EUTROFICATION- eutrophication. Excessive intake of organic and mineral substances into water bodies, especially nitrogen and phosphorus. E. manifests itself during the active development of hydrophytes. During the massive die-off of algae, their decomposing remains are deposited in large quantities at the bottom of reservoirs, the oxidation of which is spent a large number of oxygen. Oxygen deficiency often leads to the death of fish and other aquatic organisms.
The process of eutrophication of water bodies is the most studied. This natural process, characteristic of the entire geological past of the planet, usually proceeds very slowly and gradually, but last decades, due to increased anthropogenic impact, the speed of its development has increased sharply. Accelerated, or so-called anthropogenic eutrophication is associated with the entry into water bodies of a significant amount of nutrients - nitrogen, phosphorus and other elements in the form of fertilizers, detergents, animal waste, atmospheric aerosols, etc. In modern conditions, eutrophication of water bodies occurs at a significantly higher rate. shorter periods - several decades or less. Anthropogenic eutrophication has a very negative effect on freshwater ecosystems, leading to a restructuring of the structure of trophic relationships of aquatic organisms, a sharp increase in phytoplankton biomass due to the massive proliferation of blue-green algae, causing “blooming” of water, worsening its quality and living conditions of aquatic organisms (in addition, they emit dangerous not only for hydrobionts, but also toxins for humans). An increase in the mass of phytoplankton is accompanied by a decrease in the diversity of species, which leads to an irreparable loss of the gene pool, a decrease in the ability of ecosystems to homeostasis and self-regulation (Yablokov, 1983). The processes of anthropogenic eutrophication cover many large lakes of the world - the Great American Lakes, Balaton, Ladoga, Geneva, etc., as well as reservoirs and river ecosystems, primarily small rivers. On these rivers, in addition to the catastrophically growing biomass of blue-green algae, the banks are overgrown with higher vegetation. The blue-green algae themselves, as a result of their vital activity, produce strong toxins that pose a danger to aquatic organisms and humans.
The Baltic Sea is vulnerable and faces many challenges. This summer we once again had the opportunity to see how far the process of eutrophication of the Baltic Sea has gone, and the “blooming” of water due to the massive development of blue-green algae is only one of illustrative examples how serious the situation is. Other negative effects of eutrophication include decreased seawater clarity and reduced biodiversity. The diversity of life forms in the Baltic Sea is decreasing, since at the moment certain areas of the seabed are dead, and some biotopes are completely destroyed. This, in turn, has led to a decrease in the populations of some species, while the numbers of others are increasing uncontrollably. The observed imbalance indicates that eutrophication is one of the most serious problems, which faces the natural component of the Baltic Sea.
Eutrophication, or eutrophication, is the process of enriching water bodies with nutrients, especially nitrogen and phosphorus, mainly of biogenic origin. As a result, the lake gradually becomes overgrown and turns into a swamp filled with silt and decaying plant debris, which eventually dries out completely. Under natural conditions, this process takes tens of thousands of years, but as a result of anthropogenic pollution it proceeds very quickly. For example, in small ponds and lakes under human influence it is completed in just a few decades.
Eutrophication increases when plant growth in a body of water is stimulated by nitrogen and phosphorus contained in fertilizer-laden agricultural runoff, cleaning products and other waste. The waters of the lake receiving this wastewater provide a fertile environment in which aquatic plants grow vigorously, taking over the space where fish usually live. Algae and other plants, dying, fall to the bottom and are decomposed by aerobic bacteria, which consume oxygen for this, which leads to the death of fish. The lake is filled with floating and attached algae and other aquatic plants, as well as small animals that feed on them. Blue-green algae, or cyanobacteria, make the water taste like pea soup with a foul odor and fishy taste, and coat rocks in a slimy film.
Eutrophication- increasing the level of primary productivity of reservoirs due to an increase in the concentration of nutrients in them, mainly nitrogen and phosphorus; often leads to algal blooms.
Eutrophication of water bodies
Once in natural bodies of water (for example, phosphorus and nitrogen compounds), nutrients become a breeding ground for microorganisms, including blue-green algae. The waste products of blue-greens are allergens and toxins that directly affect humans. Algae multiply especially intensively in well-warmed water, that is, in summer. This is why some of us find red spots on our bodies after swimming in the bay. And if you drink such water, even if it is boiled, you can become seriously poisoned. The process of anthropogenic eutrophication, causing rapid and sometimes irreversible disruption of the functional connections of the ecosystem, leads to deterioration in water quality, undermining useful productivity, and sometimes to the complete loss of the natural resources of the lake. The main negative consequences of this process are the massive development of planktonic algae, the appearance of an unpleasant odor and taste of water, an increase in the content of organic substances, a decrease in transparency and an increase in the color of water. Oversaturation of water with organic matter stimulates the development of saprophytic bacteria, including pathogenic ones, as well as aquatic fungi. As a result of the vital activity of some algae, especially blue-green algae, toxic effects occur, leading to diseases in animals, and in some cases, in humans (“Gaff” and “Sartland” diseases).
A significant portion of the dissolved oxygen contained in lake water is consumed to oxidize a huge amount of newly formed organic matter. As a result, commercially valuable fish species (salmon, whitefish), demanding high quality waters are replaced by low-grade species that are less sensitive in this regard.
"Water Bloom"- mass development (outbreak) of phytoplankton, causing a change in water color from green (green and blue-green algae) and yellow-brown (diatoms) to red (dinoflagellates). The intensity of this process is determined by the biomass of algae: weak (0.5 – 0.9 mg/l), moderate (1 – 9.9 mg/l), intense (10 – 99.9 mg/l) and “hyper-blooming” - more than 100 mg/l.
These phenomena have been known since ancient times, but recently they have become frequent and very intense as a result of increased anthropogenic impact on marine ecosystems. This is mainly due to the significant intake of organic substances (nitrogen, phosphorus, potassium, etc.) into water bodies.
This leads to a deterioration in the oxygen regime (even to the point of death), to the accumulation of toxic organic compounds in the aquatic environment, which causes the appearance of red tides in the seas.
