reports ecology

8/14/2019 Reports Ecology

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Report 1

Biogeochemical Cycle (Nitrogen Cycle, Oxygen Cycle, Carbon Cycle)

Nitrogen Cycle

The main component of the nitrogen cycle starts with the element nitrogen in the

air. Two nitrogen oxides are found in the air as a result of interactions with oxygen.Nitrogen will only react with oxygen in the presence of high temperatures and pressuresfound near lightning bolts and in combustion reactions in power plants or internalcombustion engines. Nitric oxide, NO, and nitrogen dioxide, NO2, are formed underthese conditions. Eventually nitrogen dioxide may react with water in rain to form nitricacid, HNO3. The nitrates thus formed may be utilized by plants as a nutrient.

Nitrogen in the air becomes a part of biological matter mostly through the actionsof bacteria and algae in a process known as nitrogen fixation. Legume plants such asclover, alfalfa, and soybeans form nodules on the roots where nitrogen fixing bacteriatake nitrogen from the air and convert it into ammonia, NH3. The ammonia is furtherconverted by other bacteria first into nitrite ions, NO2-, and then into nitrate ions, NO3-.Plants utilize the nitrate ions as a nutrient or fertilizer for growth. Nitrogen is incorporatein many amino acids which are further reacted to make proteins.

Ammonia is also made through a synthetic process called the Haber Process.Nitrogen and hydrogen are reacted under great pressure and temperature in thepresence of a catalyst to make ammonia. Ammonia may be directly applied to farm fieldsas fertilizer. Ammonia may be further processed with oxygen to make nitric acid. Thereaction of ammonia and nitric acid produces ammonium nitrate which may then be usedas a fertilizer. Animal wastes when decomposed also return to the earth as nitrates.

To complete the cycle other bacteria in the soil carry out a process known asdenitrification which converts nitrates back to nitrogen gas. A side product of thisreaction is the production of a gas known as nitrous oxide, N2O. Nitrous oxide, alsoknown as "laughing gas" - mild anesthetic, is also a greenhouse gas which contributes toglobal warming.

Oxygen Cycle

Oxygen, like carbon and hydrogen, is a basic element of life. In addition, in theform of O3, ozone, it provides protection of life by filtering out the sun's UV rays as theyenter the stratosphere. In addition to constituting about 20% of the atmosphere, oxygenis ubiquitous. It also occurs in combination as oxides in the Earth's crust and mantle, andas water in the oceans. Early in the evolution of the Earth, oxygen is believed to havebeen released from water vapor by UV radiation and accumulated in the atmosphere asthe hydrogen escaped into the earth's gravity. Later, photosynthesis became a source ofoxygen. Oxygen is also released as organic carbon in CHO, and gets buried insediments. The role of oxygen in life is describe in the unit on Biological Systems.
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Oxygen is highly reactive. A colorless, odorless gas at ordinary temperatures, itturns to a bluish liquid at -183 C. Burning or combustion is essentially oxidation, orcombination with atmospheric oxygen. Figure O1 shows a very broad overview ofoxygen cycling in nature. The environment of oxygen in numerous reactions makes ithard to present a complete picture.

Oxygen is vital to us in many ways (beside the most obvious--for breathing).Water can dissolve oxygen and it is this dissolved oxygen that supports aquatic life.Oxygen is also needed for the decomposition of organic waste. Wastes from livingorganisms are "biodegradable" because there are aerobic bacteria that convert organicwaste materials into stable inorganic materials. If enough oxygen is not available forthese bacteria, for example, because of enormous quantities of wastes in a body ofwater, they die and anaerobic bacteria that do not need oxygen take over. Thesebacteria change waste material into H2S and other poisonous and foul-smellingsubstances. For this reason, the content of biodegradable substances in waste waters isexpressed by a special index called "biological oxygen demand" (BOD), representing theamount of oxygen needed by aerobic bacteria to decompose the waste. The result of notmeeting the oxygen demand is described in the section on the water cycle.

Carbon Cycle

Carbon is the fourth most abundant element in the universe, and is absolutelyessential to life on earth. In fact, carbon constitutes the very definition of life, as itspresence or absence helps define whether a molecule is considered to be organic orinorganic. Every organism on Earth needs carbon either for structure, energy, or, as inthe case of humans, for both. Discounting water, you are about half carbon. Additionally,carbon is found in forms as diverse as the gas carbon dioxide (CO 2), and in solids likelimestone (CaCO3), wood, plastic, diamonds, and graphite. The movement of carbon, inits many forms, between the atmosphere, oceans, biosphere, and geosphere isdescribed by the carbon cycle (Figure 1). This cycle consists of several storage pools of

carbon (black text) and the processes by which the various pools exchange carbon(purple arrows and numbers). If more carbon enters a pool than leaves it, that pool isconsidered a net carbon sink. If more carbon leaves a pool than enters it, that pool isconsidered net carbon source. The global carbon cycle, one of the majorbiogeochemical cycles, can be divided into geological and biological components. Thegeological carbon cycle operates on a time scale of millions of years, whereas thebiological carbon cycle operates on a time scale of days to thousands of years.

The geological carbon cycle:

The geological component of the carbon cycle is where it interacts with the rockcycle in the processes ofweathering and dissolution, precipitation ofminerals, burial andsubduction, and volcanism (see our The Rock Cycle module for information). In theatmosphere, carbonic acid forms by a reaction with atmospheric carbon dioxide (CO2)and water. As this weakly acidic water reaches the earth as rain, it reacts with mineralsat the earths surface, slowly dissolving them into their component ions through theprocess of chemical weathering. These component ions are carried in surface waterslike streams and rivers eventually to the ocean, where they precipitate out as mineralslike calcite (CaCO3). Through continued deposition and burial, this calcite sedimentforms the rock called limestone.
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This cycle continues as seafloor spreading pushes the seafloor under continentalmargins in the process ofsubduction. As seafloor carbon is pushed deeper into the earthby tectonic forces, it heats up, eventually melts, and can rise back up to the surface,where it is released as CO2 and returned to the atmosphere. This return to theatmosphere can occur violently through volcanic eruptions, or more gradually in seeps,vents, and CO2-rich hotsprings. Tectonic uplift can also expose previously buried

limestone. One example of this occurs in the Himalayas where some of the worldshighest peaks are formed of material that was once at the bottom of the ocean.Weathering, subduction, and volcanism control atmospheric carbon dioxideconcentrations over time periods of hundreds of millions of years.

The Biological carbon cycle:

Biology plays an important role in the movement of carbon between land, ocean,and atmosphere through the processes of photosynthesis and respiration. Virtually allmulticellular life on Earth depends on the production of sugars from sunlight and carbondioxide (photosynthesis) and the metabolic breakdown (respiration) of those sugars toproduce the energy needed for movement, growth, and reproduction. Plants take in

carbon dioxide (CO2) from the atmosphere during photosynthesis, and release CO2 backinto the atmosphere during respiration through the following chemical reactions:

Respiration:

C6H12O6 (organic matter) + 6O2 6CO2 + 6 H2O + energy

Photosynthesis:

energy (sunlight) + 6CO2 + H2O C6H12O6 + 6O2

Through photosynthesis, green plants use solar energy to turn atmosphericcarbon dioxide into carbohydrates (sugars). Plants and animals use these carbohydrates

(and otherproducts derived from them) through a process called respiration, the reverseof photosynthesis. Respiration releases the energy contained in sugars for use inmetabolism and changes carbohydrate fuel back into carbon dioxide, which is in turnreleased to back to the atmosphere. The amount of carbon taken up by photosynthesisand released back to the atmosphere by respiration each year is about 1,000 timesgreater than the amount of carbon that moves through the geological cycle on an annualbasis.

