Two-thirds of our planet are taken up by water. This is more than enough for all people, but water conservation is a global problem for mankind. The fact is that most water resources are not suitable for drinking — some water is a salty liquid, and mankind needs fresh water not only for drinking, but also for growing crops and feeding livestock.
However, in the modern world, fewer and fewer people pay attention to their direct interaction with nature, not noticing the destructive consequences of their actions.
Water in the human body makes up 60-80% of body weight, without it the body cannot function for more than 72 hours. For humans, water also has production value, being a source of energy, raw material for production, transportation, etc. Despite the awareness of the importance of the role of water in his life, humanity continues to ignore the need to respect water bodies and preserve their natural regime, subjecting them to constant exploitation and pollution.
Currently, many countries around the world lack water that is suitable for drinking and cooking, industrial production, and irrigation. If we continue to ignore this problem, the next generations will fully experience the destructive impact of anthropogenic water pollution. Over the past 40 years, the amount of fresh water per person in the world has decreased by 60%. Over the next 25 years, it is expected to further decrease by another 2 times. Waterborne diseases kill 3 million people every year.
Accordingly, it is necessary to start solving this problem as soon as possible and radically reconsider our attitude to the problem of cleaning industrial waste.
Water pollution is manifested in a change in its properties (change of transparency, color, odors, taste), an increase in the content of toxic heavy metals, a reduction in the oxygen dissolved in water, the appearance of radioactive elements, pathogenic bacteria and other pollutants.
The world economy dumps 1,500 cubic meters per year.
Types and sources of pollution of the hydrosphere
Pollution of surface and groundwater can be divided into the following types:
· Chemical — the presence in water of organic and inorganic substances of toxic and non-toxic action. The most common chemical pollutants are oil and petroleum products, synthetic surfactants (synthetic surfactants), pesticides, heavy metals, dioxins, etc. Chemical pollution is the most common, persistent and far-reaching. It can be organic (phenols, naphthenic acids, pesticides, etc.) and inorganic (salts, acids, alkalis), toxic (arsenic, compounds of mercury, lead, cadmium, etc.) and non-toxic. During sedimentation on the bottom of reservoirs or during filtration in a stratum, harmful chemicals are sorbed by rock particles, oxidized and reduced, precipitated, etc., however, as a rule, complete self-purification of contaminated waters does not occur. A hotbed of chemical contamination of groundwater in highly permeable soils can spread up to 10 km or more.
The most intensively polluted surface waters are the result of the operation of such industries as metallurgy, chemical, oil refining, and paper industry.
Wastewater contains salts, acids, alkalis, and other minerals resulting in mineral pollution. Industrial effluents contain 40% minerals and 60% organic substances.
Substances of organic origin include vegetable fibers, animal and vegetable fats, residues of fruits and vegetables, waste of the pulp and paper, leather, food industries. Wastewater containing these substances is the cause of organic pollution of water bodies.
Wastewater is divided into three groups: wastewater, or fecal water; household water, including drains from the galley, showers, laundries, etc.; oil-containing water.
Wastewater is characterized by high bacterial pollution, as well as organic pollution (chemical oxygen consumption reaches 1500-2000 mg / l.). The volume of these waters is relatively small.
Domestic wastewater is characterized by low organic pollution. This wastewater is usually discharged overboard as it is generated. Dumping it is prohibited only in the sanitary protection zone.
Another kind of polluted waters is generated in the engine rooms of ships. They are distinguished by a high content of petroleum products.
Industrial wastewater is polluted mainly with industrial waste and emissions. Their quantitative and qualitative composition is diverse and depends on the branch of industry, its technological processes. They are divided into two main groups: containing inorganic impurities, and including both toxic and containing poisons.
The first group includes wastewater from soda, sulphate, nitrogen-fertilizer plants, enrichment factories of lead, zinc, nickel ores, etc., which contain acids, alkalis, heavy metal ions, etc. The wastewater of this group mainly changes the physical properties of water.
