Thermal pollution

Overview

Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.

A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. When water used as a coolant is returned to the natural environment at a higher temperature, the change in temperature (a) decreases oxygen supply, and (b) affects ecosystem composition. Urban runoff--storm water discharged to surface waters from roads and parking lots--can also be a source of elevated water temperatures.

When a power plant first opens or shuts down for repair or other causes, fish and other organisms adapted to particular temperature range can be killed by the abrupt rise in water temperature known as 'thermal shock'.

As we will show a summary to the event of this pollution happening:

Raw materials for productivity (organic and inorganic products) Undergo different chemical reactions with several process Excess heat energy is produced as a waste product Heat is released through into atmosphere (vapor) and riverine system (liquid). Increase of temperature of environmental system  

And view of the pollution, global temperature had increased significantly.

Measurements of atmospheric temperature are done by meteorological center of the weather forecast annually, and the graph to detect the temperature trend from a period of 10 years will be compared with the previous batch of period. Thus we may be able to know the rate of temperature increase overall and make reference to the standard level of heat that should be maintain in the atmosphere to avoid large deviation of heat in the system.

Sources and MethodsWe can classify major sources that lead to thermal pollution to the following categories:

power plants creating electricity from fossil fuel water as a cooling agent in industrial facilities deforestation of the shoreline soil erosion

Sources and Methods of Thermal Pollution (4)

Major sources Methods of pollution

Power plants creating electricity from fossil fuel

1. Electricity is generated by heat stored in the fossil fuels and the stored energy creates a heat flow that drives turbine

2. The turbines then generate electricity3. All the electricity try to be organized so that it

may travel in the same direction in a small line4. Organization of this sort is created by man and

so it does not occur naturally

5. Excess heat is then created because of the unnatural processes of creating organization

Water as cooling agent heat exchangersexchange heat with other streams in the factory because there steps which needs heat while other steps generates heat, leaving streams no options for intermediate temperature 

Evaporate cooling

steam is used in many final heating processes. Cooling by condensation generates great amount of waste heat from factory. Cooling comes from evaporation because ambient air is not saturated with water. Air discharged from cooling tower is a direct contribution to global warming

Deforestation of shoreline

further contributes to the problem in two ways:

o aggravates soil erosion activity

o increases amount of light that strikes the water 

Soil erosion

sedimentation at lakes and streams makes the water muddy   muddy water lowers the clarity of water, with the introduction of impurities to the water, containing microbes and dissolved minerals, which increase the light absorption from the atmosphere 

Increase light absorption will see a rise in the temperature of water from the heat energy of light.

Why is it Harmful to Water Bodies?

Thermal pollution is detrimental to the aquatic life in the water body, especially if the water temperature historically supported a cold-water fishery and can no longer do so because of the temperature increase. To be considered a cold-water stream, the average range of temperatures during July must be from 14° to 19° C (41° to 55° F) and a warm water stream ranges from 22° to 26° C (68° to 77° F).

IMPACTS

All plant and animal species that live in water are adapted to temperatures within a certain range. When water in an area warms more than they can tolerate, species that cannot move, such as rooted plants and shellfish, will die. Species that can move, such as fish, will leave the area in search of cooler conditions, and they will die if they can not find them. Typically, other species, often less desirable, will move into the area to fill the vacancy.

In general, cold waters are better habitat for plants and animals than warm ones because cold waters contain more dissolved oxygen. Many freshwater fish species that are valued for sport and food, especially trout and salmon, do poorly in warm water. Some organisms do thrive in warm water, often with undesirable effects. Algae and other plants grow more rapidly in warm

water than in cold, but they also die more rapidly; the bacteria that decompose their dead tissue use up oxygen, further reducing the amount available for animals. The dead and decaying algae make the water look, taste, and smell unpleasant

