In the body, mercury is deposited mainly in the liver and kidneys.

Mercury is slowly excreted from the body. Even two weeks after acute mercury poisoning, certain amounts of it can be detected in individual tissues. Mercury is excreted from the body with urine and feces, as well as sweat, salivary and mammary glands.

Destruction of biological material. Mercury in biological material is in a bound form with sulfhydryl and some other functional groups of protein substances. In the process of destruction under the influence of strong acids during heating, there is a break in strong covalent bonds between mercury and sulfhydryl or other functional groups of protein substances. As a result of degradation, mercury passes into the destructate in the form of ions, which can be detected and determined using appropriate reactions and physicochemical methods. Thus, after the destruction of biological material, various amounts of mercury ions, proteins, peptides, amino acids, lipids, etc. are present in the destructate.

To accelerate the degradation, ethyl alcohol is added to the biological material, which is a catalyst for this process. Urea is added to remove nitric, nitrous acids and nitrogen oxides from the destructate, which are formed in the process of destruction.

Nitrogen oxides are oxidized by atmospheric oxygen to nitric oxide (IV), upon interaction of which with water, nitric and nitrous acids are formed, which are decomposed by urea, as indicated above.

The method of destruction of the organs of corpses. 20 g of crushed organs of corpses are introduced into a 200 ml conical flask, into which 5 ml of water, 1 ml of ethyl alcohol and 10 ml of concentrated nitric acid are added. Then 20 ml of concentrated sulfuric acid are added to the flask in small portions at such a rate that no nitrogen oxides are released from the flask. After the completion of the addition of concentrated sulfuric acid, the flask is left for 5-10 minutes at room temperature (until the release of nitrogen oxides stops). The flask is then placed in a boiling water bath and heated for 10-20 minutes. If, after heating the flask in a boiling water bath, pieces of biological material remain intact, then they are carefully rubbed with a glass rod on the walls of the flask. With the rapid course of the reaction with the release of nitrogen oxides, 30-50 ml are added to the flask hot water. The resulting hot destructate is mixed with a double volume of boiling water and, without cooling the liquid, it is filtered through a double humidified filter. The filter, through which the destructate was filtered, and the fat residues on it are washed 2-3 times with hot water. Wash water is added to the filtered destructate. The liquid thus obtained is collected in a flask containing 20 ml of a saturated solution of urea, intended for denitration of the destructate. Then the destructate is cooled, brought to a certain volume with water and examined for the presence of mercury.

Destruction organic matter in urine. In the urine of healthy people, mercury and its compounds are absent. However, in case of mercury poisoning, it can affect the kidneys and be excreted from the body in the urine in the form of compounds with proteins, amino acids and other organic substances. A certain amount of mercury can also pass into the urine in the form of ions. Therefore, to detect mercury in urine, it is necessary to destroy protein and other mercury-containing compounds that pass into the urine.

A. F. Rubtsov and A. N. Krylova developed two methods for the destruction of organic substances in urine:

1. A sample of unfiltered daily urine with a volume of 200 ml is introduced into a Kjeldal flask with a capacity of 500 ml. 35 ml of concentrated nitric acid, 2 ml of ethyl alcohol are added to the urine, and 25 ml of concentrated sulfuric acid are introduced into the flask in small portions. This acid is added so that the liquid in the flask does not foam and nitrogen oxides are not released from it. After the completion of the addition of concentrated sulfuric acid, the contents of the flask are heated on a boiling water bath for 40 minutes, then 20 ml of a saturated urea solution are added. If there is a precipitate in the destructate, then it is filtered off, the filter is washed with hot water. Wash water is added to the destructate, which is subjected to a study for the presence of mercury.

2. In a Kjeldal flask with a capacity of 500 ml, add 200 ml of unfiltered daily urine, to which 25 ml of concentrated sulfuric acid are added in small portions, and then 7 g of potassium permanganate are added in small portions. The contents of the flask are left for 40 minutes at room temperature, shaking occasionally, then the flask is added in small portions. saturated solution oxalic acid until the color of potassium permanganate disappears. The resulting destructate is used to detect and quantify mercury.

This method of destruction of protein substances in the urine is faster than that described above.

Destruction of organic substances in the blood. For this purpose, a technique is used that is used for the destruction of organs of corpses (see above), with the only difference that water is not added to the blood sample. 50-100 ml of blood is taken for the study.

METHYL ALCOHOL

Methyl alcohol (methanol) is a colorless liquid (bp 64.5 ° C, density 0.79), miscible in all proportions with water and many organic solvents.

Methyl alcohol can enter the body through the alimentary canal, as well as with inhaled air containing vapors of this alcohol. In small quantities, methyl alcohol can penetrate the body and through the skin. The lethal dose of methyl alcohol taken orally is 30-100 ml. Death occurs as a result of respiratory arrest, swelling of the brain and lungs, collapse or uremia. The local effect of methyl alcohol on the mucous membranes is stronger, and the narcotic effect is weaker than that of ethyl alcohol.

The simultaneous intake of methyl and ethyl alcohols in the body reduces the toxicity of methyl alcohol. This is due to the fact that ethyl alcohol reduces the rate of oxidation of methyl alcohol by almost 50%, and therefore reduces its toxicity.

Metabolism. Methyl alcohol that enters the body is distributed between organs and tissues. The greatest amount of it accumulates in the liver, and then in the kidneys. Smaller amounts of this alcohol accumulate in muscle, fat, and the brain. The metabolite of methyl alcohol is formaldehyde, which is oxidized to formic acid. Some of this acid decomposes into carbon monoxide (IV) and water. Some unmetabolized methanol is excreted in exhaled air. It can be excreted in the urine as a glucuronide. However, small amounts of unchanged methyl alcohol may also be excreted in the urine. Methyl alcohol is oxidized in the body more slowly than ethyl alcohol.

ETHANOL

Ethyl alcohol C 2 H 5 OH (ethanol, ethyl alcohol, wine alcohol) is a colorless, volatile liquid with a characteristic odor, burning in taste (pl. 0.813-0.816, b.p. 77-77.5 ° C). Ethyl alcohol burns with a bluish flame, mixes in all proportions with water, diethyl ether and many other organic solvents, distills with water vapor.

Ethyl alcohol is unevenly distributed in tissues and body fluids. It depends on the amount of water in the organ or biological fluid. The quantitative content of ethyl alcohol is directly proportional to the amount of water and inversely proportional to the amount of adipose tissue in the body. The body contains about 65% of water from the total body weight. Of this amount, 75-85% of the water is contained in whole blood. Given the large volume of blood in the body, it accumulates a much larger amount of ethyl alcohol than in other organs and tissues. Therefore, the determination of ethyl alcohol in the blood is of great importance for assessing the amount of this alcohol that has entered the body.

Metabolism. Part of ethyl alcohol (2-10%) is excreted from the body unchanged with urine, exhaled air, sweat, saliva, feces, etc. The rest of this alcohol is metabolized. Moreover, the metabolism of ethyl alcohol can occur in several ways. A certain amount of ethyl alcohol is oxidized to form water and carbon monoxide (IV). A slightly larger amount of this alcohol is oxidized to acetaldehyde and then to acetic acid.

ISOAMYL ALCOHOL

Isoamyl alcohol (CH 3) 2 -CH-CH 2 -CH 2 -OH (2-methyl-butanol-4 or isobutylcarbinol) is an optically inactive liquid (bp 132.1 ° C, pl. 0.814 at 20 ° C) with an unpleasant odor.

Isoamyl alcohol (2-methylbutanol-4) is the main constituent of fusel oils. The composition of fusel oils also includes optically active isoamyl alcohol CH 3 -CH 2 -CH (CH 3) -CH 2 -OH (2-methylbutanol-1), isobutyl alcohol and normal propyl alcohol. In addition to these alcohols, fusel oils contain small amounts of fatty acids, their esters and furfural. The presence of 2-methylbutanol-4 in fusel oils explains its sharp unpleasant odor and high toxicity. Isoamyl alcohol (2-methylbutanol-4) is a by-product of the alcoholic fermentation of carbohydrates found in beets, potatoes, fruits, grains of wheat, rye, barley and other agricultural crops.

Isoamyl alcohol is 10-12 times more toxic than ethyl alcohol. It acts on the central nervous system, has narcotic properties.

Metabolism. Part of the dose of isoamyl alcohol that enters the body is converted into isovaleric acid aldehyde, and then into isovaleric acid. Some of the unchanged isoamyl alcohol and the above metabolites are excreted from the body in the urine and exhaled air.

ETHYLENE GLYCOL

Ethylene glycol (HO-CH 2 -CH 2 -OH) is one of the representatives of dihydric alcohols that have toxicological significance. It is a colorless oily liquid (bp 197 ° C) with a sweetish taste. Ethylene glycol is miscible with water in all proportions, poorly soluble in diethyl ether, well-soluble in ethyl alcohol. Ethylene glycol is steam distilled.

Metabolism. The metabolism of ethylene glycol is complex. The main metabolic pathway of this drug is that it is oxidized to glycolic acid aldehyde HO-CH 2 -CHO, which is further oxidized to glycolic acid HO-CH 2 -COOH, which decomposes into carbon monoxide (IV) and formic acid. Part of the ethylene glycol in the body is converted to oxalic acid, which can cause kidney damage due to the deposition of oxalates in the renal tubules. Carbon monoxide (IV), as a metabolite of ethylene glycol, is excreted from the body with exhaled air. The remaining metabolites and part of unchanged ethylene glycol are excreted from the body in the urine.

Isolation of ethylene glycol from biological material. The method for isolating ethylene glycol from objects of chemical-toxicological analysis was proposed by N. B. Lapkina and V. A. Nazarenko. This method is based on the use of benzene as a selective carrier of ethylene glycol from objects to distillate. Benzene, together with ethylene glycol vapor and a small amount of water vapor, is transferred to the distillate. The water that is distilled in this case contains practically all the ethylene glycol.

