Water transparency in hydrology and oceanology is the ratio of the intensity of light passing through a layer of water to the intensity of light entering the water. Water transparency is a value that indirectly indicates the amount of suspended particles and colloids in water.

The transparency of water is determined by its selective ability to absorb and scatter light rays and depends on the conditions of surface illumination, changes in the spectral composition and attenuation of the light flux, as well as the concentration and nature of living and non-living suspended matter. With high transparency, the water acquires an intense blue color, which is characteristic of the open ocean. In the presence of a significant amount of suspended particles that strongly scatter light, the water has a blue-green or green color, characteristic of coastal areas and some shallow seas. At the confluence of large rivers carrying a large number of suspended particles, the color of the water takes on yellow and brown shades. River runoff, saturated with humic and fulvic acids, can cause the dark brown color of sea water.

The transparency (or light transmission) of natural waters is determined by their color and turbidity, i.e. their content of various colored and suspended organic and mineral substances.

Determining water transparency is a mandatory component of monitoring programs for the state of water bodies. Transparency is the ability of water to transmit light rays deep into it. A decrease in light flux reduces the efficiency of photosynthesis and, consequently, the biological productivity of watercourses.

Even the purest waters, free of impurities, are not absolutely transparent and in a layer of sufficiently large thickness they completely absorb light. However, natural waters are never completely clean - they always contain dissolved and suspended substances. Maximum transparency is observed in winter period. When the spring flood passes, transparency noticeably decreases. Minimum transparency values ​​are usually observed in summer, during the period of mass development (“blooming”) of phytoplankton.

For lakes in Belarus with a natural hydrochemical regime, transparency values ​​(based on the Secchi disk) vary from several tens of centimeters

up to 2-3 meters. In places where wastewater enters, especially with unauthorized discharges, transparency can decrease to several centimeters.

Depending on the degree of transparency, water is conventionally divided into clear, slightly turbid, medium turbid, turbid, and very turbid (Table 1.4). A measure of transparency is the height of the cable of a Secchi disk of certain dimensions lowered into the water.

Table 1.4

Characteristics of water transparency

Conclusion: Lakes are bodies of water occupying a natural depression on the earth's surface. There are a number of classifications of reservoirs with stagnant water, the main indicators of pollution of which are the degree of saprobity and trophic status. To classify lakes as water bodies of one kind or another in terms of saprobity and trophicity, their physical characteristics and species composition macrozoobenthos.

Transparency of sea water is the ratio of the radiation flux that has passed through water without changing direction, a path equal to unity, to the radiation flux that has entered the water in the form of a parallel beam. The transparency of sea water is closely related to the transmittance coefficient T of sea water, which is understood as the ratio of the radiation flux transmitted by a certain layer of water Iz to the radiation flux incident on this layer I0, i.e. Т = =e - с z. Transmittance is the opposite of light attenuation, and transmittance is a measure of how much light travels a certain length in seawater. Then the transparency of sea water will be Θ=e - c, which means that it is related to the light attenuation index c.

Along with the indicated physical definition of transparency, the concept is used conditional (or relative) n transparency, which is understood as the depth of cessation of visibility of a white disk with a diameter of 30 cm (Secchi disk).

The depth of disappearance of the white disk or relative transparency is related to the physical concept of transparency, since both characteristics depend on the light attenuation coefficient.

The physical nature of the disappearance of the disk at a certain depth is that when the light flux penetrates into the water column, it weakens due to scattering and absorption. In this case, with increasing depth, the flux of scattered light increases to the sides (due to higher-order scattering). At a certain depth, the laterally scattered flux turns out to be equal to the flux of direct light. Consequently, if the disk is lowered below this depth, then the flow scattered to the sides will be greater than the main flow going down, and the disk ceases to be visible.

