Oil pollution of the environment. environmental pollution by oil spills
According to estimates, 6-15 million tons of oil and oil products enter the World Ocean annually. Here, first of all, it is necessary to note the losses associated with its transportation by tankers. After unloading the oil, in order to give the tanker the necessary stability, its tanks are filled with ballast water; Few tankers have dedicated ballast water tanks that are never filled with oil.
Significant quantities of oil enter the sea after washing tanks and oil vessels. It is estimated that about 1% of oil and oil products from all transported cargo gets into the sea. For example, an oil tanker with a displacement of about 30,000 tons dumps about 300 tons of fuel oil into the sea on each voyage. When transporting 500 million tons of oil per year, the loss of fuel oil is about 5 million tons per year, or 13,700 tons per day!
A huge amount of oil products enters the oceans at them use. Only diesel engines of ships throw into the sea up to 2 million tons of heavy oil products (lubricating oils, unburned fuel).
Great losses offshore drilling, collection of oil in local reservoirs and pumping through main oil pipelines. Here, up to 0.25% of the total amount of oil produced is lost.
With the growth of offshore oil production, the number of its transportation by tankers increases sharply, and, consequently, the number of accidents also increases. In recent years, the number of large tankers carrying oil has increased. The share of supertankers accounts for more than half of the total volume of oil transported. Such a giant, even after turning on emergency braking, travels more than 1 mile (1852 m) to a complete stop. Naturally, the risk of catastrophic collisions for such tankers increases several times.
Removal of oil and oil products into the sea with river waters. In this way, up to 28% of the total amount of incoming oil enters the seas.
Influx of oil products with atmospheric precipitation. Light fractions of oil evaporate from the sea surface and enter the atmosphere. Thus, about 10% of oil and oil products from the total amount enter the World Ocean.
Discharge of raw water from factories and oil depots located on the sea coasts and in ports. In the United States, more than 500,000 tons of oil a year enter the World Ocean this way.
Covered with oil films.
Oil slicks cover: vast areas of the Atlantic and Pacific oceans; the South China and Yellow Seas, the Panama Canal zone, a vast zone along the coast of North America (up to 500-600 km wide), the water area between the Hawaiian Islands and San Francisco in the North Pacific Ocean and many other areas are completely covered. Such oil films are especially harmful in semi-enclosed, inland and northern seas, where they are brought by current systems. Thus, the Gulf Stream and the North Atlantic Current carry hydrocarbons from the shores of North America and Europe to the areas of the Norwegian and Barents Seas. Especially dangerous is the ingress of oil into the seas of the Arctic Ocean and Antarctica, since low air temperatures slow down the processes of chemical and biological oxidation of oil even in summer. Thus, oil pollution is global.
Usually, the loss of oil and oil products during extraction and processing is 1-2%, for Russia it is about 5 million tons per year. According to more pessimistic estimates, 1.5% of the total fuel seeps into the soil during oil refining alone. In the soil around many oil refineries over the decades of their work, a huge amount of oil and oil products has accumulated - sometimes hundreds of thousands of tons. No wonder there are entire lakes of gasoline underneath most factories, warehouses, factories, fleets, and airports. For example, the soil near Grozny in Chechnya has turned into one of the largest oil "fields" created by man: experts say that its reserves reach a million tons. The land near Moscow, according to some estimates, annually absorbs 37 thousand tons of oil products.
The annual global costs of cleaning and restoring soil from hydrocarbon pollution amount to tens of billions of dollars.
Sources of oil pollution
Of course, the main sources of environmental pollution with oil products are enterprises and equipment of the oil and gas producing and oil refining industries. In areas of oil production, all components of the biosphere experience intense impact, leading to imbalance in ecosystems.
First of all, environmental pollution by oil and oil products has caused serious concern due to accidents at offshore drilling wells and tanker wrecks. When a film of oil spreads over the water surface, it forms a layer of hydrocarbons of various thicknesses covering large surfaces. So 15 tons of fuel oil spreads within 6-7 days, covering the surface of about 20 square meters. km. Soil pollution with oil and products of its processing, as a rule, has a local character, causing no less devastating consequences.
