Lecture notes "problems of using minerals and energy resources." Environmental issues associated with mining
Ecological foundations of environmental management
Course of lectures for students of secondary vocational education, full-time and correspondence forms training
Lecture 7 . Problems of use and reproduction of natural resources
Water is an inexhaustible natural resource on a planetary scale, since its total amount on the planet is maintained by constant moisture circulation between the ocean, atmosphere and land of the globe.
Water occupies 70.8% of the planet's total surface. The World Ocean accounts for 97% of all water resources. Most of the fresh water (70%) is contained in glaciers and snow covers. Groundwater accounts for 23% of freshwater reserves, therefore only 7% of freshwater remains available for use. The annual water withdrawal in the Russian Federation from water sources for use is 75 billion m 3 .
The main problem currently is the pollution of fresh waters by various pollutants: pesticides and pesticides, oil and petroleum products, surfactants. Increasing pollution of water bodies and drains is observed in all industrial countries.
In table 1 presents data on the content of some organic matter in industrial waters.
Content of pollutants in industrial wastewater
PollutantsWorld runoff,
million tons per year
Petroleum products
26,563
Phenols
0,460
Waste from the production of synthetic fibers
5,500
Plant organic residues
0,170
Total
33,273
The main areas of rational use of water resources are: recycling, the use of new treatment technologies, and organizational measures.
Recycling water used in industrial enterprises in various technological processes.
New water purification technologies. Currently, more advanced methods of water purification are used: physical-chemical, biotechnological. Physicochemical methods include: radiation, ion exchange, redox and other purification methods.
Organizational events are reduced to administrative-legal and economic regulation water use. Relations in the field of use and protection water bodies regulated by the Water Code of the Russian Federation, adopted on October 18, 1995 State environmental control carried out by the State Inspectorate for the Protection of Water Resources, which monitors the condition of water treatment equipment, the availability of permits for water use, and monitors the condition of water protection zones.
Problems with the use of mineral resources
Minerals are mineral formations of the earth's crust, the chemical composition and physical properties of which make it possible to effectively use them to ensure human life and in the sphere of material production. Mineral resources are divided into solid (coals, ores, non-metallic raw materials), liquid (oil, mineral waters) and gaseous (natural flammable and inert gases).
Classification of minerals. The place of minerals in the classification of natural resources is defined in Lecture 6 (Fig. 2). Let us now consider the classification of minerals.
Minerals are divided into metallic, non-metallic, combustible and water-mineral (Fig. 3
Rice. 3 . classification of minerals
Use of minerals . Russia produces about 17% of oil, 25% of gas, 15% of coal, iron ore- 14% of the total volume of these minerals mined in the world. Mineral reserves make it possible to maintain the level of production for hundreds of years, but subject to the development of technology at a greater depth (5-7 km). In general, the problem of quantitative growth of Russia's mineral resource base is only for a limited range of minerals (manganese, chromium, antimony, mercury).
The state of affairs in the field of subsoil protection and mining ecology in last years has deteriorated significantly. The main reasons for this are both the general state of the country’s economy and insufficiently thought-out reforms in the management system of the mineral resource complex. There are many prerequisites for the predatory development of the country's mineral potential.
Plants as indicators of soil composition. The chemical composition of soils determines the distribution of individual species, and sometimes entire groups of plants. You can observe the appearance of special forms of plants on soils with a high content of one or another chemical element (ugliness, special color of petals, etc.).
Some plant species, and sometimes plant communities, selectively develop in different deposits. Such species and communities serve as indicators of mineral resources. There are plants that are indicators of increased or decreased content of minerals in the soil, of salinity or increased acidity of soils.
On soils rich in minerals, scillas, duckweeds, plants of black soil steppes and lowland swamps. On soils poor in minerals, sundew, cinquefoil, and cinquefoil grow, i.e., plants of raised bogs. Plants growing in soils rich in nitrogen (nitrate) - nettle, fireweed, elderberry.
Woody plants as their requirements for minerals in the soil are grouped as follows: 1) ash, elm, beech; 2) fir, black alder, linden, hornbeam, oak, maple; 3) aspen, cedar, gray alder, common spruce; 4) Scots pine, birch.
Problems of land use
Types of land use. Any type of land use leads to its degradation. Degradation refers to the restructuring and destruction of natural ecosystems, the reduction and elimination of their ability to ensure environmental sustainability. There are two types of land use - industrial and agricultural.
Industrial use of land, starting from the extraction of minerals and ending with their processing, the creation of industrial infrastructure and settlements, is accompanied by the complete destruction of ecosystems, the soil layer, disruption of the regime of water bodies, and pollution of all environments.
Agricultural land use also leads to the destruction of natural ecosystems and the planting of monocultures over large areas.
In Russia, built-up areas occupy about 1 million km 2 , agricultural lands - 2.2 million km 2 , roads and runs - 8.2 thousand km 2 , water bodies- 710 thousand km 2 . Thus, it can be argued that at least 14% of Russia’s territory has disturbed and severely damaged ecosystems. The total area of such lands is 2.5 million km 2 . The affected areas are scattered in patches and serve as centers of disturbance to the natural ecosystems surrounding them.
Ecological role of soil and its properties . Soil is formed from rocks through prolonged exposure to plants, animals, microorganisms and climate. Unlike rock, soil has a special property - fertility.
Soil fertility - its ability to satisfy the plant’s need for substances necessary for its life. Fertility depends on chemical composition, physical properties and water regime of the soil.
The properties of the soil together create a certain ecological regime. The result of the processes occurring in the soil ecosystem ishumus - soil organic matter, the result of the interaction of living organisms and parent rock. In chernozems the humus content can reach 10%, in podzolic soils - 2-4%. The thickness of the humus layer in chernozems on the plain can reach 60-100 cm, and in forest soils - 10-30 cm. Mountain soils, called underdeveloped, have a thin humus horizon. Soil destruction usually occurs through depletion of nutrients, deterioration of structure and, as a result,erosion, i.e. physical destruction.
Types of erosion and measures to combat them. Soil erosion largely depends on agricultural practices. Depleted arable land is more easily eroded because, losing humus, it loses its ability to absorb and retain water. I distinguish between wind and water erosion (Fig. 4).
Rice. 4. Types of soil erosion
The caused intense movement of soil particles and underlying rocks along the earth's surface (blowing, fluttering, blowing, black storms, etc.) is calledwind erosion . It can occur at any time of the year and at any wind strength, but most often when strong winds-15-20 m/s, when the soil is loosened and agricultural crops have not yet developed on it.
