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Mechanical and physical properties of the soil

Soil temperature - determines the temperature of the surface layer of the atmosphere, as well as the thermal regime of the basement rooms and first floors of buildings. At a depth of 1 m, the soil no longer has daily temperature fluctuations. At a depth of 7-8 m, the lowest temperature remains in May, the highest - in December. This is of great sanitary importance for storing food in the basement, where it is cooler in summer and warmer in winter than on the surface. Soil temperature significantly affects the vital activity of soil organisms and self-cleaning processes.

The mechanical and physical properties of the soil (particle size, soil water, soil air, porosity, air permeability, moisture capacity, capillarity, heat capacity) that affect the chemical composition of soils and groundwater, the intensity of biochemical self-cleaning processes, the quality and safety of agricultural products, and etc.

The size of soil particles determines the mechanical properties of the soil. So, stone soil has a particle size of more than 3 mm, sand - 0.2-0.3 mm, clay - 0.01-0.001 mm, humus - less than 0.0001 mm.

Soil water. Soil has a huge impact on the formation, composition and properties of groundwater and open water. Groundwater is formed from soil water. The hygienic significance of soil water is that all chemicals, as well as biological soil contaminants (helminth eggs, protozoa, bacteria, viruses) can move in it only with soil moisture. In addition, all chemical and biological processes occurring in the soil, including self-purification, are carried out in aqueous solutions.

Soil air. Its quantity and properties depend on the nature of the soil. Soil air is constantly exchanged with atmospheric air. However, even clean soil air always contains a reduced amount of oxygen (up to 14%) and an increased amount of carbon dioxide (up to 8%). With severe soil contamination with organic substances and insufficient oxygen supply, toxic products of decay (hydrogen sulfide, ammonia, hydrogen fluoride, indole, skatol, methyl mercaptan) are released, which can penetrate underground structures and basements and worsen their sanitary condition. There are known cases of soil air poisoning during the laying of underground structures, digging pits, wells. Soil air significantly affects the human body in residential areas and recreation areas.

Porosity is the total pore volume per unit volume of soil, expressed as a percentage. The higher the porosity, the lower the filtration capacity of the soil. So, the porosity of sandy soil is 40%, peaty 82%. With a porosity of 60-65%, optimal conditions are created in the soil for self-cleaning processes from biological and chemical contaminants.
At higher porosity, self-cleaning processes of the soil deteriorate. Soil of this type is rated as unsatisfactory.

Breathability of the soil - the ability of the soil to pass air. This property of the soil is determined only by the size of its pores. Breathability of the soil increases with increasing barometric pressure and decreases with increasing thickness of the soil layer and its moisture content. The movement of soil air and its exchange with atmospheric air occurs constantly under the influence of a difference in their temperatures, fluctuations in atmospheric pressure and the level of soil water. High air permeability of the soil contributes to its enrichment with oxygen, which is of great hygienic importance associated with an increase in the biochemical processes of oxidation of organic substances.

The water permeability (filtration ability) of the soil is the ability of the soil to absorb and pass water coming from the surface. Absorption is the first phase of water permeability, when free pores are successively filled with water. With excess moisture, its absorption continues until the soil is completely saturated. The second phase - filtration - is characterized by the movement of water in the soil pores under the action of gravity with complete saturation of the soil with water. The water permeability of the soil has a decisive influence on the formation of soil waters, the accumulation of their reserves in the bowels of the Earth and the supply of water to the population from underground sources.

The moisture content of the soil is the amount of water that the soil is able to retain in its bowels by sorption and capillary forces. The moisture content is greater, the smaller the pores of the soil and the greater their total volume.

Peat bogs possess the highest moisture capacity (up to 500-700%). The moisture capacity is expressed as a percentage of the weight of dry soil. The hygienic value of the soil moisture capacity is due to the fact that the large moisture capacity causes the soil and the buildings located on it to become damp, reduces the soil permeability for air and water, and interferes with wastewater treatment. Such soils are moist and cold.

Soil capillarity is the ability of the soil to raise water from the lower horizons to the upper by capillaries. The finer the porous (fine-grained) soil, the greater its capillarity, the higher the water rises along it. High capillarity of the soil can cause dampness of buildings. Coarse-grained soils raise water faster, but to a small height.

Even in ancient times, Hippocrates distinguished between “healthy” and “unhealthy” soils. Healthy areas were elevated, dry and sunny. Unhealthy people included low-lying, cold, flooded, raw. Healthy soil should be coarse and dry, as fine-grained and moist soils are poorly ventilated and poorly self-cleaning.
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Mechanical and physical properties of the soil