Eutrophication(eutrophication, eutrophication) - an increase in the biological productivity of water bodies as a result of the accumulation of nutrients in water under the influence of natural and mainly anthropogenic factors. The main reasons are the supply of huge quantities of biogenic components (especially nitrogen and phosphorus), which are supplied to the environment by agricultural production (the use of fertilizers), as well as various detergents (over 30 million tons of soap are used annually in the world), etc.
According to B. Henderson-Sellers, the main criteria for characterizing the process of eutrophication of water bodies are: - a decrease in the concentration of dissolved oxygen in water; - increase in the content of biogenic components; - increase in the content of suspended particles, especially of organic origin; - consistent change of algae populations with a predominance of blue-green and green ones; - increase in water turbidity (decreased light penetration); - a significant increase in phytoplankton biomass (with a simultaneous decrease in species diversity), etc. Eutrophication processes have affected many large freshwater bodies of the USA and Canada (Great American Lakes), Japan, Europe (Lake Geneva, Ladoga, Onega, Balaton, etc.), as well as many marine basins (Mediterranean, Black, Baltic, etc.). Since the eutrophication of water bodies has become a serious global environmental problem, work has begun through UNESCO to monitor inland waters and control the eutrophication of water bodies around the globe.
red tide – an environmental phenomenon caused by excessive discharge of organic matter into the ocean and a massive outbreak of pyrophytic algae. Studies have shown that after heavy rains, a large amount of nutrients (especially nitrogen and phosphorus) are washed off from the coasts and, at the same time, the influx of fresh water reduces the salinity of the ocean, and the rise of deep waters brings additional water to the surface. organic matter, which stimulate the growth and mass reproduction of pyrophytic algae. All this leads to large economic losses, as the beaches become empty and become covered with masses of decaying fish. IN last years in the World Ocean, as a result of the discharge of huge amounts of organic matter, red tides have become more frequent, which are observed off the coasts of India, Australia, Japan, Scandinavia, in the Black and Mediterranean seas. In this regard, it is necessary to organize monitoring of the content of toxic species of phytoplankton in ocean waters, causing eutrophication and red tides.
Negative environmental consequences of eutrophication of water bodies
EUTROFICATION PROCESSES IN THE VOLGOGRAD RESERVOIR AND WAYS TO PREVENT THEM
eutrophication processes
in the Volgograd reservoir
and ways to prevent them
Mamontova A.S. (PR-051), Shepeleva E.S. (assistant of the Department of E&P), Scientific supervisor – Novikov V.V., Ph.D., Associate Professor
Volzhsky Humanitarian Institute (branch) VolSU
In the lake section of the Volgograd reservoir with stagnant zones, the processes of overgrowing with aquatic vegetation (eutrophication) are intensifying, which causes deterioration in water quality and impoverishment species composition ecosystems. Eutrophication leads to the development of blue-green algae Cyanophyta, which cause “blooming” of water, worsening its quality. Therefore, this problem is relevant for the city of Volzhsky, which abstracts water from the Volgograd reservoir.
To combat blue-green algae, modern methods of biological, physical and chemical treatment are used surface waters, as well as the algolization method - the introduction of a single-celled green algae - chlorella, which exhibits antagonism to blue-green algae. The latter method is used in the Volgograd branch of GosNIORH, whose scientists have shown an improvement in the condition of the reservoir (Fig. 1).
The above method is being tested at the Volgograd and Tsimlyansk reservoirs, where positive results were obtained. Later, upon confirmation positive results, it is planned wide application on reservoirs of the Volga-Kama cascade, including the Kuibyshev reservoir and other reservoirs where this problem also exists.
The goal of our work was to trace the dynamics of water blooms in the Volgograd Reservoir in connection with the ongoing algolization.
During the period of greatest development of blue-green algae biomass, we collected phytoplankton samples at 73 points of the Volgograd Reservoir in July 2006 and 2007. and analyzed in the environmental educational laboratory of the VGI VolSU in accordance with GOST 17.1.4.02 - 90.
The content of chlorophyll A in the samples varied from 0.95 μg/L in the upper reaches of Pichuga Bay to 8.87 μg/L in the middle of the dam area. In a number of bays and sections in 2007, the level of biomass decreased compared to 2006. However, in the area near the dam, on the contrary, an increase in the level of biomass was observed. This dynamics can be traced in 2007-2008. (Fig. 2). In a number of bays - Erzovka, Dubovka, where the anthropogenic impact is especially great, an increase in biomass is noted.
III. Aquatic ecosystems.
Limiting factors of aquatic ecosystems:
1. Salinity – the content of soluble salts, mainly sodium chloride, in the water mass;
2. Depth of penetration of sunlight;
3. Amount of oxygen;
4. Availability of nutrients;
5. Water temperature.
Based on the degree of water salinity, aquatic ecosystems are divided into two large classes.
Brackish water(marine) Freshwater
Oceans - lakes, reservoirs
River mouths (estuaries) - ponds
Coastal marshes - swamps
Coral reefs - rivers and streams (watercourses)
Main zones of the ocean.
In any of the oceans globe Two main zones can be distinguished: coastal and open ocean.
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Due to the significant volume of contaminated wastewater, water quality in the regions does not meet regulatory requirements. Overall volume Wastewater, discharged into surface water bodies in Russia as a whole amounts to more than 60 km3, including 22.4 km3 that are untreated and heavily polluted. Most surface water quality water bodies Russian Federation, despite a constant decline in production and a decrease in the volume of pollutants discharged, still does not meet regulatory requirements. The largest rivers in Russia, which play a leading role in water supply to the population, industry and agriculture - the Volga, Don, Kuban, Ob, Yenisei, Lena, Pechora - are assessed as “polluted”, and their tributaries as “heavily polluted”.
Unsustainable agricultural practices and an increase in the volume of domestic and industrial wastewater lead to a significant increase in the amounts of nutrients and organic substances entering water bodies. This leads to an increase in the trophic status of water bodies, a reduction in their biological diversity, and a deterioration in water quality. An additional reason for eutrophication is the entry of nutrients into the catchment areas through atmospheric transport. The process of eutrophication, which began in Western Europe in 1950-1960, came to us 10-15 years late, and in the 1970-1980s it covered almost all water bodies of the European part of Russia.