According to the calculations of Academician V.V. Shuleikin, the depth at which the energies of the main flow and the flow scattered to the sides are equalized, corresponding to the depth of the disappearance of the disk, is equal for all seas to two natural light attenuation lengths. In other words, the product of the scattering index and transparency is a constant value equal to 2, i.e. k λ × z = 2, where z - depth of disappearance of the white disk. This relationship makes it possible to connect the conditional characteristic of sea water - relative transparency with a physical characteristic - the dispersion index k λ. Since the scattering index is an integral part of the attenuation index, it is possible to relate also the relative transparency with the attenuation index, and, consequently, with the physical characteristics of transparency. But since there is no direct proportionality between the absorption and scattering indices, the relationship between the attenuation index and transparency will be different in each sea.

Relative transparency depends on the height from which observations are made, the state of the sea surface, and lighting conditions.

As the observation altitude increases, the relative transparency increases due to a decrease in the influence of the light flux reflected from the sea surface, which interferes with observations.

During waves, the reflected flow increases and the flow penetrating into the depths of the sea weakens, which leads to a decrease in relative transparency. This was noticed in ancient times by pearl seekers who dived on the bottom of the sea with olive oil in your mouth. The oil released from their mouths floated to the surface of the sea, smoothed out small waves and improved the illumination of the bottom.

In the absence of clouds, the relative transparency decreases, since observations are hampered by solar glare. Heavy cumulus clouds significantly reduce the light flux incident on the sea surface, which also reduces relative transparency. The most favorable lighting conditions are created in the presence of cirrus clouds.

The largest number of optical observations relate to measurements of the relative transparency of the white disk.

Relative transparency varies greatly depending on the suspended solids content of seawater. In coastal waters rich in plankton, the relative transparency does not exceed several meters, and in the open ocean it reaches tens of meters.

The clearest waters are observed in the subtropical zone of the World Ocean. In the Sargasso Sea, the relative transparency is 66.5 m, and this sea is considered the standard of transparency. Such high transparency in the subtropical zone is associated with the almost complete absence of suspended particles and weak development of plankton. In the Weddell Sea and in the Pacific Ocean near the Tonga Islands, even higher transparency was measured - 67 m. In temperate and high latitudes, the relative transparency reaches 10-20 m.

In the seas, transparency varies widely. So, in the Mediterranean Sea it reaches 60 m, in the Japanese Sea - 30 m, Cherny - 28 m, Baltiysky - 11-13 m. In bays and especially near river mouths, transparency ranges from several centimeters to several tens of centimeters.

When considering the question of the color of the sea, two concepts are distinguished: the color of the sea and the color of sea water.

Under the color of the sea refers to the visible color of its surface. The color of the sea is strong depends on the optical properties of the water itself and on external factors . Therefore, it changes depending on external conditions (illumination of the sea by direct sunlight and diffused light, the angle of view, waves, the presence of impurities in the water, and other reasons).

Own color of sea water is a consequence of selective absorption and scattering, i.e. it depends on the optical properties of water and the thickness of the water layer in question, but does not depend on external factors. Taking into account the selective attenuation of light in the sea, it can be calculated that even for clear ocean water at a depth of 25 m, sunlight will be deprived of all the red part of the spectrum, then with increasing depth the yellow part will disappear and the color of the water will appear greenish, by a depth of 100 m only the blue part will remain and the color of the water will be blue. Therefore, we can talk about the color of water when we consider the thickness of the water. Moreover, depending on the thickness of the water, the color of the water will be different, although its optical properties do not change.

The color of sea water is assessed using a water color scale (Forel-Uhle scale), which consists of a set of test tubes with colored solutions. Determining the color of water consists of visually selecting a test tube whose solution color is closest to the color of the water. The color of the water is indicated by the number of the corresponding test tube on the color scale.

An observer standing on the shore or watching from a ship sees not the color of the water, but the color of the sea. In this case, the color of the sea is determined by the ratio of the magnitudes and spectral composition of the two main light fluxes entering the observer's eye. The first of them is the flow of light reflected by the surface of the sea, falling from the Sun and the vault of heaven, the second is the light flow of diffuse light emanating from the depths of the sea. So As the reflected flow is white, as it increases, the color of the sea becomes less saturated (whitish). When an observer looks vertically down at the surface, he sees a stream of diffuse light, and the reflected stream is small - the color of the sea is saturated. As the gaze moves toward the horizon, the color of the sea becomes less saturated (whitish), approaching the color of the sky, due to an increase in the reflected flow.

