Water pollution

Raw sewage and industrial waste flows across international borders New River passes from Mexicali to Calexico, California.

Water pollution:

Is the contamination of water bodies (e.g. lakes, rivers, oceans, groundwater).

Water pollution affects plants and organisms living in these bodies of water; and, in almost all cases the effect is damaging either to individual species and populations, but also to the natural biological communities.

Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds.

Table of Contents

1 Introduction

2 Water pollution categories o 2.1 Point source pollution o 2.2 Non-point source pollution

3 Groundwater pollution

4 Causes of water pollution o 4.1 Pathogens o 4.2 Chemical and other contaminants o 4.3 Thermal pollution

5 Transport and chemical reactions of water pollutants

6 Measurement of water pollution o 6.1 Sampling o 6.2 Physical testing o 6.3 Chemical testing

o 6.4 Biological testing

7 Control of water pollution o 7.1 Domestic sewage o 7.2 Industrial wastewater o 7.3 Agricultural wastewater o 7.4 Construction site stormwater o 7.5 Urban runoff (stormwater)

8 References

Introduction:

Millions depend on the polluted Ganges river.

Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases,[1][2] and that it accounts for the deaths of more than 14,000 people daily.[2] An estimated 700 million Indians have no access to a proper toilet, and 1,000 Indian children die of diarrheal sickness every day.[3] Some 90% of China's cities suffer from some degree of water pollution,[4] and nearly 500 million people lack access to safe drinking water.[5] In addition to the acute problems of water pollution in developing countries, industrialized countries continue to struggle with pollution problems as well. In the most recent national report on water quality in the United States, 45 percent of assessed stream miles, 47 percent of assessed lake acres, and 32 percent of assessed bay and estuarine square miles were classified as polluted.[6]

Water is typically referred to as polluted when it is impaired by anthropogenic contaminants and either does not support a human use, like serving as drinking

water, and/or undergoes a marked shift in its ability to support its constituent biotic communities, such as fish. Natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water.

Water pollution categories: Surface water and groundwater have often been studied and managed as separate resources, although they are interrelated.[7] Sources of surface water pollution are generally grouped into two categories based on their origin.

Point source pollution:

Point source pollution - Shipyard - Rio de Janeiro.

Point source pollution refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage treatment plant, a factory, or a city storm drain. The U.S. Clean Water Act (CWA) defines point source for regulatory enforcement purposes.[8] The CWA definition of point source was amended in 1987 to include municipal storm sewer systems, as well as industrial stormwater, such as from construction sites.[9]

Non-point source pollution:

Non-point source (NPS) pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often accumulative effect of small amounts of contaminants gathered from a large area. The leaching out of nitrogen compounds from agricultural land which has been fertilized is a typical example. Nutrient runoff in stormwater from "sheet flow" over an agricultural field or a forest are also cited as examples of NPS pollution.

Contaminated storm water washed off of parking lots, roads and highways, called urban runoff, is sometimes included under the category of NPS pollution. However, this runoff is typically channeled into storm drain systems and discharged through pipes to local surface waters, and is a point source. However where such water is not channeled and drains directly to ground it is a non-point source.

Groundwater pollution: Interactions between groundwater and surface water are complex. Consequently, groundwater pollution, sometimes referred to as groundwater contamination, is not as easily classified as surface water pollution.[7] By its very nature, groundwater aquifers are susceptible to contamination from sources that may not directly affect surface water bodies, and the distinction of point vs. non-point source may be irrelevant. A spill of a chemical contaminant on soil, located away from a surface water body, may not necessarily create point source or non-point source pollution, but nonetheless may contaminate the aquifer below. Analysis of groundwater contamination may focus on soil characteristics and hydrology, as well as the nature of the contaminant itself. See Hydrogeology.

Causes of water pollution: The specific contaminants leading to pollution in water include a wide spectrum of chemicals, pathogens, and physical or sensory changes such as elevated temperature and discoloration. While many of the chemicals and substances that are regulated may be naturally occurring (calcium, sodium, iron, manganese, etc.) the concentration is often the key in determining what is a natural component of water, and what is a contaminant.

Oxygen-depleting substances may be natural materials, such as plant matter (e.g. leaves and grass) as well as man-made chemicals. Other natural and anthropogenic substances may cause turbidity (cloudiness) which blocks light and disrupts plant growth, and clogs the gills of some fish species.[10]

Many of the chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts. Alteration of water's physical chemistry includes acidity (change in pH), electrical conductivity, temperature, and eutrophication. Eutrophication is an increase in the concentration of chemical nutrients in an ecosystem to an extent that increases in the primary productivity of the ecosystem. Depending on the degree of eutrophication, subsequent negative environmental effects such as anoxia (oxygen depletion) and severe reductions in water quality may occur, affecting fish and other animal populations.

Pathogens:

A manhole cover unable to contain a sanitary sewer overflow.

Coliform bacteria are a commonly-used bacterial indicator of water pollution, although not an actual cause of disease.

Other microorganisms sometimes found in surface waters which have caused human health problems include:

Burkholderia pseudomallei Cryptosporidium parvum Giardia lamblia Salmonella Novovirus and other viruses Parasitic worms (helminths).[11][12]

High levels of pathogens may result from inadequately treated sewage discharges.[13] This can be caused by a sewage plant designed with less than secondary treatment (more typical in less-developed countries). In developed countries, older cities with aging infrastructure may have leaky sewage collection systems (pipes, pumps, valves), which can cause sanitary sewer overflows. Some cities also have combined sewers, which may discharge untreated sewage during rain storms.[14]

Pathogen discharges may also be caused by poorly-managed livestock operations.

Chemical and other contaminants:

Muddy river polluted by sediment.

Contaminants may include organic and inorganic substances.

Organic :

Water pollutants include:

Detergents Disinfection by-products found in chemically disinfected drinking water,

such as chloroform Food processing waste, which can include oxygen-demanding substances,

fats and grease Insecticides and herbicides, a huge range of organohalides and other

chemical compounds Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and

fuel oil) and lubricants (motor oil), and fuel combustion byproducts, from stormwater runoff[15]

Tree and bush debris from logging operations Volatile organic compounds (VOCs), such as industrial solvents, from

improper storage. Chlorinated solvents, which are dense non-aqueous phase liquids (DNAPLs), may fall to the bottom of reservoirs, since they don't mix well with water and are denser.

Various chemical compounds found in personal hygiene and cosmetic products.