Water erosion represents the washing away of soil by trickles and rivulets of melt or storm water.
Erosion Control Techniques soils are very diverse and depend on soil-climatic and agroeconomic conditions. The following measures have been developed to protect soils from wind and water erosion:
in areas of distributionwind erosion - soil-protective crop rotations with strip placement of crops and fallows, wings, grassing of heavily eroded lands, buffer strips of perennial grasses, etc.
in areas of distributionwater erosion - tillage of soils and sowing of agricultural crops across the slope, contour plowing, deepening of the arable layer, and other methods of treatment that reduce surface water runoff.
in mountainous areas - installation of anti-mudflow structures, terracing, afforestation and grassing of slopes, regulation of livestock grazing, conservation of mountain forests.
Wetlands. Swamps in Russia occupy 108.7 million hectares, which is 6.3% of the total area of the country's land fund.Swamp is defined as a geographical landscape with waterlogged soil, specific marsh vegetation and a marsh type of soil formation, which determines the development of restoration processes and incomplete decomposition of plant residues accumulating in the form of peat. Waterlogging is possible only under conditions of constant or prolonged waterlogging of the soil.
The formation of swamps is always accompanied by the accumulation of peat, the deposits of which are mostly 2-4 m deep (sometimes their depth reaches 10 m).Peat - this is an accumulation of incompletely decomposed remains of marsh plants, formed under conditions of excess humidity and insufficient aeration. It consists of organic matter and ash. Swamps are lowland, raised and transitional.
Lowland marshes characterized by high water content, water flow, large species diversity of vegetation, significant fluctuations in the level groundwater, ash content, high degree peat decomposition.
Raised bogs have low water content, are characterized by stagnant water, the predominance of sphagnum mosses and a limited species composition of vegetation.
Transitional swamps occupy an intermediate position. They are characterized by significant water content and low flow.
Wetlands are valuable land. After drainage, peat is extracted from them. The soils of drained swamps are very fertile. In drained lowland and partially transitional swamps, forests, potatoes, grain crops, cabbage, beets, and flax are grown, with grain yields reaching 30-40 c/ha, and potatoes reaching 300-400 c/ha.
Problems of use and reproduction of flora
The rational use of flora in Russia involves, first of all, the effective use of the lands of the Russian forest fund and increasing their productivity, as well as the use of the multifunctional properties of forest biogeocenoses in the interests of the national economy of the country as a whole, and not just some of its sectors.
Integrated development of forest resources presupposes rational and maximumuse of the main forest product - trees, not only stem wood of coniferous and deciduous species, but alsowaste recycling logging production and woodworking, stumps, bark, greenery.
Comprehensive development includesuse of non-timber products: fruits, seeds, juices, mushrooms, berries, medicinal plants, organization of haymaking, development of beekeeping, hunting and use of recreational functions of forests.
Reproduction of flora can be considered in a broad biogeocenotic or ecosystem sense, i.e., as a renewal of a community. Reproduction can be natural, artificial and combined.
Natural reproduction - the process of formation of new generations of ecosystems in a natural way. It can occur spontaneously, as a process of self-renewal - this ispassive form reproduction, or may be a regulated process directed by man- active form renewal (selective felling, measures to store undergrowth, etc.).
Artificial reproduction is expressed in the fact that seeds, plants or their parts are introduced into the soil not by nature, but by man (sowing, planting, etc.).
Combined renewal - a combination of artificial and natural reproduction in the same area.
Problems of use and reproduction of the animal world
In almost all ecosystems, animals predominate over plants in the number of species, although their biomass is many times less. In undisturbed natural ecosystems, each animal species occupies its own specific niche and performs a specific job.
The division of animals into useful and harmful is very relative: even generally recognized pests are not always dangerous for natural ecosystems.
Rational use of wild animals . Animals bring great benefits to humans. They serve as food, are used for the production of clothing, as medicinal raw materials, etc. Meat products are provided by 20 species of wild ungulates (especially elk, roe deer, reindeer, saigas, wild boars), 7 species of upland game (hazel grouse, black grouse, wood grouse , white partridge, etc.).
The skins of sables, black-brown foxes, beavers, ermines, squirrels, etc. are highly valued in the foreign and domestic markets. By the beginning of the 20th century. The stocks of fur and other animals sharply decreased. The sable, sea otter, river beaver, fur seal, muskrat, as well as polar bear, Ussuri tiger, and among ungulates - bison, sika deer, saiga, kulan, etc.
Work on domesticating animals continues. For example, elk can become a fast-growing meat, dairy and pack animal. An elk can carry 80-120 kg in a saddle, and up to 300-400 kg when harnessed to a sleigh. Work is underway and the possibilities of domesticating the eland antelope, musk ox and some other species are being studied.
Specially protected natural areas
Specially protected natural areas of Russia are the least polluted areas by world standards, and in a few years they can become the center of Russia's ecological revival.
Today there are over 2,000 nature reserves in the world, and in Russia there are 100 nature reserves, including 16 biosphere reserves with a total area of more than 34 million hectares or about 2.2% of the country's territory.
Reserve - a specially protected area in which any economic activity (including tourism) is completely prohibited in order to preserve natural complexes, protect animals and plants, as well as monitor processes occurring in nature.
With the help of nature reserves, three main tasks are solved:
security flora, fauna and natural landscapes with strictly limited or completely prohibited presence on its territory;
research and control the state of ecosystems and their constituent populations of animals and plants (reserves are scientific institutions where biologists of various profiles work);
recovery populations of rare and endangered species of plants and animals.
State natural reserves - Thistemporarily protected natural complexes designed for the conservation, reproduction and restoration of some natural resources (objects) in combination with the limited, regulated and rational use of others. More than 1,500 reserves have been created in Russia, which are divided according to their functional purpose:zoological, botanical, landscape, hydrological, geological .
National natural parks used for environmental, recreational, educational, scientific and cultural purposes.
Largest national park Europe “Valdai” is located between Moscow and St. Petersburg on an area of about 160 thousand hectares. In Russia there are 35 national natural parks with a total area of 7 million hectares.
Natural monuments and especially valuable forest areas - as a rule, samples of typical landscapes, places where rare and valuable plant species grow, usually performing the functions of micro-reserves of local importance. Currently in Russian Federation About 8,000 natural monuments are protected.