EFFECTS OF THERMAL POLLUTION

Warm water typically decreases the level of dissolved oxygen in the water. The decrease in levels of dissolved oxygen can harm aquatic animals such as fish, amphibians and copepods. Thermal pollution may also increase the metabolic rate of aquatic animals, as enzyme activity, resulting in these organisms consuming more food in a shorter time than if their environment were not changed. An increased metabolic rate may result in food source shortages, causing a sharp decrease in a population. Changes in the environment may also result in a migration of organisms to another, more suitable environment and to in-migration of organisms that normally only live in warmer waters elsewhere. This leads to competition for fewer resources; the more adapted organisms moving in may have an advantage over organisms that are not used to the warmer temperature. As a result one has the problem of compromising food chains of the old and new environments. Biodiversity can be decreased as a result.

In the 1970s there was considerable activity from scientists in quantifying effects of thermal pollution. Hydrologists, physicists, meteorologists, and computer scientists combined their skills in one of the first interdisciplinary pursuits of the modern environmental science era. First came the application of Gaussian function dispersal modeling that forecasts how a

thermal plume is formed from a thermal point source and predicts the distribution of aquatic temperatures. The ultimate model was developed by the U.S. Environmental Protection Agency introducing the statistical variations in meteorology to predict the resulting plume from a thermal outfall.

Coal-burning power plants are known producers of thermal pollution in nearby bodies of water that they use as cooling ponds. This research focused on the effects that thermal pollution caused by the Marshall Steam Station had on Lake Norman, North Carolina. It was found that dissolved oxygen in the steam station's discharge cove was decreased by approximately four mg/L as compared to a site ten miles upstream, and was decreased by about three mg/L as compared to a cove several hundred yards downstream. Temperatures of the surface water in the discharge

1) Ecological effects — warm water

Elevated temperature typically decreases the level of dissolved oxygen (DO) in water. The decrease in levels of DO can harm aquatic animals such as fish, amphibians and copepods. Thermal pollution may also increase the metabolic rate of aquatic animals, as enzyme activity, resulting in these organisms consuming more food in a shorter time than if their environment were not changed. An increased metabolic rate may result in fewer resources; the more adapted organisms moving in may have an advantage over organisms that are not used to the warmer temperature. As a result one has the problem of compromising food chains of the old and new environments. Biodiversity can be decreased as a result.

It is known that temperature changes of even one to two degrees Celsius can cause significant changes in organism metabolism and other adverse cellular biology effects. Principal adverse changes can include rendering cell walls less permeable to necessary osmosis, coagulation of cell proteins, and alteration of enzyme metabolism. These cellular level effects can adversely affect mortality and reproduction.

Primary producers are affected by warm water because higher water temperature increases plant growth rates, resulting in a shorter lifespan and species overpopulation. This can cause an algae bloom which reduces oxygen levels.

A large increase in temperature can lead to the denaturing of life-supporting enzymes by breaking down hydrogen- and disulphide bonds within the quaternary structure of the enzymes. Decreased enzyme activity in aquatic organisms can cause problems such as the inability to break down lipids, which leads to malnutrition.

In limited cases, warm water has little deleterious effect and may even lead to improved function of the receiving aquatic ecosystem. This phenomenon is seen especially in seasonal waters and is known as thermal enrichment. An extreme case is derived from the aggregational habits of the manatee, which often uses power plant discharge sites during winter. Projections suggest that manatee populations would decline upon the removal of these discharges.

Ecological effects — cold water

Releases of unnaturally cold water from reservoirs can dramatically change the fish and macro invertebrate fauna of rivers, and reduce river productivity. In Australia, where many rivers have warmer temperature regimes, native fish species have been eliminated, and macro invertebrate fauna have been drastically altered.

2) Physical and chemical effects

Water is naturally constituted of chemical components (metals, salts, trace elements, gases, carbonates,) in balance. A change in temperature can modify it and accelerate chemical and biochemical reactions: it is a catalyst. For example, the hotter the temperature of rejected water is, the more its effects on benthic organizations are harmful.