Inorganic:

Water pollutants include:

Acidity caused by industrial discharges (especially sulfur dioxide from power plants)

Ammonia from food processing waste Chemical waste as industrial by-products Fertilizers containing nutrients--nitrates and phosphates--which are found in

stormwater runoff from agriculture, as well as commercial and residential use[15]

Heavy metals from motor vehicles (via urban stormwater runoff)[15][16] and acid mine drainage

Silt (sediment) in runoff from construction sites, logging, slash and burn practices or land clearing sites

Macroscopic pollution—large visible items polluting the water—may be termed "floatables" in an urban stormwater context, or marine debris when found on the open seas, and can include such items as:

Trash (e.g. paper, plastic, or food waste) discarded by people on the ground, and that are washed by rainfall into storm drains and eventually discharged into surface waters

Nurdles, small ubiquitous waterborne plastic pellets Shipwrecks, large derelict ships

Potrero Generating Station discharges heated water into San Francisco Bay.[17]

Thermal pollution: Thermal pollution is the rise or fall in the temperature of a natural body of water caused by human influence. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. Elevated water temperatures decreases oxygen levels (which can kill fish) and affects ecosystem composition, such as invasion by new thermophilic species. Urban runoff may also elevate temperature in surface waters.

Thermal pollution can also be caused by the release of very cold water from the base of reservoirs into warmer rivers.

Transport and chemical reactions of water pollutants:

Most water pollutants are eventually carried by rivers into the oceans. In some areas of the world the influence can be traced hundred miles from the mouth by studies using hydrology transport models. Advanced computer models such as SWMM or the DSSAM Model have been used in many locations worldwide to examine the fate of pollutants in aquatic systems. Indicator filter feeding species such as copepods have also been used to study pollutant fates in the New York Bight, for example. The highest toxin loads are not directly at the mouth of the Hudson River, but 100 kilometers south, since several days are required for incorporation into planktonic tissue. The Hudson discharge flows south along the coast due to coriolis force. Further south then are areas of oxygen depletion, caused by chemicals using up oxygen and by algae blooms, caused by excess nutrients from algal cell death and decomposition. Fish and shellfish kills have been reported, because toxins climb the food chain after small fish consume copepods, then large fish eat smaller fish, etc. Each successive step up the food chain causes a stepwise concentration of pollutants such as heavy metals (e.g. mercury) and persistent organic pollutants such as DDT. This is known as biomagnification, which is occasionally used interchangeably with bioaccumulation.

Large gyres (vortexes) in the oceans trap floating plastic debris. The North Pacific Gyre for example has collected the so-called "Great Pacific Garbage Patch" that is now estimated at 100 times the size of Texas. Many of these long-lasting pieces wind up in the stomachs of marine birds and animals. This results in obstruction of digestive pathways which leads to reduced appetite or even starvation.

Many chemicals undergo reactive decay or chemically change especially over long periods of time in groundwater reservoirs. A noteworthy class of such chemicals is the chlorinated hydrocarbons such as trichloroethylene (used in industrial metal degreasing and electronics manufacturing) and tetrachloroethylene used in the dry cleaning industry (note latest advances in liquid carbon dioxide in dry cleaning that avoids all use of chemicals). Both of these chemicals, which are carcinogens themselves, undergo partial decomposition reactions, leading to new hazardous chemicals (including dichloroethylene and vinyl chloride).

Groundwater pollution is much more difficult to abate than surface pollution because groundwater can move great distances through unseen aquifers. Non-porous aquifers such as clays partially purify water of bacteria by simple filtration (adsorption and absorption), dilution, and, in some cases, chemical reactions and biological activity: however, in some cases, the pollutants merely transform to soil contaminants. Groundwater that moves through cracks and caverns is not filtered

and can be transported as easily as surface water. In fact, this can be aggravated by the human tendency to use natural sinkholes as dumps in areas of Karst topography.

There are a variety of secondary effects stemming not from the original pollutant, but a derivative condition. An example is silt-bearing surface runoff, which can inhibit the penetration of sunlight through the water column, hampering photosynthesis in aquatic plants.

Marine pollutionFrom Wikipedia, the free encyclopedia

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While marine pollution can be obvious, as with the marine debris shown above, it is often the pollutants that cannot be seen that cause most harm.

Marine pollution:

Occurs when harmful effects, or potentially harmful effects, can result from the entry into the ocean of chemicals, particles, industrial, agricultural and residential waste, noise, or the spread of invasive organisms. Most sources of marine pollution are land based. The pollution often comes from nonpoint sources such as agricultural runoff and wind blown debris.

Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthos animals, most of which are either deposit or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. Many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic.

When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web.

Toxic metals can also be introduced into marine food webs. These can cause a change to tissue matter, biochemistry, behaviour, reproduction, and suppress growth in marine life. Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products.

Pathways of pollution:

There are many different ways to categorize, and examine the inputs of pollution into our marine ecosystems. Patin (n.d.) notes that generally there are three main types of inputs of pollution into the ocean: direct discharge of waste into the oceans, runoff into the waters due to rain, and pollutants that are released from the atmosphere.

One common path of entry by contaminants to the sea are rivers. The evaporation of water from oceans exceeds precipitation. The balance is restored by rain over the continents entering rivers and then being returned to the sea. The Hudson in New York State and the Raritan in New Jersey, which empty at the northern and southern ends of Staten Island, are a source of mercury contamination of zooplankton (copepods) in the open ocean. The highest concentration in the filter-

feeding copepods is not at the mouths of these rivers but 70 miles south, nearer Atlantic City, because water flows close to the coast. It takes a few days before toxins are taken up by the plankton[2].

Pollution is often classed as point source or nonpoint source pollution. Point source pollution occurs when there is a single, identifiable, and localized source of the pollution. An example is directly discharging sewage and industrial waste into the ocean. Pollution such as this occurs particularly in developing nations. Nonpoint source pollution occurs when the pollution comes from ill-defined and diffuse sources. These can be difficult to regulate. Agricultural runoff and wind blown debris are prime examples.

Direct discharge:

Acid mine drainage in the Rio Tinto River.

Pollutants enter rivers and the sea directly from urban sewerage and industrial waste discharges, sometimes in the form of hazardous and toxic wastes.

Inland mining for copper, gold. etc., is another source of marine pollution. Most of the pollution is simply soil, which ends up in rivers flowing to the sea. However, some minerals discharged in the course of the mining can cause problems, such as copper, a common industrial pollutant, which can interfere with the life history and development of coral polyps.[2] Mining has a poor environmental track record. For

example, according to the United States Environmental Protection Agency, mining has contaminated portions of the headwaters of over 40% of watersheds in the western continental US.[3] Much of this pollution finishes up in the sea.