During the process of eutrophication, fundamental changes occur in the trophic structure of the ecosystem, ranging from bacterio-, phyto- and zooplankton to fish. Aquatic ecosystems respond to the enrichment of nutrients and organic substances, first of all, by the intensive development of algae and cyanobacteria, which convert excess nutrients into biomass. Their rapid reproduction causes “blooming” of water. The main agents of “blooming” in most cases are cyanobacteria (aphanizomenon, microcystis, anobaena, oscillatoria). Excessive development of cyanobacteria and algae has profound negative consequences for freshwater ecosystems. Cyanobacteria release metabolites into water that are toxic to invertebrates, fish, warm-blooded animals and humans. Water blooms lead to oxygen deficiency and siltation of water bodies. Favorable conditions are created for the development of pathogenic microflora and pathogens, including Vibrio cholerae. In the structure of zooplankton and fish populations, large and long-lived forms are replaced by small and early-maturing ones. Valuable commercial fish with long life cycle are replaced by “trash” fish with a high level of reproduction and a high increase in production. The change in the fish part of the community occurs, as a rule, in the following sequence: salmon → whitefish → smelt → perch → cyprinids. Profound changes also occur in the plant components of ecosystems. Total production and biomass increase, the trophic structure becomes simpler, and species diversity decreases.
The particular danger of these processes is that they are apparently irreversible.
Today, a process has emerged that is the opposite of the eutrophication of water bodies - their re-oligotrophization. In Russian reservoirs it is associated with a decline industrial production in the 1990s and with the decline in fertilizer use in agriculture. First of all, this process was noticed on small rivers in the European part of Russia. However, during the process of re-oligotrophization, the structure of the fish population does not return to its original state.
Toxification of water bodies. Particularly dangerous is the entry into aquatic ecosystems. toxic substances. In recent years, there has been increased pollution of water bodies with heavy metals, phenols, petroleum products and other toxicants. Chemical indicators cannot provide a complete picture of the toxicity of the environment; they do not take into account the synergistic, cumulative or antagonistic effects of the simultaneous presence of many pollutants and therefore cannot serve as a reliable basis for predicting the environmental consequences of pollution. Chemical analysis gives an idea of the content of substances in water or in organisms only at the time of sampling, but tells little about the impact of pollutants on aquatic organisms. At the same time, it is well known that the state of aquatic organisms and the integral biological assessment of the “health” of an ecosystem can serve as a general indicator of the ecological state of a reservoir.
The problem of toxification becomes relevant even when the concentration of toxicants in water does not exceed the established maximum permissible concentrations, since the vast majority of hydrobionts have pronounced accumulative abilities. Because of this, they themselves become toxic. The accumulation coefficients of many hydrobionts are extremely high.
The harmful consequences of toxification of water bodies manifest themselves at the organismal, population and biocenotic levels. At the organismal level, many physiological functions are disrupted, the behavior of individuals changes, their growth rate decreases, and resistance to various stress conditions decreases. external environment, damage occurs in the genetic apparatus, and the original gene pool is transformed. At the population level, under the influence of pollution, changes occur in numbers and biomass, mortality and birth rates, size, age and sex structure. At the biocenotic level, there is a change in species diversity, a change in dominant species, a change in species composition, and a change in the intensity of metabolism of the biocenosis.
Each toxicant has a specific mechanism of action. For example, heavy metals and their compounds, along with a direct toxic effect on the body, can cause mutagenic, gonadotoxic, embryotoxic and other effects. Heavy metals have a pronounced ability to damage the enzymatic systems of organisms. Thus, mercury, silver and copper block many enzymatic reactions. Zinc already at a concentration of 0.065 mg/l inhibits phosphorylating respiration. Salts of heavy metals can accumulate in water and bottom sediments, while maintaining an active form for a long time. Heavy metals are excreted extremely slowly from the body, which serves as a prerequisite for the so-called nutritional effect - an increase in concentration in organisms of subsequent trophic levels. For example, the highest concentrations of mercury in freshwater ecosystems are found in fish.
Toxification of freshwater ecosystems is also associated with the entry of pesticides into them. Persistent pesticides, which were intensively used in the USSR in the 50-60s, have firmly entered the cycle of substances. As they are washed out of soils and accumulate in water bodies, they have an increasingly detrimental effect on aquatic ecosystems. This impact is often hidden and manifests itself unexpectedly in the form of mass mortality of fish and aquatic invertebrates. In trophic chains, pesticide concentrations increase on average 10 times with each transition from more low level to a higher one. The longer the trophic chain, the higher the concentration in the last link. There is a biological concentration of pesticides in water and sludge up to milligrams and tens of milligrams per 1 kg of slave weight. Therefore, even the most minimal concentrations of persistent pesticides in water and bottom sediments pose a threat to higher trophic links.
Pollution of water bodies and watercourses with other toxicants, such as antiseptics, such as arsenic compounds, hydrofluoric acid salts, etc., has significant negative consequences for freshwater ecosystems.
Mixed pollution with toxic and organic substances. Depending on which components – organic or toxic – predominate, processes of oppression or complete death of animals can occur in the ecosystem against the background of eutrophication, even at high oxygen concentrations. Under such conditions, an increase in biomass or an increase in the number of animals is observed only up to the class of “dirty” waters. In the class of “dirty” waters, there is a significant decrease in the number and biomass of animals, and, consequently, in the self-purifying ability of the reservoir.