An effect of thermal pollution

An increase in temperature can also cause a reduction of solubility. It's an important consequence because the amount of dissolved oxygen (DO) in water decreases. This makes it more difficult for fish and other aquatic organisms to obtain the necessary oxygen for cellular respiration. But, in the first part, we could see that the seaweeds rate increase, so, they use up more O2: there is a lack of oxygen so aquatic living beings are asphyxiated. Another

repercussion of this phenomenon is taste and odor. In fact, products which are in water become more volatile, it is why there are impacts on the surrounding air.

Salinity is an important measurement in biology because salt is dissolved in the bodily fluids of all living things. The level of dissolved salts in a fluid controls many of the processes of life. Most animals are adapted to a narrow range of salinity and cannot live in water that is outside that range. But, when the temperature of water increases, salinity decreases so, there are important repercussions on aquatic life.

 

       A particular problem is the stratification in lakes. Because of density difference, layers of different temperature are formed in accordance with the depth of water. So the temperature of water changes suddenly with the depth. These have consequences on fauna and flora, which modifies the landscape.

Stratification in lakes

Increase in temperature = Reduction of solubility

Increase in temperature = Change of salinity

Change in temperature = Stratification

3) Biological effects of this pollution

Temperature is an important factor for life. So, an increase, or a reduction, of this one can destroy ecologic niches, which are very sensitive to little variation of their environment. Their disappearance is followed by that of the fauna and flora living there.

        Producing or catching heat in or from a source of water can involve the death of micro-organisms by thermal shock. This problem also affects other living beings that feed on it, and so on and so forth. So, the tropic chain is broken.

        We have presented you the problem of the destruction of nature, but this pollution can also generate the proliferation of bacteria that occupy the niches of other types of living beings. So, almost the same result is achieved through another way ... Secondly, with a higher temperature, algae grow much more rapidly. They use up dissolved oxygen (DO) in water, block the sunlight from getting to the submerged aquatic vegetation (SAV), and the entire ecosystem suffers.

Proliferation of algae

Temperature directly affects the physiology of fish. So, thermal pollution has a direct impact on the evolution of life. Metabolism can change up to the lethal limit. It varies and is affected by oxygen level and salinity (these properties will be presented in the second part: physical and chemical effects).

Increase \ reduction in temperature = Destruction of fauna and flora

Increase in temperature = Proliferation of bacteria \ reduction of O2

Control of thermal pollution

Industrial wastewaterIn the United States, thermal pollution from industrial sources is generated mostly by power plants, petroleum refineries, pulp and paper mills, chemical plants, steel mills and smelters. Heated water from these sources may be controlled with:

cooling ponds, man-made bodies of water designed for cooling by evaporation, convection, and radiation

cooling towers, which transfer waste heat to the atmosphere through evaporation and/or heat transfer

Cogeneration, a process where waste heat is recycled for domestic and/or industrial heating purposes.

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Cooling tower at Gustav Knepper Power Station, Dortmund, Germany

Some facilities use once-through cooling (OTC) systems which do not reduce temperature as effectively as the above systems. For example, the Potrero Generating Station in San

Francisco, which uses OTC, discharges water to San Francisco Bay approximately 10°C (20°F) above the ambient bay temperature

Potrero Generating Station discharges heated water into San Francisco Bay.

Urban runoffDuring warm weather, urban runoff can have significant thermal impacts on small streams, as storm water passes over hot parking lots, roads and sidewalks. Storm water management facilities that absorb runoff or direct it into groundwater, such as bioretention systems and infiltration basins, can reduce these thermal effects. Retention basins tend to be less effective at reducing temperature, as the water may be heated by the sun before being discharged to a receiving stream.

Conclusion

Thermal pollution is a problem that we have to deal with more and more. This pollution is principally located in rivers and waterways nearby industries. Even if we can't see immediately the effects of  thermal pollution it has an impact on our environment. So, scientists have to research solutions to reduce it (heat!!).