However, pollution caused by accidents is only a small fraction of the total pollution. Thus, according to the National Academy of Sciences in Washington, disasters and accidents during the extraction and transportation of oil and petroleum products are less than 6%, while losses during transportation account for 34.9% of the total amount of hydrocarbon pollution, and 31.1 % of oil products, and only 0.8% into the atmosphere.
Car exhaust gases contain more than 200 compounds, 170 of which pose a danger to biota, primarily heavy metals that accumulate in the soil along the roadway, and, above all, lead. The upper organogenic horizons of the soil cover are especially strongly fixed by heavy metals. Therefore, the object of monitoring is forest litter and the top five-centimeter layer of soil at a distance of 5-10 m and 20-25 m from the edge of the carriageway.
Cars are not the only mobile oil pollutants. As a rule, non-electrified railways have a high oil content in the area of the railway track, and the constant supply of oil products to the railway track makes biological cleaning of the territory practically impractical.
Ways to eliminate oil pollution
With the increase in the scale of production, transportation, storage and processing of oil, the problem of combating accidental leaks and emissions of oil and oil products is becoming an acute global problem, in which environmental and economic issues are decisive and paramount. Methods and means of protection against emergency spreading have not yet been sufficiently developed. In accordance with the new national and international laws “on environmental protection, significant efforts are being made to practically resolve this problem.
Until now, the cleaning of soil and oil sludge is not carried out efficiently enough and by and large remains a practically unsolved problem, and this despite the fact that the development and improvement of treatment and recovery equipment are carried out by almost all leading companies in the field of chemical equipment.
At one time, the world's first separator stations for cleaning oil sludge were built at the Yaroslavl and Volgograd refineries. Due to the unsuccessful experience of using separators for cleaning oil sludge, they were not continued, and after 25 years our technology returned to Russia through Western companies. In 1971, a plant for burning oil sludge, bottom sediments of sludge tanks and flotation foam was built at the Ufa refinery, but due to inefficiency, its use continued until 1980. Around the same time, the Swedish company Alfa-Laval created an oil sludge treatment plant. Alas, operating experience has shown that only fresh, newly formed oil sludge can be cleaned at such a plant; it is absolutely not intended for cleaning bottom sediments of sludge reservoirs. In 1990, the oil sludge treatment plant of the German company KHD was installed at the Permnefteorgsintez Production Association (the plant of the Flottweg company can also be considered its analogue). In the early 1990s, methods for the destruction of spilled oil by biostrains became widely known. Currently, specially created biostrains are used: putedoil, devoroil, etc. The American company Bogart Environmental Services developed its own method for cleaning soil from oil products. For several years, she has been working quite successfully in Kuwait, cleaning up sandy soil from emergency oil spills.
The environmental consequences of oil spills are difficult to take into account, since oil pollution disrupts many natural processes and relationships, significantly changes the living conditions of all types of living organisms and accumulates in biomass.
Oil is a product of a long decay and very quickly covers the surface of the waters with a dense layer of oil film, which prevents the access of air and light.
The US Environmental Protection Agency describes the effect of an oil spill as follows. 10 minutes after one ton of oil has been in the water, an oil slick is formed, the thickness of which is 10 mm. Over time, the film thickness decreases (to less than 1 mm) while the spot expands. One ton of oil can cover an area of up to 12 square kilometers. Further changes occur under the influence of wind, waves and weather. The slick usually drifts at the behest of the wind, gradually breaking up into smaller slicks that can move far away from the spill site. Strong winds and storms speed up the film dispersion process.
The International Petroleum Industry Environmental Conservation Association points out that during catastrophes there is no simultaneous mass death of fish, reptiles, animals and plants. However, in the medium and long term, the impact of oil spills is extremely negative. A spill hits the organisms most severely living in the coastal zone, especially those living on the bottom or on the surface.
Birds that spend most of their lives on the water are the most vulnerable to oil spills on the surface of water bodies. External oil pollution destroys plumage, tangles feathers, and causes eye irritation. Death is the result of exposure to cold water. Medium to large oil spills typically kill 5,000 birds. Bird eggs are very sensitive to oil. A small amount of some types of oil may be sufficient to kill during the incubation period.
If the accident occurred near a city or other settlement, then the toxic effect is enhanced, because oil / oil products form dangerous "cocktails" with other pollutants of human origin.