Acidification of water bodies. In recent years, the problem of toxification of water bodies has been greatly complicated by the acidification of lake water as a result of the deposition of acidic substances. atmospheric precipitation, the formation mechanism of which is associated with the leaching from the atmosphere of nitrogen and sulfur oxides formed during the combustion of fossil fuels and other types of economic activity person. Acidification of lake water is accompanied by an increase in the concentration of toxic metals, such as aluminum, manganese, cadmium, lead, mercury, due to their release from soils and bottom sediments. In lake waters with increased bicarbonate alkalinity, additional amounts of free carbonic acid are formed, which has toxic effect on hydrobionts. In Russia, the problem of acidification of lake waters as a result of transboundary transport from air currents and the fallout of acidic precipitation, primarily sulfur oxides, was most clearly identified in Karelia and the Kola Peninsula. In the Karelian and Kola lakes, located on crystalline rocks, the water is the least mineralized and contains minimum quantities bases, so here the process of anthropogenic acidification of waters occurs very quickly. Of the fish inhabiting the waters of Karelia and Kola Peninsula, the most sensitive to water acidification were noble salmon, char, whitefish, and grayling.
When lake water is acidified, the total biomass of hydrobionts and the amount of primary production of the reservoir sharply decrease, and the species diversity of biocenoses decreases. First of all, many species are disappearing, which are important elements valuable fodder base commercial fish. A pH level of 5.0 and below can be detrimental to all aquatic organisms.
Acid rain also affects fish reproduction. The situation is especially difficult in the spring, when a lot of sulfates enter the melt water. A so-called “pH shock” is observed. It is during this period that the larvae of whitefish and salmon fish hatch, and the spawning of grayling, pike and perch takes place. Acidification has a particularly negative effect on juvenile fish. A sharp decrease in water pH, combined with high concentrations of metals, has a detrimental effect on fish and the entire community as a whole. In some lakes, as a result of acidification, the reproduction of fish populations stops and they die out. Many lakes in Russia have already practically lost their fish population.
One of the main reasons for the death of fish in acidic waters is a violation of the active transport of Na and Ca ions through the gill epithelium. However, in a number of cases, the death of fish begins long before the pH drops to lethal values and is caused by indirect reasons, for example, aluminum poisoning, which is provoked by an increase in water acidity. Aluminum primarily affects the gills and the fish begins to experience acute oxygen starvation. One “acid shock” can lead to a sharp increase in aluminum concentrations to lethal levels within a few days. That's why mass death fish infection can occur in a body of water in which average pH values do not cause serious concern.
Thermification of reservoirs. In some reservoirs, an additional prerequisite for eutrophication is a change in their natural temperature regime, caused by the supply of heated water from enterprises and, above all, from thermal and nuclear power plants. An increase in water temperature contributes to an increase in the intensity of metabolism of biocenoses, in particular primary production, which is a significant factor in the eutrophication of freshwater ecosystems.
Thermification of reservoirs and watercourses entails changes in their flora and fauna, often provoking deep shifts in the structure and functions of the original ecosystems in undesirable directions. An increase in temperature to 35°C favors the development of toxic cyanobacteria, which are the most resistant to heating, while simultaneously inhibiting other phytoplankton.
Dispersal of alien organisms. In recent decades, the rate of invasion of alien organisms (biological invasion) into aquatic ecosystems has sharply increased. The main reasons for this are the intensification of shipping and the unregulated discharge of ballast water by ships. The introduction of alien species negatively affects the biological diversity, structure and functioning of aquatic ecosystems, and pathogenic organisms and toxic algae species pose a direct threat to human health.
The relevance of this problem in Russia is due to the existence of numerous hydraulic structures, a wide network of water communications, and extensive inland reservoirs. All this contributes to a freer exchange of fauna and flora between different, previously isolated water systems.
The deliberate introduction of alien species into ecosystems also poses great environmental and economic risks, since the introduction of a new species always leads to a radical restructuring of food chains.
The penetration of some organisms into new water systems often causes great harm to fisheries, urban water supplies, hydraulic structures, water transport, etc.
For example, thanks to the canals, the zebra mussel mollusk has spread widely. This mollusk quickly reaches high numbers in the freshwater streams and reservoirs it repopulates, which disrupts the normal operation of various hydraulic structures, penetrates water pipes in countless quantities, clogs them, and when dying, causes damage drinking water. The displacement of native aquatic species by these molluscs can cause serious changes at the ecosystem level.
A striking example negative influence on freshwater ecosystems is the widespread spread of the sleeper firebrand (percottus glenii) in many small reservoirs of the European part of Russia, which practically replaced all other fish species from them.
Another example of such an invasion is the appearance of smelt (osmerus eperlanus) in Syamozero and the outbreak of its population in the 1970-1980s, along with the beginning of eutrophication processes, which led to a restructuring of the structure of the fish population and food chains of the lake. Smelt is an active planktivore in the first years of its life and an equally active predator in adulthood. Therefore, on the one hand, smelt has become a powerful competitor in the diet of other planktivores (vendice, whitefish and bleak), and, on the other hand, it is also a competitor for predators, in particular pike perch and large perch. Previously, in the 1950s, Syamozero was considered a vendace-perch lake, and in the 1990s it was transformed into a smelt-perch lake. Smelt quickly spread throughout the lake, having mastered all possible biotopes, and occupied the food niche of the main planktivore – vendace.
Pumps with filters allow us to enjoy the beautiful blue surface of the pond in our area. Also for this purpose, various chemical and biological additives are intended, which destroy harmful microflora and normalize the composition of water.
A body of water in its area is often subject to an unpleasant and harmful phenomenon called eutrophication. WITH Greek language this word can be translated as “abundant nutrition.” Its meaning is that nutrients (nitrogen and phosphorus) cause “blooming” of water and the hyperactive development of anaerobic microorganisms.
Every pond, lake, river backwater and artificial reservoir may become unsuitable for further use due to the fact that the water in it “blooms”. Oxygen levels during eutrophication interfere with the normal functioning of fish and plants. sunlight cannot break through the thickness of the proliferating algae, which also entails a decrease in the diversity of the flora and fauna of the reservoir.
Causes and consequences
The reasons for this unpleasant phenomenon are different. In some cases this is caused natural factors. For example, by slowing down the flow of water, which stops the normal supply of oxygen to the bottom areas. Or the excessive development of certain types of algae.
Very often, eutrophication is the result of human activity. Fertilizers are washed off from the fields, orthophosphate powders end up in drains, and nearby livestock farms and poultry farms disrupt the nitrogen content in the reservoir.