Self-test questions
Name the main methods of industrial water purification.
What types of minerals are there?
What factors determine soil fertility?
What measures can prevent water and wind soil erosion?
What flora and fauna corresponds to each type of wetland?
Name the types and main tasks of specially protected natural areas Russia.
Such indicators are beginning to be developed not only to identify excess amounts of pollutants, but also to determine the deficiency of vital (essential) substances in drinking water. chemical elements. In particular, such an indicator for selenium is available for the EEC countries.
The regulatory approach is the initial step in assessing the state of water, allowing you to quickly and inexpensively identify priority pollutants and develop practical recommendations to reduce or stop the negative consequences of water pollution.
However, it does not take into account the manifestations of synergism and antagonism during the joint effects of pollutants. This is especially true in cases where these substances are present in concentrations approaching MPC values, and such water is consumed for a long time. It has been established that the long-term effect of low doses can have more harmful influence on the population of aquatic organisms than acute but short-term toxic effects. In addition, each body of water is unique due to large differences in chemical composition, mixing speed, temperature regime, vertical zonation of the water mass and other characteristics. Significant disadvantages of the normative approach include the insufficiency of experimental observations in establishing MPC values
Strict adherence to the quality of water sources used in accordance with standard indicators is currently receiving increased attention in all developed countries. In the USA, a special law on the safety of drinking water was adopted in 1974.
Reliable assessment and forecast of the state of a water system is a very complex task due to the fact that this system is affected by numerous and time-varying natural and anthropogenic factors, and complex physicochemical and microbiological processes occur in the aquatic environment.
To understand such processes, it is necessary to take into account bottom sediments, which take an active part in the water-sediment chemical exchange. This is especially true in the case of inflow of deep fluid components into the aquatic environment. The wide distribution and high intensity of such an inflow is evidenced by the thick and extensive deposits of gas hydrates in the bottom sediments of the shelves, the accumulation of mercury and other heavy metals in the silts of lakes. A gas hydrate layer was discovered in the bottom sediments of Lake Baikal.
An important role has been established in chemical reactions, occurring in water, compounds of carbon, sulfur, nitrogen and phosphorus, redox potential, microorganisms. For example, biogenic processes (biofiltration) determine the behavior of both terrigenous and biogenic components in Lake Baikal.
In the best way obtaining empirical data on processes in the aquatic environment is hydrogeochemical mapping with subsequent justification of the monitoring network. Information obtained as a result of long-term observations serves as the basis for forecasting the state of the water system over time.
Currently, for the purposes of environmental forecasting, computer modeling of hydrogeochemical processes of pollution of surface and groundwater using high quality software. This allows you to bring huge amounts of data into the field of study and obtain qualitatively new information.
A more reliable ecological forecast can be obtained from studying model ecological systems involving living organisms in laboratory conditions.
A promising direction for assessing and forecasting the state of water systems is an approach that involves elucidating their responses to the influx of pollutants over a long period of time. Artificial gradual acidification of a small lake in the northwestern ecologically clean part of the province of Ontario (Canada) over a period of 8 years showed that difficult-to-detect irreversible changes in the chain of ecological interactions within the reservoir occurred already at the very initial stage negative impact.
This approach is considered the most direct and effective method for predicting changes in the state of an entire aquatic ecosystem in response to chemical, physical and biological influences. It is he who will make the main contribution to the creation of the scientific base necessary to regulate the behavior of ecosystems.
In recent years, in developed countries, the concept of environmental risk has become widely used to assess and forecast the state of the environment and its components. The basic principles and criteria underlying its methodology are risk identification, assessment of the impact of pollution on the population, the biosphere and the environment, dose-response assessment, risk management and determination of ways to reduce it, clarification of risk acceptability conditions, development of control methods and methods.
Assessment and forecast of the state of water systems polluted under the influence of natural or anthropogenic processes differ markedly. Control of such natural processes as modern volcanic and fluid activity of the Earth is essentially impossible. Therefore, efforts should be aimed primarily at minimizing negative consequences.
Rational water use in the Russian Federation should include the development of a strategy for water protection measures throughout the entire territory, the development and implementation of a long-term program for the protection of drinking water from pollution and depletion, taking into account regional natural and socio-economic characteristics. The Ministry of Natural Resources of the Russian Federation has developed a draft Program for rational use and protection of water resources, based on the concept of the country’s transition to sustainable development. The sustainable development of the water sector is understood as such a state of water bodies, hydraulic structures and operational measures that guarantee a reliable supply of the population and national economy of the Russian Federation with high-quality water in the required quantity and mode, stable reproduction of water resources, restoration and protection of water bodies, prevention and liquidation consequences of harmful effects of water, restoration and preservation of the sustainability of aquatic ecosystems.
The threat to the sustainable development of the water sector in the Russian Federation is determined by the action of several negative factors. Firstly, the European part of Russia, where the majority of the population lives and the main industrial and agricultural potential is concentrated, accounts for less than 8% of the total river flow. Secondly, water quality is deteriorating and the number of water bodies with high and very high levels of pollution is increasing every year. About half of the Russian population uses drinking water, not corresponding hygienic requirements according to various quality indicators, and in a number of regions (lower Volga, Southern Urals, Kuzbass) water pollution has reached a level hazardous to health. The situation is aggravated by the aging of fixed production assets and the low technological level of the water sector, the instability of the financial condition of water-using enterprises, and the imperfection of the economic mechanism.
The following are proposed as practical measures to solve problems of rational water use:
– accounting of all sources of pollution and the level of waste water treatment;
– development of methods for modeling the consequences of pollution of surface and groundwater in all areas of their use:
– economic incentives for the development and implementation of water circulation schemes with the minimum possible share of natural water intake;
– expand the practice of operating small water intakes, which allows reducing the negative impact of water intake on all elements of the hydrosphere and on the environment as a whole;
– implementation of the most effective, economical and timely preventive measures, taking into account complex processes in aquatic ecosystems.
35 Water protection products. Measures to protect water bodies from industrial pollution include:
♦ application of waterless and low-water technologies and closed loops water supply;
♦ preventing or reducing pollution of water taken from natural sources;
Water supply to water consumers can be direct-flow, sequential and recirculating. At direct-flow water supply, all taken water, with the exception of irretrievable losses (evaporation, spillage, inclusion in products), after the technological process is returned to the reservoir. At consistent In the scheme, water coming from the water supply source is reused in several processes.