For research take the liver of a corpse, which after poisoning contains more ethylene glycol than in other organs. In acute poisoning with ethylene glycol, the stomach and contents are also examined. 5 g of crystalline oxalic acid are added to 10 g of the liver or stomach contents, the mixture is triturated until a thin slurry is obtained, transferred to a 100 ml round-bottomed flask and 50 ml of benzene are added. The flask is closed with a vertically placed refrigerator 3, equipped with a device 2 for trapping water. The flask is then placed in a water bath and heated. Benzene vapor and the water and ethylene glycol entrained by it condense in the refrigerator and enter a special device. Since benzene (density 0.879) is on top of the water in this device (nozzle), it flows into the flask. The water and the ethylene glycol in it remain in the nozzle. After the end of the distillation, the device is disassembled and the amount of liquid necessary for analysis is taken from the nozzle with a pipette.

detection of ethylene glycol.

Oxidation reaction of ethylene glycol with periodate and detection of formed formaldehyde. As a result of this reaction, formaldehyde is formed, which can be detected using fuchsine sulphurous acid:

Oxidation of ethylene glycol with nitric acid and detection of oxalic acid. With repeated evaporation of ethylene glycol with nitric acid, oxalic acid is formed, which, with calcium salts, forms calcium oxalate crystals having a characteristic shape. These crystals in some cases appear after 2-3 days.

Reaction with copper sulfate. From the addition of copper sulfate and alkali to ethylene glycol, a compound is formed that has a blue color:

CHLOROFORM

Chloroform (trichloromethane) CHCl 3 is a colorless transparent volatile liquid with a characteristic odor. Miscible with diethyl ether, ethyl alcohol and other organic solvents, slightly soluble in water (see Table 1). Under the influence of light, air, moisture and temperature, chloroform gradually decomposes. In this case, phosgene, formic and hydrochloric acids can be formed.

Metabolism. Chloroform entering the body quickly disappears from the blood. After 15-20 minutes, 30-50% of chloroform is released unchanged with exhaled air. Within an hour, up to 90% of the chloroform that enters the body is excreted through the lungs. However, even after 8 hours, small amounts of chloroform can be detected in the blood. Part of the chloroform undergoes biotransformation. In this case, carbon monoxide (IV) and hydrogen chloride are formed as metabolites. In chemical and toxicological studies, the main objects of analysis for the presence of chloroform in the body are exhaled air, fat-rich tissues of corpses, and the liver.

Chloroform detection

Chlorine elimination reaction. When chloroform is heated with an alcoholic solution of alkali, chlorine atoms are split off, which can be detected by reaction with silver nitrate:

Before performing this reaction, it is necessary to make sure that there are no chloride ions in the test solution (distillate) and reagents.

Fujiwara reaction. Chloroform and a number of other halogen-containing compounds can be detected using the Fujiwara reaction, which is based on the interaction of these substances with pyridine in the presence of alkali. When chloroform reacts with pyridine and alkali, a polymethine dye is formed. In this reaction, a pyridinium salt is first formed:

Under the influence of alkali, the pyridinium salt is converted into a derivative of glutaconic aldehyde (I), upon hydrolysis of which glutaconic aldehyde (II) is formed, which has a color:

Two versions of the Fujiwara reaction have been described. When using the first option, the color of the resulting glutaconic aldehyde is observed. In the second variant of this reaction, an aromatic amine or another compound containing a mobile hydrogen atom is added to the resulting glutaconic aldehyde, and then the color is observed.

Reaction with resorcinol. When chloroform is heated with resorcinol in the presence of alkali, a pink or crimson-red color appears.

Isonitrile formation reaction. When chloroform is heated with primary amines and alkali, isonitrile (carbylamine) is formed, which has an unpleasant odor:

Reaction with Fehling's reagent. When chloroform interacts with alkali, a salt of formic (formate) acid is formed:

Fehling's reagent, containing the intracomplex compound K 2 Na 2 , which is formed by the interaction of copper (II) ions with Rochelle salt, oxidizes formic acid and its salts when heated. As a result of the reaction, a red precipitate of copper oxide (I) precipitates:

CHLOROALHYDRATE

Chloral hydrate or

Colorless crystals or finely crystalline powder with a characteristic pungent odor and slightly bitter, soluble in water, ethyl alcohol, diethyl ether and chloroform. Chloral hydrate is hygroscopic and volatilizes slowly in air.

Metabolism. Chloral hydrate is rapidly absorbed into the blood from the alimentary canal. It is metabolized in the body. The metabolites of chloral hydrate are trichloroethanol and trichloroacetic acid. It is believed that the toxic effect of chloral hydrate on the body is due to the formation of trichloroethanol. Trichloroacetic acid can be formed in the body in two ways: directly from chloral hydrate and from trichloroethanol. Trichloroethanol is excreted from the body in the urine as a glucuronide. After death resulting from poisoning with chloral hydrate, a certain amount of it in unchanged form can be found in the liver and stomach.

Detection of chloral hydrate

Chloral hydrate gives all the reactions that are used in chemical-toxicological analysis to detect chloroform. This is due to the fact that the reactions to chloroform used in the chemical-toxicological analysis are carried out in the presence of alkali, under the influence of which chloral hydrate decomposes with the release of chloroform:

To distinguish chloral hydrate from chloroform, a reaction with Nessler's reagent can be used. This reaction gives chloral hydrate containing an aldehyde group. Chloroform does not give this reaction.

Reaction with Nessler's reagent. When chloral hydrate interacts with Nessler's reagent, free mercury is released:

CARBON TETROCHLORIDE

Carbon tetrachloride CCl 4 is a clear liquid with a peculiar odor (bp 75-77 °C). It is miscible in any ratio with acetone, benzene, gasoline, carbon disulfide and other organic solvents. About 0.01% carbon tetrachloride dissolves in water at 20 °C. Carbon tetrachloride is not flammable, its vapors are several times heavier than air.

Carbon tetrachloride enters the body by inhalation of its vapors, and can also enter through intact skin and the alimentary canal. Carbon tetrachloride is unevenly distributed in the body. The amount of it in tissue rich in fats is several times greater than in the blood. The content of carbon tetrachloride in the liver and bone marrow is much higher than in the lungs. The blood erythrocytes of corpses contain approximately 2.5 times more carbon tetrachloride than plasma.

Metabolism. Carbon tetrachloride is rapidly excreted from the body. Already 48 hours after entering the body, it cannot be detected in the exhaled air. Its metabolites are chloroform and carbon monoxide (IV).

DICHLOROETHANE

Two isomers of dichloroethane (C 2 H 4 Cl 2) are known: 1,1-dichloroethane and 1,2-dichloroethane.

1,1-Dichloroethane (ethylidene chloride) CH 3 CHCl 2 is a colorless liquid (density 1.189 at 10 °C), boiling at 58 °C. 1,2-Dichloroethane (ethylene chloride) Cl-CH 2 -CH 2 -Cl - liquid (density 1.252 at 20 ° C), boiling at 83.7 ° C. In industry, 1,2-dichloroethane is more widely used than 1,1-dichloroethane.

1,2-Dichloroethane is slightly soluble in water, soluble in most organic solvents. It is resistant to acids and alkalis. It ignites with difficulty. Technical 1,2-dichloroethane contains an admixture of trichlorethylene C1-CH = CC1 2 .

Isolation of dichloroethane from biological material. Separation of dichloroethane from biological material is carried out by steam distillation. The first portions of the distillate are taken for research. In cases where there are special instructions to examine the biological material for the presence of 1,2-dichloroethane, about 300 ml of distillate is obtained, which is subjected to repeated distillation and the first 200 ml of distillate are collected. This distillate is refluxed twice. The last distillate (volume 10 ml), obtained by distilling off the liquid with a reflux condenser, is subjected to a study for the presence of 1,2-dichloroethane.

FORMALDEHYDE

Formaldehyde (aldehyde formic acid) is a gas that is highly soluble in water and has a sharp specific odor. An aqueous solution containing 36.5-37.5% formaldehyde is called formalin.

Formaldehyde is isolated from biological material by steam distillation. However, only a small part of the formaldehyde is distilled by this method. It is believed that formaldehyde in aqueous solutions is in the form of a hydrate (methylene glycol), which is difficult to distill with steam:

HCHO + HOH ---> CH 2 (OH) 2.

Formaldehyde depresses the central nervous system, as a result of this, loss of consciousness may occur, convulsions appear. Under the influence of formaldehyde, degenerative lesions of the liver, kidneys, heart and brain develop. Formaldehyde affects some enzymes. 60-90 ml of formalin is a lethal dose.

Metabolism. Formaldehyde metabolites are methyl alcohol and formic acid, which, in turn, undergo further metabolism.

Formaldehyde detection

Reaction with chromotropic acid. Chromotropic acid (1,8-dioxinaphthalene-3,6-disulfonic acid) with formaldehyde in the presence of sulfuric acid gives a violet color.

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Course work

Determination of lead in the vegetation of an urban area

Introduction

lead titrimetric metal reagent

Lead is a poisonous substance whose accumulation affects a number of body systems and is particularly harmful to young children.

It is estimated that childhood lead exposure is one of the factors responsible for about 600,000 new cases of mental impairment in children each year.

Lead exposure is estimated to cause 143,000 deaths per year, with the heaviest burden occurring in developing regions.

In the body, lead enters the brain, liver, kidneys, and bones. Over time, lead accumulates in teeth and bones. Exposure in humans is usually determined by measuring lead levels in the blood.

There is no known level of lead exposure that is considered safe.

The main sources of lead pollution are road transport using lead-containing gasoline, metallurgical plants, smoke sources such as thermal power plants and others.

Plants absorb lead from soil and air.

They perform a useful role for humans, acting as adsorbents for lead in the soil and in the air. Dust containing lead accumulates on plants without spreading.

According to the data of the content of the movable forms heavy metals in plants, one can judge the contamination of a certain space by them.

This course work examines the content of lead in the vegetation of the urban area.