        When prevention is inefficient, industries use some techniques to solve thermal pollution. The first technique is the control by dilution; it consists in diluting warm water in cool water to decrease the impact on water life. Another solution is to use cooling towers to transfer heat from water to the atmosphere. The last one is the discharging of heated water in shallow ponds and canals. The last two are very much used even if the last one is the least costly.

 

When I think about pollution I usually envision smoke stacks spewing out black clouds. Most of us do right? What do you think of when I say "thermal pollution"? Nothing coming to mind? The word "thermal", in a general sense, refers to heat. Heat pollution sounds weird though, doesn't it? The most common example of it is the urban heat island. Due to the increased amounts of asphalt, concrete, and air pollution, plus the decrease in vegetation, cities tend to be warmer than the surrounding areas. Just about every large city experiences it, even traditionally hot cities like Phoenix.

Check out this table. The population in Phoenix has gone from 28,000 in 1900 to over 4 million presently. To support that kind of population you have to create roads and buildings, and a lot of them.

Table 1. Population of the Phoenix Metropolitan Area (U.S. Census Bureau, 2008).

Year 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2006

Population (in 28 44 106 173 215 375 726 1,035 1,670 2,238 3,252 4,039

thousands)

Now check out this graph. This is the population projection through 2025. Phoenix will have 6.5 million people!

So, has the population explosion in Phoenix affected temperatures? Check out this graph.

t shows the number of 110 degree days, by decade. The numbers don't lie. Phoenix is experiencing warmer summers now than at anytime in modern history. In fact, last summer, Phoenix had an astounding 32 days above 110 degrees! The meteorologists at the National Weather Service in Phoenix attribute the increase to urbanization and regional/global climate change. It's hard to argue that cities don't affect micro-climates in a noticeable way.

What do you think? Do you live in a big city? Do you feel like the temperatures are getting warmer? I'd like to know your thoughts.

I've realized that it's a really big issue on our planet but really hasn't been dealt with at all. There could be severe consequences if this isn't solved or at least reduced. The main sources causing thermal pollution are power plants, industrial facilities, the deforestation of the shoreline, and soil erosion.

The water temperature of a river is very important for water quality. Many of the physical, biological, and chemical characteristics of a river are directly affected by temperature. For example, temperature influences:

1. the amount of oxygen that can be dissolved in water; 2. the rate of photosynthesis by algae and larger aquatic plants;3. the metabolic rates of aquatic organisms;4. the sensitivity of organisms to toxic wastes, parasites, and diseases.

Remember, cool water can hold more oxygen than warm water, because gases are more easily dissolved in cool water.

Human-Caused Changes in Temperature

One of the most serious ways that humans change the temperature of rivers and lakes is through thermal pollution. Thermal pollution is an increase in water temperature caused by adding relatively warm water to a body of water. Industries, such as nuclear power plants, may cause thermal pollution by discharging water used to cool machinery. Thermal pollution may also come from stormwater running off warmed urban surfaces, such as streets, sidewalks, and parking lots.

People also affect water temperature by cutting down trees that help shade the river, exposing the water to direct sunlight.

Soil erosion can also contribute to warmer water temperatures. Soil erosion can be caused by many types of activities, including the removal of streamside vegetation, overgrazing, poor farming practices, and construction. Soil erosion raises water temperatures because it increases the amount of suspended solids carried by the river, making the water cloudy (turbid). Cloudy water absorbs the sun's rays, causing water temperature to rise.

Changes in Aquatic Life

As water temperature rises, the rate of photosynthesis and plant growth also increases. More plants grow and die. As plants die, they are decomposed by bacteria that consume oxygen. Therefore, when the rate of photosynthesis is increased, the need for oxygen in the water (BOD) is also increased.

The metabolic rate of organisms also rises with increasing water temperatures, resulting in even greater oxygen demand. The life cycles of aquatic insects tend to speed up in warm water. Animals that feed on these insects can be negatively affected, particularly birds that depend on insects emerging at key periods during their migratory flights.