On land, the major exchange of carbon with the atmosphere results fromphotosynthesis and respiration. During daytime in the growing season, leaves absorbsunlight and take up carbon dioxide from the atmosphere. At the same time plants,animals, and soil microbes consume the carbon in organic matter and return carbon

dioxide to the atmosphere. Photosynthesis stops at night when the sun cannot providethe driving energy for the reaction, though respiration continues. This kind of imbalancebetween these two processes is reflected in seasonal changes in the atmospheric CO 2concentrations. During winter in the northern hemisphere, photosynthesis ceases whenmany plants lose their leaves, but respiration continues. This condition leads to anincrease in atmospheric CO2 concentrations during the northern hemisphere winter. Withthe onset of spring, however, photosynthesis resumes and atmospheric CO2concentrations are reduced. This cycle is reflected in the monthly means (the light blueline) of atmospheric carbon dioxide concentrations shown in Figure 2.
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In the oceans, phytoplankton (microscopic marine plants that form the base ofthe marine food chain) use carbon to make shells of calcium carbonate (CaCO 3 ). Theshells settle to the bottom of the ocean when phytoplankton die and are buried in thesediments. The shells of phytoplankton and other creatures can become compressedover time as they are buried and are often eventually transformed into limestone.Additionally, under certain geological conditions, organic matter can be buried and over

time form deposits of the carbon-containing fuels coal and oil. It is the non-calciumcontaining organic matter that is transformed into fossil fuel. Both limestone formationand fossil fuel formation are biologically controlled processes and represent long-termsinks for atmospheric CO2.

Human Alteration of the Carbon Cycle

Recently, scientists have studied both short- and long-term measurements ofatmospheric CO2 levels. Charles Keeling, an oceanographer at the Scripps Institute ofOceanography, is responsible for creating the longest continuous record of atmosphericCO2 concentrations, taken at the Mauna Loa observatory in Hawaii. His data (now widelyknown as the Keeling curve, shown in Figure 2) revealed that human activities are

significantly altering the natural carbon cycle. Since the onset of the industrial revolutionabout 150 years ago, human activities such as the burning of fossil fuels anddeforestation have accelerated, and both have contributed to a long-term rise inatmospheric CO2. Burning oil and coal releases carbon into the atmosphere far morerapidly than it is being removed, and this imbalance causes atmospheric carbon dioxideconcentrations to increase. In addition, by clearing forests, we reduce the ability ofphotosynthesis to remove CO2 from the atmosphere, also resulting in a net increase.Because of these human activities, atmospheric carbon dioxide concentrations arehigher today than they have been over the last half-million years or longer.

Because CO2 increases the atmospheres ability to hold heat, it has been calleda greenhouse gas. Scientists believe that the increase in CO2 is already causing

important changes in the global climate. Many attribute the observed 0.6 degree Cincrease in global average temperature over the past century mainly to increases inatmospheric CO2. Without substantive changes in global patterns of fossil fuelconsumption and deforestation, warming trends are likely to continue. The best scientificestimate is that global mean temperature will increase between 1.4 and 5.8 degrees Cover the next century as a result of increases in atmospheric CO2 and other greenhousegases. This kind of increase in global temperature would cause significant rise inaverage sea-level (0.09-0.88 meters), exposing low-lying coastal cities or cities locatedby tidal rivers such as New Orleans, Portland, Washington, and Philadelphia toincreasingly frequent and severe floods. Glacial retreat and species range shifts are alsolikely to result from global warming, and it remains to be seen whether relativelyimmobile species such as trees can shift their ranges fast enough to keep pace with

warming.

Even without the changes in climate, however, increased concentrations of CO2could have an important impact on patterns of plant growth worldwide. Because somespecies of plants respond more favorably to increases in CO2 than others, scientistsbelieve we may see pronounced shifts in plant species as a result of increasingatmospheric CO2 concentrations, even without any change in temperature. For example,under elevated CO2 conditions, shrubs are thought to respond more favorably than
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certain grass species due to their slightly different photosynthetic pathway. Because ofthis competitive inequality, some scientists have hypothesized that grasslands will beinvaded by CO2-responsive grass species or shrubby species as CO2 increases.

Report 2

Problems Associated with Rapid Population Growth

Effects of overpopulation

Some problems associated with or exacerbated by human overpopulation:

Inadequate fresh water fordrinking wateruse as well as sewage treatment andeffluent discharge. Some countries, like Saudi Arabia, use energy-expensivedesalination to solve the problem of water shortages.

Depletion of natural resources, especially fossil fuels. Increased levels of airpollution, water pollution, soil contamination and noise pollution. Once a countryhas industrialized and become wealthy, a combination of government regulationand technological innovation causes pollution to decline substantially, even asthe population continues to grow.

Deforestation and loss of ecosystems that sustain global atmospheric oxygen

and carbon dioxide balance; about eight million hectares of forest are lost eachyear.

Changes in atmospheric composition and consequent global warming Irreversible loss ofarable land and increases in desertification. Deforestation and

desertification can be reversed by adopting property rights, and this policy issuccessful even while the human population continues to grow. Mass speciesextinctions from reduced habitat in tropical forests due to slash-and-burntechniques that sometimes are practiced by shifting cultivators, especially incountries with rapidly expanding rural populations; present extinction rates maybe as high as 140,000 species lost per year.[146] As of 2008, the IUCN Red Listlists a total of 717 animal species having gone extinct during recorded humanhistory.

High infant and child mortality. High rates of infant mortality are caused bypoverty. Rich countries with high population densities have low rates of infantmortality.

Intensive factory farming to support large populations. It results in human threatsincluding the evolution and spread of antibiotic resistant bacteria diseases,excessive air and water pollution, and new virus that infect humans.

Increased chance of the emergence of new epidemics and pandemics. For manyenvironmental and social reasons, including overcrowded living conditions,
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malnutrition and inadequate, inaccessible, or non-existent health care, the poorare more likely to be exposed to infectious diseases.

Starvation, malnutrition or poor diet with ill health and diet-deficiency diseases(e.g. rickets). However, rich countries with high population densities do not havefamine.

Poverty coupled with inflation in some regions and a resulting low level of capital

formation. Poverty and inflation are aggravated by bad government and badeconomic policies. Many countries with high population densities have eliminatedabsolute poverty and keep their inflation rates very low.

Low life expectancy in countries with fastest growing populations Unhygienic living conditions for many based upon water resource depletion,

discharge of raw sewage and solid waste disposal. However, this problem can bereduced with the adoption of sewers. For example, after Karachi, Pakistaninstalled sewers, its infant mortality rate fell substantially.

Elevated crime rate due to drug cartels and increased theft by people stealingresources to survive

Conflict over scarce resources and crowding, leading to increased levels ofwarfare

Lower wages. In the supply and demand economic model, an increase in thenumber of workers (supply-increase) results in lower demand and wages fall(price-decrease) as more people compete for available work.

Less Personal Freedom / More Restrictive Laws. Laws regulate interactionsbetween humans. Law "serves as a primary social mediator of relations betweenpeople." The higher the population density, the more frequent such interactionsbecome, and thus there develops a need for more laws to regulate theseinteractions.

Some economists, such as Thomas Sowell and Walter E. Williams have argued thatthird world poverty and famine are caused by bad government and bad economicpolicies, and not by overpopulation. Most biologists and sociologists see overpopulation

as a serious problem.