Land runoff:

Surface runoff from farming, as well as urban runoff and runoff from the construction of roads, buildings, ports, channels, and harbours, can carry soil and particles laden with carbon, nitrogen, phosphorus, and minerals. This nutrient-rich water can cause fleshy algae and phytoplankton to thrive in coastal areas, known as algal blooms, which have the potential to create hypoxic conditions by using all available oxygen.

Polluted runoff from roads and highways can be a significant source of water pollution in coastal areas. About 75 percent of the toxic chemicals that flow into Puget Sound are carried by stormwater that runs off paved roads and driveways, rooftops, yards and other developed land.[4]

Ship pollution:

A cargo ship pumps ballast water over the side.

Ships can pollute waterways and oceans in many ways. Oil spills can have devastating effects. While being toxic to marine life, polycyclic aromatic hydrocarbons (PAHs), the components in crude oil, are very difficult to clean up, and last for years in the sediment and marine environment.[5]

Discharge of cargo residues from bulk carriers can pollute ports, waterways and oceans. In many instances vessels intentionally discharge illegal wastes despite foreign and domestic regulation prohibiting such actions. It has been estimated that container ships lose over 10,000 containers at sea each year (usually during storms).[6] Ships also create noise pollution that disturbs natural wildlife, and water from ballast tanks can spread harmful algae and other invasive species.[7]

Ballast water taken up at sea and released in port is a major source of unwanted exotic marine life. The invasive freshwater zebra mussels, native to the Black, Caspian and Azov seas, were probably transported to the Great Lakes via ballast water from a transoceanic vessel.[8] Meinesz believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless jellyfish. Mnemiopsis leidyi, a species of comb jellyfish that spread so it now inhabits estuaries in many parts of the world. It was first introduced in 1982, and thought to have been transported to the Black Sea in a ship’s ballast water. The population of the jellyfish shot up exponentially and, by 1988, it was wreaking havoc upon the local fishing industry. “The anchovy catch fell from 204,000 tons in 1984 to 200 tons in 1993; sprat from 24,600 tons in 1984 to 12,000 tons in 1993; horse mackerel from 4,000 tons in 1984 to zero in 1993.”[7] Now that the jellyfish have exhausted the zooplankton, including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem.

Invasive species can take over once occupied areas, facilitate the spread of new diseases, introduce new genetic material, alter underwater seascapes and jeopardize the ability of native species to obtain food. Invasive species are responsible for about $138 billion annually in lost revenue and management costs in the US alone.[9]

Atmospheric pollution:

Graph linking atmospheric dust to various coral deaths across the Caribbean Sea and Florida [10]

Another pathway of pollution occurs through the atmosphere. Wind blown dust and debris, including plastic bags, are blown seaward from landfills and other areas. Dust from the Sahara moving around the southern periphery of the subtropical ridge moves into the Caribbean and Florida during the warm season as the ridge builds and moves northward through the subtropical Atlantic. Dust can also be attributed to a global transport from the Gobi and Taklamakan deserts across Korea, Japan, and the Northern Pacific to the Hawaiian Islands.[11] Since 1970, dust outbreaks have worsened due to periods of drought in Africa. There is a large variability in dust transport to the Caribbean and Florida from year to year;[12] however, the flux is greater during positive phases of the North Atlantic Oscillation.[13] The USGS links dust events to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s.[14]

Climate change is raising ocean temperatures[15] and raising levels of carbon dioxide in the atmosphere. These rising levels of carbon dioxide are acidifying the oceans.[16] This, in turn, is altering aquatic ecosystems and modifying fish distributions,[17] with impacts on the sustainability of fisheries and the livelihoods

of the communities that depend on them. Healthy ocean ecosystems are also important for the mitigation of climate change.[18]

Deep sea mining:

Deep sea mining is a relatively new mineral retrieval process that takes place on the ocean floor. Ocean mining sites are usually around large areas of polymetallic nodules or active and extinct hydrothermal vents at about 1,400 - 3,700 meters below the ocean’s surface.[19] The vents create sulfide deposits, which contain precious metals such as silver, gold, copper, manganese, cobalt, and zinc.[20][21] The deposits are mined using either hydraulic pumps or bucket systems that take ore to the surface to be processed. As with all mining operations, deep sea mining raises questions about environmental damages to the surrounding areas

Because deep sea mining is a relatively new field, the complete consequences of full scale mining operations are unknown. However, experts are certain that removal of parts of the sea floor will result in disturbances to the benthic layer, increased toxicity of the water column and sediment plumes from tailings.[22] Removing parts of the sea floor disturbs the habitat of benthic organisms, possibly, depending on the type of mining and location, causing permanent disturbances.[23] Aside from direct impact of mining the area, leakage, spills and corrosion would alter the mining area’s chemical makeup.

Among the impacts of deep sea mining, sediment plumes could have the greatest impact. Plumes are caused when the tailings from mining (usually fine particles) are dumped back into the ocean, creating a cloud of particles floating in the water. Two types of plumes occur: near bottom plumes and surface plumes.[24] Near bottom plumes occur when the tailings are pumped back down to the mining site. The floating particles increase the turbidity, or cloudiness, of the water, clogging filter-feeding apparatuses used by benthic organisms.[25] Surface plumes cause a more serious problem. Depending on the size of the particles and water currents the plumes could spread over vast areas.[26][27] The plumes could impact zooplankton and light penetration, in turn affecting the food web of the area.[28][29]

Acidification:

Island with fringing reef in the Maldives. Coral reefs are dying around the world.[30]

The oceans are normally a natural carbon sink, absorbing carbon dioxide from the atmosphere. Because the levels of atmospheric carbon dioxide are increasing, the oceans are becoming more acidic.[31][32] The potential consequences of ocean acidification are not fully understood, but there are concerns that structures made of calcium carbonate may become vulnerable to dissolution, affecting corals and the ability of shellfish to form shells.[33].

Oceans and coastal ecosystems play an important role in the global carbon cycle and have removed about 25% of the carbon dioxide emitted by human activities between 2000 and 2007 and about half the anthropogenic CO2 released since the start of the industrial revolution. Rising ocean temperatures and ocean acidification means that the capacity of the ocean carbon sink will gradually get weaker,[34] giving rise to global concerns expressed in the Monaco[35] and Manado[36] Declarations.