Wastewaters of the second group are discharged by oil refineries, petrochemical plants, organic synthesis plants, coke-chemical plants, etc. The wastewater contains various oil products, ammonia, aldehydes, resins, phenols, and other harmful substances. The harmful effect of wastewater from this group is mainly in oxidative processes, as a result of which the oxygen content in the water decreases, the biochemical need for it increases, and the organoleptic characteristics of water deteriorate.
The influence of agriculture on the pollution of the hydrosphere
Of all the branches of agriculture, crop production intensively pollutes water bodies, due to the use of fertilizers and pesticides. About a quarter of nitrogen fertilizers, a third of potash, and 4% of phosphorus fertilizers enter water bodies. If in unpolluted rivers the average level of nitrate content is 100 mg / l, then in Western and Central Europe — 4500 mg / l, the concentration of phosphorus in the rivers of this region is 2.5 times higher than in unpolluted water bodies.
An increase in the concentration of nutrients leads to the eutrophication of water bodies.
Eutrophication (eutrophication) is an increase in the biological productivity of water bodies as a result of the accumulation of nutrients in water under the influence of anthropogenic or natural factors. Biogenic elements are chemical elements necessary to sustain life. For example, eutrophication of surface waters is observed throughout Europe. Analysis of water samples showed that in 8-28% of samples there was an increased content of nitrates, exceeding the national standards. In groundwater, such excess is contained in 4-18% of samples, in private wells — in 11% of samples, in public water supply systems — in 0-2.8% of samples.
Livestock breeding also affects the ecological state of water bodies. A pig-breeding complex for 100 thousand heads can pollute a reservoir in the same way as a city with a half-million population. Manure and manure runoff, getting into surface and ground waters, cause:
The wastewater of livestock complexes contains many bacteria of the intestinal group that live for a long time: salmonella — 2.5 years, tuberculosis microorganisms — 475 days, etc.
A serious environmental problem is that the usual way of using water to absorb heat in thermal power plants is to directly pump fresh lake or river water through a cooler and then return it to natural bodies of water without preliminary cooling. A 1000 MW power plant requires a lake with an area of 810 hectares and a depth of about 8.7 m.
Power plants can increase the temperature of the water in comparison with the ambient temperature by 5-15 C. Under natural conditions, with slow increases or decreases in temperature, fish and other aquatic organisms gradually adapt to changes in ambient temperature. But if a new temperature regime is quickly established as a result of the discharge of hot wastewater from industrial enterprises into rivers and lakes, there is not enough time for acclimatization, living organisms receive a heat shock and die.
Heat shock is the extreme result of heat pollution. The discharge of heated wastewater into water bodies can also have more insidious consequences. One of them is the impact on metabolic processes.
As a result of an increase in water temperature, the oxygen content in it decreases, while the need for it in living organisms increases. The increased need for oxygen, its lack of it causes severe physiological stress and even death. Artificial heating of water can significantly change the behavior of fish — cause untimely spawning, or disrupt migration.
An increase in water temperature can disrupt the structure of the flora of water bodies. The algae characteristic of cold water are replaced by more thermophilic ones and, finally, at high temperatures, they are completely displaced by them, thus creating favorable conditions for the mass development of blue-green algae in reservoirs — the so-called “water bloom”. All of the above consequences of thermal pollution of water bodies cause enormous harm to natural ecosystems and lead to a detrimental change in the human environment.
Damage resulting from thermal pollution can be divided into:
Rivers are also polluted during rafting, hydropower construction, and with the beginning of the navigation period, pollution by ships of the river fleet increases.
The world economy dumps 1,500 cubic meters of polluted per year. 1 km of wastewater requires varying degrees of purification, which require 50-100-fold dilution to give them natural properties and further purification in the biosphere. This does not take into account the waters of agricultural production. World river runoff (37.5-45 thousand cubic km per year) is insufficient for the necessary dilution of wastewater. Thus, as a result of industrial activity, fresh water has ceased to be a renewable resource.