According to the International Bird Rescue Research Center, whose specialists are involved in rescuing birds affected by oil spills, people are gradually learning how to save birds. So, in 1971, the experts of this organization managed to save only 16% of the birds that became victims of the oil spill in the San Francisco Bay - in 2005 this figure approached 78% (that year the Center nursed birds on the Pribylov Islands, in Louisiana, South Carolina and in South Africa). According to the Center, in order to wash one bird, it takes two people, 45 minutes of time and 1.1 thousand liters of clean water. After that, the washed bird needs from several hours to several days of heating and adaptation. In addition, she should be fed and protected from stress caused by the shock of being covered in oil, close contact with people, etc.
Oil spills lead to the death of marine mammals. Sea otters, polar bears, seals, and newborn fur seals (which are distinguished by their fur) are the most commonly killed. Oil-contaminated fur begins to tangle and lose its ability to retain heat and water. Oil, affecting the fat layer of seals and cetaceans, increases heat consumption. In addition, oil can irritate the skin, eyes and interfere with normal swimming ability.
Oil that has entered the body can cause gastrointestinal bleeding, kidney failure, liver intoxication, and blood pressure disorders. Vapors from oil fumes lead to respiratory problems in mammals that are near or in close proximity to large oil spills.
Fish are exposed to oil spills in water by ingesting contaminated food and water, and by contact with oil during the movement of eggs. The death of fish, except for juveniles, usually occurs during serious oil spills. However, crude oil and oil products are characterized by a variety of toxic effects on different fish species. A concentration of 0.5 ppm or less of oil in water can kill trout. Oil has an almost lethal effect on the heart, changes breathing, enlarges the liver, slows down growth, destroys fins, leads to various biological and cellular changes, affects behavior.
Fish larvae and juveniles are most sensitive to the effects of oil, spills of which can kill fish eggs and larvae that are on the surface of the water, and juveniles in shallow waters.
The impact of oil spills on invertebrate organisms can last from a week to 10 years. It depends on the type of oil; the circumstances under which the spill occurred and its effect on organisms. Invertebrates most often perish in the coastal zone, in sediments or in the water column. Colonies of invertebrates (zooplankton) in large volumes of water return to their previous (pre-spill) state faster than those in small volumes of water.
Plants of water bodies die completely if the concentration of polyaromatic hydrocarbons (formed during the combustion of petroleum products) reaches 1%.
Oil and oil products violate the ecological state of soil covers and generally deform the structure of biocenoses. Soil bacteria, as well as invertebrate soil microorganisms and animals, are not able to qualitatively perform their most important functions as a result of intoxication with light fractions of oil.
Not only flora and fauna suffer from such accidents. Serious losses are borne by local fishermen, hotels and restaurants. In addition, other sectors of the economy also face problems, especially those enterprises whose activities require large amounts of water. In the event that an oil spill occurs in a fresh water body, the local population also experiences negative consequences (for example, it is much more difficult for utilities to purify water entering the water supply networks) and agriculture.
The long-term effect of such incidents is not exactly known: one group of scientists is of the opinion that oil spills have a negative impact over many years and even decades, the other - that the short-term consequences are extremely serious, but the affected ecosystems are restored in a fairly short time.
The damage from large-scale oil spills is difficult to calculate. It depends on many factors, such as the type of oil spilled, the condition of the affected ecosystem, the weather, ocean and sea currents, the time of year, the state of local fisheries and tourism, etc.
The material was prepared on the basis of information from open sources
The problem of protecting the environment becomes especially acute in connection with the pollution of water bodies and soils with oil and oil products. These impacts are most noticeable during oil production, its processing, transportation, due to technological and accidental releases of products into the environment.
It is known that 1 liter of oil pollutes up to 1000 m 3 of water, which is due to the presence of natural surfactants in it, which form stable oil-water emulsions (Gandurina LV, 1987).
It should be noted that at all stages of production and transportation, more than 45 million tons of oil are lost annually (on land - 22 million tons, at sea - 7 million tons, 16 million tons enter the atmosphere in the form of products of incomplete combustion of fuel). The total amount of oil hydrocarbons entering the marine environment is 2-8 million tons per year, of which 2.1 million tons are losses during transportation by ships and tankers, 1.9 million tons are carried out by rivers, the rest comes with municipal and industrial waste coastal areas, urbanized areas and from other sources (Shaporenko S.I., 1997).