External signs of pond (reservoir) pollution
- Unpleasant “heavy” odor
- Cloudy film on the surface
- Massive sediment of organic sediments on the bottom
- Uncontrolled proliferation of algae, mud, duckweed and other microorganisms, due to which the liquid acquires a stable green color.
Read about how to make a fish pond.
Eutrophication has a detrimental effect on the biogeocenosis of a pond with stagnant water:
- Due to the increase in nutrients for fouling algae and phytoplankton-eating zooplankton, the upper layer of the reservoir turns into a green carpet. The unpleasant heavy aroma is probably familiar to everyone who has ever been on the shore of such a body of water.
- The bottom layer does not receive the required amount of oxygen. Because of this, aerobic microorganisms, plants and fish die. There is a rapid increase in the total mass of anaerobic living organisms in the bottom layer.
- Since oxygen-eating bacteria are not able to process dead parts of algae and animals in a timely manner, poisons accumulate below. These are phenol, hydrogen sulfide and methane. The greenhouse effect is evident, killing off vegetation and oxygen-demanding living cells. Read also about pond aerators.
Pollution of water bodies can also be combined. That is, eutrophication plus wastewater, fallen leaves and branches, fallen trees, iron and plastic casings of used mechanisms, anthropogenic garbage, etc.
All information about fish farming in artificial reservoirs you will find.
Methods for cleaning reservoirs
Once upon a time, our ancestors simply poured a large amount of charcoal into a dirty pond. This was a kind of prototype of filtration. Now there are more advanced and convenient methods for cleaning industrial, natural and country water bodies. In total, there are four types of cleaning measures:
Ultraviolet irradiation is still a rather exotic way to clean a pond of “bloom” and mud. But filters used simultaneously with the addition of chemical and biological agents to water active substances, are a common method. Here it is important to determine the level of green mass content and, based on this, order a pump of the required power.
This will tell you what to feed crucian carp in your home pond.
The pump with filter is placed at the desired depth. When preventing eutrophication, you only need to turn it on once a week or so. If the reservoir is quite dirty, then it is necessary to get rid of all algae, dead sediments, microscopic particles and other debris of biogenic origin.
It is important to correctly calculate the throughput of the pump and filter. For industrial needs, powerful units are produced that purify tons of water per hour.. A country pond does not require high pump parameters, so stable operation and high-quality cleaning are more important here.
Biological and chemical methods for cleaning indoor pools and ponds are usually used together. The process of dying off of duckweed, mud and protozoan algae starts immediately after the recommended dose of the drug is poured out. It usually lasts from one to three months. After this, the number of fouling algae and anaerobic benthic microorganisms begins to decrease. 
Find out why butyl rubber film is used for a pond.
Only a relatively small pool can be quickly cleaned using a filter. To clean a pond of significant size, depending on the degree of contamination and the drugs used, it may take from several weeks to several months.
If the reservoir on your site is supplied with running water from pipes, then it is also worth cleaning them. The fact is that colonies of microorganisms and protozoa algae necessarily settle on the surface of the internal walls of pipelines. As a result, the water entering the pond is already contaminated, which should be avoided in every possible way.
It is possible that you will find information about .
Getting rid of anaerobic microorganisms and bacteria is a long and expensive process. Therefore, you should not let your pond become a swamp. It is necessary to constantly monitor the level of nitrogen and phosphorus, prevent the ingress of biogenic microelements, and monitor what flows into your pond. It is customary to use oxygen to enrich water bodies.
You can make a pond water filtration system yourself, as shown in this video:
Pumps with filters are an integral part of any reservoir, the owner of which strictly controls all processes in its depths and on the surface. The addition of chemicals and biological agents completes the removal of unwanted algae and zooplankton.
An anthropogenic change in the composition of water in a reservoir is an increase in the load of the reservoir with dissolved chemicals and suspended substances. Among them, mineral nutrients most often predominate, but substances that are toxic to aquatic organisms often also appear, which is why the chemical load is called
pollution reservoir, changing its water quality. An ensemble of interconnected physical, physicochemical, biological and hydrological processes is involved in restoring the natural quality of water in reservoirs. Along with the three most important processes (see Section 12.1), many other processes mentioned are also involved. They are divided into two groups - processes that change the concentration of pollutants, and processes that reduce the mass of the pollutant in water and lead to its self-purification(Fig. 12.12).
Rice. 12.12.
The process of mixing atmospheric and river waters forms its main water mass(OBM) with uniform distribution chemical substances and the smallest fractions of suspended matter, thereby ensuring the homogeneity of abiotic factors for the development of planktonic organisms. In areas of reservoirs into which wastewater is discharged, the mixing process is especially important, since it reduces their toxic effect on aquatic organisms. It is also important for them to mix melted, oxygenated water, formed when the snow and ice cover melts, with the upper layer of winter waters of the reservoir.
At this time, the early spring outbreak of diatom development begins. nannoplankton, oligocarbophilic forms of bacterioplankton, followed by zooplankton. Their large numbers ensure increased biosedimentation and self-purification of the water column from pollutants brought in during floods.
The concentration of dissolved substances in the surface microlayer of water occurs due to evaporation from the open water surface and during ice formation in winter. It promotes development microconvection, which is favorable for production-destruction processes in the trophogenic layer. It regulates the uniform saturation of water with nutrients and oxygen around the phyto-, zoo- and bacterioplankton organisms that use them.
Concentration of technogenic substances in aquatic organisms (heavy metal ions, radioactive substances etc.) when some aquatic organisms are eaten by others, more high level trophic pyramid, is one of the main mechanisms for removing toxic substances from a reservoir. On the one hand, this process creates danger food poisoning with excessive accumulation of such substances in caught fish. But, on the other hand, much more important is that bioconcentration and biosedimentation burial of the bulk of these substances in bottom sediments is ensured.