A report from NOAA scientists published in the journal Science in May 2008 found that large amounts of relatively acidified water are upwelling to within four miles of the Pacific continental shelf area of North America. This area is a critical zone where most local marine life lives or is born. While the paper dealt only with areas from Vancouver to northern California, other continental shelf areas may be experiencing similar effects.[37]

A related issue is the methane clathrate reservoirs found under sediments on the ocean floors. These trap large amounts of the greenhouse gas methane, which ocean warming has the potential to release. In 2004 the global inventory of ocean methane clathrates was estimated to occupy between one and five million cubic kilometres.[38] If all these clathrates were to be spread uniformly across the ocean floor, this would translate to a thickness between three and fourteen metres.[39] This estimate corresponds to 500-2500 gigatonnes carbon (Gt C), and can be compared with the 5000 Gt C estimated for all other fossil fuel reserves.[38][40]

Eutrophication:

Polluted lagoon.

Effect of eutrophication on marine benthic life

Eutrophication is an increase in chemical nutrients, typically compounds containing nitrogen or phosphorus, in an ecosystem. It can result in an increase in the ecosystem's primary productivity (excessive plant growth and decay), and further effects including lack of oxygen and severe reductions in water quality, fish, and other animal populations.

The biggest culprit are rivers that empty into the ocean, and with it the many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. An excess of oxygen depleting chemicals in the water can lead to hypoxia and the creation of a dead zone.[41]

Estuaries tend to be naturally eutrophic because land-derived nutrients are concentrated where runoff enters the marine environment in a confined channel. The World Resources Institute has identified 375 hypoxic coastal zones around the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly in Japan.[42] In the ocean, there are frequent red tide algae blooms[43] that kill fish and marine mammals and cause respiratory problems in humans and some domestic animals when the blooms reach close to shore.

In addition to land runoff, atmospheric anthropogenic fixed nitrogen can enter the open ocean. A study in 2008 found that this could account for around one third of the ocean’s external (non-recycled) nitrogen supply and up to three per cent of the annual new marine biological production.[44] It has been suggested that accumulating reactive nitrogen in the environment may have consequences as serious as putting carbon dioxide in the atmosphere.[45]

Plastic debris:

A mute swan builds a nest using plastic garbage.

Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Eighty percent of marine debris is plastic - a component that has been rapidly accumulating since the end of World War II.[46] The mass of plastic in the oceans may be as high as one hundred million metric tons.[47]

Discarded plastic bags, six pack rings and other forms of plastic waste which finish up in the ocean present dangers to wildlife and fisheries.[48] Aquatic life can be threatened through entanglement, suffocation, and ingestion.[49][50][51] Fishing nets, usually made of plastic, can be left or lost in the ocean by fishermen. Known as ghost nets, these entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs, and other creatures, restricting movement, causing starvation, laceration and infection, and, in those that need to return to the surface to breathe, suffocation.[52]

Remains of an albatross containing ingested flotsam

Many animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural prey.[53] Plastic debris, when bulky or tangled, is

difficult to pass, and may become permanently lodged in the digestive tracts of these animals, blocking the passage of food and causing death through starvation or infection.[54][55]

Plastics accumulate because they don't biodegrade in the way many other substances do. They will photodegrade on exposure to the sun, but they do so properly only under dry conditions, and water inhibits this process.[56] In marine environments, photodegraded plastic disintegrates into ever smaller pieces while remaining polymers, even down to the molecular level. When floating plastic particles photodegrade down to zooplankton sizes, jellyfish attempt to consume them, and in this way the plastic enters the ocean food chain. [57] [58] Many of these long-lasting pieces end up in the stomachs of marine birds and animals,[59] including sea turtles, and black-footed albatross.[60]

Marine debris on Kamilo Beach, Hawaii, washed up from the Great Pacific Garbage Patch

Plastic debris tends to accumulate at the centre of ocean gyres. In particular, the Great Pacific Garbage Patch has a very high level of plastic particulate suspended in the upper water column. In samples taken in 1999, the mass of plastic exceeded that of zooplankton (the dominant animal life in the area) by a factor of six.[46][61] Midway Atoll, in common with all the Hawaiian Islands, receives substantial amounts of debris from the garbage patch. Ninety percent plastic, this debris accumulates on the beaches of Midway where it becomes a hazard to the bird population of the island. Midway Atoll is home to two-thirds (1.5 million) of the global population of Laysan Albatross.[62] Nearly all of these albatross have plastic in their digestive system[63] and one-third of their chicks die.[64]

Toxic additives used in the manufacture of plastic materials can leach out into their surroundings when exposed to water. Waterborne hydrophobic pollutants collect and magnify on the surface of plastic debris,[47] thus making plastic far more deadly in the ocean than it would be on land.[46] Hydrophobic contaminants are also known to bioaccumulate in fatty tissues, biomagnifying up the food chain and putting pressure on apex predators. Some plastic additives are known to disrupt the endocrine system when consumed, others can suppress the immune system or decrease reproductive rates.[61] Floating debris can also absorb persistent organic pollutants from seawater, including PCBs, DDT and PAHs.[65] Aside from toxic effects,[66] when ingested some of these are mistaken by the animal brain for estradiol, causing hormone disruption in the affected wildlife.[60]

Toxins:

Apart from plastics, there are particular problems with other toxins that do not disintegrate rapidly in the marine environment. Examples of persistent toxins are PCBs, DDT, pesticides, furans, dioxins, phenols and radioactive waste. Heavy metals are metallic chemical elements that have a relatively high density and are toxic or poisonous at low concentrations. Examples are mercury, lead, nickel, arsenic and cadmium. Such toxins can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation. They are also known to accumulate in benthic environments, such as estuaries and bay muds: a geological record of human activities of the last century.

Specific examples

Chinese and Russian industrial pollution such as phenols and heavy metals in the Amur River have devastated fish stocks and damaged its estuary soil.[67]

Wabamun Lake in Alberta, Canada, once the best whitefish lake in the area, now has unacceptable levels of heavy metals in its sediment and fish.