Most aquatic organisms have adapted to survive within a range of water temperatures, Some organisms prefer cooler water, such as trout, stonefly nymphs, while others thrive under warmer conditions, such as carp and dragonfly nymphs. As the temperature of a river increases, cool water species will be replaced by warm water organisms. Few organisms can tolerate extremes of heat or cold.

Temperature also affects aquatic life's sensitivity to toxic wastes, parasites, and disease. For example, thermal pollution may cause fish to become more vulnerable to disease, either due to the stress of rising water temperatures or the resulting decrease in dissolved oxygen.

Sampling Procedure

The temperature test measures the change in water temperature between two points, the test site and a site one mile upstream. By detecting significant temperature changes along a section of the river, we can begin to uncover the sources of thermal pollution.

Because the temperature test compares the difference in water temperature at two different stream sites, it is important to match as closely as possible the physical conditions at these sites - current speed, amount of sunlight reaching the water, and the depth of the stream.

To reduce errors, the same thermometer should be used at both sites. Rubber gloves should be worn if there is any chance that hands might come in contact with the water.

Temperature Testing Procedure

1. At the site where the other water quality tests are being performed, lower the thermometer four inches below the water surface.

2. Keep the thermometer in the water until a constant reading is attained (approximately two minutes).

3. Record your measurement in Celsius.4. Repeat the test approximately one mile upstream as soon as possible. 5. Subtract the upstream temperature from the temperature downstream using the

following equation: temp. downstream - temp. upstream = temp. change 6. Record the change in temperature.

portrero generating stations outflow

Sulphur Dioxide Chokes Bulgaria's Dimitrovgrad Once Again

Poisonous emissions from the thermal power plants of the Maritza-Iztok Complex are the cause for the elevated concentration of sulphur dioxide in the town of Dimitrovgrad Tuesday. Photo by BGNES.

Yet another high concentration of sulphur dioxide in the southern Bulgarian town of Dimitrovgrad was reported Tuesday.

The pollution monitoring system in the town detected levels of the chemical substance exceeding the permitted threshold of 350 micrograms per cubic meter at 3 pm and 4 pm.

Poisonous emissions from the thermal power plants of the Maritza-Iztok Complex are the cause for the elevated concentration of sulphur dioxide in the area.

Even though nuclear power plants do not cause air pollution, they are a conspicuous source of thermal pollution. Nuclear power plants are usually built near large water reservoirs such as lakes, rivers or oceans due to requirement for cooling water. Although the water used for cooling purposes in plant condensers is recycled before returning to the source, its temperature remains significantly high and may have severe impacts.

Effects of Thermal Pollution

The residual heat released by power plants adds to the environment and impacts its inhabitants harshly. Since hot water holds relatively less oxygen; many species in these habitats face difficulty in survival. The cooling towers used in power plants release heat directly into the atmosphere, which raises the air temperature drastically, thus contributing to global warming .

Water heating due to thermal pollution alters marine ecology to a great extent; hotter water favors some species while it is harmful to others. In a similar way, during nuclear plant startup, shutdown for repair and maintenance and then sudden startup creates abrupt temperature changes in water contained in lakes. These thermal shocks can be lethal for certain aquatic species.

How to Control Thermal Pollution

The problem of thermal pollution is unavoidable. It can be reduced, however. Engineers can make efforts to ensure minimum heat losses by improving thermal efficiencies of heat engines. Nonetheless, the best solution is to reduce consumption of fossil fuels and to limit

day-to-day energy usage. The development of alternative energy resources such as solar power, wind energy and hydropower can also be beneficial.

The Problem of Thermal Pollution

Thermal pollution is caused by burning of fossil fuels in cars and power plants. Nuclear power plants are also a significant source of heat release to lakes and rivers. The excessive heat discharged to the environment damages aquatic species and contributes to global warming. The problem can be countered by reducing fossil fuel consumption and dedicating less energy for daily needs. Efficiency improvement of heat engines and development of alternative energy resources can also help.