Photosynthesis and sorption of dissolved substances on mineral and organic suspension reduce their concentration in water, converting them into suspended organic matter, organomineral complexes and allochthonous and abrasive mineral suspension enriched with them. These processes serve as the first preparatory stage self-purification of the aquatic ecosystem by sedimentation from excess amounts of nutrients and toxic substances, and photosynthesis, in addition, replenishes the supply of dissolved 0 2 necessary for the decomposition of organic pollutants. The formation of iron hydroxide in layers of water with a high content of 0 2 and the sorption of phosphorus-containing compounds on it, and then their coprecipitation can lead to a decrease in the concentration of phosphorus in water by 5-10% and reach 30-40% during periods of maximum accumulation of iron in the hypolimnion 1. At the Bratsk Reservoir, copper is removed from its water mass by gly-
base minerals, iron and manganese hydroxide, other heavy metals are bound by dissolved organic compounds into complexes, which ensures detoxification of water.
The transformation of humic substances, which determine the natural color of water, occurs due to coagulation and coprecipitation of colloids with fine suspended matter and iron oxide, as well as photochemical and biochemical oxidation (Datsenko, 2007). The rate of this process is minimal in February, when the concentration of suspended matter in the reservoir is lowest. Discoloration reaches 30% or more in the “phase clean water"(Fig. 12.13 l), thanks to sedimentation and biosedimentation of fine suspended fractions, absorption of solar radiation (see section 7.1).
Rice. 12.13. Decrease in average monthly values of water color in the Uchinsky reservoir (“) and average annual values depending on annual water exchange, Kv, year -1, (b)(based on: Datsenko, 2007)
The longer the impact of these processes, the greater the bleaching of water in years with the slowest water exchange (Fig. 12.13 b).
Self-purification of polluted waters in water bodies occurs in two zones. At the wastewater discharge point, toxic zone biocenosis, where some species of hydrobionts die, while others (saprophytes) rapidly develop, decomposing anthropogenic organic substances, reducing their toxicity. This uses up the oxygen contained in the water. Here the organoleptic characteristics - taste, smell, and often the color of the water - deteriorate even more, but at the same time it is enriched with CO2, nitrates, and phosphates.
On the periphery of this zone, in which the primary natural processing of even wastewater treated at aeration stations occurs, a more extensive eutrophication zone biocenosis In it, using the resulting nutrients, phyto-, zoo- and bacterioplankton organisms rapidly develop. The growth of their biomass increases the turbidity of the water, but at the same time the water is very intensively saturated with photosynthetic oxygen. Co-precipitation of phosphates, heavy metals, and petroleum products with biogenic suspensions (pellets) increases. Aerobic bacteria complete the oxidation of anthropogenic organic substances, which restores the natural organoleptic properties of water. As a result of these processes of self-purification of the aquatic ecosystem on the outer periphery of the eutrophication zone, the composition and concentration of chemicals, biomass and composition of aquatic organisms become similar to the background ecological state of the water mass of rivers, reservoirs, lakes or other water bodies.
Under ice cover on locally polluted water bodies that freeze in winter, the restoration of the normal functioning of the aquatic ecosystem is greatly slowed down due to a lack of light for photosynthesis aquatic plants. Therefore, the toxic zone expands, turning into a vast kill zone, where fish and other aquatic organisms die due to oxygen deficiency. The self-purification of reservoirs by oxidation of substances settled to the bottom continues in the bottom sediments until the consumption of oxygen in this process exhausts its supply in the bottom layer of water.
Secondary pollution - This is the removal into the water column from the bottom of dissolved biogenic compounds of nitrogen, phosphorus, ferrous iron, CO2, hydrogen sulfide, methane and other products of bacterial decomposition, mainly detritus, desorption of substances co-precipitated with suspended matter due to the occurrence of reducing conditions during a deficiency of 0 2 in hypolimnions and silts. Secondary pollution often includes resuspension suspended substances in shallow waters during a storm, since this process increases the concentration of substances in the water mass of the reservoir.
The negative role of these two processes in the deterioration of water quality is small, local and many times less than their primary, anthropogenic pollution. One of the reasons for the small role of secondary water pollution in reservoirs is their generally favorable oxygen regime, since the decay products of organic substances released into the water are oxidized under aerobic conditions. The second reason for the low probability of secondary pollution is the alternation of synoptically determined states of the water column - density stratification in calm and sunny weather and stormy and/or convective vertical mixing of the water column in cold and sunny weather. cloudy weather. There are often cases when these processes alternately stimulate the self-purification of water in reservoirs.
Anthropogenic eutrophication. Eutrophication 1- the phenomenon of accumulation of organic matter in the water of a reservoir. In GOST 17.1.1.01-77: “Eutrophication is an increase in the biological productivity of water bodies as a result of the accumulation of nutrients under the influence of anthropogenic or natural factors.” The main natural factor is the accumulation of suspended substances at the bottom of the reservoir and its gradual siltation with allochthonous and autochthonous mineral and organic substances. The rate of siltation of lakes varies due to climate fluctuations and runoff of substances from their catchment areas, and can be accelerated and slowed down by vertical movements of the lithosphere over long hydroclimatic epochs and geological periods.
Anthropogenic eutrophication (eutrophication) - a phenomenon caused by an increase in the flow of nutrients into hydrographic network watersheds due to population growth and its economic activities. It was discovered at the beginning of the 20th century in Central Europe and became ubiquitous. At the UNEP session in 1984, eutrophication of reservoirs, rivers and coastal areas of the seas was placed in first place in terms of the degree of danger of global anthropogenic impact on the environment. The main danger of eutrophication is that this phenomenon is difficult to reverse (Datsenko, 2007). It changes the pasture type cycle of substances into the detrital one, and subsequently simplifies the biotic structure of the ecosystem, reducing the number of species of aquatic organisms.In contrast to natural, anthropogenic eutrophication accelerates due to the increasing mass of substances participating in its large and small biochemical cycles, and due to the increasing internal load of nutrients substances.