Acute and chronic pollution events have been shown to impact southern California kelp forests, though the intensity of the impact seems to depend on both the nature of the contaminants and duration of exposure.[68][69][70][71][72]

Due to their high position in the food chain and the subsequent accumulation of heavy metals from their diet, mercury levels can be high in larger species

such as bluefin and albacore. As a result, in March 2004 the United States FDA issued guidelines recommending that pregnant women, nursing mothers and children limit their intake of tuna and other types of predatory fish.[73]

Some shellfish and crabs can survive polluted environments, accumulating heavy metals or toxins in their tissues. For example, mitten crabs have a remarkable ability to survive in highly modified aquatic habitats, including polluted waters.[74] The farming and harvesting of such species needs careful management if they are to be used as a food.[75][76]

Surface runoff of pesticides can alter the gender of fish species genetically, transforming male into female fish.[77]

Heavy metals enter the environment through oil spills - such as the Prestige oil spill on the Galician coast - or from other natural or anthropogenic sources.[78]

In 2005, the 'Ndrangheta, an Italian mafia syndicate, was accused of sinking at least 30 ships loaded with toxic waste, much of it radioactive. This has led to widespread investigations into radioactive waste disposal rackets.[79]

Since the end of World War II, various nations, including the Soviet Union, the United Kingdom, the United States, and Germany, have disposed of chemical weapons in the Baltic Sea, raising concerns of environmental contamination.[80][81]

Noise pollution:

Marine life can be susceptible to noise or sound pollution from sources such as passing ships, oil exploration seismic surveys, and naval low-frequency active sonar. Sound travels more rapidly and over larger distances in the sea than in the atmosphere. Marine animals, such as cetaceans, often have weak eyesight, and live in a world largely defined by acoustic information. This applies also to many deeper sea fish, who live in a world of darkness.[82] Between 1950 and 1975, ambient noise in the ocean increased by about ten decibels (that is a ten-fold increase).[83]

Noise also makes species communicate louder, which is called the Lombard vocal response.[84] Whale songs are longer when submarine-detectors are on.[85] If

creatures don't "speak" loud enough, their voice can be masked by anthropogenic sounds. These unheard voices might be warnings, finding of prey, or preparations of net-bubbling. When one species begins speaking louder, it will mask other specie voices, causing the whole ecosystem to eventually speak louder.[86]

According to the oceanographer Sylvia Earle, "Undersea noise pollution is like the death of a thousand cuts. Each sound in itself may not be a matter of critical concern, but taken all together, the noise from shipping, seismic surveys, and military activity is creating a totally different environment than existed even 50 years ago. That high level of noise is bound to have a hard, sweeping impact on life in the sea."[87]

Adaptation and mitigation:

Aerosol can polluting a beach.

Much anthropogenic pollution ends up in the ocean. Bjorn Jenssen (2003) notes in his article, “Anthropogenic pollution may reduce biodiversity and productivity of marine ecosystems, resulting in reduction and depletion of human marine food resources” (p. A198). There are two ways the overall level of this pollution can be mitigated: either the human population is reduced, or a way is found to reduce the ecological footprint left behind by the average human. If the second way is not adopted, then the first way may be imposed as world ecosystems falter.

The second way is for humans, individually, to pollute less. That requires social and political will, together with a shift in awareness so more people respect the environment and are less disposed to abuse it. At an operational level, regulations,

and international government participation is needed. It is often very difficult to regulate marine pollution because pollution spreads over international barriers, thus making regulations hard to create as well as enforce.

Perhaps the most important strategy for reducing marine pollution is education. Most are unaware of the sources, and harmful effects of marine pollution, and therefore little is done to address the situation. In order to inform the population of all the facts, in depth research must be done to provide the full scale of the situation. Then this information must be made public.

As expressed in Daoji and Dag’s research,[88] one of the reasons why environmental concern is lacking among the Chinese is because the public awareness is low and therefore should be targeted. Likewise, regulation, based upon such in-depth research should be employed. In California, such regulations have already been put in place to protect Californian coastal waters from agricultural runoff. This includes the California Water Code, as well as several voluntary programs. Similarly, in India, several tactics have been employed that help reduce marine pollution, however, they do not significantly target the problem. In Chennai city, India, sewage has been dumped further into open waters. Due to the mass of waste being deposited, open-ocean is best for diluting, and dispersing pollutants, thus making them less harmful to marine ecosystems.

Oil spill:

A beach after an oil spill

Oil Slick from the Montara oil spill in the Timor Sea, September, 2009. For the 2010 Oil Spill in the Gulf of Mexico, see Deepwater Horizon oil spill.

An oil spill is the release of a liquid petroleum hydrocarbon into the environment due to human activity, and is a form of pollution. The term often refers to marine oil spills, where oil is released into the ocean or coastal waters. The oil may be a variety of materials, including crude oil, refined petroleum products (such as gasoline or diesel fuel) or by-products, ships' bunkers, oily refuse or oil mixed in waste. Spills take months or even years to clean up.[1] Oil also enters the marine environment from natural oil seeps.[2] Most human-made oil pollution comes from land-based activity, but public attention and regulation has tended to focus most sharply on seagoing oil tankers.

Environmental effects:

Surf Scoter covered in oil as a result of the 2007 San Francisco Bay oil spill.

The oil penetrates up the structure of the plumage of birds, reducing its insulating ability, and so making the birds more vulnerable to temperature fluctuations and much less buoyant in the water. It also impairs birds' flight abilities to forage and escape from predators. As they attempt to preen, birds typically ingest oil that covers their feathers, causing kidney damage, altered liver function, and digestive tract irritation. This and the limited foraging ability quickly causes dehydration and metabolic imbalances. Hormonal balance alteration including changes in luteinizing protein can also result in some birds exposed to petroleum.[3] Most birds affected by an oil spill die unless there is human intervention.[4][5] Marine mammals exposed to oil spills are affected in similar ways as seabirds. Oil coats the fur of Sea otters and seals, reducing its insulation abilities and leading to body temperature fluctuations and hypothermia. Ingestion of the oil causes dehydration and impaired digestions. Because oil floats on top of water, less sunlight penetrates into the water, limiting the photosynthesis of marine plants and phytoplankton. This, as well as decreasing the fauna populations, affects the food chain in the ecosystem.

Cleanup and Recovery:

Clean-up efforts after the Exxon Valdez oil spill.

A US Navy oil spill response team drills with a "Harbour Buster high-speed oil containment system".

A sheen is usually dispersed (but not cleaned up) with detergents which makes oil settle to the bottom. Oils that are denser than water, such as Polychlorinated biphenyls (PCBs), can be more difficult to clean as they make the seabed toxic.