The most promising way to reduce fresh water consumption and minimize the discharge of wastewater into water bodies is to implement negotiable And closed water supply systems. Negotiablewater used in heat exchangers to remove excess heat, for washing parts and products, and also as a solvent or reaction medium.
Depending on the intended purpose of the recycled water supply, schemes with cooling, with purification of recycled water and combined schemes with simultaneous purification and cooling of water are possible.
To prevent corrosion and biological fouling of pipelines and equipment, part of the recycled water is removed from the system by adding fresh water from the reservoir or purified wastewater (blowdown water). In addition, some of the water is lost in cooling units - cooling towers (evaporation from the surface, splashing). To compensate for irretrievable water losses, the system is recharged from open reservoirs and underground water supply sources. The amount of added water, as a rule, does not exceed 5-10% of the amount circulating in the system. The use of recycled water supply makes it possible to reduce the consumption of fresh water in industrial production by 10-50 times.
In a closed (drainless) system, water is used repeatedly in production processes without purification or after appropriate treatment, which excludes the formation of any waste and the discharge of wastewater into a reservoir. Closed systems are technically more complex, but they are most consistent with the principles of waste-free production. They should be introduced at reconstructed and newly built enterprises.
A closed water supply system ensures savings in fresh water in all industries, maximum recovery of wastewater and virtually eliminates environmental pollution.
Various methods of wastewater treatment (Fig. 10.8) are divided into recuperative and destructive. The first involves the extraction of valuable substances from industrial wastewater and their further processing. In destructive treatment methods, pollutants are destroyed by oxidation or reduction, followed by removal of the destroyed products from the water in the form of gases or sediments. Mechanicalcleaning serves as a preliminary stage in the treatment of industrial wastewater. Removal of suspended impurities is achieved by settling, filtering or cycloning. Settlement is carried out in settling tanks (Fig. 10.9, A), sand traps, and clarifiers of various designs. During settling, both sediment and floating impurities are separated - fats, oils, petroleum products, which are removed using oil traps. To intensify the sedimentation of suspended particles, water is subjected to centrifugal force in open or pressure hydrocyclones and centrifuges. The design of a hydrocyclone (Fig. 10.9, B) is similar to that of a cyclone for gas purification.
Filtration is used to separate finely dispersed impurities of solid or liquid substances from wastewater. Two main types of filters are common: granular and microfilters. In granular filters, water is passed through nozzles made of non-cohesive porous materials (anthracite, sand, marble chips, etc.). Microfilter filter elements are made of meshes with cells ranging in size from 40 to 70 microns and from solid porous materials. To purify wastewater from oil products, polyurethane foam, which has a high oil absorption capacity, is widely used.
Chemical cleaning used to remove soluble impurities from wastewater before discharging it into a reservoir or city sewer, sometimes before or after biological treatment, as well as in closed water supply systems. The main methods of chemical cleaning are: neutralization, oxidation and reduction. Wastewater containing acids or alkalis is subjected to neutralization in order to bring the reaction of the medium close to neutral (pH = 6.5 - 8.0). Neutralization is carried out by mixing acidic and alkaline wastewater, adding reagents, and filtering wastewater through neutralizing materials. A method is being developed to neutralize alkaline waters with flue gases containing CO2, SO2, NO2, which allows for simultaneous effective cleaning of harmful components and gas emissions themselves.
Oxidation used to neutralize wastewater from toxic impurities (cyanides, dissolved arsenic compounds, etc.), the extraction of which is impractical or impossible by other methods. Gaseous and liquefied chlorine, air oxygen, ozone and other reagents are used as oxidizing agents in wastewater treatment. Ozone, being a strong oxidizing agent, can destroy aqueous solutions organic matter and other impurities. Ozonation is used to purify wastewater from petroleum products, phenol, hydrogen sulfide, cyanide and other impurities. At the same time, the elimination of tastes, odors, discoloration and disinfection of water is ensured. The advantages of ozonation (compared to chlorination) include the possibility of producing ozone directly at treatment facilities in ozonizers, where it is formed from atmospheric oxygen under the influence of an electric discharge.
Biological treatmentWastewater plays main role in freeing water from organic and some mineral contaminants. It is similar to the natural process of self-purification of water bodies. Bioremediation is carried out by a community of organisms, which consists of various bacteria, algae, fungi, protozoa, worms, etc. The purification process is based on the ability of these organisms to use dissolved impurities for nutrition, growth and reproduction.
Under the influence of microorganisms, two processes can occur - oxidative (aerobic) and reductive (anaerobic). IN aerobicprocesses microorganisms cultivated in activated sludge or in biofilm use oxygen dissolved in water. Their life requires a constant flow of oxygen and a temperature of 20-30°C. Anaerobiccleaning proceeds without oxygen, the main process here is sludge digestion. These methods are used to remove organic matter from highly concentrated wastewater and to neutralize sediments,
Biological wastewater treatment can take place in natural conditions(in irrigation fields, filtration fields, biological ponds) and in artificial structures - aeration tanks and biofilters of various designs. Biological treatment of industrial wastewater is usually carried out. V artificial conditions, where cleaning processes proceed at a faster rate.
Aerotank It is a reinforced concrete tank divided by partitions into separate corridors, which is equipped with devices for forced aeration. The cleaning process in the aeration tank proceeds as an aerated mixture of waste water and activated sludge, consisting of living organisms and a solid substrate (dead part of algae and various solid residues), is passed through it. In a few hours, the bulk of organic matter is processed. From the aeration tank, a mixture of treated wastewater and activated sludge enters the secondary settling tank. The activated sludge that has settled to the bottom is discharged into the reservoir of the pumping station, and the purified wastewater is supplied either for further purification or disinfected. In the process of biological oxidation, the biomass of activated sludge increases. Its excess is sent to sludge treatment facilities, and the main part in the form of circulating activated sludge is returned to the aeration tank.
IN biofilters wastewater is filtered through a layer of lump loading, which is used as crushed stone, gravel, slag, expanded clay, plastic, metal mesh and other materials, on the surface of which a biological film is formed that performs the same. same functions as activated sludge. It adsorbs and processes organic substances found in wastewater. The oxidative power of biofilters increases when compressed air is supplied to them in the direction opposite to filtration.