1. Leeliterature review

The literature review is based on the book Analytical Chemistry of Elements. Lead".

1. 1 Aboutgeneral information about lead

Lead (lat. Plumbum; denoted by the symbol Pb) - an element of the 14th group (an outdated classification - the main subgroup of group IV), the sixth periodic system chemical elements DI. Mendeleev, with atomic number 82 and thus contains the magic number of protons. The simple substance lead (CAS number: 7439-92-1) is a malleable, relatively low-melting metal of a silvery-white color with a bluish tint. Known since ancient times.

The lead atom has the electronic structure 1s 2 2s 2 p 6 3s 2 p 6 d 10 4s 2 p 6 d 10 f 14 5s 2 p 6 d 10 6s 2 p 2 . The atomic mass is assumed to be 207.2, however, its fluctuations by 0.03 - 0.04 u.h. are possible.

Lead is an integral part of more than 200 minerals, but only three of them (galena, anglesite, cerussite) are found in nature in the form of industrial deposits of lead ores. The most important of these is galena PbS (86.5% Pb).

Under the influence of substances dissolved in natural waters, and during weathering it turns into anglesite PbSO 4 (63.3% Pb), which, as a result of double exchange with calcium and magnesium carbonates, forms cerussite PbCO 3 (77.5% Pb).

In terms of industrial production, lead ranks fourth in the group of non-ferrous metals, second only to aluminum, copper and zinc.

To get lead highest value have polymetallic sulfide and mixed ores, since pure lead ores are rare.

It is applied for the purpose radiation protection, as a structural material in the chemical industry, for the manufacture of protective coatings for electric cables and battery electrodes. Large amounts of lead are used in the manufacture of various alloys: with bismuth (a coolant in nuclear technology), with tin and small additions of gold and copper (solders for the manufacture of printed circuits), with antimony, tin and other metals (solders and alloys for printing and antifriction purposes). The ability to form intermetallic compounds is used to obtain lead telluride, from which detectors of infrared rays and converters of thermal radiation energy into electrical energy are prepared. A large proportion of lead is used for the synthesis of organometallic compounds.

Many lead-containing organic compounds are products of "small" chemistry, but have a large practical value. These include lead stearate and phthalate (thermal and light stabilizers for plastics), basic lead fumarate (thermal stabilizer for electrical insulators and vulcanizing agent for chlorosulfo polyethylene), lead diamildithiocarbamate (multifunctional lubricating oil additive), ethylenediaminetetraacetate lead (radiocontrast), lead tetraacetate (oxidizing agent in organic chemistry). Of the practically important inorganic compounds, one can name lead oxide (which is used in the production of glasses with a high refractive index, enamels, batteries and high-temperature lubricants); lead chloride (manufacturing of current sources); basic carbonate, sulfate and chromate of lead, minium (components of paints); titanate - zirconate. lead (production of piezoelectric ceramics). Lead nitrate is used as a titrant.

The exceptional variety and importance of the mentioned fields of application of lead stimulated the development of numerous methods for the quantitative analysis of various objects. 1.2. Lead content in natural objects

The earth's crust contains 1.6 * 10 -3% by mass of Pb. The cosmic abundance of this element, according to the data of various authors, varies from 0.47 to 2.9 atoms per 106 silicon atoms. For solar system the corresponding value is 1.3 atoms per 10 6 silicon atoms.

Lead is found in high concentrations in many minerals and ores, in micro- and ultra-micro quantities - in almost all objects of the surrounding world.

Other objects contain lead (% mass); rain water - (6-29) * 10 -27, open source water - 2 * 10 -8, sea water - 1.3 open ocean water on the surface - 1.4 * 10 -9, at a depth of 0.5 and 2 km - respectively 1.2 * 10 -9 and 2 * 10 -10, granites, black shale, basalts - (1 - 30) * 10 -4, sedimentary clay minerals - 2 * 10 -3, volcanic rocks of the Pacific belt - 0 ,9 * 10 -4, phosphorites - from 5 * 10 -4 to 3 * 10 -2.

Brown coal - from 10 -4 to 1.75 * 10 -2, oil - 0.4 4 * 10 -4, meteorites - from 1.4 * 10 -4 to 5.15 * 10 -2.

Plants: average content - 1 * 10 -4, in areas of lead mineralization - 10 -3, food 16 * 10 -6, puffball mushrooms collected near the highway - 5.3 * 10 -4, ash: lichens - 10 - 1, coniferous trees - 5 * 10 -3, deciduous trees and shrubs - up to 3 * 10 -3. The total lead content (in tons): in the atmosphere - 1.8 * 10 4, in soils - 4.8 * 10 9, in sedimentary deposits - 48 * 10 12, in ocean waters - 2.7 * 10 7, in waters rivers and lakes - 6.1 * 10 -4, in subsoil waters - 8.2 * 10 4, in organisms of water and land: living - 8.4 * 10 4, dead - 4.6 * 10 6.

1.2 Islead pollution sources

Sources of lead in various areas of human and animal habitats are divided into natural (volcanic eruptions, fires, decomposition of dead organisms, sea and wind dust) and anthropogenic (lead production and processing enterprises, combustion of fossil fuels and waste from its processing).

In terms of the scale of emissions into the atmosphere, lead ranks first among trace elements.

A significant part of the lead contained in coal, when burned, together with flue gases, enters the atmosphere. The activity of only one thermal power plant, which consumes 5000 tons of coal per day, annually sends 21 tons of lead and commensurate amounts of other harmful elements into the air. A considerable contribution to the air pollution with lead is made by the production of metals, cement, etc.

The atmosphere is polluted not only by stable, but also by radioactive isotopes of lead. Their source is radioactive inert gases, of which the longest-lived - radon reaches even the stratosphere. The resulting lead is partially returned to the ground with precipitation and aerosols, polluting the soil surface and water bodies.

1.3 Thattoxicity of lead and its compounds

Lead is a poison that affects all living things. He and his compounds are dangerous not only because of the pathogenic effect, but also because of the cumulative therapeutic effect, the high coefficient of accumulation in the body, the low rate and incomplete excretion with waste products. Facts about the dangers of lead:

1. Already at a concentration of 10 -4% in the soil, lead inhibits the activity of enzymes, and highly soluble compounds are especially harmful in this respect.

2. The presence of 2 * 10 -5% lead in water is harmful to fish.

3. Even low concentrations of lead in water reduce the amount of carotenoid and chlorophyll in algae.

4. Many cases of occupational diseases have been registered in workers with lead.

5. According to the results of 10 years of statistics, a correlation has been established between the number of deaths from lung cancer and an increased content of lead and other metals in the air of industrial enterprises that consume coal and oil products.

The degree of toxicity depends on the concentration, physicochemical state and nature of the lead compounds. Lead is especially dangerous in the state of molecular-ion dispersity; it passes from lungs to circulatory system and from there it is transported throughout the body. Although lead and its inorganic compounds act qualitatively in a similar way, toxicity increases symbately with their solubility in body fluids. This does not diminish the danger of sparingly soluble compounds that change in the intestine with a subsequent increase in their absorption.

Lead inhibits many enzymatic processes in the body. With lead intoxication, serious changes occur in the nervous system, thermoregulation, blood circulation and trophic processes are disturbed, the immunobiological properties of the body and its genetic apparatus change.

1. 4 osadditive and titrimetric methods

1. Gravimetric method - the formation of weight forms of lead with organic and inorganic reagents is used. Among inorganic compounds, preference is given to lead sulfate and chromate. Methods based on their precipitation are comparable in selectivity and the value of the conversion factor, but the determination of Pb in the form of chromate requires less time. Both precipitates are recommended to be obtained by "homogeneous" precipitation methods.

Organic reagents give weight forms suitable for the determination of smaller amounts of Pb, with more favorable conversion factors than lead chromate or lead sulfate.

Advantages of the method: precipitate crystallinity and high accuracy of results in the absence of interfering impurities. Relative error of determination 0.0554-0.2015 Pb< 0,3%. С применением микроаппаратуры выполнены определения 0,125-4,528 мг РЬ с relative error < 0,8%. Однако присутствие свободной HN0 3 недопустимо, а содержание солей щелочных металлов и аммония должно быть возможно малым.

2. Precipitation titration with visual indicators. Titration with organic and inorganic reagents is used. In the absence of impurity ions precipitated by chromate, direct titrimetric methods are most convenient with indication of the end point of titration (CTT) by changing the color of methyl red or adsorption indicators. The best option for the titrimetric determination of Pb by the chromate method is the precipitation of PbCr0 4 from an acetic acid solution, followed by dissolution of the precipitate in 2 M HC1 or 2 M HC10 4, the addition of an excess of potassium iodide and titration of the released iodine Na 2 S 2 0 3.

3. Titration with EDTA solutions. In view of the versatility of EDTA as an analytical reagent for most cations, the question arises of increasing the selectivity of Pb determination. To do this, they resort to preliminary separation of mixtures, the introduction of masking reagents and regulation of the reaction of the medium to pH values \u003e 3. Usually they titrate in a slightly acidic or alkaline medium.

The end point of the titration is most often indicated using metallochromic indicators from the group of azo- and triphenylmethane dyes, derivatives of dihydric phenols and some other substances, the colored Pb complexes of which are less stable than lead ethylenediaminetetraacetate. In weakly acidic media, titrate with 4 - (2-pyridylazo) - resorcinol, thiazolyl-azo-and-cresol, 2 - (5-bromo-2-pyridylazo) - 5-diethylaminophenol, 1 - (2-pyridylazo) - 2-naphthol , 2 - (2-thiazolilazo) - resorcinol, azo derivatives of 1-naphthol4-sulfonic acid, xylenol orange, pyrocatechol violet, methylxylenol blue, pyrogallol and bromopyrogallol red, methylthymol blue, hematoxylin, sodium rodizonate, alizarin S and dithizone.