Recovering the oil is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (in warmer waters, some oil may evaporate), and the types of shorelines and beaches involved.[6] Methods for cleaning up include:

Bioremediation : use of microorganisms [7] or biological agents [8] to break down or remove oil

Bioremediation Accelerator: Oleophilic, hydrophobic chemical, containing no bacteria, which chemically and physically bonds to both soluble and insoluble hydrocarbons. The bioremedation accelerator acts as a herding agent in water and on the surface, floating molecules to the surface of the water, including solubles such as phenols and BTEX, forming gel-like agglomerations. Non-detectable levels of hydrocarbons can be obtained in produced water and manageable water columns. By over spraying sheen with bio remediation accelerator, sheen is eliminated within minutes. Whether applied on land or on water, the nutrient-rich emulsion, creates a bloom of local, indigenous, pre-existing, hydrocarbon-consuming bacteria. Those specific bacteria break down the hydrocarbons into water and carbon dioxide, with EPA tests showing 98% of alkanes biodegraded in 28 days; and aromatics being biodegraded 200 times faster than in nature[9].

Controlled burning can effectively reduce the amount of oil in water, if done properly.[10] But it can only be done in low wind,[citation needed] and can cause air pollution.[11]

Oil slicks on Lake Maracaibo.

Volunteers cleaning up the aftermath of the Prestige oil spill.

Dispersants act as detergents, clustering around oil globules and allowing them to be carried away in the water.[12] This improves the surface aesthetically, and mobilizes the oil. Smaller oil droplets, scattered by currents, may cause less harm and may degrade more easily. But the dispersed oil droplets infiltrate into deeper water and can lethally contaminate coral. Recent research indicates that some dispersant are toxic to corals.[13]

Watch and wait: in some cases, natural attenuation of oil may be most appropriate, due to the invasive nature of facilitated methods of remediation, particularly in ecologically sensitive areas.[citation needed]

Dredging : for oils dispersed with detergents and other oils denser than water. Skimming : Requires calm waters Solidifying.[citation needed]

Equipment used includes:[10]

Booms: large floating barriers that round up oil and lift the oil off the water Skimmers : skim the oil

Sorbents: large absorbents that absorb oil Chemical and biological agents: helps to break down the oil Vacuums: remove oil from beaches and water surface Shovels and other road equipments: typically used to clean up oil on beaches Certain Products such as Nokomis 3

Prevention :

Secondary containment - methods to prevent releases of oil or hydrocarbons into environment.

Oil Spill Prevention Containment and Countermeasures (SPCC) program by the United States Environmental Protection Agency.

Double hulling - build double hulls into vessels, which reduces the risk and severity of a spill in case of a collision or grounding. Existing single-hull vessels can also be rebuilt to have a double hull.

Environmental Sensitivity Index (ESI) Mapping: Environmental Sensitivity Index (ESI) maps are used to identify sensitive shoreline resources prior to an oil spill event in order to set priorities for protection and plan cleanup strategies.[14][15] By planning spill response ahead of time, the impact on the environment can be minimized or prevented. Environmental sensitivity index maps are basically made up of information within the following three categories: shoreline type, and biological and human-use resources.[16]

Shoreline Type:

Shoreline type is classified by rank depending on how easy the oil would be to cleanup, how long the oil would persist, and how sensitivity of the shoreline.[17] The floating oil slicks put the shoreline at particular risk when they eventually come ashore, covering the substrate with oil. The differing substrates between shoreline types vary in their response to oiling, and influence the type of cleanup that will be required to effectively decontaminate the shoreline. In 1995, the National Oceanic and Atmospheric Administration extended ESI maps to lakes, rivers, and estuary shoreline types.[16] The exposure the shoreline has to wave energy and tides, substrate type, and slope of the

shoreline are also taken into account – in addition to biological productivity and sensitivity. The productivity of the shoreline habitat is also taken into account when determining ESI ranking.[18] Mangroves and marshes tend to have higher ESI rankings due to the potentially long-lasting and damaging effects of both the oil contamination and cleanup actions. Impermeable and exposed surfaces with high wave action are ranked lower due to the reflecting waves keeping oil from coming onshore, and the speed at which natural processes will remove the oil.

Biological Resources:

Habitats of plants and animals that may be at risk from oil spills are referred to as “elements” and are divided by functional group. Further classification divides each element into species groups with similar life histories and behaviors relative to their vulnerability to oil spills. There are eight element groups: Birds, Reptiles and Amphibians, Fish, Invertebrates, Habitats and Plants, Wetlands, and Marine Mammals and Terrestrial Mammals. Element groups are further divided into sub-groups, for example, the ‘marine mammals’ element group is divided into dolphins, manatees, pinnipeds (seals, sea lions & walruses), polar bears, sea otters and whales.[16][18] Issues taken into consideration when ranking biological resources include the observance of a large number of individuals in a small area, whether special life stages occur ashore (nesting or molting), and whether there are species present that are threatened, endangered or rare.[19]

Human-Use Resources:

Human use resources are divided into four major classifications; archaeological importance or cultural resource site, high-use recreational areas or shoreline access points, important protected management areas, or resource origins.[16][19] Some examples include airports, diving sites, popular beach sites, marinas, natural reserves or marine sanctuaries.

Estimating the volume of a spill:

Bottsand class oil recovery ship of the German Navy.

By observing the thickness of the film of oil and its appearance on the surface of the water, it is possible to estimate the quantity of oil spilled. If the surface area of the spill is also known, the total volume of the oil can be calculated.[20]

Film thicknessQuantity spread

Appearance

in mmgal/sq

miL/ha

Barely visible

0.0000015

0.0000380

25 0.370

Silvery sheen

0.0000030

0.0000760

50 0.730

First trace of color

0.0000060

0.0001500

100 1.500

Bright bands of color

0.0000120

0.0003000

200 2.900

Colors begin to dull

0.0000400

0.0010000

666 9.700

Colors are much darker

0.0000800

0.0020000

1332 19.500

Oil spill model systems are used by industry and government to assist in planning and emergency decision making. Of critical importance for the skill of the oil spill

model prediction is the adequate description of the wind and current fields. There is a worldwide oil spill modelling (WOSM) program.[21]

Largest oil spills: Oil spills of over 100,000 tonnes or 30 million US gallons, ordered by tonnes [a]

Spill / Tanker Location Date *Tons of crude oil Reference

Gulf War oil spill

Persian GulfJanuary 21, 1991

1,360,000–113,293,207 (9,969,000–830,439,000 barrels)

[22][23]

[24]

Ixtoc I oil well Gulf of MexicoJune 3, 1979–March 23, 1980

454,000–480,000 (3,328,000–3,518,000 barrels)

[25]

Atlantic Empress / Aegean Captain

Trinidad and Tobago July 19, 1979287,000 (2,104,000 barrels)

[26][27]

Fergana Valley Uzbekistan March 2, 1992285,000 (2,089,000 barrels)

[23]