In the oceans there are vast expanses of dark blue water (the color of the ocean desert), indicating the absence of foreign impurities in the water and its exceptional transparency. As you approach the shores, there is a gradual transition to bluish-green, and in the immediate vicinity of the shores - to green and yellow-green tones (the color of biological productivity). Near the mouth of the Yellow River, which flows into the Yellow Sea, yellow and even brown tints of water predominate, due to the removal of a huge amount of yellow loess by the river.

The transparency of Lake B. Miassovo for most of the ice-free period fluctuates within 1-3-5 m and only shortly before freeze-up it increases to 6.5 m. In May, after the ice melts, and in the fall, starting from the end of August, the lowest water transparency is observed. The minimum transparency in spring and autumn depends on the massive development and death of phytoplankton and the entry of allochthonous suspensions into the water during ice melting and intense precipitation. An important role is played by spring and autumn homothermy, which promotes mixing and removal of sediments into the water column.[...]

The transparency of water depends on its color and the presence of suspended matter. . nnx substances.[...]

Water clarity is determined using a glass cylinder with a ground bottom (Snellen cylinder). The cylinder is graduated in height in centimeters, starting from the day. The height of the graduated part is 30 cm.[...]

The transparency of water to ultraviolet rays is one of its most important properties, due to which the decomposition of chemicals in all areas is possible environment. Effective wavelengths (approximately 290 nm) entering the atmosphere quickly lose energy and become almost inactive (450 nm). However, such radiation is sufficient to break a number of chemical bonds.[...]

The transparency of water depends on the amount of mineral and organic substances suspended and dissolved in it, and in the summer - on the development of algae. The color of water, which often reflects the content of dissolved substances in it, is also closely related to transparency. Transparency and color of water are important indicators of the state of the oxygen regime of a reservoir and are used to predict fish kills in ponds.[...]

Water transparency determines the amount of sunlight entering the water, and therefore the intensity of photosynthesis in aquatic plants. In turbid waters, photosynthetic plants live only at the surface, but in clear water they penetrate to great depths. The transparency of water depends on the amount of mineral particles suspended in it (clay, silt, peat), on the presence of small animals and plant organisms. [...]

Water transparency is one of the indicative signs of the level of development of life in water bodies and, along with thermals. chemistry and circulation conditions constitute the most important environmental factor.[...]

Clear water and bright sun require the use of baits with a matte surface or dull color. The fish-repellent shine of the bait can be easily and quickly extinguished by holding it over a piece of burning birch bark.[...]

Water transparency ranges from 1.5 m in summer to 9.5 m in winter, and in deep lakes it is much higher. [...]

The transparency of water depends on the amount and degree of dispersion of substances suspended in water (clay, silt, organic suspensions). It is expressed in centimeters of water column, through which lines 1 l m thick are visible, forming a cross (defined by the “cross”) or lead No. 1 (by Snellen or by the “font”). [...]

Water transparency is one of the main criteria for judging the condition of a reservoir. It depends on the amount of suspended particles, the content of dissolved substances and the concentration of phyto- and zooplankton. Affects the transparency and color of water. The closer the color of the water is to blue, the more transparent it is, and the yellower it is, the less transparent it is.[...]

Water transparency is a measure of the self-purification of open reservoirs and a criterion for the efficiency of treatment facilities. For the consumer, it serves as an indicator of the good quality of water.[...]

The color of the water in the lake experiences seasonal variations and is not uniform in various parts lakes, as well as transparency. So, in the open part of the lake. Baikal, with high transparency, the water has a dark blue color, in the Selenga shallow water area it is grayish-green, and near the river. Selenga is even brown. In Lake Teletskoye, in the open part, the color of the water is green, and near the shore it is yellow-green. The massive development of plankton not only reduces transparency, but also changes the color of the lake, giving it the color of the organisms in the water. During the bloom, green algae color the lake green color, blue-greens give it a turquoise color, diatoms give it a yellow color, and some bacteria color the lake crimson and red.[...]