Mitigation measures

While the current world trends are not indicative of any realistic solution to humanoverpopulation during the 21st century, there are several mitigation measures that haveor can be applied to reduce the adverse impacts of overpopulation.

Overpopulation is related to the issue of birth control; some nations, like thePeople's Republic of China, use strict measures to reduce birth rates. Religious andideological opposition to birth control has been cited as a factor contributing tooverpopulation and poverty.] Some leaders and environmentalists (such as Ted Turner)have suggested that there is an urgent need to strictly implement a China-like one-childpolicy globally by the United Nations, because this would help control and reducepopulation gradually and most successfully as is evidenced by the success and resultanteconomic-growth of China due to reduction ofpoverty in recent years.

Indira Gandhi, late Prime Minister of India, implemented a forced sterilizationprogramme in the 1970s. Officially, men with two children or more had to submit tosterilization, but many unmarried young men, political opponents and ignorant men were
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also believed to have been sterilized. This program is still remembered and criticized inIndia, and is blamed for creating a wrong public aversion to family planning, whichhampered Government programmes for decades.

Urban designerMichael E. Arth has proposed a "choice-based, marketable birthlicense plan" he calls "birth credits." Birth credits would allow any woman to have as

many children as she wants, as long as she buys a license for any children beyond anaverage allotment that would result in zero population growth (ZPG). If that allotmentwas determined to be one child, for example, then the first child would be free, and themarket would determine what the license fee for each additional child would cost. Extracredits would expire after a certain time, so these credits could not be hoarded byspeculators. Another advantage of the scheme is that the affluent would not buy thembecause they already limit their family size by choice, as evidenced by an average of 1.1children per European woman. The actual cost of the credits would only be a fraction ofthe actual cost of having and raising a child, so the credits would serve more as a wake-up call to women who might otherwise produce children without seriously consideringthe long term consequences to themselves or society.

Education and empowerment

One option is to focus on education about overpopulation, family planning, and birthcontrol methods, and to make birth-control devices like male/female condoms and pillseasily available. An estimated 350 million women in the poorest countries of the worldeither did not want their last child, do not want another child or want to space theirpregnancies, but they lack access to information, affordable means and services todetermine the size and spacing of their families. In the developing world, some 514,000women die annually of complications from pregnancy and abortion. Additionally, 8 millioninfants die, many because ofmalnutrition or preventable diseases, especially from lackof access to clean drinking water. In the United States, in 2001, almost half ofpregnancies were unintended.Egypt announced a program to reduce its overpopulation

by family planning education and putting women in the workforce. It was announced inJune 2008 by the Minister of Health and Population Hatem el-Gabali. The governmenthas set aside 480 million Egyptian pounds (about 90 million U.S. dollars) for theprogram.

Extraterrestrial settlement

In the 1970s, Gerard O'Neill suggested building space habitats that could support30,000 times the carrying capacity of Earth using just the asteroid belt and that the solarsystem as a whole could sustain current population growth rates for a thousand years.Marshall Savage (1992, 1994) has projected a human population of five quintillionthroughout the solar system by 3000, with the majority in the asteroid belt. Arthur C.Clarke, a fervent supporter of Savage, argued that by 2057 there will be humans on theMoon, Mars, Europa, Ganymede, Titan and in orbit around Venus, Neptune and Pluto.Freeman Dyson (1999) favours the Kuiper belt as the future home of humanity,suggesting this could happen within a few centuries. In Mining the Sky, John S. Lewissuggests that the resources of the solar system could support 10 quadrillionpeople.
http://en.wikipedia.org/wiki/Family_planninghttp://en.wikipedia.org/wiki/Urban_designerhttp://en.wikipedia.org/wiki/Michael_E._Arthhttp://en.wikipedia.org/wiki/Zero_population_growthhttp://en.wikipedia.org/wiki/Cost_of_raising_a_childhttp://en.wikipedia.org/wiki/Educationhttp://en.wikipedia.org/wiki/Family_planninghttp://en.wikipedia.org/wiki/Birth_controlhttp://en.wikipedia.org/wiki/Birth_controlhttp://en.wikipedia.org/wiki/Condomshttp://en.wikipedia.org/wiki/Pillshttp://en.wikipedia.org/wiki/Developing_worldhttp://en.wikipedia.org/wiki/Pregnancyhttp://en.wikipedia.org/wiki/Abortionhttp://en.wikipedia.org/wiki/Malnutritionhttp://en.wikipedia.org/wiki/Unintended_pregnancyhttp://en.wikipedia.org/wiki/Egypthttp://en.wikipedia.org/w/index.php?title=Hatem_el-Gabali&action=edit&redlink=1http://en.wikipedia.org/wiki/Gerard_O'Neillhttp://en.wikipedia.org/wiki/Space_habitatshttp://en.wikipedia.org/wiki/Marshall_Savagehttp://en.wikipedia.org/wiki/Solar_systemhttp://en.wikipedia.org/wiki/Asteroid_belthttp://en.wikipedia.org/wiki/Arthur_C._Clarkehttp://en.wikipedia.org/wiki/Arthur_C._Clarkehttp://en.wikipedia.org/wiki/Moonhttp://en.wikipedia.org/wiki/Marshttp://en.wikipedia.org/wiki/Europa_(moon)http://en.wikipedia.org/wiki/Ganymede_(moon)http://en.wikipedia.org/wiki/Titan_(moon)http://en.wikipedia.org/wiki/Venushttp://en.wikipedia.org/wiki/Neptunehttp://en.wikipedia.org/wiki/Plutohttp://en.wikipedia.org/wiki/Freeman_Dysonhttp://en.wikipedia.org/wiki/Kuiper_belthttp://en.wikipedia.org/wiki/Mining_the_Sky:_Untold_Riches_from_the_Asteroids,_Comets,_and_Planetshttp://en.wikipedia.org/wiki/Mining_the_Sky:_Untold_Riches_from_the_Asteroids,_Comets,_and_Planetshttp://en.wikipedia.org/wiki/John_S._Lewishttp://en.wikipedia.org/wiki/Family_planninghttp://en.wikipedia.org/wiki/Urban_designerhttp://en.wikipedia.org/wiki/Michael_E._Arthhttp://en.wikipedia.org/wiki/Zero_population_growthhttp://en.wikipedia.org/wiki/Cost_of_raising_a_childhttp://en.wikipedia.org/wiki/Educationhttp://en.wikipedia.org/wiki/Family_planninghttp://en.wikipedia.org/wiki/Birth_controlhttp://en.wikipedia.org/wiki/Birth_controlhttp://en.wikipedia.org/wiki/Condomshttp://en.wikipedia.org/wiki/Pillshttp://en.wikipedia.org/wiki/Developing_worldhttp://en.wikipedia.org/wiki/Pregnancyhttp://en.wikipedia.org/wiki/Abortionhttp://en.wikipedia.org/wiki/Malnutritionhttp://en.wikipedia.org/wiki/Unintended_pregnancyhttp://en.wikipedia.org/wiki/Egypthttp://en.wikipedia.org/w/index.php?title=Hatem_el-Gabali&action=edit&redlink=1http://en.wikipedia.org/wiki/Gerard_O'Neillhttp://en.wikipedia.org/wiki/Space_habitatshttp://en.wikipedia.org/wiki/Marshall_Savagehttp://en.wikipedia.org/wiki/Solar_systemhttp://en.wikipedia.org/wiki/Asteroid_belthttp://en.wikipedia.org/wiki/Arthur_C._Clarkehttp://en.wikipedia.org/wiki/Arthur_C._Clarkehttp://en.wikipedia.org/wiki/Moonhttp://en.wikipedia.org/wiki/Marshttp://en.wikipedia.org/wiki/Europa_(moon)http://en.wikipedia.org/wiki/Ganymede_(moon)http://en.wikipedia.org/wiki/Titan_(moon)http://en.wikipedia.org/wiki/Venushttp://en.wikipedia.org/wiki/Neptunehttp://en.wikipedia.org/wiki/Plutohttp://en.wikipedia.org/wiki/Freeman_Dysonhttp://en.wikipedia.org/wiki/Kuiper_belthttp://en.wikipedia.org/wiki/Mining_the_Sky:_Untold_Riches_from_the_Asteroids,_Comets,_and_Planetshttp://en.wikipedia.org/wiki/John_S._Lewis


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K. Eric Drexler, famous inventor of the futuristic concept ofmolecular nanotechnology,has suggested in Engines of Creation that colonizing space will mean breaking theMalthusian limits to growth for the human species.