In alkaline environments, eriochrome black T, sulfarsazene, 4 - (4,5 - dimegyl-2-thiazolylazo) - 2-methylresorcinol, a mixture of acidic alizarin black SN and eriochrome red B, pyrocatechinphthalein, strong solochrome 2 RS, methylthymol blue and murexide ( titration of the total amounts of Pb and Cu).

4. Titration with other complexing substances. The formation of chelates with DTCA, TTGA, sulfur-containing complexing substances is used.

1.5 Fotometric methods of analysisabout light absorption and scattering

1. Determination as sulfide. The origins of this method and its first critical appraisal date back to the beginning of our 20th century. The color and stability of the PbS sol depend on the particle size of the dispersed phase, which is affected by the nature and concentration of dissolved electrolytes, the reaction of the medium, and the method of preparation. Therefore, these conditions must be strictly observed.

The method is not very specific, especially in an alkaline environment, but the convergence of results in alkaline solutions is better. In acid solutions, the sensitivity of the determination is less, but it can be somewhat increased by adding electrolytes, such as NH 4 C1, to the analyzed sample. The selectivity of determination in an alkaline medium can be improved by introducing masking complexing agents.

2. Determination in the form of complex chlorides. It has already been indicated that Pb chlorine complexes absorb light in the UV region, and the molar extinction coefficient depends on the concentration of Cl ions - In a 6 M solution of HC1, the absorption maxima of Bi, Pb and Tl are sufficiently distant from each other, which makes it possible to simultaneously determine them by light absorption at 323, 271, and 245 nm, respectively. The optimal concentration range for determining Pb is from 4-10*10-4%.

3. The determination of Pb impurities in concentrated sulfuric acid is based on the use of the characteristic absorbance at 195 nm with respect to a standard solution prepared by dissolving lead in H2SO4 (high purity).

Determination using organic reagents.

4. In the analysis of various natural and industrial objects, the photometric determination of Pb using dithizone occupies a leading position due to its high sensitivity and selectivity. In various versions of existing methods, the photometric determination of Pb is performed at the wavelength of the absorption maximum of dithizone or lead dithizonate. Other variants of the dithizone method are described: photometric titration without phase separation and a non-extraction method for the determination of lead in polymers, in which a solution of dithizone in acetone is used as a reagent, diluted with water to a concentration of the organic component of 70% before use.

5. Determination of lead by reaction with sodium diethyldithiocarbamate. Lead is well extracted with CCl4 as a colorless diethyldithiocarbamate at various pH values. The resulting extract is used in an indirect method for determining Pb, based on the formation of an equivalent amount of yellow-brown copper diethyldithiocarbamate as a result of exchange with CuSO4.

6. Determination by reaction with 4 - (2-pyridylazo) - resorcinol (PAR). The high stability of the red Pb complex with PAR and the solubility of the reagent in water are the advantages of the method. For the determination of Pb in some objects, such as steel, brass and bronze, the method based on the formation of a complex with this azo compound is preferable to the dithizone method. However, it is less selective and, therefore, in the presence of interfering cations, it requires preliminary separation by the BC method or extraction of lead dibenzyldithiocarbamate with carbon tetrachloride.

7. Determination by reaction with 2-(5-chloropyridip-2-azo)-5-diethylaminophenol and 2-(5-bromopyridyl-2-azo)-5-diethylaminophenol. Both reagents form 1:1 complexes with Pb with almost identical spectrophotometric characteristics.

8. Determination by reaction with sulfarsazene. The method uses the formation of a reddish-brown water-soluble complex with a composition of 1: 1 with an absorption maximum at 505-510 nm and a molar extinction coefficient of 7.6 * 103 at this wavelength and pH 9-10.

9. Determination by reaction with arsenazo 3. This reagent in the pH range of 4-8 forms a blue complex with lead in the composition 1:1 with two absorption maxima - at 605 and 665 nm.

10. Determination by reaction with diphenylcarbazone. According to the sensitivity of the reaction, during the extraction of the chelate in the presence of KCN, and in terms of selectivity, it approaches dithizone.

11. Indirect method for determining Pb using diphenylcarbazide. The method is based on the precipitation of lead chromate, its dissolution in 5% HCl, and the photometric determination of dichromic acid by reaction with diphenylcarbazide using a filter with a transmission maximum at 536 nm. The method is lengthy and not very accurate.

12. Determination by reaction with xylenol orange. Xylenol orange (KO) forms a 1:1 complex with lead, the optical density of which reaches a limit at pH 4.5-5.5.

13. Determination by reaction with bromopyrogalpol red (BOD) in the presence of sensitizers. As sensitizers that increase the color intensity, but do not affect the position of the absorption maximum at 630 nm, at pH 6.5, diphenylguanidinium, benzylthiuronium, and tetraphenylphosphonium chlorides are used, and at pH 5.0, cetyltrimethylammonium and cetylpyridinium bromides are used.

14. Determination by reaction with glycinthymol blue. A 1:2 complex with glycinthymol blue (GTS) has an absorption maximum at 574 nm and a corresponding molar extinction coefficient of 21300 ± 600.

15. Determination with methylthymol blue is carried out under conditions as for the formation of a complex with GTS. In sensitivity, both reactions approach each other. Light absorption is measured at pH 5.8-6.0 and a wavelength of 600 nm, which corresponds to the position of the absorption maximum. The molar extinction ratio is 19,500. Interference from many metals is eliminated by masking.

16. Determination by reaction with EDTA. EDTA is used as a titrant in non-indicator and indicator photometric titration (PT). As in visual titrimetry, reliable FT with EDTA solutions is possible at pH > 3 and titrant concentration of at least 10-5 M.

Luminescent analysis

1. Determination of Pb using organic reagents

A method is proposed in which the intensity of chemiluminescence emission in the presence of Pb is measured due to the catalytic oxidation of luminol with hydrogen peroxide. The method was used to determine from 0.02 to 2 μg Pb in 1 ml of water with an accuracy of 10%. The analysis lasts 20 minutes and does not require preliminary sample preparation. In addition to Pb, traces of copper catalyze the luminol oxidation reaction. A method based on the use of the fluorescence quenching effect of fluores-132 derivatives is much more difficult in terms of instrumentation and is valuable in the formation of chelates with lead. More selective in the presence of many geochemical satellites of Pb, although less sensitive, is a fairly simple method based on increasing the fluorescence intensity of aquatic blue lumogen in a dioxane-water (1:1) mixture in the presence of Pb.

2. Methods of low-temperature luminescence in frozen solutions. Freezing the solution is most easily solved in the method for the determination of lead in HC1, based on the photoelectric detection of green fluorescence of chloride complexes at -70°C.

3. Analysis by luminescence burst during sample defrosting. The methods of this group are based on the shift of the luminescence spectra during the thawing of the analyzed sample and the measurement of the observed increase in the radiation intensity. The wavelength of the maximum of the luminescence spectrum at -196 and - 70 ° C, respectively, is 385 and 490 nm.

4. A method is proposed based on measuring the analytical signal at 365 nm in the quasi-linear luminescence spectrum of CaO-Pb crystal phosphorus cooled to liquid nitrogen temperature. This is the most sensitive of all luminescent methods: if an activator is applied to the tablet surface (150 mg CaO, diameter 10 mm, pressing pressure 7–8 MN/m2), then the detection limit on the ISP-51 spectrograph is 0.00002 μg. The method is characterized by good selectivity: a 100-fold excess of Co, Cr(III), Fe(III), Mn(II), Ni, Sb(III), and T1(I) does not interfere with the determination of Pb. Simultaneously with Pb, Bi can also be determined.

5. Determination of lead by the luminescence of the chloride complex adsorbed on paper. In this method, luminescence analysis is combined with the separation of Pb from interfering elements using a ring bath. The determination is carried out at ordinary temperature.

1.6 Alectro chemical methods

1. Potentiometric methods. Direct and indirect determination of lead is used - by titration with acid-base, complexometric and precipitation reagents.

2. Electrogravimetric methods use lead deposition on electrodes, followed by weighing or dissolution.

3. Coulometry and coulometric titration. Electrogenerated sulfohydryl reagents are used as titrants.

4. Volt-amperometry. Classical polarography, which combines rapidity with a rather high sensitivity, is considered one of the most convenient methods for determining Pb in the concentration range of 10-s-10 M. In the vast majority of works, lead is determined by the reduction current of Pb2+ to Pb proceeding reversibly and in the diffusion mode. As a rule, cathodic waves are well pronounced, and polarographic maxima are especially easily suppressed by gelatin and Triton X-100.

5. Amperometric titration

In amperometric titration (AT), the equivalence point is determined by the dependence of the electrochemical conversion current Pb and (or) titrant at a certain value of the electrode potential on the volume of the titrant. Amperometric titration is more accurate than the conventional polarographic method, does not require mandatory temperature control of the cell, and to a lesser extent depends on the characteristics of the capillary and the indifferent electrolyte. The great possibilities of the AT method should also be noted, since analysis is possible by an electrochemical reaction involving both Pb itself and the titrant. Although the overall time spent on performing an AT is longer, it is quite compensated by the fact that there is no need for calibration. Titration is used with solutions of potassium dichromate, chloranilic acid, 3.5 - dimethyldimercapto - thiopyrone, 1.5-6 uc (benzylidene) - thio - carbohydrazone, thiosalicylamide.

1.7 fiPhysical methods for the determination of lead

Lead is determined by atomic emission spectroscopy, atomic fluorescence spectrometry, atomic absorption spectrometry, x-ray methods, radiometric methods, radiochemical methods and many others.

2 . experimentalpart

2.1 Medefinition method

The work uses the definition of lead in the form of a dithizonate complex.

Figure 1 - structure of dithizone:

The absorption maximum of lead dithizonate complexes is 520 nm. Photometry is used against a solution of dithizone in CCl 4 .

Double incineration of the test sample is carried out - dry and "wet" method.

Double extraction and reaction with auxiliary reagents serve to separate interfering impurities and ions and increase the stability of the complex.

The method has high accuracy.

2. 2 Etcborons and reagents

Spectrophotometer with cuvettes.