In the process of biological wastewater treatment, a large mass of sediment is formed, which must be disposed of or neutralized and isolated. For this purpose, activated sludge compaction, dewatering, heat treatment and other operations are used. After neutralization, sediments can be used as organo-mineral fertilizers or a component of certain materials. When applying treated sludge to fields, there are quantitative restrictions due to the presence of toxic metal ions and trace amounts of toxic organic compounds in the sludge. Activated sludge recovery technologies have been developed, with the help of which protein and vitamin products, feed yeast and technical vitamins for the feed industry are produced.
Effective cleaning industrial and municipal wastewater represents one of the most pressing engineering and environmental problems. It becomes more complicated using common systems sewers for domestic and industrial wastewater, the widespread use of hydraulic flushing of human and animal excrement, mixing their waste products with solutions of washing powders, shampoos and other surfactants; Even when treating wastewater using the biological method, no more than 90% of organic substances and only 10-40% of inorganic compounds are extracted from them.
Existing processes for the biological treatment of wastewater allow the destruction of only relatively simple organic compounds; the degree of purification from inorganic and complex organic substances is much lower. This leads to the need to obtain new strains of microorganisms suitable for the treatment of special industrial wastewater: There are already many examples of the use of selected strains to improve the treatment of wastewater containing heavy metal ions, phenols, cyanides and other toxic pollutants.
Physico-chemical methods used for deep purification of wastewater, removing finely dispersed suspended particles (solid and liquid) and soluble impurities from it. Compared to other cleaning methods, they have a number of advantages and the scope of their application has been constantly expanding in recent years. This group of methods includes: coagulation, flotation, sorption, ion exchange, extraction, hyperfiltration, electrochemical purification, evaporation, desorption, deodorization, degassing and others.
Adjacent to them electrochemical methods wastewater treatment, including the processes of anodic oxidation and cathodic reduction, electrocoagulation, electroflotation and electrodialysis. All these processes occur when a direct electric current is passed through wastewater. Electrochemical treatment allows you to extract soluble and suspended impurities from wastewater without the use of chemical reagents, provides the ability to automate the treatment process, and simplifies the operation of treatment facilities. The main disadvantage of electrochemical methods is the high energy consumption.
When designing treatment facilities industrial enterprises it is necessary to select effective methods and schemes for wastewater treatment. The most rational is considered to be a combination of circulating water supply systems, local and general treatment methods. Local treatment allows you to extract from wastewater different industries the most valuable components, as well as substances that complicate general cleaning. Waters purified from characteristic of this production impurities undergo the second stage of purification in general plant treatment facilities. In the general runoff, you can use the neutralizing, coagulating and other properties of the components of local runoff.
Industrial wastewater is divided or combined into streams according to the predominant pollutants, taking into account the places of formation and the amount of wastewater. In the absence of pronounced types of pollution, all industrial wastewater is combined into one stream, installing special containers at the entrance of treatment facilities - collector homogenizers.
A promising direction for water supply and protection of water bodies from pollution is the creation of intersectoral water management systems that take into account the interrelated development of technologies for production, water use, treatment and disposal of discharged water (Kukhar et al., 1989). In the one shown in Fig. 10.10 of the scheme provides for recycling and reuse of water, local and general wastewater treatment at industrial and energy enterprises. Part of the industrial wastewater that has undergone local treatment and municipal wastewater is processed jointly at centralized (regional, city) treatment facilities. Intersectoral water management systems make it possible to use treated domestic and industrial wastewater for irrigated agriculture, and the heat of waste water from electricity generation for the intensification of agricultural production (for example, heating greenhouses) and fisheries. At the same time, environmental problems are also solved, as water resources are saved and wastewater discharge into water bodies is reduced.
37. Subsoil. The concept of subsoil. Classification of minerals. Features of the extraction and use of minerals in the subsoil and the World Ocean. Dangerous trends in the increasing use of mineral and hydrocarbon resources.
Under subsoil understand top part the earth's crust within which mineral extraction takes place.
Minerals- rock, directly used in national economy, as well as natural mineral formations from which minerals valuable for various industries can be extracted.
For the main types of products of mining enterprises, natural resources are minerals, which are divided into flammable, metallic and non-metallic.
Classification of minerals:
fuel and energy - oil, gas, coal, oil shale, peat, uranium ores, etc.;
ore resources - iron and manganese ore, bauxite, chromite, copper, lead-zinc, nickel, tungsten, molybdenum, tin, antimony ores, precious metal ores, etc.;
Complex mineral raw materials are solid mineral fuels - coal, oil shale. It distinguishes between the combustible part (88-60%) and the ballast (12-40%). The combustible part contains carbon, hydrogen, as well as impurities of oxygen and nitrogen, and sulfur. The organic combustible part in many cases contains pyrite (marcasite). Ballast consists of a mixture of minerals: silicon oxide, alumina, carbonates (lime), as well as sulfates, iron, nickel, chromium, mercury and rare metals.
Many of these components of the ballast part easily sublimate when burned and enter the atmosphere along with flue gases. When burning such fuel at large thermal power plants, as well as in the production of coke, much attention is paid to the preliminary extraction of these compounds during the enrichment process, for example, sulfur pyrites. Thus, more than 2 million tons of coal containing up to 10% admixture of sulfur pyrite (pyrite) are sent annually from the Kimovsky open-pit mine and the Mosbassa coal mines (Tula region) for enrichment.
At a coal processing plant, coal from an open pit or mine undergoes special enrichment, which makes it possible to obtain solid fuel - commercial coal concentrate that does not contain harmful sulfur impurities (sulfur pyrites), clay for the production of bricks at a local brick factory. Pyrite concentrate is a valuable raw material for the production of sulfuric acid.
The use of subsoil for the development of mineral deposits requires the use of the most rational and effective methods for extracting from the subsoil the main and co-occurring mineral resources. Along with the expansion of the use of open-pit mining of coal, ferrous and non-ferrous metal ores, and agrochemical raw materials, much attention is paid to improving underground mining systems. As a result, the extraction of reserves has significantly increased, which has made it possible to significantly increase the production of mineral raw materials while saving labor and capital costs. For example, end-to-end iron extraction from 1960 to 1980. increased from 68.2% to 73.7%, and apatites - from 84 to 87.8%, potassium salts - from 26.8 to 32.7%. End-to-end coal recovery increased over this period from 69.7 to 81.4 percent. Since the 60s of the 20th century, iron ore enrichment capacities have also been developing: the production of concentrate with an iron content of more than 65% increased 63.5 times in the period from 1965 to 1975 alone, and the production of iron ore pellets - a new type of iron ore product - increased over the same period 40 times. Tens of millions of tons of coal are lost in waste rocks that form in open-pit mines and mines.