Composition of interdependent processes - signs of eutrophication:
- increase in phosphorus load on the aquatic ecosystem (orthophosphates are the leading component mineral nutrition aquatic plants, phytoplankton, since with a lack of nitrogen and nitrates, more than a dozen species of blue-green algae are able to use N 2 dissolved in water (Kuznetsov, 1970);
- an increase in the annual production of organic matter to the extent of its destruction or even to PPv >D, outbreaks of prolonged “blooming” of blue-green and dinophyte algae, which leads to the accumulation of everything in the aquatic ecosystem every year more organic substances;
- strong supersaturation of water with oxygen in the epilimnion and its deficiency in the hypolimnion;
- overgrowing of the littoral zone with submerged and aerial-aquatic plants, the appearance among them of a cover of floating duckweed, and on the surface - bottom sediments outside the macrophyte belt - algae mats(a dense layer of dying phytoplankton) from blue-green and dinophyte algae;
- reduction in the species diversity of plankton and benthos, the disappearance of valuable fish species (for them, a decrease in the concentration of 0 2 below 6 mg/l is unfavorable) are clear signs of degradation of the biotic structure of the aquatic ecosystem;
- deterioration of organoleptic indicators of water quality, due to which it becomes unsuitable for water supply and recreation, and the recreational attractiveness of reservoirs, rivers and sea beaches is lost.
As a result of eutrophication of water bodies, the thickness of the trophogenic layer decreases due to a decrease in its transparency. And when dying network(non-feeding) species of algae in the aphotic layer, their microbial decomposition depletes the Cb dissolved in water. Because of this, in the tropholitic layer of the reservoir and in its silts, the destruction of detritus occurs by anaerobic microorganisms with the release of lake gases and organic compounds, giving water strong and unpleasant odors, taste and color. The accumulation of undecomposed autochthonous OM in silts accelerates - the source secondary pollution water column during its convective-dynamic mixing from the surface to the bottom.
To limit eutrophication, it is proposed to shade recreational ponds, periodically clean them of silt, and aerate the hypolimnion with compressed air. For large bodies of water, the most radical remedy is to stop the discharge of pollutants.
Without reservoirs, technogenic heavy metals in a biologically accessible form would partially precipitate during high-water floods on the Volga floodplain and would then be included in the terrestrial biochemical cycle of microelements with their progressive accumulation in meadow grasses, milk and livestock meat. Another part of their runoff during low-water periods would enter the Volga delta and the shallow-water estuary coastal zone of the river with a concentration exceeding the maximum permissible concentration during summer and winter low-water periods. In the unregulated Volga with all modern chemical loads, entry sturgeon fish spawning would stop. It is likely that the delta itself would lose its fishery significance as the world’s largest sturgeon feeding area due to toxicosis and progressive eutrophication of water bodies in the delta region.
Principles of ecological reconstruction of reservoirs. In order to regulate biological productivity, intensify water self-purification and prevent hypertrophy of reservoirs, principles for managing the internal water exchange of reservoirs have been developed (Edelstein, 1998). This requires environmental reconstruction of existing reservoirs, turning (if necessary) reservoirs of deep seasonal and long-term flow regulation into floor and sectional reservoirs.
For effective management internal water exchange determines the optimal number of water protection sections within the water area of the reservoir. The position of the intersection dams separating them from the deep-water main section is outlined. In this section it is necessary to preserve best quality water with a mesotrophic-eutrophic status and a “pasture” type of cycle of biogenic and organic substances.
In multi-blade reservoirs, water protection sections can become bays at the mouths of non-navigable tributaries. When organizing a police reservoir, the following should be provided:
I - constancy of external water exchange and approved dispatch schedule, guaranteeing the design mode of use water resources;
II - localization of the largest part of the external chemical load and sediment influx in water protection sections, in which the water level is maintained at the FPU throughout the entire growing season (Fig. 12.14) for the most complete utilization of absorbed water by the biocenosis of shallow waters solar energy on processes of self-purification of water and disposal of pollutants;
Rice. 12.14. Water level in a polysectional morphologically simple reservoir of long-term flow regulation: A - in the spring after the end of the flood; b in autumn at the end of the growing season; V - in winter;
1 - level in high-water and 2 - in low-water floods; 3 - intersectional dam; 4 - main section; 5 - water protection section; 6 - hydraulic unit.
III - recycling of water from water protection sections in the pre-winter period (if necessary) to the main one to replenish water resources in it. in spring river waters(the most turbid and contaminated at the rise of the flood) fill these sections first. After this, the transit flow of water slowed down in these sections fills the main section. In emergency situations, water protection sections can be prepared by early operation to receive particularly polluted waters to prevent their entry into the main section. In summer, on calm days, when algae are concentrated at the surface of the water, water is discharged into the main section through bottom water conduits, and when the silts in the water protection sections become agitated and flood waters enter them, water is discharged through weirs. A stable level in water protection sections is optimal for the development of macrophyte antagonists net phytoplankton causing "bloom" reservoirs. If it is necessary to empty the water protection sections before winter, the wintering conditions for macrophytes will improve. The areas of the bottom exposed during rapid drainage will be covered with snow. Due to the low thermal conductivity of the snow cover, the rhizomes of macrophytes will not freeze out, and in the spring they will not be torn out of the bottom by ice when the sections are filled with water.
When implementing reconstruction projects, the problem of economic use of drained shallow waters is solved by turning water protection sections into fish farms or hunting and fishing grounds, overgrown with macrophytes, and then, with their accelerating siltation, into agricultural polders. In the main section, sandy beaches expand during summer drainage, contributing not only to increasing the recreational attractiveness of the reservoir, but also to purifying the water psammon. Its role in the mineralization of net phytoplankton increases 4-5 times in hot and calm weather, when the development of blue-green and dinophyte algae reaches a “bloom”.
Regulation of water exchange between sections through surface and bottom culverts allows for migration aquatic fish for spawning in water protection sections, feeding of young fish there and their pre-winter migration to the main section for wintering, stimulated by the accelerated release of water from water protection sections. This will increase the fish productivity of reservoirs and increase the catch of older fish during migration. In winter, the bottom layer of the main section is aerated by the density current 1. In summer, when the bottom holes of the intersection dams are closed, the phosphorus load on the tropholitic region is sharply reduced.