Many authors, including Carl Sagan, Arthur C. Clarke, and Isaac Asimov haveargued that shipping the excess population into space is no solution to human

overpopulation. According to Clarke, "the population battle must be fought or won hereon Earth". The problem for these authors is not the lack of resources in space (as shownin books such as Mining the Sky]), but the physical impracticality of shipping vastnumbers of people into space to "solve" overpopulation on Earth. However, GerardO'Neill's calculations show that Earth could offload all new population growth with alaunch services industry about the same size as the current airline industry.

Other approaches and effects

Many philosophers, including Thomas Malthus, have said at various times thatwhen humankind does not check population-growth, nature takes its course. But thiscourse might not result in the death of humans through catastrophes; instead it mightresult in infertility. German scientists have reported that a virus called Adeno-associatedvirus might have a role in male infertility, but is otherwise harmless to humans. Thus, ifthis or similar viruses mutate, they might cause infertility on a large-scale, causing amass scale viral epidemic and thus resulting in a natural human population-control overtime.

Report 3

Anthropogenic Impact on Aquatic Ecosystem

1. Water Pollution

Comprising over 70% of the Earths surface, water is undoubtedly the mostprecious natural resource that exists on our planet. Without the seemingly invaluablecompound comprised of hydrogen and oxygen, life on Earth would be non-existent: it isessential for everything on our planet to grow and prosper. Although we as humansrecognize this fact, we disregard it by polluting our rivers, lakes, and oceans.Subsequently, we are slowly but surely harming our planet to the point where organismsare dying at a very alarming rate. In addition to innocent organisms dying off, our

drinking water has become greatly affected as is our ability to use water for recreationalpurposes. In order to combat water pollution, we must understand the problems andbecome part of the solution.
http://en.wikipedia.org/wiki/K._Eric_Drexlerhttp://en.wikipedia.org/wiki/Molecular_nanotechnologyhttp://en.wikipedia.org/wiki/Engines_of_Creationhttp://en.wikipedia.org/wiki/Malthusian_catastrophehttp://en.wikipedia.org/wiki/Carl_Saganhttp://en.wikipedia.org/wiki/Isaac_Asimovhttp://en.wikipedia.org/wiki/Gerard_O'Neillhttp://en.wikipedia.org/wiki/Gerard_O'Neillhttp://en.wikipedia.org/wiki/Philosopherhttp://en.wikipedia.org/wiki/Thomas_Malthushttp://en.wikipedia.org/wiki/Catastrophehttp://en.wikipedia.org/wiki/Infertilityhttp://en.wikipedia.org/wiki/Germanyhttp://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Adeno-associated_virushttp://en.wikipedia.org/wiki/Adeno-associated_virushttp://en.wikipedia.org/wiki/K._Eric_Drexlerhttp://en.wikipedia.org/wiki/Molecular_nanotechnologyhttp://en.wikipedia.org/wiki/Engines_of_Creationhttp://en.wikipedia.org/wiki/Malthusian_catastrophehttp://en.wikipedia.org/wiki/Carl_Saganhttp://en.wikipedia.org/wiki/Isaac_Asimovhttp://en.wikipedia.org/wiki/Gerard_O'Neillhttp://en.wikipedia.org/wiki/Gerard_O'Neillhttp://en.wikipedia.org/wiki/Philosopherhttp://en.wikipedia.org/wiki/Thomas_Malthushttp://en.wikipedia.org/wiki/Catastrophehttp://en.wikipedia.org/wiki/Infertilityhttp://en.wikipedia.org/wiki/Germanyhttp://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Adeno-associated_virushttp://en.wikipedia.org/wiki/Adeno-associated_virus


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POINT AND NONPOINT SOURCES

According to the American College Dictionary, pollution is defined as: to make foulor unclean; dirty. Water pollution occurs when a body of water is adversely affecteddue to the addition of large amounts of materials to the water. When it is unfit for itsintended use, water is considered polluted. Two types of water pollutants exist; point

source and nonpoint source. Point sources of pollution occur when harmful substancesare emitted directly into a body of water. The Exxon Valdez oil spill best illustrates apoint source water pollution. A nonpoint source delivers pollutants indirectly throughenvironmental changes. An example of this type of water pollution is when fertilizer froma field is carried into a stream by rain, in the form of run-off which in turn effects aquatic life. The technology exists for point sources of pollution tobe monitored and regulated, although political factors may complicate matters. Nonpointsources are much more difficult to control. Pollution arising from nonpointsources accounts for a majority of the contaminants in streams and lakes.

CAUSES OF POLLUTION

Many causes of pollution including sewage and fertilizers contain nutrients such as

nitrates and phosphates. In excess levels, nutrients over stimulate the growth of aquaticplants and algae. Excessive growth of these types of organisms consequently clogs ourwaterways, use up dissolved oxygen as they decompose, and block light to deeperwaters.This, in turn, proves very harmful to aquatic organisms as it affects the respiration abilityor fish and other invertebrates that reside in water.

Pollution is also caused when silt and other suspended solids, such as soil, washoffplowed fields, construction and logging sites, urban areas, and eroded river banks whenit rains. Under natural conditions, lakes, rivers, and other water bodies undergoEutrophication, an aging process that slowly fills in the water body with sediment and

organic matter. When these sediments enter various bodies of water, fishrespirationbecomes impaired, plant productivity and water depth become reduced, andaquatic organisms and their environments become suffocated. Pollution in the form oforganicmaterial enters waterways in many different forms as sewage, as leaves and grassclippings, or as runoff from livestock feedlots and pastures. When natural bacteria andprotozoan in the water break down this organic material, they begin to use up theoxygen dissolved in the water. Many types of fish and bottom-dwelling animals cannotsurvive when levels of dissolved oxygen drop below two to five parts per million. Whenthis occurs, it kills aquatic organisms in large numbers which leads to disruptions in thefood chain.

Polluted River in the United KingdomThe pollution of rivers and streams with chemical contaminants has become one of themost crutial environmental problems within the 20th century. Waterborne chemicalpollution entering rivers and streams cause tramendous amounts of destruction.

Pathogens are another type of pollution that prove very harmful. They can causemany illnesses that range from typhoid and dysentery to minor respiratory and skindiseases. Pathogens include such organisms as bacteria, viruses, and protozoan.These pollutants enter waterways through untreated sewage, storm drains, septic tanks,runoff from farms, and particularly boats that dump sewage. Though microscopic, these


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pollutants have a tremendous effect evidenced by their ability to cause sickness.