Less clear water it heats up more strongly at the surface (in the case when there is no intense mixing of water due to wind or current). More intense heating has serious consequences. Since warm water has a lower density, the heated layer seems to “float” on the surface of cold and therefore heavier water. This effect of water stratification into almost non-mixing layers is called stratification of a water body (usually a body of water - a pond or lake).[...]

Typically, water transparency is correlated with biomass and plankton production. Under different conditions natural areas moderate pop, the lower the transparency, the better, on average, the plankton is developed, i.e. there is a negative correlation. Researchers pointed this out at the end of the last and beginning of this century. Further, the study of water transparency makes it possible to delineate the distribution of water masses of various genesis and indirectly judge the distribution of currents in reservoirs of slow water exchange [Butorin, 1969; Rumyantsev, 1972; Bogoslovsky et al., 1972; Vologdin, 1981; Ayers et al, 1958].[...]

Particulate matter and plankton suspended in the water, as well as snow and ice in winter, make it difficult for light to penetrate the water. Only 47% of light rays penetrate through a meter-thick layer of distilled water, and almost no light passes through dark water (for example, swamp lakes) to a depth of more than one meter. Approximately 50 cm of ice allows less than 10% of light to pass through. And if the ice is covered with snow, then only 1% of the light reaches the water. Of the light rays, green and blue penetrate deepest into clear water.[...]

Research on lake water transparency. B. Miassovo were carried out in 1996-1997, the results are presented in Fig. 11. Transparency measurements were carried out on the main measuring vertical using the standard Secchi disk method. The frequency of measurements is monthly.[...]

To determine the transparency of water directly in a reservoir, the Secchi method is used: a white enamel disk is lowered on a string into the reservoir; The depth in centimeters is noted at the following moments; a) when the visibility of the disk disappears and b) when it becomes visible when raised. The average of these two observations determines the transparency of the water in the reservoir.[...]

Lighting conditions in water can be very different and depend, in addition to the strength of illumination, on the reflection, absorption and scattering of light and many other reasons. A significant factor determining the illumination of water is its transparency. The transparency of water in different bodies of water is extremely diverse, ranging from the muddy, coffee-colored rivers of India, China and Central Asia, where an object immersed in water becomes invisible as soon as it is covered with water, and ending with the clear waters of the Sargasso Sea (transparency 66.5 m), central part Pacific Ocean(59 m) and a number of other places where the white circle - the so-called Secchi disk, becomes invisible to the eye only after diving to a depth of more than 50 m. Naturally, the lighting conditions in different bodies of water, located even at the same latitudes at the same same depth, are very different, not to mention different depths, because, as is known, with depth the degree of illumination quickly decreases. Thus, in the sea off the coast of England, 90% of the light is absorbed already at a depth of 8-9 M.[...]

Seasonal fluctuations in the transparency of lake waters include winter and autumn maximums and spring and summer minimums. Sometimes the summer minimum shifts by autumn months. In some lakes, the lowest transparency is caused by a large amount of sediment delivered by tributaries during high water and rain floods, in others - by the massive development of zoo- and phytoplankton (“blooming” of water), in others - by the accumulation of organic substances.[...]

The amount of coagulant introduced into water (mg/l, mg-eq/l, g/m3 or g-eq/m3) is called the coagulant dose. The minimum concentration of a coagulant that corresponds to the best clarification or discoloration of water is called the optimal dose. It is determined experimentally and depends on the salt composition, hardness, alkalinity of the water, etc. The optimal dose of the coagulant is considered to be its minimum amount, which during test coagulation gives large flakes and maximum water transparency after 15-20 minutes. For aluminum sulfate, this concentration usually ranges from 0.2 to 1.0 mEq/l (20-100 mg/l). During a flood, the dose of the coagulant increases by approximately 50%. At water temperatures below 4 ° C, the dose of aluminum coagulant is increased almost twice.[...]

When the source water contains suspended substances up to 1000 mg/l and a color value of up to 150 degrees, clarifiers ensure water transparency of at least 80-100 cm along the cross and a color value of no higher than 20 degrees of the platinum-cobalt scale. In this regard, in some cases, clarifiers without: filters are used. Clarifiers are designed to be round (diameter no more than 12-14 m) or rectangular (area no more than 100-150 m2). Typically, clarifiers operate without flocculation chambers.[...]