Drying cabinet.

Muffle furnace.

Electric stove.

Electronic balance

Dropping funnel 100 ml.

Chemical vessels.

A sample of dry plant material 3 pcs. 10 gr.

0.01% solution of dithizone in CCl 4 .

0.02 N HCl solution.

0.1% hydroxylamine solution.

10% solution of yellow blood salt.

10% ammonium citrate solution.

10% HCl solution.

Ammonia solution.

Soda solution.

Indicators are thymol blue and phenol red.

Standard solutions of lead, with its content from 1,2,3,4,5,6 µg/ml.

2. 3 Etcpreparation of solutions

1. 0.1% hydroxylamine solution.

W=m in-va /m p-ra =0.1%. The mass of the solution is 100 gr. Then the sample is 0.1 gr. Dissolved in 99.9 ml of bidistilled water.

2.10% solution of yellow blood salt. W \u003d m in-va / m p-ra \u003d 10%. The mass of the solution is 100 gr. Then the sample is 10 gr. Dissolved in 90 ml of bidistilled water.

3.10% ammonium citrate solution. W \u003d m in-va / m p-ra \u003d 10%. The mass of the solution is 100 gr. Hanging - 10 gr. Dissolved in 90 ml of bidistilled water.

4.10% HCl solution. Made from concentrated HCl:

You need 100 ml of a solution with W=10%. d conc HCl = 1.19 g/ml. Therefore, it is necessary to take 26 g of concentrated HCl, V= 26/1.19=21.84 ml. 21.84 ml of concentrated HCl was diluted to 100 ml with bidistilled water in a 100 ml volumetric flask to the mark.

5. 0.01% solution of dithizone in CCl 4 . W \u003d m in-va / m p-ra \u003d 10%. The mass of the solution is 100 gr. Then the sample is 0.01 gr. Dissolved in 99.9 ml CCl 4 .

6. Soda solution. Prepared from dry Na 2 CO 3 .

7. 0.02 N HCl solution. W \u003d m in-va / m r-ra \u003d? Conversion to mass fraction. 1 liter of 0.02 N HCl solution contains 0.02 * 36.5 = 0.73 g of HCl solution. d conc HCl = 1.19 g/ml. Therefore, it is necessary to take 1.92 g of concentrated HCl, volume = 1.61 ml. 1.61 ml of concentrated HCl was diluted to 100 ml with bidistilled water in a 100 ml volumetric flask to the mark.

9. Thymol blue indicator solution was prepared from dry matter by dissolving in ethyl alcohol.

2. 4 Medisturbing influences

In an alkaline medium containing cyanide, thallium, bismuth and tin (II) are extracted with dithizone together with lead. Thallium does not interfere with colorimetric determination. Tin and bismuth are removed by extraction in an acid medium.

Silver, mercury, copper, arsenic, antimony, aluminum, chromium, nickel, cobalt and zinc do not interfere with the determination in concentrations not exceeding twelve times the concentration of lead. The interfering influence of some of these elements, if they are present in a fifty-fold concentration, is eliminated by double extraction.

The determination is hindered by manganese, which, when extracted in an alkaline medium, catalytically accelerates the oxidation of dithizone with atmospheric oxygen. This interfering influence is eliminated by adding hydrochloric acid hydroxylamine to the extracted sample.

Strong oxidizing agents interfere with the determination, as they oxidize dithizone. Their reduction with hydroxylamine is included in the course of the determination.

2. 5 ThoseExperimental technique

The plant material was dried in an oven in a crushed state. Drying was carried out at a temperature of 100 0 C. After drying to an absolutely dry state, the plant material was thoroughly crushed.

Three samples of dry material, 10 g each, were taken. They were placed in a crucible and placed in a muffle furnace, where they were ashed for 4 hours at a temperature of 450 0 C.

After that, the ashes of the plants were dipped in nitric acid when heated and dried (henceforth, the operations are repeated for all samples).

Then the ash was again treated with nitric acid, dried on an electric stove and placed in a muffle furnace for 15 minutes at a temperature of 300 0 C.

After the clarified ash was dug in with hydrochloric acid, dried, and dug in again. Then the samples were dissolved in 10 ml of 10% hydrochloric acid.

Next, the solutions were placed in 100 ml dropping funnels. 10 ml of a 10% ammonium citrate solution was added, then the solution was neutralized with ammonia until the thymol blue color turned blue.

This was followed by extraction. Was poured 5 ml of a 0.01% solution of dithizone in CCl 4 . The solution in the dropping funnel was vigorously shaken for 5 minutes. The dithizone layer after its separation from the main solution was drained separately. The extraction operation was repeated until the initial color of each new portion of dithizone ceased to turn red.

The aqueous phase was placed in an addition funnel. It was neutralized with a soda solution until the color of phenol red changed to orange. Then 2 ml of 10% yellow blood salt solution, 2 ml of 10% ammonium citrate solution, 2 ml of 1% hydroxylamine solution were added.

Then the solutions were neutralized with a soda solution until the color of the indicator (phenol red) changed to crimson.

Next, 10 ml of a 0.01% solution of dithizone in CCl 4 was added, the sample was vigorously shaken for 30 seconds, then the dithizone layer was poured into a cuvette and spectophotometrically measured against a solution of dithizone in CCl 4 at 520 nm.

The following optical densities were obtained:

The calibration graph was built under the same conditions, standard solutions of lead concentrations from 1 to 6 µg/ml were used. They were prepared from a 1 µg/mL lead solution.

2.6 Reexperimental resultsdata and statistical processing

Data for building a calibration graph

Calibration curve

According to the calibration graph, the concentration of lead in one kilogram of dry plant matter is

1) 0.71 mg/kg

2) 0.71 mg/kg

3) 0.70 mg/kg

What follows from the conditions of determination - the concentration of lead in the standards is measured in μg / ml, for the analysis the lead content in 10 ml was measured, recalculated for one kilogram of dry plant material.

Average value of the mass: X cf = 0.707 gr.

Dispersion =0.000035

Standard deviation: = 0.005787

Youwater

1. According to the literature review.

With the help of a literature review, general information about the element, its methods of determination were studied, the most suitable of them was selected according to its accuracy and compliance with those used in everyday practice.

2. According to the results of the experiment.

The experiment showed that using the method it is possible to determine the low content of lead, the results are highly accurate and convergent.

3. In accordance with MPC.

List of used literary sources

1. Polyansky N.G. Lead.-M.: Nauka, 1986. - 357 p. (Analytical chemistry of elements).

2. Vasiliev V.P. Analytical chemistry. At 2 p.m. 2. Physico-chemical methods of analysis: Proc. For chemical-technological Specialist. Universities.-M.: Higher. school, 1989. - 384 p.

3. Basics analytical chemistry. In 2 books. Book. 2. Methods of chemical analysis: Proc. For universities / Yu.A. Zolotov, E.N. Dorohova, V.I. Fadeev and others. Ed. Yu.A. Zolotova. - 2nd ed., revised. And extra. - M.: Higher. school, 2002. - 494 p.

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findings

The systematic method of hydrogen sulfide analysis of metal and arsenic cations currently used in forensic practice is outdated.
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.

Municipal budgetary educational institution

"Ryzhkovskaya secondary school"

Kardymovsky district of the Smolensk region

Competition of students of educational organizations

and organizations of additional education of the Smolensk region

for the best environmental project "We live in the Smolensk region"

Environmental project

« Complex analysis content of heavy metal compounds

in environment and their effect on organisms

Biryukova Alina Alexandrovna

Grade: 9

FULL NAME. work manager:

Baranova Olga Alekseevna

village Titkovo

2017

Table of contents

Introduction…………………………………………………………………………………….………3

Chapter I . Heavy metals ……………………………………………………………….…….. 5

Chapter II . Sources of heavy metal compounds entering the environment and living organisms …………….………………………………………………………………..…7

2.1. The entry of heavy metal compounds into the soil ………………………..………..8

2.2. Receipt of heavy metal compounds in water bodies…………………………………9

2.3. The release of heavy metal compounds into the atmosphere ………………………….…9

2.4. Entry of heavy metal compounds into living organisms ……………………10

Chapter III . Determination of the presence of heavy metal compounds in the environment and their impact on living organisms……………………………………………………….12

3.1. Compounds of heavy metals in soil ………………………………………………………………13

3.1.1. Method for determining the presence of heavy metal compounds in the soil ...... 13

3.1.2. The results of the analysis of the content of heavy metal compounds in the soil……..…14

3.2. Compounds of heavy metals in natural waters………………………….………...14

3.2.1. Method for determining the presence of heavy metal compounds in natural waters ………………………………………………………………………………………..14

3.2.2. The results of the analysis of the content of heavy metal compounds in natural waters……………………………………………………………………………………………....14

3.3. Compounds of heavy metals in the atmosphere………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….

3.3.1. Method for determining the presence of heavy metal compounds in the atmosphere …………………………………………………………………………………………………..15

3.3.2. The results of the analysis of the content of heavy metal compounds in the atmosphere………………………………………………………………………………………………...16

3.4. Compounds of heavy metals and living organisms……………………………………17

3.4.1. Methodology for determining the impact of heavy metal compounds on organisms …………………………………………………………………………………………………...17

3.4.2. Results of determining the impact of heavy metal compounds on living organisms ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….

Conclusion …………………………………………………………………………………………..20

References…………………………………………………………………………..…..21

Application ……………………………………………………………..……………………….22

Introduction

The environment is the habitat of living organisms that are in contact with it all their lives. Organisms receive from the environment everything they need for normal life: oxygen for breathing, water, nutrients, trace elements and much more. Among the chemical elements entering organisms, a special place is occupied by heavy metals in the form of ions.

It has been established that heavy metal ions are normally present in the environment due to their intake from natural compounds, but their natural content is extremely low. Recently, human impact on the environment has been increasing, and now human activity (metallurgical production, vehicles, fertilizers) is also a source of heavy metal compounds, and the number of heavy metal ions of anthropogenic origin in the environment is increasing every year. Consequently, these ions will also enter organisms in greater quantities.