ADDITIONAL FORMS OF WATER POLLUTION

Three last forms of water pollution exist in the forms of petroleum, radioactivesubstances, and heat. Petroleum often pollutes waterbodies in the form of oil, resulting

from oil spills. The previously mentioned Exxon Valdez is an example of this type ofwater pollution. These large-scale accidental discharges of petroleum are an importantcause of pollution along shore lines. Besides the supertankers, off-shore drillingoperations contribute a large share of pollution. One estimate is that one ton of oil isspilled for every million tons of oil transported. This is equal to about 0.0001 percent.Radioactive substances are produced in the form of waste from nuclear power plants,and from the industrial, medical, and scientific use of radioactive materials. Specificforms of waste are uranium and thorium mining and refining. The last form of waterpollution is heat. Heat is a pollutant because increased temperatures result in thedeaths of many aquatic organisms. These decreases in temperatures are caused whena discharge of cooling water by factories and power plants occurs.

Demonstrators Protest DrillingOil pollution is a growing problem, particularly devestating to coastal wildlife. Smallquantities of oil spread rapidly across long distances to form deadly oil slicks. In thispicture, demonstrators with "oil-covered" plastic animals protest a potential drillingproject in Key Largo, Florida. Whether or not accidental spills occur during the project, itsimpact on the delicate marine ecosystem of the coral reefs could be devastating.Oil Spill Clean-upWorkers use special nets to clean up a California beach after an oil tanker spill. Tankerspills are an increasing environmental problem because once oil has spilled, it is virtuallyimpossible to completely remove or contain it. Even small amounts spread rapidlyacross large areas of water. Because oil and water do not mix, the oil floats on the water

and then washes up on broad expanses of shoreline. Attempts to chemically treat or sinkthe oil may further disrupt marine and beach ecosystems.

CLASSIFYING WATER POLLUTION

The major sources of water pollution can be classified as municipal, industrial, andagricultural. Municipal water pollution consists of waste water from homes andcommercial establishments. For many years, the main goal of treating municipalwastewater was simply to reduce its content of suspended solids, oxygen-demandingmaterials, dissolved inorganic compounds, and harmful bacteria. In recent years,however, more stress has been placed on improving means of disposal of the solid

residues from the municipal treatment processes. The basic methods of treatingmunicipal wastewater fall into three stages: primary treatment, including grit removal,screening, grinding, and sedimentation; secondary treatment, which entails oxidation ofdissolved organic matter by means of using biologically active sludge, which is thenfiltered off; and tertiary treatment, in which advanced biological methods of nitrogenremoval and chemical and physical methods such as granular filtration and activatedcarbon absorption are employed. The handling and disposal of solid residues canaccount for 25 to 50 percent of the capital and operational costs of a treatment plant.The characteristics of industrial waste waters can differ considerably both within and


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among industries. The impact of industrial discharges depends not only on theircollective characteristics, such as biochemical oxygen demand and the amount ofsuspended solids, but also on their content of specific inorganic and organic substances.Three options are available in controlling industrial wastewater. Control can take placeat the point of generation in the plant; wastewater can be pretreated for discharge tomunicipal treatment sources; or wastewater can be treated completely at the plant and

either reused or discharged directly into receiving waters.

Wastewater TreatmentRaw sewage includes waste from sinks, toilets, and industrial processes. Treatment ofthe sewage is required before it can be safely buried, used, or released back into localwater systems. In a treatment plant, the waste is passed through a series of screens,chambers, and chemical processes to reduce its bulk and toxicity. The three generalphases of treatment are primary, secondary, and tertiary. During primary treatment, alarge percentage of the suspended solids and inorganic material is removed from thesewage. The focus of secondary treatment is reducing organic material by acceleratingnatural biological processes. Tertiary treatment is necessary when the water will bereused; 99 percent of solids are removed and various chemical processes are used to

ensure the water is as free from impurity as possible.Agriculture, including commercial livestock and poultry farming, is the source of many

organic and inorganic pollutants in surface waters and groundwater. Thesecontaminants include both sediment from erosion cropland and compounds ofphosphorus and nitrogen that partly originate in animal wastes and commercialfertilizers. Animal wastes are high in oxygen demanding material, nitrogen andphosphorus, and they often harbor pathogenic organisms. Wastes from commercialfeeders are contained and disposed of on land; their main threat to natural waters,therefore, is from runoff and leaching. Control may involve settling basins for liquids,limited biological treatment in aerobic or anaerobic lagoons, and a variety of othermethods.

GROUND WATERNinety-five percent of all fresh water on earth is ground water. Ground water is found

in natural rock formations. These formations, called aquifers, are a vital natural resourcewith many uses. Nationally, 53% of the population relies on ground water as a source ofdrinking water. In rural areas this figure is even higher. Eighty one percent ofcommunity water is dependent on ground water. Although the 1992 Section 305(b)State Water Quality Reports indicate that, overall, the Nations ground water quality isgood to excellent, many local areas have experienced significant ground watercontamination.Some examples are leaking underground storage tanks and municipal landfills.

LEGISLATIONSeveral forms of legislation have been passed in recent decades to try to control

water pollution. In 1970, the Clean Water Act provided 50 billion dollars to cities andstates to build wastewater facilities. This has helped control surface water pollution fromindustrial and municipal sources throughout the United States. When congress passedthe Clean Water Act in 1972, states were given primary authority to set their ownstandards for their water. In addition to these standards, the act required that all statebeneficial uses and their criteria must comply with the fishable and swimmable


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goals of the act. This essentially means that state beneficial uses must be able tosupport aquatic life and recreational use. Because it is impossible to test water for everytype of disease-causing organism, states usually look to identify indicator bacteria. Onefor a example is a bacteria known as fecal coliforms.(Figure 1 shows the quality of waterfor each every state in the United States, click on the US link). These indicator bacteriasuggest that a certain selection of water may be contaminated with untreated sewage

and that other, more dangerous, organisms are present. These legislations are animportant part in the fight against water pollution. They are useful in preventingEnvioronmental catastrophes. The graph shows reported pollution incidents since 1989-1994. If stronger legislations existed, perhaps these events would never have occurred.

GLOBAL WATER POLLUTION

Estimates suggest that nearly 1.5 billion people lack safe drinking water and that atleast 5 million deaths per year can be attributed to waterborne diseases. With over 70percent of the planet covered by oceans, people have long acted as if these very bodiesof water could serve as a limitless dumping ground for wastes. Raw sewage, garbage,and oil spills have begun to overwhelm the diluting capabilities of the oceans, and most

coastal waters are now polluted. Beaches around the world are closed regularly, oftenbecause of high amounts of bacteria from sewage disposal, and marine wildlife isbeginning to suffer.

Perhaps the biggest reason for developing a worldwide effort to monitor and restrictglobal pollution is the fact that most forms of pollution do not respect nationalboundaries. The first major international conference on environmental issues was heldin Stockholm, Sweden, in 1972 and was sponsored by the United Nations (UN). Thismeeting, at which the United States took a leading role, was controversial because manydeveloping countries were fearful that a focus on environmental protection was a meansfor the developed world to keep the undeveloped world in an economically subservientposition. The most important outcome of the conference was the creation of the United

Nations Environmental Program (UNEP).

UNEP was designed to be the environmental conscience of the UnitedNations, and, in an attempt to allay fears of the developing world, it became the firstUN agency to be headquartered in a developing country, with offices in Nairobi, Kenya.In addition to attempting to achieve scientific consensus about major environmentalissues, a major focus for UNEP has been the study of ways to encourage sustainabledevelopment increasing standards of living without destroying the environment. At thetime of UNEP's creation in 1972, only 11 countries had environmental agencies. Tenyears later that number had grown to 106, of which 70 were in developing countries.