In reservoirs that inevitably gradually age due to siltation, their area after reconstruction will decrease faster than their volume, since the water protection sections will silt first. Siltation of the main section will slow down. Consequently, the average depth of the reconstructed reservoir will increase and the loss of water due to evaporation will decrease, its lifetime will extend, which is of interest to all sectors of the water industry that use its water, biological and recreational resources.
Control questions:
- 1. What are the main processes that carry out the intra-reservoir transformation of energy and substances?
- 2. What is called the primary production and destruction of substances in water bodies, nutrients?
- 3. What processes are involved in the gas exchange of a reservoir with the atmosphere, and on what factors does the intensity of these processes depend?
- 4. Why does intense photosynthesis of algae release oxygen, increase water alkalinity, and form chemogenic calcite?
- 5. What is the role of aerobic, anaerobic and iron bacteria in the transformation of substances in water and bottom silt?
- 6. What groups are aquatic organisms divided into according to their habitat in water bodies?
- 7. What aquatic organisms are autotrophs, heterotrophs, consumers, decomposers?
- 8. What is a trophic pyramid, trophic levels, bacterial loop, grazing and grazing trophic cycles?
- 9. What is the principle of the bottle method for determining primary production (gross and net) and destruction in a water body?
- 10. What organic substances are considered stable, labile, what is the genesis of dissolved and suspended organic matter?
- 11. What is the difference between water bodies of the four main types of trophic state?
- 12. What are the differences in the productivity of reservoirs in Arctic, temperate and intertropical latitudes?
- 13. What processes begin and end the growing season in water bodies of arctic and temperate latitudes?
- 14. What is the reason and differences between the spring and summer “blooming” of eutrophic reservoirs?
- 15. Why does the “clean water phase” begin at the beginning of summer in biologically productive reservoirs?
- 16. What processes are involved in the formation of the large and small cycle of substances in dimictic and monomictic reservoirs?
- 17. What is the difference between the trophogenic and tropholitic layers in a reservoir? What is a “compensation point”, and what is the change in its depth during the day and in different weather conditions?
- 18. What is oxygen hysteresis? Orthograde and clinograde stratification of dissolved oxygen? In what trophic types of water bodies are they observed?
- 19. What processes distinguish the two stages of the trophic state of valley reservoirs? What is the difference between the trophogenic and tropholitic regions in them?
- 20. What intra-reservoir processes change the concentration of substances in the water of reservoirs and which lead to its pollution and self-purification?
- 21. What processes contribute to the self-purification of water at the source of its pollution in zones of toxicity and eutrophication?
- 22. What factors determine the retention of substances in water bodies? Why is the retention rate of substances higher in reservoirs than in lakes?
- 23. How does natural eutrophication of water bodies differ from their eutrophication?
- 24. What measures can be used to de-eutrophicate a pond, lake, reservoir, etc.?
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 and natural factors.
Eutrophication is a natural process in the evolution of a reservoir. From the moment of “birth”, a reservoir under natural conditions goes through several stages in its development: in the early stages from ultraoligotrophic to oligotrophic, then it becomes mesotrophic and eventually the reservoir turns into eutrophic and hypereutrophic - “aging” and death of the reservoir occurs with the formation of a swamp. If under natural conditions the eutrophication of a lake takes 1000 years or more, then as a result of anthropogenic impact this can happen a hundred or even a thousand times faster.
Anthropogenic eutrophication is associated with the entry of significant amounts of nutrients into water bodies, primarily nitrogen and phosphorus. If the ratio of the total nitrogen content to the total phosphorus content is less than 10, then the primary production of phytoplankton is limited by nitrogen, with N: P > 17 - by phosphorus, with N: P = 10-17 - by nitrogen and phosphorus simultaneously. For reservoirs temperate zone Phosphorus plays a decisive role. Currently, the critical concentrations of nitrogen and phosphorus (including total phosphorus, orthophosphates, total nitrogen and dissolved inorganic nitrogen ammonium, nitrites and nitrates) during intense mixing of waters, which create potential conditions for algal blooms, are as follows: for phosphorus 0.01 mg/dm 3, for nitrogen 0.3 mg/dm 3.
Biogenic components enter natural ecosystems both by water and by air. The main pollutants of water bodies with nutrients are nitrogen and phosphorus fertilizers, livestock waste, and phosphorus-containing pesticides. Eutrophication can be caused by the construction of reservoirs without proper cleaning of the bed, the construction of dams, the formation of stagnant zones, thermal pollution of water, the discharge of wastewater, especially municipal wastewater containing detergents, including those that have undergone biological treatment,
The main criteria for characterizing the eutrophication of water bodies are:
· decrease in the concentration of dissolved oxygen in the water column;
· increase in the content of suspended particles, especially of organic origin;
· increase in phosphorus concentration in bottom sediments;
· decreased light penetration (increased water turbidity);
· an increase in the concentration of gases formed during the decomposition of organic residues with a lack of oxygen - ammonia, methane, hydrogen sulfide;
· water acidity indicator at 100% oxygen saturation (pH 100%);
· consistent change of algae populations with a predominance of blue-green and green algae;
· significant increase in phytoplankton biomass;
· detection of algitoxins.
The concentration of chlorophyll a, which is the main photosynthetic pigment, is usually used as a direct indicator of the trophic state of a reservoir. The value of its concentration in a water sample is a representative indicator of algae biomass, an accurate measure of eutrophication of water bodies. Therefore, the determination of chlorophyll “a” is regularly used when measuring the “responses” of water bodies to nutrient loading for the purpose of their restoration.
Due to the massive proliferation of blue-green algae, which causes “blooming” of water, the living conditions of aquatic organisms and the quality of water, especially its organoleptic properties, deteriorate. Blue-green algae, as a result of their vital activity, produce, under certain conditions, strong toxins that pose a danger to living organisms and humans. They have neither color nor odor and are not destroyed by boiling. Algitoxins have no equal in their toxicity. They can cause cirrhosis of the liver, dermatitis in humans, poisoning and death of animals.
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