Does the “more is better” rule work here? Everyone knows that living organisms contain metals, including heavy ones: for example, iron in the composition of hemoglobin, zinc in the composition of insulin and many enzymes, copper is needed for the formation of nervous tissue and in the processes of hematopoiesis, and molybdenum activates the binding of atmospheric nitrogen by nodule bacteria. But these and many other chemical elements - heavy metals are required by living organisms for normal life in fairly small quantities, while some of the heavy metals, even in trace amounts, have a toxic effect, being the strongest toxic metals (mercury, lead, cadmium).

Is human activity really a powerful source of heavy metal compounds entering the environment, and do heavy metals themselves negatively affect living organisms? The work is devoted to the study of these issues.

At the beginning of the work was put forwardhypothesis: heavy metal compounds are present in the environment of the study area (rural areas), the content of heavy metal compounds is higher, the closer the sampling area to the highway; heavy metal compounds have a depressing effect on living organisms.

Target: study of the content of heavy metal compounds in the environment (air, soil, water) and their impact on living organisms.

To achieve this goal, it is necessary to solvetasks :

Study the scientific literature on this issue.

To study methods for the determination of heavy metal compounds in the environment.

Carry out a qualitative analysis of samples of soil, snow, water, biological material (lichens) for the content of heavy metal compounds.

Determine the effect of heavy metal compounds on living organisms.

Assess the degree of environmental pollution by heavy metal compounds in the study area.

Object of study : pollution by compounds of heavy metals of the environment and living organisms.

Subject of study : soil, snow, water, living organisms (lichens, watercress).

Research methods:

Theoretical Method

Morphometric method

experimental method

Organoleptic method

mathematical method

Location of the study: village of Titkovo, Kardymovsky district.

Terms of the study: February-March 2017.

Chapter I . Heavy metals

Heavy metals - a group of chemical elements with the properties of metals and a significant atomic weight, more than 40. About forty different definitions of the term heavy metals are known, and it is impossible to point to one of them as the most accepted. Accordingly, the list of heavy metals according to different definitions will include different elements.

The term "heavy metals" is most often considered not from a chemical, but from a medical and environmental point of view. Thus, when included in this category, not only chemical and physical properties element, but also its biological activity and toxicity, as well as the amount of use in economic activity.

In the works devoted to the problems of environmental pollution and environmental monitoring, to date, toheavy metals include more than 40 metals of the periodic system D.I. Mendeleev with an atomic mass of more than 50 atomic units:V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Sn, Hg, Pb, Bi and others. At the same time, an important role in the categorization of heavy metals is played by following conditions: their high toxicity to living organisms in relatively low concentrations, as well as the ability to bioaccumulate and biomagnify. Almost all metals that fall under this definition (with the exception of lead, mercury, cadmium and bismuth, whose biological role is currently not clear), are actively involved in biological processes and are part of many enzymes. According to the classification of N. Reimers, heavy metals should be considered with a density of more than 8 g / cm 3 . Thus, heavy metals arePb, Cu, Zn, Ni, Cd, Co, Sb, Sn, Bi, Hg .

Manyheavy metals , such as the , , , , participate in biological processes and in certain quantities are necessary for the functioning of plants, animals and humans . On the other side,heavy metals and their compounds can provide harmful effect on living organisms. Moreover, the negative impact of heavy metals on living organisms and human health is manifested not only in the direct impact of high concentrations, but also in the long-term consequences associated with their cumulative effect. Compounds of heavy metals cause a number of diseases and general inhibition of vital processes. Metals with no useful role in biological processes, such as and , are defined astoxic metals . In particularlead, which referred to the class of highly hazardous substances along with arsenic, cadmium, mercury, selenium, zinc, fluorine and benzaprene (GOST 3778-98).Some elements such as or , which are usually toxic to living organisms, may be beneficial to some species.

Chapter II . Sources of heavy metal compounds

to the environment and living organisms

Among the pollutants of the biosphere, which are of the greatest interest for various quality control services, metals (primarily heavy, that is, having atomic weight more than 40) are among the most important. This is largely due to the biological activity of many of them.

Sources of heavy metals are divided into natural (weathering of rocks and minerals, erosion processes, volcanic activity) and man-made (mining and processing of minerals, fuel combustion, traffic, agricultural activities). A part of technogenic emissions entering the environment in the form of fine aerosols is transported over considerable distances and causes global pollution. The other part enters drainless water bodies, where heavy metals accumulate and become a source of secondary pollution, i.e. the formation of hazardous contaminants in the course of physical and chemical processes occurring directly in the environment (for example, the formation of poisonous phosgene gas from non-toxic substances). Heavy metals accumulate in the soil, especially in the upper humus horizons, and are slowly removed by leaching, consumption by plants, erosion and deflation - soil blowing.

The period of half-removal or removal of half of the initial concentration is a long time: for zinc - from 70 to 510 years, for cadmium - from 13 to 110 years, for copper - from 310 to 1500 years and for lead - from 740 to 5900 years. In the humus part of the soil, the primary transformation of the compounds that have fallen into it occurs.

Heavy metals have a high capacity for a variety of chemical, physicochemical and biological reactions. Many of them have a variable valency and are involved in redox processes. Heavy metals and their compounds, like other chemical compounds, are able to move and redistribute in living environments, i.e. migrate. The migration of heavy metal compounds occurs largely in the form of an organo-mineral component.

Possible sources of pollution of the biosphere with heavy metals of technogenic origin include enterprises of ferrous and non-ferrous metallurgy (aerosol emissions that pollute the atmosphere, industrial effluents that pollute surface waters), mechanical engineering (electroplating baths of copper plating, nickel plating, chromium plating, cadmium plating), factoriesbattery recycling, road transport.

In addition to anthropogenic sources of heavy metal pollution of the environment, there are other natural eruptions, such as volcanic eruptions: cadmium was discovered relatively recently in the products of the Etna volcano eruption on the island of Sicily in the Mediterranean Sea. An increase in the concentration of toxic metals in the surface waters of some lakes can occur as a result of acid rain, leading to the dissolution of minerals and rocks washed by these lakes. All these sources of pollution cause in the biosphere or its components (air, water, soil, living organisms) an increase in the content of pollutant metals compared to the natural, so-called background level.

2.1. The entry of heavy metal compounds into the soil

Soil is the main medium into which heavy metals enter, including from the atmosphere.from industrial emissions, and lead from car exhaust. From the atmosphere, heavy metals enter the soil most often in the form of oxides, where they gradually dissolve, turning into hydroxides, carbonates, or into the form of exchange cations. Soil withIt serves as a source of secondary pollution of surface air and waters that enter the World Ocean from it. Heavy metals are assimilated from the soil by plants, which then get into the food of more highly organized animals.

The residence time of polluting components in the soil is much longer than in other parts of the biosphere, which leads to a change in the composition and properties of the soil as a dynamic system and ultimately causes an imbalance in ecological processes.

Under natural normal conditions, all processes occurring in soils are in balance. Changes in the composition and properties of the soil can be caused natural phenomena, but most often a person is guilty of violating the equilibrium state of the soil:

atmospheric transport of pollutants in the form of aerosols and dust (heavy metals);

unearthly pollution - dumps of large-tonnage industries and emissions from fuel and energy complexes;

plant debris. Toxic elements in any state are absorbed by the leaves or deposited on the leaf surface. Then, when the leaves fall, these compounds enter the soil. .

The determination of heavy metals is primarily carried out in soils located in ecological disaster zones, on agricultural lands adjacent to soil pollutants with heavy metals, and in fields intended for growing environmentally friendly products.

If the soils are contaminated with heavy metals and radionuclides, then it is almost impossible to clean them. So far, the only way is known: to sow such soils with fast-growing crops that give a large phytomass. Such cultures that extract heavy metals are subject to destruction after maturation. It takes decades to restore polluted soils.

2.2. The entry of heavy metal compounds into water bodies

Metal ions are indispensable components of natural water bodies. Depending on environmental conditions (pH, redox potential), they exist in varying degrees oxidation and are part of a variety of inorganic and organometallic compounds. Many metals form fairly strong complexes with organic matter; these complexes are one of the most important forms of element migration in natural waters.

Heavy metals as microelements are constantly found in natural reservoirs and organs of aquatic organisms. Depending on the geochemical conditions, there are wide fluctuations in their level.

At the same time, heavy metals and their salts are widespread industrial pollutants. They enter water bodies both from natural sources (rocks, surface layers of soil and groundwater), and with wastewater from many industrial enterprises and atmospheric precipitation, which are polluted by smoke emissions. For example, natural sources lead entry into surface waters are the processes of dissolution of endogenous (galena) and exogenous (anglesite, cerussite, etc.) minerals. A significant increase in the content of lead in the environment (including in surface waters) is associated with the combustion of coal, the use of tetraethyl lead as an antiknock agent in motor fuel, with the removal into water bodies with wastewater from ore processing plants, some metallurgical plants, chemical industries, mines, etc.

2.3. The release of heavy metal compounds into the atmosphere

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.

The release of heavy metals into the atmosphere, % of the amount

Source

Heavy metal

Сd

General natural source

26,3

29,0

4,5

81,0

anthropogenic source

73,7

71,0

95,5

19,0

2.4. Entry of heavy metal compounds into living organisms

Plant foods are the main source of heavy metals in humans and animals. According to the data, 40–80% of heavy metals come with it, and only 20–40%. - with air and water. The chemical composition of plants, as is known, reflects the elemental composition of soils. Therefore, the excessive accumulation of heavy metals by plants is primarily due to their high concentrations in soils. Despite the significant variability of various plants to the accumulation of heavy metals, the bioaccumulation of elements has a certain tendency, which allows them to be ordered into several groups:

1) Cd, Cs, Rb - elements of intense absorption;

2) Zn, Mo, Cu, Pb, Co, As - medium degree of absorption;

3) Mn, Ni, Cr - weak absorption;

4) Se, Fe, Ba, Te - elements difficult for plants to access. Another way for heavy metals to enter plants is through foliar absorption from air currents.