Coal in dump rocks can serve as a reliable base for meeting local fuel needs. In our country at the Korkinsky section ( Chelyabinsk region) a hydraulic steeply inclined separator has been operating for more than 30 years, making it possible to extract more than 250 thousand tons of coal from the dump coal rocks of the open pit annually. Currently, such installations operate in the Moscow region and others. The use of installations in open-pit coal mines and coal mines can significantly reduce the cost of mined coal and increase the degree of coal extraction from the subsoil during mining. During the development of deposits in the 90s of the XX century. the degree of ore extraction from the subsoil has increased. Using the open-pit method of mining non-ferrous metals, about 70% of minerals are extracted. In underground mines and mines, goaf filling systems are widely used. The use of stowing complexes makes it possible to immediately reduce ore losses in the subsoil, improve the quality of extracted raw materials, and reduce labor costs several times. As a result, the annual irretrievable loss of non-ferrous and rare metal ore in the ground decreased by 1.5 million tons. Significant reserves exist for improving the quality and productivity of work due to the use of progressive mining methods - heap and underground leaching, which make it possible to mine reserves of poor, off-balance ores, and tailings.
The noted directions for improving the development of mineral deposits require the creation of specialized high-performance machine complexes, the widespread introduction of automation and telemechanization, and the solution of complex problems of improvement technological processes production on an integrated basis.
Subsoil protection
Soil protection measures must be carried out as a whole. Complexity is determined by the reclamation effective and economically feasible combination of four groups of soil protection measures: organizational and economic, agrotechnical, forest reclamation and hydraulic engineering. Organizational and economic measures include the establishment of the correct combination and interconnected placement on the ground necessary for the organization of the territory (borders, fields, roads, etc.) and other groups of soil protection measures, taking into account the natural and economic conditions of the economy.
Agrotechnical soil protection measures are carried out in all zones and under any natural and economic conditions and are divided into the following subgroups.
Mineral resources- minerals that form naturally in the earth's crust. They can be of organic and inorganic origin.
More than two thousand minerals have been identified, and most of them contain inorganic compounds formed by various combinations of eight elements (O, Si, Al, Fe, Ca, Na, K, and Mg), which make up 98.5% of the Earth's crust. The world's industries depend on about 80 known minerals.
A mineral deposit is an accumulation of solid, liquid or gaseous minerals in or above the earth's crust. Mineral resources are non-renewable and exhaustible natural resources and may also have metallic (eg iron, copper and aluminum) as well as non-metallic properties (eg salt, gypsum, clay, sand, phosphates).
Minerals are valuable. This is an extremely important raw material for many basic sectors of the economy, which is the main resource for development. Mineral resource management must be closely integrated with overall strategy development, and the exploitation of mineral resources should be guided by long-term goals and prospects.
Minerals provide society with all the necessary materials, as well as roads, cars, computers, fertilizers, etc. Demand for minerals is increasing around the world as populations grow and the extraction of the Earth's mineral resources accelerates with environmental consequences.
Classification of mineral resources
| Energy (fuel) mineral resources (coal, oil and natural gas) |
Non-energy mineral resources | |
| Metallic properties | Non-metallic properties | |
| Precious metals (gold, silver and platinum) | Building materials and stones (sandstone, limestone, marble) | |
| Ferrous metals (iron ore, manganese) | Other non-metallic mineral resources (salt, sulfur, potash, asbestos) | |
| Non-ferrous metals (nickel, copper, tin, aluminum, lead, chrome) | ||
| Feroalloys (alloys of iron with chromium, silicon, manganese, titanium, etc.) | ||
World Mineral Resources Map
The role of mineral resources
Mineral resources play important role in the economic development of countries around the world. There are regions rich in minerals, but unable to extract them. Other resource-producing regions have the opportunity to grow economically and gain a number of benefits. The significance of mineral resources can be explained as follows:
1. Industrial development
If mineral resources can be extracted and used, the industry that uses them will develop or expand. Gasoline, diesel fuel, iron, coal, etc. necessary for industry.
2. Employment
The presence of mineral resources creates jobs for the population. They enable skilled and unskilled personnel to have employment opportunities.
3. Development of agriculture
Some mineral resources serve as the basis for the production of modern agricultural equipment, machinery, fertilizers, etc. They can be used for modernization and commercialization of agriculture, which help develop the agricultural sector of the economy.
4. Energy source
There are various energy sources such as gasoline, diesel, natural gas, etc. They can provide the necessary energy to industry and populated areas.
5. Developing your own independence
The development of the mineral resources industry allows creating more jobs with high quality products, as well as the independence of individual regions and even countries.
6. And much more
Mineral resources are a source of foreign currency, making it possible to earn money from the development of transport and communications, increase exports, supplies of building materials, etc.
Mineral Resources of the Oceans
Oceans cover 70% of the planet's surface and are involved in a huge number of different geological processes responsible for the formation and concentration of mineral resources, and are also a repository for many of them. Consequently, the oceans contain a huge amount of resources, which are the basic needs of mankind today. Resources are now extracted from the sea or areas that used to be within it.
Chemical analyzes have shown that seawater contains about 3.5% dissolved solids and more than sixty identified chemical elements. The extraction of dissolved elements, as well as the extraction of solid minerals, is almost always economically expensive, since it takes into account geographical location object (transportation), technological limitations (depth of ocean basins) and the process of obtaining the necessary elements.
Today, the main mineral resources obtained from the oceans are:
- Salt;
- Potassium;
- Magnesium;
- Sand and gravel;
- Limestone and gypsum;
- Ferromanganese nodules;
- Phosphorite;
- Metallic sediments associated with volcanism and vents on the ocean floor;
- Gold, tin, titanium and diamond;
- Fresh water.
Extraction of many mineral resources from the depths of the oceans is prohibitively expensive. However, population growth and the depletion of readily available land-based resources will undoubtedly lead to increased exploitation of ancient deposits and increased extraction directly from the waters of the oceans and ocean basins.
Extraction of mineral resources
The purpose of mining mineral resources is to obtain minerals. Modern mining processes include mineral prospecting, profit potential analysis, method selection, direct extraction and processing of resources, and final land reclamation upon completion of the operation.