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WATER QUALITY

Water quality is closely linked to water use and to the state of economicdevelopment. In industrialized countries, bacterial contamination of surface watercaused serious health problems in major cities throughout the mid 1800s. By the turnof the century, cities in Europe and North America began building sewer networks to

route domestic wastes downstream of water intakes. Development of these sewagenetworks and waste treatment facilities in urban areas has expanded tremendously inthe past two decades. However, the rapid growth of the urban population (especially inLatin America and Asia) has outpaced the ability of governments to expand sewage andwater infrastructure. While waterborne diseases have been eliminated in the developedworld, outbreaks of cholera and other similar diseases still occur with alarming frequencyin the developing countries. Since World War II and the birth of the chemical age,water quality has been heavily impacted worldwide by industrial and agriculturalchemicals. Eutrophication of surface waters from human and agricultural wastes andnitrification of groundwater from agricultural practices has greatly affected large parts ofthe world. Acidification of surface waters by air pollution is a recent phenomenon andthreatens aquatic life in many area of the world. In developed countries, these general

types of pollution have occurred sequentially with the result that most developedcountries have successfully dealt with major surface water pollution. In contrast,however, newly industrialized countries such as China, India, Thailand, Brazil, andMexico are now facing all these issues simultaneously.

CONCLUSION

Clearly, the problems associated with water pollution have the capabilities to disruptlife on our planet to a great extent. Congress has passed laws to try to combat waterpollution thus acknowledging the fact that water pollution is, indeed, a seriousissue. Butthe government alone cannot solve the entire problem. It is ultimately up to us, to beinformed, responsible and involved when it comes to the problems we face with our

water. We must become familiar with our local water resources and learn about waysfor disposing harmful household wastes so they dont end up in sewage treatmentplants that cant handle them or landfills not designed to receive hazardous materials.In our yards, we must determine whether additional nutrients are needed beforefertilizers are applied, and look for alternatives where fertilizers might run off into surfacewaters. We have to preserve existing trees and plant new trees and shrubs to helpprevent soil erosion and promote infiltration of water into the soil. Around our houses,we must keep litter, pet waste, leaves, and grass clippings out of gutters and stormdrains. These are

just a few of the many ways in which we, as humans, have the ability to combat waterpollution. As we head into the 21st century, awareness and education will mostassuredly continue to be the two most important ways to prevent water pollution. If

these measures are not taken and water pollution continues, life on earth will sufferseverely.

Global environmental collapse is not inevitable. But the developed world must workwith the developing world to ensure that new industrialized economies do not add to theworld's environmental problems. Politicians must think of sustainable development ratherthan economic expansion. Conservation strategies have to become more widelyaccepted, and people must learn that energy use can be dramatically diminished withoutsacrificing comfort. In short, with the technology that currentlyexists, the years of global environmental mistreatment can begin to be reversed.


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2. Thermal Pollution

The broadest definition of thermal pollution is the degradation of water quality byany process that changes ambient water temperature. Thermal pollution is usuallyassociated with increases of water temperatures in a stream, lake, or ocean due to thedischarge of heated water from industrial processes, such as the generation of

electricity. Increases in ambient water temperature also occur in streams where shadingvegetation along the banks is removed or where sediments have made the water moreturbid . Both of these effects allow more energy from the sun to be absorbed by thewater and thereby increase its temperature. There are also situations in which theeffects of colder-than-normal water temperatures may be observed. For example, thedischarge of cold bottom water from deep-water reservoirs behind large dams haschanged the downstream biological communities in systems such as the Colorado River.Direct, such as the burning of wood in a fireplace to create heat, or by the conversion ofheat energy into mechanical energy by the use of a heat engine. Examples of heatengines include steam engines, turbines , and internal combustion engines. Heatengines work on the principal of heating and pressuring a fluid, the performance ofmechanical work, and the rejection of unused or waste heat to a sink . Heat engines can

only convert 30 to 40 percent of the available input energy in the fuel source intomechanical energy, and the highest efficiencies are obtained when the inputtemperature is as high as possible and the sink temperature is as low as possible. Wateris a very efficient and economical sink for heat engines and it is commonly used inelectrical generating stations.

The waste heat from electrical generating stations is transferred to cooling waterobtained from local water bodies such as a river, lake, or ocean. Large amounts of waterare used to keep the sink temperature as low as possible to maintain a high thermalefficiency. The San Onofre Nuclear Generating Station between Los Angeles and SanDiego, California, for example, has two main reactors that have a total operatingcapacity of 2,200 megawatts (MW). These reactors circulate a total of 2,400 million

gallons per day (MGD) of ocean water at a flow rate of 830,000 gallons per minute foreach unit. The cooling water enters the station from two intake structures located 3,000feet offshore in water 32 feet deep. The water is heated to approximately 19F aboveambient as it flows through the condensers and is discharged back into the oceanthrough a series of diffuser -type discharges that have a series of sixty-three exit pipesspread over a distance of 2,450 feet. The discharge water is rapidly mixed with ambientseawater by the diffusers and the average rise in temperature after mixing is less than2F.

These ASTER false-color images were acquired over Joliet 29, a coal-burningpower plant in Illinois. Joliet 29 can be seen in the VNIR image (top) as the bright blue-

white pixels just above the large cooling pond. Like many power plants, Joliet 29 uses acooling pond to discharge heated effluent water. In the bottom image a single ASTERThermal Infrared band was color-coded to represent heat emitted from the surface. Theprogression from warmest to coolest is shown with the following colors: white, red,orange, yellow, green, blue, and black.


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Environmental Effects

The primary effects of thermal pollution are direct thermal shock , changes indissolved oxygen, and the redistribution of organisms in the local community. Becausewater can absorb thermal energy with only small changes in temperature, most aquaticorganisms have developed enzyme systems that operate in only narrow ranges of

temperature. These stenothermic organisms can be killed by sudden temperaturechanges that are beyond the tolerance limits of their metabolic systems. The coolingwater discharges of power plants are designed to minimize heat effects on local fishcommunities. However, periodic heat treatments used to keep the cooling system clearof fouling organisms that clog the intake pipes can cause fish mortality. A heat treatmentreverses the flow and increases the temperature of the discharge to kill the mussels andother fouling organisms in the intake pipes. Southern California Edison had developed a"fish-chase" procedure in which the water temperature of the heat treatment is increasedgradually, instead of rapidly, to drive fish away from the intake pipes before thetemperature reaches lethal levels. The fish chase procedure has significantly reducedfish kills related to heat treatments.

Small chronic changes in temperature can also adversely affect the reproductivesystems of these organisms and also make them more susceptible to disease. Coldwater contains more oxygen than hot water so increases in temperature also decreasethe oxygen-carrying capacity of water. In addition, raising the water temperatureincreases the decomposition rate of organic matter in water, which also depletesdissolved oxygen. These decreases in the oxygen content of the water occur at thesame time that the metabolic rates of the aquatic organisms, which are dependent on asufficient oxygen supply, are rising because of the increasing temperature.

The composition and diversity of communities in the vicinity of cooling waterdischarges from power plants can be adversely affected by the direct mortality oforganisms or movement of organisms away from unfavorable temperature or oxygen

environments. A nuclear power-generating station on Nanwan Bay in Taiwan causedbleaching of corals in the vicinity of the discharge channel when the plant first beganoperation in 1988. Studies of the coral Acropora grandis in 1988 showed that the coralwas bleached within two days of exposure to temperatures of 91.4F. In 1990 samplesof coral taken from the same area did not start bleaching until six days after exposure tothe same temperature. It appears that the thermotolerance of these corals wasenhanced by the production of heat-shock proteins that help to protect many organismsfrom potentially damaging changes in temperature. The populations of some speciescan also be enhanced by the presence of cooling water discharges. The only largepopulation of sea turtles in California, for example, is found in the southern portion ofSan Diego Bay near the discharge of an electrical generating station.