The entry of elements into plants through the leaves occurs mainly through non-metabolic penetration through the cuticle. Heavy metals absorbed by the leaves can be transferred to other organs and tissues and included in the metabolism. Lead and cadmium are highly toxic metals. In roadside plants, the amount of lead is sharply increased, it is 10–100 times higher than in plants growing far from roads. A large amount of cadmium is found in plants growing near highways. So, for example, in the needles of common spruce growing near roads, the amount of cadmium increases by 11–17 times.

The entry of heavy metals into plants can occur directly from the air with dust deposited on leaves and needles and translocation from the soil: the proportion of heavy metals in the composition of dust on the surface of leaves near the source is on average 30% of the total content of heavy metals in them. In depressions and on the windward side, this proportion can reach up to 60%. As you move away from the source, the role of atmospheric pollution noticeably decreases.

Chapter III . Determination of the presence of heavy metal compounds in the environment and their impact on living organisms

The method for determining the content of heavy metal ions is reduced to the analysis of melt water, water from a reservoir or water extracts using high-quality reagents.

Qualitative determination of lead ions Р b 2+

Potassium iodide gives a characteristic yellow lead iodide precipitate in solution with lead ions.

Research progress :

1 ml of water, melt water or aqueous extract from each sample is poured into test tubes and 1 ml of KI solution and 1 ml of 6% HNO are added. 3. The tubes with the contents are left for a day. In the presence of lead ions, a yellow precipitate forms at a lead content of 60 μg in the sample. At lower concentrations, the contents of the tube are stained with yellow :

R b 2+ + I - = R b I 2

Qualitative determination of iron ions

total iron

Ammonium thiocyanateNH 4 SCN or potassium KSCN form in acid medium withFe 3+ iron thiocyanates, colored blood red. Depending on the concentration of the rhodanide ion, complexes of variouscomposition:

Fe 3+ +SCN - = 2+

Fe 3+ + 2 SCNs - = +

Fe 3+ + 3 SCN- = Fe( SCN) 3

To 1 ml of test water add 2-3 drops of hydrochloric acid solution and2- 3 drops of reagent solution.

Atiron content0.1 mg/lappearspinkstaining,aatmorehigh content -red.

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

Iron(II)

Potassium hexacyanoferrate(III)K 3 [ Fe( CN) 6 ] , in an acidic environment(рН ~ 3) forms with Fe cation 2+ precipitate of turnbull blue dark bluecolors:

3Fe 2+ + 2 3- = Fe 3 2

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

Iron(III)

Potassium hexacyanoferrate(II)K 4 [ Fe( CN) 6 ] in a slightly acidic medium with a cationFe 3+ forms a dark blue precipitate of Prussian blue:

4Fe 3+ + 3 4- = Fe 4 3

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

The following equipment, reagents and materials were used for the qualitative determination of lead and iron ions.

Equipment: training scales, weights, a ruler, a tripod with a clutch and a foot, a burette with a tap, a 2 ml measuring pipette, 100 ml and 50 ml beakers, a 100 ml graduated cylinder, 250 ml round flat-bottomed flasks, rubber stoppers, conical funnels , filter paper, test tube rack, test tubes, scissors, spatula, glass rods, glass tubes, Petri dishes.

Reagents: nitric acid concentrated (HNO 3 ), potassium iodide solution (KI), 6% nitric acid solution (HNO 3 ), hydrogen peroxide (H 2 O 2 ), potassium thiocyanate (solution) (KSCN), sulfuric acid (solution) (H 2 SO 4 ), hexacyanoferrate (III) potassium (K 3 [ Fe( CN) 6 ]), hexacyanoferrate (II) potassium (K 4 [ Fe( CN) 6 ), hydrochloric acid (solution) (HCl), boiled water.

Materials: watercress seeds, lichen thalli of xanthoria wall (goldwort) and parmelia furrowed.

3.1. Heavy metal compounds in soil

3.1.1. Method for determining the presence of heavy metal compounds in the soil

Soil samples were taken (approximately 100 g each) at two points: near the highway in the immediate vicinity (Appendix, Fig. 1), in a coniferous forest belt away from the road (Appendix, Fig. 2), where mainly pines and spruces grow, and there are also some hardwoods.

The soil was dried for 5 days.

Weighed on pre-balanced scales, 10 g of each soil sample.

The samples were transferred to round flat-bottomed flasks with designations (a soil sample taken near the road - “p dor”; a soil sample taken in a forest belt - “p forest”). Pour into each flask 50 ml of boiled water, add 1 drop of concentrated nitric acid HNO 3 , shaken for 5 minutes. Left for a day (Appendix, Fig. 3).

Soil extracts were filtered into labeled beakers, using a separate filter for each extract (Appendix, Fig. 4).

The obtained filtrates were used for the qualitative determination of the content of lead and iron ions in the soil according to the previously described method.

3.1.2. The results of the analysis of the content of heavy compounds

metals in soil

Analysis of samples for the content of lead ions in the soil gave the following results. In a test tube with an aqueous extract from the soil taken near the road, no obvious precipitate fell out, but the contents of the test tube turned into a rich golden brown color, which indicates a rather significant content of lead ions in this soil sample. In a test tube with an aqueous extract of the soil taken in the forest belt, neither sediment nor a clear change in color was noted (the soil extract initially had a weak pale yellow color, which can be explained by the coloring property of the organic matter contained in the forest soil) (Appendix, Fig. 5, 6) .

The analysis of samples for the content of iron ions in the soil did not give visible changes: when the reagents were added, there was no change in coloring and precipitation did not occur.

3.2. Heavy metal compounds in natural waters

3.2.1. Method for determining the presence of heavy metal compounds in natural waters

1. We took water samples from the reservoir into a clean container (Appendix, Fig. 7).

2. Filtered a sample of water taken from the lake into a beaker to purify the sample from mechanical impurities.

3. The resulting filtrate was used to conduct a qualitative determination of the content of lead and iron ions in the water of the lake according to the previously described method.

3.2.2. Compound content analysis results

heavy metals in natural waters

The analysis of samples for the content of lead ions in water gave the following result: no obvious precipitate fell out, but the contents of the test tube turned into a barely distinguishable pale yellow color (Appendix, Fig. 8).

The analysis of samples for the content of iron ions in water did not give visible results: when reagents were added, there was no change in coloring and no precipitation occurred.

3.3. Heavy metal compounds in the atmosphere

3.3.1. Method for determining the presence of heavy metal compounds in the atmosphere

Snow cover

Snow cover accumulates in its composition almost all substances entering the atmosphere. In this regard, it has a number of properties that make it a convenient indicator of pollution not only of precipitation itself, but also of atmospheric air. During the formation of snow cover due to the processes of dry and wet precipitation of impurities, the concentration of pollutants in the snow is 2-3 orders of magnitude higher than in the atmospheric air. Therefore, the analysis of snow samples gives results with a high degree reliability. When sampling withneg must be taken throughout the depth of its deposits in the containers reserved for this.

We took dishes for taking snow samples, made signs. Snow samples were taken in 3 places: on the roadside (Appendix, Fig. 9), in the yard near the house (Appendix, Fig. 10), in the forest belt (Appendix, Fig. 11).

The containers were filled with snow.

Delivered snow to the classroom.

After the snow melted, the melt water was filtered to remove mechanical impurities from the samples (Appendix, Fig. 12).

The obtained filtrates from three samples were used to conduct a qualitative determination of the content of lead and iron ions in the snow (and, therefore, in the atmosphere) according to the previously described method (Appendix, Fig. 13, 14).

Lichens

The sensitivity of lichens to atmospheric pollution has long been noted. Lichens are able to accumulate elements from the environment in quantities that far exceed their physiological needs. The absence of special organs for water and gas exchange and the extremely low ability for autoregulation lead to a high degree of correspondence between the chemical composition of lichens and their environment. This quality determined the widespread use of lichens as accumulative bioindicators of environmental pollution by heavy metals. It has been established that Co, Ni, Mo, Au are present in lichens in the same concentrations as in higher plants, while the content of Zn, Cd, Sn, Pb is much higher.

For the qualitative determination of the content of heavy metal ions, the following method was used:

The collection of lichens was carried out from the birch tree (Betula pendula ) and goat willow (Salix caprea ) at a height of 0.5 to 1 meter.

If possible, lichen samples were taken without bark; if it was impossible to separate the thallus from the bark, they were cut along with it.

For analysis, lichen thalli of Xanthoria walla and Parmelia sulciforma were collected, and a visual assessment of the state of the thalli during collection was also carried out.

Sampling was carried out in two places: on trees near the highway (Appendix, Fig. 15, 16) and on trees growing in the forest belt (Appendix, Fig. 17).

Lichens of the same species, collected from one tree, were placed in general package with symbols (Appendix, Fig. 18).

In the office, 25 g of lichen thalli of each species from each sample were weighed on a scale, and they were crushed.

Two weighed portions of lichen thalli of both species (xanthoria + parmelia for each sampling site) were placed in round flat-bottomed flasks, 50 ml of boiled water was poured into each flask, 1 drop of concentrated nitric acid was added, shaken for 5 minutes, left for a day (Appendix, Fig. 3).

Then the water extract was filtered, the obtained filtrates were used forconducting a qualitative determination of the content of lead and iron ions in lichen thalli (and, therefore, in the atmosphere) according to the previously described method.

3.3.2. Compound content analysis results

heavy metals in the atmosphere

Snow cover

Analysis of samples for the content of lead ions in the snow gave the following results. In a test tube with melt water filtrate from snow taken on the side of the road (sample No. 3), there was no obvious precipitate, but the contents of the test tube turned bright golden, which indicates a significant content of lead ions in this snow sample. In a test tube with a filtrate of melt water from snow taken in a forest belt far from the road (sample No. 2), the precipitate did not fall out, the contents of the test tube acquired a faint pale yellow color. In a test tube with a filtrate of melt water from snow taken in the backyard near the house (sample No. 1), the precipitate did not fall out, the contents of the test tube turned pale yellow (Appendix, Fig. 8).