Nowruz oil field Persian Gulf February 1983260,000 (1,906,000 barrels)

[28]

ABT Summer700 nautical miles (1,300 km) off Angola

1991260,000 (1,906,000 barrels)

[26]

Castillo de Bellver

Saldanha Bay, South Africa

August 6, 1983252,000 (1,847,000 barrels)

[26]

Amoco Cadiz Brittany, France March 16, 1978223,000 (1,635,000 barrels)

[23][26]

Amoco Haven tanker disaster

Mediterranean Sea near Genoa, Italy

1991144,000 (1,056,000 barrels)

[26]

Odyssey700 nautical miles (1,300 km) off Nova Scotia, Canada

1988132,000 (968,000 barrels)

[26]

Sea Star Gulf of OmanDecember 19, 1972

115,000 (843,000 barrels)

[23][26]

Torrey Canyon Scilly Isles, UK March 18, 196780,000–119,000 (586,000–872,000 barrels)

[23][26]

Irenes Serenade Navarino Bay, Greece 1980100,000 (733,000 barrels)

[26]

Urquiola A Coruña, Spain May 12, 1976100,000 (733,000 barrels)

[26]

a One tonne of crude oil is roughly equal to 308 US gallons, or 7.33 barrels.

The Deepwater Horizon oil spill, which started on April 20, 2010 in the Gulf of Mexico, is predicted to be the largest oil spill in US history, eclipsing the 1989 spill from Exxon Valdez that spilled 37,000 tonnes (257,000 barrels) of oil into an ecologically sensitive area of the Prince William Sound. One difference between the spills is that, in 1989, the cause was an oil tanker, which holds a finite amount of oil. The Deepwater Horizon oil spill, in contrast, is tapped to an underwater well, which may continue to leak for up to 3 months. By then, it would have leaked 61,000-307,000 tonnes (450,000-2,250,000 barrels) of oil.[29]

Measurement of water pollution:

Environmental Scientists preparing water autosamplers.

Water pollution may be analyzed through several broad categories of methods: physical, chemical and biological. Most involve collection of samples, followed by specialized analytical tests. Some methods may be conducted in situ, without sampling, such as temperature. Government agencies and research organizations have published standardized, validated analytical test methods to facilitate the comparability of results from disparate testing events.[18]

Sampling:

Sampling of water for physical or chemical testing can be done by several methods, depending on the accuracy needed and the characteristics of the contaminant. Many contamination events are sharply restricted in time, most commonly in association with rain events. For this reason "grab" samples are often inadequate for fully quantifying contaminant levels. Scientists gathering this type of data often employ auto-sampler devices that pump increments of water at either time or discharge intervals.

Sampling for biological testing involves collection of plants and/or animals from the surface water body. Depending on the type of assessment, the organisms may be identified for biosurveys (population counts) and returned to the water body, or they may be dissected for bioassays to determine toxicity.

Physical testing: Common physical tests of water include temperature, solids concentration like total suspended solids (TSS) and turbidity.

Chemical testing:

Water samples may be examined using the principles of analytical chemistry. Many published test methods are available for both organic and inorganic compounds. Frequently-used methods include pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients (nitrate and phosphorus compounds), metals (including copper, zinc, cadmium, lead and mercury), oil and grease, total petroleum hydrocarbons (TPH), and pesticides.

Biological testing:

Biological testing involves the use of plant, animal, and/or microbial indicators to monitor the health of an aquatic ecosystem.

Control of water pollution:

Domestic sewage:

Deer Island Waste Water Treatment Plant serving Boston, Massachusetts and vicinity.

Domestic sewage is 99.9% pure water, the other 0.1% are pollutants. While found in low concentrations, these pollutants pose risk on a large scale.[19] In urban areas, domestic sewage is typically treated by centralized sewage treatment plants. In the U.S., most of these plants are operated by local government agencies, frequently referred to as publicly owned treatment works (POTW). Municipal treatment plants are designed to control conventional pollutants: BOD and suspended solids. Well-designed and operated systems (i.e., secondary treatment or better) can remove 90 percent or more of these pollutants. Some plants have additional sub-systems to treat nutrients and pathogens. Most municipal plants are not designed to treat toxic pollutants found in industrial wastewater.[20]

Cities with sanitary sewer overflows or combined sewer overflows employ one or more engineering approaches to reduce discharges of untreated sewage, including:

utilizing a green infrastructure approach to improve stormwater management capacity throughout the system, and reduce the hydraulic overloading of the treatment plant[21]

repair and replacement of leaking and malfunctioning equipment[14]

increasing overall hydraulic capacity of the sewage collection system (often a very expensive option).

A household or business not served by a municipal treatment plant may have an individual septic tank, which treats the wastewater on site and discharges into the soil. Alternatively, domestic wastewater may be sent to a nearby privately-owned treatment system (e.g. in a rural community).

Industrial wastewater:

Dissolved air flotation system for treating industrial wastewater.

Some industrial facilities generate ordinary domestic sewage that can be treated by municipal facilities. Industries that generate wastewater with high concentrations of conventional pollutants (e.g. oil and grease), toxic pollutants (e.g. heavy metals, volatile organic compounds) or other nonconventional pollutants such as ammonia, need specialized treatment systems. Some of these facilities can install a pre-treatment system to remove the toxic components, and then send the partially-treated wastewater to the municipal system. Industries generating large volumes of wastewater typically operate their own complete on-site treatment systems.

Some industries have been successful at redesigning their manufacturing processes to reduce or eliminate pollutants, through a process called pollution prevention.

Heated water generated by power plants or manufacturing plants 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.[22]

Agricultural wastewater:

Riparian buffer lining a creek in Iowa

Nonpoint source controls: Sediment (loose soil) washed off fields is the largest source of agricultural pollution in the United States.[10] Farmers may utilize erosion controls to reduce runoff flows and retain soil on their fields. Common techniques include contour plowing, crop mulching, crop rotation, planting perennial crops and installing riparian buffers.[23][24]:pp. 4-95–4-96

Nutrients (nitrogen and phosphorus) are typically applied to farmland as commercial fertilizer; animal manure; or spraying of municipal or industrial wastewater (effluent) or sludge. Nutrients may also enter runoff from crop residues, irrigation water, wildlife, and atmospheric deposition.[24]:p. 2-9 Farmers can develop and implement nutrient management plans to reduce excess application of nutrients.[23][24]:pp. 4-37–4-38

To minimize pesticide impacts, farmers may use Integrated Pest Management (IPM) techniques (which can include biological pest control) to maintain control over pests, reduce reliance on chemical pesticides, and protect water quality.[25]

Confined Animal Feeding Operation in the United States

Point source wastewater treatment:

Farms with large livestock and poultry operations, such as factory farms, are called concentrated animal feeding operations or confined animal feeding operations in the U.S. and

are being subject to increasing government regulation.[26][27] Animal slurries are usually treated by containment in lagoons before disposal by spray or trickle application to grassland. Constructed wetlands are sometimes used to facilitate treatment of animal wastes, as are anaerobic lagoons. Some animal slurries are treated by mixing with straw and composted at high temperature to produce a bacteriologically sterile and friable manure for soil improvement.