  1. The history of the development of sanitary protection of the soil. Indicators characterizing the basic properties of the soil, their hygienic value
    In the history of hygiene, the most ancient preventive measures to protect human health were measures aimed at the sanitary protection of the soil. At that time, people walked barefoot, slept on the ground or in earthen shelters, breathed soil air, drank ground water, and finally ate foods grown on the soil. The problem of the effect of soil on human health has interested mankind with
  2. Physical properties of water (temperature, transparency, color, taste, smell) and the effect of these properties on human health.
    These include smell, taste, color and transparency, that is, those properties that can be determined by the human senses. Turbid, dyed in any color or having an unpleasant smell and taste, the water is not sanitary-hygienic inadequate even if it is harmless to the human body. Deterioration of the properties of water adversely affects the drinking water regime, reflexively
  3. Hygienic importance of soil composition and properties
    The soil consists of solid particles and free spaces between them, filled with air or water. Soil particles with a diameter of more than 3 mm include stones and gravel, from 1 to 3 mm - coarse sand and less than 1 mm - fine sand, clay, dust, silt. From a hygienic point of view, it is important to know the basic properties of the soil in order to be able to conclude whether this or that soil will be healthy or unhealthy. These include
  4. Physical properties
    In the study of physical properties, the quantity, texture, shape, color and smell of feces are evaluated. Macroscopically visible impurities are examined. The amount of excreted excreted per day depends on the composition and amount of food taken on the eve, can vary significantly. With a normal diet, the composition approaching trial diets, the daily amount of feces is 120-200 g.
  5. Physical properties of air
    Physical properties of air include temperature, humidity, air mobility, atmospheric pressure, electrical condition, and solar radiation. Each of these factors has an independent value, but they have a complex effect on the body. When characterizing hygienic indicators of air, particular importance is attached to a set of physical factors, defined as climate. TO
  6. Physical properties of air
    The temperature on the earth ranges from -940С to + 630С. Temperature conditions depend on the latitude of the area: the farther from the equator, the sharper the angle of incidence, therefore, the earth heats less. On the surface (near the ground) the layers of air are warmer, every 100m the air temperature drops by 0.5 ° C. Thanks to the thermoregulatory mechanisms that are controlled by the central nervous system, man
  7. Physical properties of air
    1. Atmospheric pressure. As can be seen from the previous exposition of the material, the layer of air above the earth's surface extends to a height of about 1000 km. This air is held at the surface of the earth by gravity, i.e. has a certain weight. On the surface of the earth and on all objects located at its surface, this air creates a pressure equal to 1033 g / cm. Therefore, for the whole
  8. Physical properties of urine
    The amount of urine formation depends on air temperature, rest, sleep. The mechanism for reducing diuresis during sleep resembles that which occurs under the influence of the antidiuretic hormone of the posterior pituitary gland. Muscle exercises lead to a decrease in plasma renal output, which causes a decrease in sodium excretion. Heat reduces glomerular filtration, causing oliguria and also lowers excretion
  9. Soil as an environmental factor. The role of soil in the transmission of epidemic, infectious and parasitic diseases. Soil pollution and self-cleaning
    The study of soil, its assessment of various indicators can conditionally be divided into 4 stages. I. The Dopaster period (until 1852). The central point of this period is the localistic theory of Pettenkofer, who believed that all epidemics are closely linked to the mechanical composition of the soil, the content of carbon dioxide and the amount of organic substances. Unaware of infectious agents
  10. Self-cleaning of the soil and sanitary protection of the soil
    Self-cleaning of the soil is a transformation aimed at restoring the original state of the soil. Self-cleaning is of great hygiene and epidemiological importance. Soil is a natural environment for waste disposal. It detoxifies (neutralizes, destroys, turns into non-toxic compounds) the bulk of incoming exogenous organic
  11. Hygienic significance of the soil. Types of soils, their hygienic characteristics. Soil microorganisms. Water purification
    Soil - the surface layer of the earth, rich in mineral and organic compounds. Mineral part: * sand; *clay; *silicon; *lime. Organic part: humus (humus) - the remains of plant and animal organisms. The organic part of the soil is gradually turning into mineral due to the activity of microorganisms - orderlies who decompose the organic part. Soil is also populated
    Inspection of arteries: In young people, at rest, a pulsation can be observed: 1. Carotid artery on the neck. 2. Truncus brachiocephalicus in the jugular fossa. 3. Connect the arter in the subhole. 4. Abdominal aorta. In older people, an additional definition of pulsating arteries: 5. Shoulder 6. Elbow 7. Superficial temporal temporal pulsation; art can be detected in healthy people, which means physical and / or emotional stress. when ^
    The gray noises are the sounds that are called. Instead of heart sounds (C), accompanied by tones C or occur without any connection with tones C. Classification: I. inside the sulfuric: a-organ-it is 1 valve, 2 non-valve; b-functions are 1-intermediate, 2-pure functions, 3-physical ones; II extracardiac: a-perekardia-e, b-pleuropericardi-e, c-cardiopulmonary Mech m of internal noise Noise C - this is the mechanical oscillations of the engine caused by
    On palpation of the common carotid, humeral, ulnar, temporal, femoral, popliteal, and rear art stops, the tasks are narrowed down to an approximate assessment of the pulsatory movements by voltage and filling. The carotid artery is palpated on the left and right in a delicate way, removing the sternoclavicular-nipple muscle outwards at the level of the thyroid cartilage, palpating the facts of the common carotid artery on the left and right.
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