An important factor determining the transparency of water in stagnant bodies of water is biological processes. Water clarity is closely related to biomass and plankton production. The better developed the plankton, the less transparent the water. Thus, water transparency can characterize the level of development of life in a reservoir. Transparency has great importance as an indicator of the distribution of light (radiant energy) in the water column, on which photosynthesis and the oxygen regime of the aquatic environment primarily depend.[...]

Most of our planet is covered with water. The aquatic environment is a special habitat, since life in it depends on physical properties water, primarily on its density, on the amount of oxygen and carbon dioxide dissolved in it, on the transparency of the water, which determines the amount of light at a given depth. In addition, the speed of its flow and salinity are important for the inhabitants of water.[...]

For thousands of years, people have been trying to get clean water. Several centuries ago, the main efforts of people were aimed at obtaining clear water. For example, water purification in the early US water supply systems consisted mainly of removing sludge, and in many cases the reason for creating the first public water supply systems was simply the desire to eliminate dirty channels along streets and roads. Thus, almost until the beginning of the 20th century. the danger of infection through water was not the main argument in favor of creating public water supply systems. Before 1870, there were no water filtration plants in the United States. In the 70s of the 19th century, coarse sand filters were built on the river. Poughkeepsie and R. Hudson New York, and in 1893 the same filters were built in Lawrence, pcs. By 1897, more than 100 fine sand filters had been built, and by 1925 - 587 fine sand filters and 47 coarse sand filters, providing treatment for 19.4 million m3 of water.[...]

Primary production of phytoplankton correlates with water transparency (Vinberg, 1960; Romanenko, 1973; Baranov, 1979, 1980, 1981; Bouillon, 1979, 1983; Voltenvveider, 1958; Rodhe, 1966; Ahlgren, 1970]. Correlation coefficients d) between the transparency value , phytoplankton biomass and chlorophyll a content are quite reliable and amount to g = -0.48-0.57 for reservoirs of the BSSR [Ikonnikov, 1979]; Estonia - r = -0.43-0.60 [Milius, Kieask, 1982], Poland - r - -0.56, ponds in Alabama r = -0.79 [Alman, Boyd, 1978]. The average indicators of chlorophyll "a" content and water transparency according to the white disk for deep lakes are given in Table. 64.[...]

The indirect method of determining water transparency (optical density) is widely used. Optical density is determined by optoelectric devices - colorimeters and nephelometers, using calibration graphs. A number of photocolorimeters for general industrial use are produced (FEK-56, FEK-60, FAN-569, LMF, etc.), which are used at water treatment plants. However, this type of instrumental monitoring of the content of suspended substances in water is associated with large expenditures of labor and time for collecting and delivering water samples.[...]

A comparison of zooplankton biomass per unit area with transparency shows that in reservoirs of the tundra, northern and middle taiga, with increasing transparency, zooplankton biomass per unit area decreases. In lakes of the northern taiga, zooplankton biomass from 7.5 g/m1 with water transparency less than 1 m to 1.4 g/m3; with water transparency of more than 8 m, in lakes of average size from 5.78 g/m2 to 2.81 g/m2, respectively. [...]

Primary lakes, which arose when natural basins were filled with water, are gradually populated by plants and animals. Young lakes have clean, transparent water, their bottom is covered mainly with sand, and overgrowth is insignificant. Such lakes are called oligotrophic (from the Greek words oligos - “small”, and trophe - “nutrition”), i.e. low in nutrition. Gradually these lakes become saturated with organic matter. Dying aquatic organisms sink to the bottom, forming muddy bottom sediments, and serve as food for animals living on the bottom. Accumulate in water organic matter, secreted by animals and plants and remaining after their death. An increase in the amount of nutrients stimulates further development life in a pond.[...]

The upper pool of the Uglich hydroelectric power station turned out to be polluted. Despite the high water transparency of 130 cm, invertebrate filter feeders had a very low density; zebra mussels were absent.[...]