Mining generally creates a negative impact on the environment, both during mining operations and after they are completed. Consequently, most countries around the world have adopted regulations aimed at reducing exposure. Occupational safety has long been a priority, and modern methods have significantly reduced the number of accidents.
Features of mineral resources
The first and most basic characteristic of all minerals is that they occur naturally. Minerals are not produced by human activity. However, some minerals, such as diamonds, can be manufactured by humans (these are called synthesized diamonds). However, these man-made diamonds are classified as minerals because they meet their five basic characteristics.
Besides being formed through natural processes, mineral solids are stable at room temperature. This means that all solid minerals that occur on the surface of the Earth do not change in shape under normal temperature and pressure. This characteristic excludes liquid water, but includes its solid form - ice - as a mineral.
Minerals are also represented by chemical composition or atomic structure. The atoms contained in minerals are arranged in a certain order.
All minerals have a fixed or variable chemical composition. Most minerals are composed of compounds or various combinations of oxygen, aluminum, silicon, sodium, potassium, iron, chlorine and magnesium.
The formation of minerals is a continuous process, but a very long one (the level of resource consumption exceeds the rate of formation) and requires the presence of many factors. Therefore, mineral resources are classified as non-renewable and exhaustible.
The distribution of mineral resources is uneven throughout the world. This is explained by geological processes and the history of the formation of the earth's crust.
Problems of using mineral resources
Mining industry
1. Dust generated during the mining process is harmful to health and causes lung diseases.
2. Mining of certain toxic or radioactive minerals poses a threat to human life.
3. Exploding dynamite during mining is very risky as the gases released are extremely poisonous.
4. Underground mining is more dangerous than surface mining because there is a high probability of accidents due to landslides, flooding, insufficient ventilation, etc.
Rapid mineral depletion
Increasing demand for mineral resources forces everyone to extract large quantity mineral. As a result, energy demand increases and more waste is generated.
Destruction of soil and vegetation
Soil is the most valuable thing. Mining operations contribute to the complete destruction of soil and vegetation. In addition, after extraction (obtaining minerals), all waste is dumped on the ground, which also entails degradation.
Ecological problems
The use of mineral resources has led to many environmental problems, including:
1. Transformation of productive lands into mountainous and industrial areas.
2. Mining of minerals and the extraction process are among the main sources of air, water and soil pollution.
3. Extraction involves huge consumption energy resources, such as coal, oil, natural gas, etc., which in turn are non-renewable energy sources.
Rational use of mineral resources
It is no secret that the reserves of mineral resources on Earth are rapidly declining, so it is necessary to rationally use the existing gifts of nature. People can save mineral resources by using renewable resources. For example, by using hydroelectricity and solar energy as an energy source, minerals such as coal can be conserved. Mineral resources can also be conserved through recycling. A good example is scrap metal recycling. In addition, the use of new technological mining methods and training of miners saves mineral resources and saves people's lives.
Unlike other natural resources, mineral resources are non-renewable and they are not evenly distributed across the planet. They take thousands of years to form. One important way to conserve some minerals is to replace scarce resources with abundant ones. Minerals that require large amounts of energy to produce must be processed.
The extraction of mineral resources has an adverse impact on the environment, including destroying the habitats of many living organisms and polluting the soil, air and water. These negative consequences can be minimized by preserving the mineral resource base. Minerals have an increasing impact on international relationships. In those countries where mineral resources were discovered, their economies improved significantly. For example, oil-producing countries in Africa (UAE, Nigeria, etc.) are considered rich because of the profits made from oil and its products.
If you find an error, please highlight a piece of text and click Ctrl+Enter.
Problems with the use of mineral resources
Minerals are mineral formations of the earth's crust, the chemical composition and physical properties of which allow them to be effectively used to ensure human life and in the sphere of material production. Mineral resources are divided into solid (coals, ores, non-metallic raw materials), liquid (oil, mineral waters) and gaseous (natural combustible and inert gases).
Classification of minerals. Minerals are divided into metallic, non-metallic, fuel and water minerals. They can be grouped into the following types of resources:
Ore resources – iron and manganese ore, bauxite, chromite, copper, lead-zinc, nickel, tungsten, molybdenum, tin, antimony ores, precious metal ores, etc.
Natural Construction Materials– limestone, dolomite, clay, sand, marble, granite.
Non-metallic minerals - jasper, agate, rock crystal, garnet, corundum, diamonds, etc.
Mining chemical raw materials - apatite, phosphorite, table and potassium salts, sulfur, barite, bromine- and iodine-containing solutions, etc.
Fuel and energy - oil, gas, coal, oil shale, peat, uranium ores, etc.
Hydromineral resources – underground fresh and mineralized waters.
Mineral resources of the ocean are ore-bearing veins, continental shelf strata and ferromanganese inclusions at depths of 3-6 km (about 78% of mineral resources are located under the waters of the World Ocean).
Mineral resources of sea water are iron, lead, uranium, gold, sodium, chlorine, bromine, magnesium, table salt, manganese.
Use of minerals. Russia produces about 17% of oil, 25% of gas, 15% of coal, and 14% of commercial iron ore of the total volume of these minerals mined in the world. Mineral reserves make it possible to maintain the level of production for hundreds of years, but subject to the development of technology at a greater depth (5-7 km). In general, the problem of quantitative growth of Russia's mineral resource base is only for a limited range of minerals (manganese, chromium, antimony, mercury).
For many years, losses in the subsoil during underground coal mining have remained at a high level (23.5%), incl. coking (20.9%), chrome ore (27.7%), potassium salts (62.5%).
Petroleum gas is used unsatisfactorily in the production of oil, many billions of cubic meters of which are flared in Russia.
An acute problem What remains is the development of areas where mineral deposits occur, which entails additional losses in the subsoil and subsequently high production costs.
The mining complex has now become one of the largest sources of disturbance and pollution of the environment. natural environment. The pollutants released by the mining industry are so varied in composition and in such large quantities that in some areas they cause unpredictable consequences that have a detrimental effect on the health of ecosystems.
The increase in proven mineral reserves does not cover their production. At the same time, exports of raw materials are continuously increasing.
Russia's resource saturation, which is measured by the amount of resources consumed per capita, is 1.5-3 times lower than in industrialized countries. Soon Russia may turn from an exporter of mineral raw materials into an importer.
Plants as indicators of minerals. The chemical composition of soils determines the distribution of individual species, and sometimes entire groups of plants. You can observe the appearance of special forms of plants on soils with a high content of one or another chemical element (ugliness, special color of petals, etc.).