By the middle of 2004, the world tanker fleet had grown to 3.5 thousand vessels with a deadweight of 10 thousand tons and more. Its total carrying capacity is about 310 million tons. Moreover, more than 70% of ships with a total deadweight of 270 million tons are intended for the transportation of oil and oil products. For one reason or another, the tanker fleet is in distress, causing environmental pollution.
Thus, the accident of the tanker "Prestige" in November 2002 led to the pollution of 3000 km of the coast of Spain, France, Great Britain. As a result, 300 thousand birds died, fishing and mariculture suffered huge losses, 64 thousand tons of fuel oil entered the sea (from the Report of the World Wildlife Fund). In the accident of the Exxon Valdez tanker in Alaska in 1989, more than 70,000 tons of oil were spilled, polluting 1,200 kilometers of the coast. During the November storms of 2007, several ships were wrecked in the area of the Kerch Strait, as a result, about 100 tons of oil products spilled into the sea - in a small area.
In 2010, a global catastrophe occurred in the Gulf of Mexico. After a 36-hour fire, the oil platform sank, after which up to 1,000 tons of oil per day began to flow into the ocean. A huge 78 km by 128 km oil slick developed in the Gulf of Mexico and eventually reached the coasts of Louisiana, Florida, and Alabama (Figure 1-4). It was possible to reduce the leakage only after five months.
Oil and oil products in aquatic ecosystems have a detrimental effect on all links in the ecological chain, from microscopic algae to mammals.
The ongoing pollution of the seas and fresh water bodies with oil and oil products sets the task for researchers to find ways to restore the natural indicators of water.
Currently, there are a large number of methods and methods for treating polluted waters, which can be divided into the following.
mechanical cleaning is based on straining, filtering, settling and inertial separation of various impurities and waste. This method of wastewater treatment allows you to separate insoluble impurities and suspended particles in the water. Mechanical cleaning methods are the cheapest, but their use is not always effective.
In the process chemical cleaning drains a large amount of sediment can accumulate, which must be filtered out and disposed of in other ways. One of the most effective (but expensive) methods of water purification is the use of coagulation, sorption, extraction, electrolysis, ultrafiltration, ion exchange purification and reverse osmosis processes. These physical and chemical methods of wastewater treatment differ in satisfactory indicators of water purification from oil hydrocarbons. However, with their widespread use, it is necessary to build special treatment facilities, have expensive chemicals, etc.
Biological method cleaning oil-contaminated water is effective for neutralizing wastewater of various origins and is based on the use of special hydrocarbon-oxidizing microorganisms. Biofilters with a thin bacterial film, biological ponds are highly effective in removing easily degradable organic matter with microorganisms inhabiting them, aeration tanks with activated sludge from bacteria and other microorganisms (Fergusson S., 2003).
The methods listed above are mainly used to treat wastewater and land water areas. In the seas, other methods are used.
Mechanical, thermal, physicochemical and biological methods are used to clean up an oil spill on the high seas.
One of the main methods of oil spill response is the mechanical collection of spilled oil and oil products in combination with booms. Their purpose is to prevent the spread of oil on the water surface, increase its concentration to facilitate the cleaning process, as well as the removal (trawling) of oil from the most environmentally vulnerable areas. Oil-absorbing booms are a reliable, efficient and easy-to-maintain, environmentally safe and economically acceptable system for water purification from oil pollution. The greatest efficiency is achieved in the first hours after the oil spill. Various designs of oil skimmers are used to clean water areas and eliminate oil spills (collection of oil and debris).
The thermal method is based on oil burning, applied at sufficient layer thickness and immediately after contamination, before the formation of emulsions with water. This method is usually used in conjunction with other spill response methods.
The physico-chemical method using dispersants and sorbents is effective in cases where mechanical oil recovery is not possible, for example, when the film thickness is small or when spilled oil poses a real threat to environmentally sensitive areas. Dispersants are special chemicals that are used to enhance the natural dispersion (dissolution) of oil in order to facilitate its removal from the surface of the water before the spill reaches an environmentally sensitive area. Sorbents (finely crushed plant remains of herbaceous and woody plants, peat, lichens, etc.) absorb oil products when interacting with the water surface, after which clods saturated with oil are formed. They are subsequently removed mechanically, and the remaining particles are destroyed in a variety of ways, including biological ones.
biological method is based on the use of microorganisms that utilize oil and oil products. It is mainly used after the application of mechanical and physico-chemical methods.