For preparing masonry mortar High Quality 1 Water hardness is of great importance. In order to determine the hardness or softness of water at home: by heating it, dissolve a small amount of crushed soap in it, after cooling the solution remains clear - the water is soft, in; When cooled, the solution becomes covered with a film when cooled. Except in hard water, soap foam does not rise.[...]

The average values ​​of ichthyomass in lakes in the middle taiga zone and in lakes in the mixed forest zone decrease with increasing transparency (Table 66).[...]

Characteristic of rhodanium compounds is a very insignificant effect on the organoleptic properties of water. Even at concentrations of substances greater than 100 mg/l, none of the testers indicated any noticeable change in the odor of the water; There was no change in color or transparency of the water. The ability of thiocyanates to impart flavor to water is somewhat more pronounced.[...]

Ukhta River: depth on average 5 m, channel with a large number of riffles on which communities of the genus Sparganium develop. Water transparency is up to 4 m, the bottom is silted sand, pebbles, silted pebbles. The temperature in July-August reaches 18°C. Kolva River: depth up to 7 m, water transparency up to 0.7 m, sandy bottom, temperature in July-August does not exceed 12°C. [...]

A photoelectronic installation for monitoring filter washing (index AOB-7) operates on the principle of weakening the light flux in a layer of water containing suspended substances. The absorption of light is recorded by a photocell connected to an indicating electrical measuring device of the MRSchPr type. The use of a simple phototurbidimetric technique for measuring water transparency is acceptable in this case, since filters are always washed with purified water with a low, almost constant water color. The primary sensor consists of a flow cell, a sealed chamber for a photocell, a chamber with an electric light bulb, and an electromagnet with hair brushes that periodically wipe the cell window. Secondary device indicating type MRShchPr or EPV. Their position regulators are used to stop washing the filters when the specified water transparency is reached.[...]

In general, it is impossible to put an end to the definition of the concept of a small river. Some works are based on studying the level of development of aquatic organisms. So, Yu.M. Lebedev (2001, p. 154) wrote: “The Small River is a watercourse with water transparency to the bottom, the absence of true phytoplankton and adult fish, except for slow-growing local populations of roach, perch, gudgeon (trout for mountain rivers and grayling for Siberian ones), and the predominance of scraper animals in the benthos.”[...]

The amount of incident solar radiation absorbed earth's surface, is a function of the absorptive capacity of that surface, i.e., depends on whether it is covered with soil, rock, water, snow, ice, vegetation or something else. Loose, cultivated soils absorb much more radiation than ice or rocks with a highly reflective surface. The transparency of water increases the thickness of the absorbing layer, and thus, a given layer of water absorbs more energy than the same thickness of opaque land.[...]

Natural E.e. occurs on a scale of millennia; it is currently suppressed by anthropogenic energy associated with human activity. EUTROFICATION (E.) - a change in the state of an aquatic ecosystem as a result of an increase in the concentration of nutrients in water, usually phosphates and nitrates. With E.v. Cyanobacteria and algae develop in very large quantities in plankton, water transparency sharply decreases, and the decomposition of dead phytoplankton consumes oxygen in the bottom zone. This sharply impoverishes the species composition of the ecosystem, almost all fish species die, plant species adapted to life in clean water(salvinia, amphibian buckwheat), and duckweed and hornwort are growing massively. E. is the scourge of many lakes and reservoirs located in densely populated areas.[...]

Photosynthetic release of oxygen occurs when carbon dioxide is absorbed by aquatic vegetation (attached, floating plants and phytoplankton). The process of photosynthesis proceeds more intensely, the higher the water temperature, the more biogenic (nutrients) substances (phosphorus compounds, nitrogen compounds, etc.) in the water. Photosynthesis is possible only in the presence of sunlight, since it, along with chemicals Photons of light are involved (photosynthesis occurs even in non-sunny weather and stops at night). The production and release of oxygen occurs in the surface layer of the reservoir, the depth of which depends on the transparency of the water (it can be different for each reservoir and season - from several centimeters to several tens of meters).[...]