Abatement

The dilution of cooling water discharges can be effectively accomplished byvarious types of diffuser systems in large bodies of water such as lakes or the ocean.The only thermal effects seen at the San Onofre nuclear generating station are the directmortality of planktonic organisms during the twenty-five-minute transit through the


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cooling water system. The effectiveness of the dilution systems can be monitored bythermal infrared imaging using either satellite or airborne imaging systems. The use ofcooling towers has been effective for generating stations located on smaller rivers andstreams that do not have the capacity to absorb the waste heat from the cooling watereffluent . The cooling towers operate by means of a recirculating cascade of water insidea tower, with a large column of upwardly rising air that carries the heat to the

atmosphere through evaporative cooling. Cooling towers have been used extensively atnuclear generating stations in both the United States and France. The disadvantages ofcooling towers are the potential for local changes in meteorological conditions due tolarge amounts of warm air entering the atmosphere and the visual impact of the largetowers.

3. Eutrophication

Eutrophication is a syndrome of ecosystem responses to human activities thatfertilize water bodies with nitrogen (N) and phosphorus (P), often leading to changes inanimal and plant populations and degradation of water and habitat quality. Nitrogen andphosphorus are essential components of structural proteins, enzymes, cell membranes,nucleic acids, and molecules that capture and utilize light and chemical energy tosupport life. The biologically available forms of N and P are present at lowconcentrations in pristine lakes, rivers, estuaries, and in vast regions of the upperocean.Pristine aquatic ecosystems function in approximate steady state in which primaryproduction of new plant biomass is sustained by N and P released as byproducts ofmicrobial and animal metabolism. This balanced state is disrupted by human activitiesthat artificially enrich water bodies with N and P, resulting in unnaturally high rates ofplant production and accumulation of organic matter that can degrade water and habitatquality. These inputs may come from sewage treatment plants or run-off of fertilizerfromfarm fields or suburban lawns.

Eutrophication was first evident in lakes and rivers as they became choked withexcessive growth of rooted plants and floating algal scums, prompting intense study inthe 1960's-70's and culminating in the scientific basis for banning phosphate detergents(a major source of P, the most frequent culprit in eutrophication of lakes) and upgradingsewage treatment to reduce wastewater N and P discharges to inland waters.Symptoms of eutrophication in estuaries and other coastal marine ecosystems (where Nis the most frequent contributor to eutrophication) were clearly evident by the 1980's, ashuman activities doubled the transport of N and tripled the transport of P from Earth'sland surface to its oceans. Eutrophication has emerged as a key human stressor on theworld's coastal ecosystems.

Nutrient enrichment of marine waters promotes the growth of algae, either asattached multicellular forms (e.g. sea lettuce) or as suspended microscopicphytoplankton, because algae can grow faster than larger vascular plants. Smallincreases in algal abundance or biomass have subtle ecological responses that canincrease production in food webs sustaining fish and shellfish, even producing higherfish yields. However, over-stimulation of algal growth leads to a complex suite ofinterconnected biological and chemical responses that can severely degrade water
http://www.eoearth.org/article/Ecosystemhttp://www.eoearth.org/article/Nitrogenhttp://www.eoearth.org/article/Freshwater_biomeshttp://www.eoearth.org/article/Riverhttp://www.eoearth.org/article/Estuaryhttp://www.eoearth.org/article/Oceanhttp://www.eoearth.org/article/Fertilizerhttp://www.eoearth.org/article/Marine_biomeshttp://www.eoearth.org/article/Phytoplanktonhttp://www.eoearth.org/article/Ecosystemhttp://www.eoearth.org/article/Nitrogenhttp://www.eoearth.org/article/Freshwater_biomeshttp://www.eoearth.org/article/Riverhttp://www.eoearth.org/article/Estuaryhttp://www.eoearth.org/article/Oceanhttp://www.eoearth.org/article/Fertilizerhttp://www.eoearth.org/article/Marine_biomeshttp://www.eoearth.org/article/Phytoplankton


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quality and threaten human health and sustainability of living resources in the coastalzone.

As algal biomass builds during blooms it forms aggregates that sink and fuelbacterial growth in bottom waters and sediments. Bacterial metabolism consumesoxygen. If the rates of aeration of water by mixing are slower than bacterial metabolism,

then bottom waters become hypoxic (low in oxygen) or anoxic (devoid of oxygen),creating conditions stressful or even lethal for marine invertebrates and fish. Seasonaloccurrences of dead zones devoid of oxygen and animal life have expanded in the Gulfof Mexico (where the dead zone has approached the size of New Jersey), the BalticSea, and Sea of Marmara as a consequence of eutrophication from nutrients deliveredby large rivers. Seagrasses are important communities in undisturbed shallow coastalecosystems, providing essential habitat for many species of marine animals. Thedistribution and abundance of seagrasses have greatly diminished in nutrient-enrichedcoastal waters, such as Chesapeake Bay and Danish estuaries, where watertransparency and light availability to rooted plants have declined as result ofphytoplankton growth and fouling of the grass blades by epiphytes and biofilms. Thesehabitat changes propagate through food webs, and the abundance and species diversity

of fish and shellfish decrease as seagrasses are eliminated from nutrient-enrichedcoastal waters.

Some phytoplankton species excrete large quantities of mucilage during bloomsthat is whipped into foam by wind mixing and washes ashore, making beachesundesirable for holiday visitors. Other phytoplankton species produce toxic chemicalsthat can impair respiratory, nervous, digestive and reproductive system function, andeven cause death of fish, shellfish, seabirds, mammals, and humans. The economicimpacts of harmful algal blooms can be severe as tourism is lost and shellfish harvestand fishing are closed across increasingly widespread marine regions. Marine scientistsare trying to determine if and how nutrient enrichment selectively promotes the growth ofharmful algal species, and if the frequency of harmful algal blooms has increased

globally in response to nutrient enrichment. Protection of marine waters from the harmfulconsequences of nutrient enrichment is a challenge to resource managers because thesources and delivery routes of N and P are diverse. Combustion of fossil fuels producesgaseous nitrogen oxides, and animal production and fertilizer use produce volatileammonia, two sources of atmospheric N that can be carried by winds and deposited oncoastal waters and lakes hundreds of kilometers from their origin. Modern high-yieldagriculture and urban gardeners are dependent upon commercial fertilizers that becamecheap to produce in the mid 20th century the era in which N and P concentrationsbegan to increase in surface waters carrying agricultural and urban runoff to the sea.The world's human population is growing disproportionately in the coastal zone, creatingan additional challenge of reducing nutrient inputs from municipal waste, septic systems,and fertilizer runoff from lawns and gardens. Projections indicate that the largest future

increases in N and P delivery to the coastal ocean will occur in eastern and southernAsia where populations and economies are growing most rapidly.

The eutrophication problem illustrates how human activities on land can degradethe quality of coastal waters and habitats, with potentially large economic and ecologicalcosts. Solutions to the coastal eutrophication problem require changes in all theseactivities within the watersheds and airsheds connected to coastal waters. Commitmentsto these solutions are now beginning the European Union's Water Framework
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Directive mandates strategies to reduce N and P delivery to coastal waters, and a 2000National Research Council report recommended a National Coastal NutrientManagement Strategy for the United States. Proposed solutions to the eutrophicationproblem are multidimensional and include actions to restore wetlands and riparian bufferzones between farms and surface waters, reduce livestock densities, improveefficiencies of fertilizer applications, treat urban runoff from streets and storm drains,

reduce N emissions from vehicles and power plants, and further increase the efficiencyofN and P removal from municipal wastewater. As coastal fish and shellfish aquacultureexpand, management considerations of this rapidly growing internal source of nutrientswill be required as well.