The analysis of samples for the content of iron ions in the snow did not give visible results: when reagents were added, there was no change in coloring and precipitation did not occur.

Lichens

When visually assessing the state of the lichen thalli of Xanthoria walla and Parmelia sulciforma, some inhibition of the general condition of the lichen thalli growing on trees near the road was noted: the thalli are small in size, somewhat thickened, their leafy nature is weakly traced, the thalli are firmly attached to the bark of trees (Appendix, fig. nineteen). All this indicates the presence in the atmosphere of the study area (roadside zone) of substances that adversely affect living organisms - lichens.

Analysis of samples for the content of lead ions in lichen thalli gave the following results. In a test tube with an aqueous extract from lichen thalli collected from trees near the highway, no precipitate fell out, but the contents of the test tube turned into a faintly distinguishable pale yellow color, which indicates lead ions contained in the atmosphere and their accumulation in lichen thalli. In a test tube with an aqueous extract from lichen thalli collected from trees in a forest belt far from the highway, no precipitate fell out, and no color change was noted (Appendix, Fig. 6).

The analysis of samples for the content of iron ions in lichen thalli did not give visible results: when reagents were added, there was no change in color and precipitation.

General conclusion: Analyzing the results obtained in all variants of the experiments (the content of lead ions in soil, water, snow and lichens), we conclude that lead ions are found in the environment. Moreover, the content of lead ions is the greater, the closer the sampling area is to places with high human activity (in our case, a highway), which is primarily due to the release of lead ions into the environment as part of vehicle exhaust gases. The negative result of the samples for the content of iron ions in all variants of the experiments, most likely, is associated not with the complete absence of iron in the environment, but with its very low content, which cannot be determined by the methods we use and the reagents available in the laboratory.

3.4. Heavy metal compounds and living organisms

3.4.1. Method for determining the effects of heavy metal compounds on organisms

We used watercress as a test organism (Appendix, Fig. 20).

Watercress is an annual vegetable plant that is highly sensitive to soil pollution by heavy metals, as well as to air pollution from gaseous vehicle emissions. This bioindicator is characterized by rapid seed germination and almost one hundred percent germination.

In addition, the shoots and roots of this plant undergo noticeable morphological changes under the influence of pollutants. Growth retardation and curvature of shoots, reduction in length and mass of roots.

Watercress as a bioindicator is also convenient because the effect of stress can be studied simultaneously on large numbers plants in a small area of the workplace. The very short duration of the experiment is also attractive. Watercress seeds germinate already on the second or third day.

To determine the impact of heavy metal ions on living organisms (watercress), we took samples of melt water, the samples of which had already been analyzed for the content of lead and iron ions using high-quality reagents.

At the bottom of the Petri dishes were placed circles cut out of filter paper according to the size of the Petri dishes; Petri dishes are numbered.

3 ml of melt water of the corresponding sample was poured into each Petri dish (the filter paper was completely wetted) (Appendix, Fig. 21).

Watercress seeds were placed on filter paper (20 pieces in each Petri dish), covered with lids (Appendix, Fig. 22, 23).

After 3 days, a morphometric assessment of lettuce seedlings was carried out (the lengths of the roots were measured) (Appendix, Fig. 24, 25).

The data was entered into the table, the average value of the lengths of the roots for each option was found, conclusions were drawn

3.4.2. Compound exposure results

heavy metals on living organisms

Morphometric parameters of watercress seedlings

(length of spines in mm)

p/n

Sample No. 1 (snow from the yard)

Sample No. 2 (snow from the forest belt)

Sample No. 3 (snow from the road)

MEAN

44,74

56,24

22,4

Findings: lead ions contained in melt water have a depressing effect on the vital processes of organisms, the negative effect is the greater, the higher the content of lead ions in melt water. This follows from the results obtained. In the variant of experiment No. 3 (road) (Appendix, Fig. 26), morphometric changes are clearly noted: the length of the roots sharply decreases - by 20 mm or more according to average values. In addition, the germination rate was 90%. In the variants of experiments No. 1 (yard) (Appendix, Fig. 27) and No. 2 (forest belt) (Appendix, Fig. 28), germination was 95% and 85%, respectively. Such a quantitative spread in germination in options No. 1 and No. 2 can be associated with the overall germination of seed (random factor) and a relatively small sample. The lower value of the average root length in variant No. 1 in comparison with variant No. 2 is explained by the high presence of lead ions in melt water. The negative effect of lead ions on living organisms was precisely established during the experiment.

Conclusion

The environment is a home for living organisms, it also provides organisms with all the substances necessary for normal life. At the same time, living organisms absorb from the environment not only what they need, there is a joint absorption of a whole complex of substances and elements, where some are not only not useful, but also have a depressing, poisonous effect on organisms, among such substances a special place is occupied by heavy metal compounds. But usually the natural background of heavy metals in the environment is quite low, therefore, the negative impact of their compounds on plants and animals is insignificant.

Recently, the environment is experiencing a very strong impact on the part of man, which negatively affects its condition, leading to severe pollution.

In the course of our study, it was found that the degree of anthropogenic impact on the environment in the area of its pollution with heavy metal compounds is high. Lead heavy metal ions are present in the environment of the study area, and their content increases when approaching areas with a high degree of anthropogenic impact - near the roads of the study area. At a distance from roads, the concentration of metal ions decreases, but, nevertheless, the content of heavy metal compounds will be higher than the natural background, because pollution spreads over large areas with moving air masses, with flows of underground and surface waters, with precipitation. Negative tests for the presence of iron ions do not mean its absence at all; in rural areas, there are practically no sources of its entry into the environment; therefore, the content of iron ions is extremely low to establish its presence. It was also found that heavy metal ions have a general inhibitory effect on the growth and development of living organisms at relatively low concentrations.

The practical significance of the work lies in the fact that the results obtained can be used: when conducting class hours, extracurricular activities and classes devoted to the problems of the ecological state of the environment (in particular, the study area); when developing booklets on the topic “The environment and the problem of its pollution with heavy metal compounds”, to inform the population (including the installation of a sign near the reservoir “Fishing is prohibited!”). Practical results research work can be used when writing an article in a newspaper to highlight the problem of environmental pollution.

Bibliography

Ashikhmina T.Ya. School environmental monitoring. Teaching aid. M.: AGAR, 2006. 38 p.

Mansurova S.E. “We monitor the environment of our city”, M., Vlados, 2001

Muraviev A.G., Scarecrow N.A., Lavrova V.N. Ecological workshop: Tutorial with a set of instruction cards / Ed. Ph.D. A.G. Muraviev. - 2nd ed., Rev. - St. Petersburg: Krismas+, 2012. - 176 p.: ill.

Heavy metals as an environmental hazard factor: Guidelines to independent work in Ecology for 3rd year full-time students / Compiled by Yu.A.Kholopov. - Samara: SamGAPS, 2003.

Appendix

Fig.1. Soil sampling from the side of the road

Fig.2. Soil sampling in the forest belt

Fig.3. Obtaining water extracts from the soil and from lichen thalli

Fig.4. Obtaining soil extract filtrate

Fig.5. Soil extract filtrates

Fig.6. Results of detection of lead ions in water extracts from lichen thalli and soil

Fig.7. Lake water sampling

Fig.8. Results of the detection of lead ions in melt water and lake water

Fig.9. Taking a snow sample from the side of the road

Fig.10. Taking a snow sample in the yard near the house

Fig.11. Taking a snow sample in a forest belt

Fig.12. Obtaining melt water filtrate

Fig.13. Measuring a sample of melt water from a burette into an experimental test tube

Fig.14. Withdrawing the required amount of reagent into a volumetric pipette

Fig.15. Collection of lichen Parmelia sulcita near the road

Fig.16. Collection of xanthoria wall lichen near the road

Rice. 17. Collection of lichen parmelia furrowed in the forest belt

Fig.18. Collected samples of lichen thalli

Fig.19. Lichens on the trunk of a birch growing near the road

Fig.20. Test organism - watercress

Fig.21. Preparing for sowing seeds

Fig.22. Sowing watercress seeds

Fig.23. Watercress seeds in Petri dishes

Fig.24. Measuring the length of the roots of watercress sprouts

Fig.25. Measuring the length of the root of a watercress sprout

Fig.26. Watercress sprouts

(experimental version - snow taken near the road)

Fig.27. Watercress sprouts

(experimental version - snow taken in the courtyard of the house)

Fig.28. Watercress sprouts

(experimental version - snow taken in the forest belt)

Bashurova Maria

This paper considers one of the main environmental problems of our time: environmental pollution by one of the heavy metals - lead. Behind recent years most often, poisoning with compounds of this particular metal is 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. Pollution of water with lead is caused by wastewater from enterprises containing toxic amounts of lead salts, 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.
The practical significance of the 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.

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

Calculate common path(S) covered by all cars in 1 hour: S = N*100m.
Taking measurements of car emissions per 1 km, calculate how many emissions of lead compounds were produced by cars in 1 hour.
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.

To take a sample, you will need a container with a capacity of at least 250 ml.
The container is immersed in the snow with an open end, trying to reach its lower layer.
The sample is taken out and delivered to the laboratory for thawing.
100 ml of liquid is poured from each sample and filtered.
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 .
Changes in test tubes are determined.

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

Soil sampling is done.
The soil is dried for 5 days.
Each sample is weighed 10 mg and placed in test tubes.
10 ml of distilled water is added to each tube.
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:

50 pieces of leaves or 50 g of grass are selected.
The plant material is dried and crushed.
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 - middle 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.

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.
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:

If possible, remove your site from the source of pollution by not using the land directly adjacent to the route.
Do not use the land on the site to plant plants with a height of more than 1 meter (corn, dill, etc.)
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