This happened with the problem of the color of the sea: in 1921, the origin of the color of the sea was explained simultaneously by both Shuleikin (in Moscow) and Ch. Raman (in Calcutta). The area of ​​work of both authors was reflected in the interpretation of the issue: Raman, who dealt with the crystal clear waters of the Bay of Bengal, gave a theory of sea coloring based on the idea of ​​purely molecular scattering of light in water. Therefore, his theory is not applicable to seas that exhibit strong scattering of light in water.[...]

Vaamochka belongs to the estuary type of lakes, its depth does not exceed 2-3 m, water transparency is low. Pekulneyskoye is of fiord type, in the central part the depth varies from 10 to 20 m, and in the hall. Kakanaut fluctuate within 20-30 m. Lakes Vaamochka and Pekulneyskoye are connected to each other by channels, and through a common mouth, usually washed out in winter, to the Bering Sea. Compared to the lake. Vaamochka’s role in regulating the flow of Pekulneisky is much greater, since its area exceeds the area of ​​the lake. Vaamochka more than four times, and the catchment area is more than half of the total basin area of ​​the system. In this regard, from the beginning of the spring flood to the opening of the mouth, the flow in the channels is directed from the lake. Vaamochka to Pekulneyskoye, and after the opening of the mouth of Pekulneyskoye Lake is more susceptible to the influence of sea tides.[...]

In general, the requirements for environmental safety of water resource management are based on the implementation of water use plans developed taking into account the specified factors and processes that describe the state of aquatic ecosystems. The determining indicators of the state of aquatic ecosystems are: water purity class, saprobity index, species diversity index, as well as gross phytoplankton production [State Assessment..., 1992]. Parameters related to water quality also include such indicators as water transparency, pH value, content of nitrate ions and phosphate ions in water, electrical conductivity, biochemical oxygen consumption, etc.[...]

The need for fertilizer in ponds is determined by biological, organoleptic and chemical methods. The biological method consists of determining the intensity of photosynthesis in algae by observing the growth of algae in flasks into which different amounts of fertilizer are added and the development of algae in them is taken into account. More simply, the need for fertilizers can be determined by the transparency of the water. Fertilizers are applied when the water transparency is more than 0.5 m. The most accurate method is to chemically analyze the water for nitrogen and phosphorus content and bring them to a certain standard.[...]

As a result of these factors, the upper layer of the ocean is usually well mixed. That's what it's called - mixed. Its thickness depends on the time of year, wind strength and geographical area. For example, in the calm summer, the thickness of the mixed layer on the Black Sea is only 20-30 m. And in the Pacific Ocean near the equator, a mixed layer with a thickness of about 700 m was discovered (by an expedition on the research vessel "Dmitry Mendeleev"). From the surface to a depth of 700 m there was a layer of warm and clear water with a temperature of about 27 °C. This area of ​​the Pacific Ocean is similar in its hydrophysical properties to the Sargasso Sea in the Atlantic Ocean. In winter on the Black Sea, the mixed layer is 3-4 times thicker than the summer one, its depth reaches 100-120 m. Such a big difference is explained by intense mixing in winter: the stronger the wind, the greater the disturbance on the surface and the stronger the mixing. Such a jump layer is also called seasonal, since the depth of the layer depends on the season of the year.[...]

For hydrobiology, it is important that the classification of streams by size reflects ecosystem components. From this point of view, foreign studies are extremely interesting, demonstrating that in low-order watercourses the transit nature predominates, and in more large rivers- accumulative. This approach to classification, although attractive, is not very operational. It has been established that in the upper sections of the river network scrapers predominate among benthic animals, and below they are replaced by gatherers. It is also known that if water transparency exceeds the maximum depth of rivers, then periphyton algae develop in such watercourses, and true plankton is poorly represented. With increasing depths, the ecosystem acquires a planktonic character. Apparently, the last criterion can be chosen as the boundary between small and larger watercourses. Unfortunately, it is necessary, but not sufficient. So, for example, the Zeya in the upper reaches, according to its hydro-optical characteristics, can be classified as small, and its tributary in this section of the Arga, due to the high color of the water, is not transparent to the bottom. Therefore, the criterion must be supplemented. As you know, fish live in watercourses whose depth exceeds a certain minimum. For trout it is 0.1 m, for grayling - 0.5, for barbel - 1 m.