4. Red Tides

An algal bloom is a rapid increase in the population of algae in an aquaticsystem. Algal blooms may occur in freshwater as well as marine environments.Typically, only one or a small number of phytoplankton species are involved, and someblooms may be recognized by discoloration of the water resulting from the high densityof pigmented cells. Although there is no officially recognized threshold level, algae can

be considered to be blooming at concentrations of hundreds to thousands of cells permilliliter, depending on the severity. Algal bloom concentrations may reach millions ofcells per milliliter. Algal blooms are often green, but they can also be yellow-brown orred, depending on the species of algae. Bright green blooms are a result of blue-greenalgae, which are actually bacteria (cyanobacteria). Blooms may also consist ofmacroalgal, not phytoplankton, species. These blooms are recognizable by large bladesof algae that may wash up onto the shoreline. "Black water" is a dark discoloration ofsea water, first described in the Florida Bay in January 2002.

Of particular note are harmful algal blooms (HABs), which are marine algal bloomevents involving toxic phytoplankton such as dinoflagellates ofgenus Alexandrium andKarenia. Such blooms often take on a red or brown hue and are known colloquially as

red tides.

Freshwater algal blooms

Freshwater algal blooms are the result of an excess of nutrients, particularlyphosphorus. The excess of nutrients may originate from fertilizers that are applied toland for agricultural or recreational purposes, these nutrients can then enter watershedsthrough water runoff.[4] Excess carbon and nitrogen have also been suspected ascauses, although a study suggested that this is not the case. When phosphates areintroduced into water systems, higher concentrations cause increased growth of algaeand plants. Algae tend to grow very quickly under high nutrient availability, but each algais short-lived, and the result is a high concentration of dead organic matter which startsto decay. The decay process consumes dissolved oxygen in the water, resulting inhypoxic conditions. Without sufficient dissolved oxygen in the water, animals and plantsmay die offin large numbers.

Blooms may be observed in freshwater aquariums when fish are overfed andexcess nutrients are not absorbed by plants. These are not generally harmful for fish,and the situation can be corrected by changing the water in the tank and then reducingthe amount of food given.
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Water treatment

Algal blooms sometimes occur in drinking water supplies. In such cases, toxins from thebloom can survive standard water purifying treatments. Researchers at FloridaInternational University in Miami are experimenting with using 640-kilohertz ultrasoundwaves that create micropressure zones as hot as 3,700 C. This breaks some water

molecules into reactive fragments that can kill algae.

Measurement

Algal blooms are monitored using biomass measurements coupled with the examinationof species present. A widely-used measure of algal and cyanobacterial biomass is thechlorophyll concentration. Peak values of chlorophyll a for an oligotrophic lake are about1-10 g/l, while in a eutrophic lake they can reach 300 g/l. In cases ofhypereutrophy,such as Hartbeespoort Dam in South Africa, maxima of chlorophyll a can be as high as3,000 g/l.

Tai Hu Algal Bloom

Lake Tai in Eastern China has had algal blooms which has attracted the attention of theENGO sector. Greenpeace China investigated the algal bloom at Lake Tai and tookwater samples. Of 25 samples, 20 were too polluted to be used to water plants or infactories.

Harmful Algal Blooms

A harmful algal bloom (HAB) is an algal bloom that causes negative impacts toother organisms via production of natural toxins, mechanical damage to otherorganisms, or by other means. HABs are often associated with large-scale marine

mortality events and have been associated with various types of shellfish poisonings.

Background

In the marine environment, single-celled, microscopic, plant-like organisms naturallyoccur in the well-lit surface layer of any body of water. These organisms, referred to asphytoplankton or microalgae, form the base of the food web upon which nearly all othermarine organisms depend. Of the 5000+ species of marine phytoplankton that existworldwide, about 2% are known to be harmful or toxic[11]. Blooms of harmful algae canhave large and varied impacts on marine ecosystems, depending on the speciesinvolved, the environment where they are found, and the mechanism by which they exertnegative effects. Examples of common harmful effects of HABs include:

1. the production of neurotoxins which cause mass mortalities in fish, seabirds andmarine mammals

2. human illness or death via consumption of seafood contaminated by toxic algae3. mechanical damage to other organisms, such as disruption of epithelial gill

tissues in fish, resulting in asphyxiation

4. oxygen depletion of the water column (hypoxia or anoxia) from cellularrespiration and bacterial degradation
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Due to their negative economic and health impacts, HABs are often carefully monitored.

HABs occur in many regions of the world. , and in the United States are recurringphenomena in multiple geographical regions. The Gulf of Maine frequently experiencesblooms of the dinoflagellate Alexandrium fundyense, an organism that producessaxitoxin, the neurotoxin responsible for paralytic shellfish poisoning. The well-known

"Florida red tide" that occurs in the eastern Gulf of Mexico is a HAB caused by Karenia brevis, another dinoflagellate which produces brevetoxin, the neurotoxin responsible forneurotoxic shellfish poisoning. California coastal waters also experience seasonalblooms of Pseudo-nitzschia, a diatom known to produce domoic acid, the neurotoxinresponsible for amnesic shellfish poisoning. Off the west coast of South Africa, HABscaused byAlexandrium catanella occur every spring. These blooms of organisms causesevere disruptions in fisheries of these waters as the toxins in the phytoplankton causefilter-feeding shellfish in affected waters to become poisonous for human consumption ".If the HAB event results in a high enough concentration of algae the water may becomediscoloured or murky, varying in colour from purple to almost pink, normally being red orgreen. Not all algal blooms are dense enough to cause water discolouration.

"Red Tides"

"Red tide" is a term often used to describe HABs in marine coastal areas [15], as thedinoflagellate species involved in HABs are often red or brown, and tint the sea water toa reddish colour. The more correct and preferred term in use is harmful algal bloom,because:

1. these blooms are not associated with tides2. not all algal blooms cause reddish discoloration of water3. not all algal blooms are harmful, even those involving red discolouration

Causes of HABs

It is unclear what causes HABs; their occurrence in some locations appears to beentirely natural, while in others they appear to be a result of human activities[18]

Furthermore, there are many different species of algae that can form HABs, each withdifferent environmental requirements for optimal growth. The frequency and severity ofHABs in some parts of the world have been linked to increased nutrient loading fromhuman activities. In other areas, HABs are a predictable seasonal occurrence resultingfrom coastal upwelling, a natural result of the movement of certain ocean currents. [19]

The growth of marine phytoplankton (both non-toxic and toxic) is generally limited by theavailability of nitrates and phosphates, which can be abundant in coastal upwellingzones as well as in agricultural run-off. Coastal water pollution produced by humans and

systematic increase in sea water temperature have also been suggested as possiblecontributing factors in HABs. Other factors such as iron-rich dust influx from large desertareas such as the Saharan desert are thought to play a role in causing HABs. [20] Somealgal blooms on the Pacific coast have also been linked to natural occurrences of large-scale climatic oscillations such as El Nio events. While HABs in the Gulf of Mexicohave been occurring since the time of early explorers such as Cabeza de Vaca,[21] it isunclear what initiates these blooms and how large a role anthropogenic and naturalfactors play in their development. It is also unclear whether the "apparent" increase in
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frequency and severity of HABs in v

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