Some plant species, and sometimes plant communities, develop ingeniously in different deposits. Such species and communities serve as indicators of mineral resources. There are indicator plants for high levels of minerals in the soil, for salinity or high acidity of soils. In nature, migration of chemical elements occurs with the participation of living organisms. Based on this, a biogeochemical method for searching for minerals was developed.
On soils rich in minerals, blueberries, gooseberry, plants of black earth steppes and lowland swamps grow. On soils poor in minerals, sundew, cinquefoil, cinquefoil, etc. grow. bog plants. Plants growing in soils rich in nitrogen (nitrate) - nettle, fireweed, elderberry.
Most plants grow in neutral or slightly alkaline soils, but there are also those that grow in highly acidic or highly alkaline soils. Neutral soil plants: red clover, timothy, meadow fescue and broadleaf forest plants. Plants of acidic soils: pike, heather, lingonberry, blueberry, sorrel, whiteberry. Plants of alkaline soils: scilla, larch, ash.
Woody plants are grouped as follows as their requirements for mineral substances in the soil decrease: ash, elm, beech; fir, black alder, linden, hornbeam, oak, maple, aspen, cedar, gray alder, common spruce, Scots pine, birch.
Problems of using mineral resources - concept and types. Classification and features of the category "Problems of the use of mineral resources" 2017, 2018.
During the extraction and processing of minerals, there is a large-scale human impact on the natural environment. The resulting environmental problems associated with mining require comprehensive study and immediate solutions.
What is the characteristics of the mining industry?
The mining industry is widely developed in the Russian Federation, as deposits of the main types of minerals are located on the territory of the country. These accumulations of mineral and organic formations located in the bowels of the earth are effectively used, ensuring human life and production.
All minerals can be divided into three groups:
- hard, subdivided into: coal, ores, non-metallic materials, etc.;
- liquid, the main representatives of this category are: fresh, mineral water and oil;
- gaseous, which includes natural gas.
Depending on the purpose, the following types of minerals are extracted:
- ore materials(iron, manganese, copper, nickel ores, bauxite, chromite and precious metals);
- building materials(limestone, dolomite, clay, sand, marble, granite);
- non-metallic resources(jasper, agate, garnet, corundum, diamonds, rock crystal);
- mining chemical raw materials(apatites, phosphorites, table and potassium salt, sulfur, barite, bromine- and iodine-containing solutions;
- fuel and energy materials(oil, gas, coal, peat, oil shale, uranium ores);
- hydromineral raw materials(underground fresh and mineralized waters);
- ocean mineral formations(ore-bearing veins, continental shelf strata and ferromanganese inclusions);
- mineral resources of sea water.
The Russian mining industry accounts for a quarter of the world's gas production, 17% of the world's oil, 15% of coal, 14% of iron ore.
Mining industry enterprises have become the largest sources of environmental pollution. Substances released by the mining complex have a detrimental effect on the ecosystem. The problems of the negative impact of the mining and processing industries are very acute, as they affect all spheres of life.
How does the industry affect the earth's surface, air, water, flora and fauna?
The scale of development of the mining industry is amazing: when recalculating the volume of raw materials produced per inhabitant of the planet, the result is approximately 20 tons of resources. But only a tenth of this amount comes from final products, and the rest is waste. The development of the mining complex inevitably leads to negative consequences, the main of which are:
- depletion of raw materials;
- environmental pollution;
- disruption of natural processes.
All this leads to serious environmental problems. You can look at individual examples to see how different types of mining industries affect the environment.
At mercury deposits, the landscape is disrupted and dumps are formed. In this case, the dispersion of mercury occurs, which is toxic substance, which has a detrimental effect on all living things. A similar problem arises in the development of antimony deposits. As a result of the work, accumulations of heavy metals remain, polluting the atmosphere.
When mining gold, technologies are used to separate the precious metal from mineral impurities, which are accompanied by the release of toxic components into the atmosphere. The presence of radioactive radiation is observed on the dumps of uranium ore deposits.
Why is coal mining dangerous?
- deformation of the surface and coal-containing layers;
- pollution of air, water and soil in the area where the quarry is located;
- release of gas and dust when waste rocks are carried to the surface;
- shallowing and disappearance of rivers;
- flooding of abandoned quarries;
- formation of depression funnels;
- dehydration, salinization of the soil layer.
In the area located near the mine, anthropogenic forms (ravines, quarries, waste heaps, dumps) are created from raw material waste, which can extend for tens of kilometers. Neither trees nor other plants can grow on them. And the water flowing from the dumps toxic substances harms all living things in large surrounding areas.
At rock salt deposits, halite waste is formed, which is transported by sediments into reservoirs that serve to supply residents of nearby settlements with drinking water. Near magnesite mining, a change in the acid-base balance of the soil occurs, leading to the death of vegetation. Changes in the chemical composition of the soil lead to mutations in plants - changes in color, ugliness, etc.
Agricultural land is also polluted. When transporting minerals, dust can fly over long distances and settle on the ground.
Over time, the earth's crust is depleted, reserves of raw materials decrease, and the content of minerals decreases. As a result, production volumes and the amount of waste increase. One way out of this situation is to create artificial analogues of natural materials.
Lithosphere protection
One of the methods to protect earth's surface from the destructive effects of mining enterprises is land reclamation. The environmental problem can be partially solved by filling the resulting excavations with mining waste.
Since many rocks contain more than one type of minerals, it is necessary to optimize technologies by extracting and processing all components present in the ore. This approach will not only have a positive impact on the environment, but will also bring significant economic benefits.
How to save the environment?
At the present stage of development of industrial technologies, it is necessary to take measures to protect the environment. The priority is to create low-waste or waste-free production, which can significantly reduce the harmful impact on the environment.
Activities to help solve the problem
When solving the problem of environmental protection, it is important to use complex measures: production, economic, scientific, technical, and social.
You can improve the environmental situation by:
- more complete extraction of minerals from the subsoil;
- industrial use of associated petroleum gas;
- integrated use of all rock components;
- measures for water purification during underground mining;
- use of mine wastewater for technical purposes;
- use of waste in other industries.
During the extraction and processing of mineral resources, it is necessary to use modern technologies to reduce emissions of harmful substances. Despite the cost of using advanced developments, the investment is justified by the improvement in the environmental situation.