Sea water transparency- an indicator characterizing the ability of water to transmit rays of light. Depends on the size, quantity and nature of suspended substances. To characterize water transparency, the concept of “relative transparency” is used.

Story

For the first time, the degree of transparency of sea water was determined by an Italian priest and astronomer named Pietro Angelo Secchi in 1865 using a disk with a diameter of 30 cm, lowered into the water on a winch from the shadow side of the ship. This method later received his name. IN this moment Electronic instruments for measuring water transparency (transmissometers) exist and are widely used.

Methods for determining water transparency

There are three main methods for measuring water clarity. All of them involve determining the optical properties of water, as well as taking into account the parameters of the ultraviolet spectrum.

Areas of use

First of all, calculations of water transparency are an integral part of research in hydrology, meteorology and oceanology; the transparency/turbidity indicator determines the presence in water of undissolved and colloidal substances of inorganic and organic origin, thereby influencing marine pollution, and also allows us to judge accumulations plankton, turbidity content in water, silt formation. In shipping, the transparency of sea water can be a determining factor in detecting shoals or objects that can cause damage to a ship.

Sources

• Mankovsky V.I. An elementary formula for estimating the light attenuation index in sea water based on the depth of visibility of the white disk (Russian) // Oceanology. - 1978. - T. 18(4). - pp. 750–753.
• Smith, R. C., Baker, K. S. Optical properties of the clearest natural waters (200-800 nm)
• Gieskes, W. W. C., Veth, C., Woehrmann, A., Graefe, M. Secchi disc visibility world record shattered
• Berman, T., Walline, P. D., Schneller, A. Secchi disk depth record: A claim for the eastern Mediterranean
• Guidelines. Determination of temperature, odor, color (color) and transparency in wastewater, including treated wastewater, storm water and melt water. PND F 12.16.1-10

The transparency of water depends on the amount of mechanical suspended substances and chemical impurities it contains. Turbid water is always suspicious from an epizootic and sanitary point of view. There are several methods for determining water transparency.

Comparison method. The test water is poured into one colorless glass cylinder, and distilled water into the other. Water can be rated as clear, slightly clear, slightly opalescent, opalescent, slightly turbid, turbid and very turbid.

Disk method. To determine the transparency of water directly in a reservoir, a white enamel disk is used - a Secchi disk (Fig. 2). When a disc is immersed in water, the depth at which it ceases to be visible and at which it becomes visible again when removed is noted. The average of these two values ​​shows the transparency of the water in the reservoir. In clear water the disk remains visible at a depth of several meters; in very turbid water it disappears at a depth of 25-30 cm.

Type Method (Snellen). More accurate results are achieved when using a glass calorimeter with a flat bottom (Fig. 3). The calorimeter is installed at a height of 4 cm from standard font No. 1:

After shaking, the water to be tested is poured into the cylinder. Then they look down through the column of water at the font, gradually releasing water from the calorimeter tap until it is possible to clearly see font No. 1. The height of the liquid in the cylinder, expressed in centimeters, is a measure of transparency. Water is considered transparent if the font is clearly visible through a column of water of 30 cm. Water with a transparency of 20 to 30 cm is considered slightly turbid, from 10 to 20 cm - cloudy, up to 10 cm is unsuitable for drinking purposes. Good clear water does not produce sediment after standing.

Ring method. Water transparency can be determined using a ring (Fig. 3). To do this, use a wire ring with a diameter of 1-1.5 cm and a wire cross-section of 1 mm. Holding it by the handle, the wire ring is lowered into a cylinder with the water being tested until its contours become invisible. Then use a ruler to measure the depth (cm) at which the ring becomes clearly visible when removed. An indicator of acceptable transparency is considered to be 40 cm. The obtained data “by ring” can be converted into readings “by font” (Table 1).

Table 1

Converting water transparency values ​​“by ring” to values ​​“by font”