Among the known biological methods, a special place is occupied by biotechnologies using biological products and consortiums of microorganisms created on the basis of native microflora present in natural wastewater. A wide variety of commercial biological preparations is known, the action of which is based on the biochemical destruction of hydrocarbons that are part of it by strains of microorganisms. The composition of biological products most often includes one or more varieties of microorganisms.
The use of a biological cleaning method differs from other methods in environmental safety, high efficiency, as well as economic profitability. With the optimal choice of a consortium of microorganisms in combination with the use of biostimulating substances (some organic substances, mineral fertilizers, etc.), it is possible to accelerate the biological oxidation of oil pollution by tens and hundreds of times and reduce the residual content of oil products to almost zero values (Morozov N.V., 2001 ).
When utilizing oil hydrocarbons with the help of consortiums of microorganisms and biological products, it is necessary to take into account climatic conditions (mainly pH and temperature indicators), the properties of oil from certain deposits, as well as the interaction of the microorganisms used with the native microflora of the objects being cleaned.
Currently, there is a wide class of heterotrophic microorganisms included in the composition of bacterial preparations. At the same time, each individual complex of microorganisms is distinguished by its individuality in relation to certain oil hydrocarbons. For example, monobacterial preparations are characterized by a narrow specificity with respect to individual hydrocarbons, a small range of pH, salinity, temperature, and concentration of hydrocarbons. This is their shortcoming.
Under natural conditions, a whole microbiocenosis with a characteristic structure of trophic relationships and energy metabolism takes part in the decomposition of oil. Therefore, polybacterial preparations have wider adaptive and environmental opportunities for the use of microorganisms in purification processes.
At the Kazan (Volga Region) Federal University (Russia, Kazan), consortiums have been created by targeted selection, which include associations of three, nine, and ten strains of hydrocarbon-oxidizing microorganisms. They were isolated from the wastewater of the oil refinery JSC Kazanorgsintez, numerous car fleets and the city sewer that discharges oil-contaminated water. The consortium has a high oxidizing activity (for the final product of the oxidation of commercial oil (desalted and dehydrated) and petroleum products 2040 mg CO 2 in 20 days); able to grow on a depleted nutrient medium with a high rate of oil oxidation (including aromatic hydrocarbons contained in paraffins of heavy oils); at 5-35°C and a wide pH range (from 2.5 to 10 units). One of the main advantages of the consortium of bacteria developed by us is their unique ability to adapt to specific conditions of use, they are resistant to a long and continuous process of wastewater treatment from oil pollution, and the simplicity of the technology.
Due to the fact that the consortium includes a large number of strains of microorganisms, they quickly adapt to various environmental conditions. The consortium, as it were, is "tuning" to work with certain hydrocarbons contained in wastewater. When environmental conditions change, including the composition of pollutants, they quickly rebuild their metabolism by changing the structure of the consortium. The drug does not have a destructive effect (unlike aggressive chemicals) on equipment and is environmentally friendly.
The consortium of hydrocarbon-oxidizing microorganisms is designed for deep treatment and post-treatment of hydrocarbon-containing wastewater:
1) autonomous floating ships, gas stations, car wash and repair stations, mechanized transport stations, local industry enterprises and small sewage facilities;
2) large-tonnage factory effluents from various industries, agriculture and everyday life with a wide range of residual oil products and hydrocarbons;
3) in the preparation of highly concentrated hydrocarbon-containing wastewater from local industries, organic synthesis shops and farms to the norm of discharge to biological treatment facilities for their complete neutralization;
4) when cleaning and post-treatment of oil-producing ballast wastewater of autonomous floating ships;
5) in the post-treatment of large-tonnage process effluents from the residue of oil impurities after biological wastewater treatment.
6) The consortium can also be used to clean up large marine areas.
The full version of the article can be found on the website of the Moscow Society of Naturalists (http://www.moip.msu.ru)
Authors: Nikolai Vasilievich Morozov, Olga Vadimovna Zhukov(Kazan (Volga Region) Federal University [email protected] [email protected]), Anatoly Pavlovich Sadchikov(International Biotechnology Center of Moscow State University named after M.V. Lomonosov [email protected] yandex. ru)