Construction site stormwater:

Silt fence installed on a construction site.

Sediment from construction sites is managed by installation of:

erosion controls, such as mulching and hydroseeding, and sediment controls, such as sediment basins and silt fences.[28]

Discharge of toxic chemicals such as motor fuels and concrete washout is prevented by use of:

spill prevention and control plans, and

specially-designed containers (e.g. for concrete washout) and structures such as overflow controls and diversion berms.[29]

Urban runoff (stormwater):

Retention basin for controlling urban runoff

Effective control of urban runoff involves reducing the velocity and flow of stormwater, as well as reducing pollutant discharges. Local governments use a variety of stormwater

management techniques to reduce the effects of urban runoff. These techniques, called best management practices (BMPs) in the U.S., may focus on water quantity control, while others focus on improving water quality, and some perform both functions.[30]

Pollution prevention practices include low impact development techniques, installation of green roofs and improved chemical handling (e.g. management of motor fuels & oil, fertilizers and pesticides).[31] Runoff mitigation systems include infiltration basins, bioretention systems, constructed wetlands, retention basins and similar devices.[32][33]

Thermal pollution from runoff can be controlled by stormwater management facilities that absorb the runoff or direct it into groundwater, such as bioretention systems and infiltration basins. 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.[30]:p. 5-5

References:1. ̂ Pink, Daniel H. (April 19, 2006). "Investing in Tomorrow's Liquid Gold". Yahoo.

http://finance.yahoo.com/columnist/article/trenddesk/3748.2. ^ a b West, Larry (March 26, 2006). "World Water Day: A Billion People Worldwide

Lack Safe Drinking Water". About. http://environment.about.com/od/environmentalevents/a/waterdayqa.htm.

3. ̂ "A special report on India: Creaking, groaning: Infrastructure is India’s biggest handicap". The Economist. 11 December 2008. http://www.economist.com/specialreports/displaystory.cfm?story_id=12749787.

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5. ̂ "As China Roars, Pollution Reaches Deadly Extremes". The New York Times. August 26, 2007.

6. ̂ United States Environmental Protection Agency (EPA). Washington, DC. "The National Water Quality Inventory: Report to Congress for the 2002 Reporting Cycle – A Profile." October 2007. Fact Sheet No. EPA 841-F-07-003.

7. ^ a b United States Geological Survey (USGS). Denver, CO. "Ground Water and Surface Water: A Single Resource." USGS Circular 1139. 1998.

8. ̂ Clean Water Act, section 502(14), 33 U.S.C. §   1362 (14).9. ̂ CWA section 402(p), 33 U.S.C. §   1342(p) 10. ^ a b EPA. "Protecting Water Quality from Agricultural Runoff." Fact Sheet No. EPA-

841-F-05-001. March 2005.11. ̂ USGS. Reston, VA. "A Primer on Water Quality." FS-027-01. March 2001.

12. ̂ Schueler, Thomas R. "Microbes and Urban Watersheds: Concentrations, Sources, & Pathways." Reprinted in The Practice of Watershed Protection. 2000. Center for Watershed Protection. Ellicott City, MD.

13. ̂ EPA. “Illness Related to Sewage in Water.” Accessed 2009-02-20.14. ^ a b EPA. "Report to Congress: Impacts and Control of CSOs and SSOs." August 2004.

Document No. EPA-833-R-04-001.15. ^ a b c G. Allen Burton, Jr., Robert Pitt (2001). Stormwater Effects Handbook: A Toolbox

for Watershed Managers, Scientists, and Engineers. New York: CRC/Lewis Publishers. ISBN 0-87371-924-7. http://unix.eng.ua.edu/~rpitt/Publications/BooksandReports/Stormwater%20Effects%20Handbook%20by%20%20Burton%20and%20Pitt%20book/MainEDFS_Book.html. Chapter 2.

16. ̂ Schueler, Thomas R. "Cars Are Leading Source of Metal Loads in California." Reprinted in The Practice of Watershed Protection. 2000. Center for Watershed Protection. Ellicott City, MD.

17. ̂ Selna, Robert (2009). "Power plant has no plans to stop killing fish." San Francisco Chronicle, January 2, 2009.

18. ̂ For example, see Clescerl, Leonore S.(Editor), Greenberg, Arnold E.(Editor), Eaton, Andrew D. (Editor). Standard Methods for the Examination of Water and Wastewater (20th ed.) American Public Health Association, Washington, DC. ISBN 0-87553-235-7. This publication is also available on CD-ROM and online by subscription.

19. ̂ "Environmental works: types of sewage.Encyclopaedia Britannica Online. N.p., 2009. Web. 9 Oct. 2009. <http://www.search.eb.com/eb/article-72342>

20. ̂ EPA (2004)."Primer for Municipal Wastewater Treatment Systems." Document No. EPA 832-R-04-001.

21. ̂ EPA. "Green Infrastructure Case Studies: Philadelphia." December 9, 2008.22. ̂ EPA (1997) Profile of the Fossil Fuel Electric Power Generation Industry . (Report).

Document No. EPA/310-R-97-007. p. 2423. ^ a b U.S. Natural Resources Conservation Service (NRCS). Washington, DC. "National

Conservation Practice Standards." National Handbook of Conservation Practices. Accessed 2009-03-28.

24. ^ a b c EPA. "National Management Measures to Control Nonpoint Source Pollution from Agriculture." July 2003. Document No. EPA-841-B-03-004.

25. ̂ EPA. "Integrated Pest Management Principles." March 13, 2008.26. ̂ EPA. "Animal Feeding Operations." December 15, 2008.27. ̂ Iowa Department of Natural Resources. Des Moines, IA. "Animal Feeding Operations

in Iowa." Accessed 2009-03-05.28. ̂ Tennessee Department of Environment and Conservation. Nashville, TN."Tennessee

Erosion and Sediment Control Handbook." 2002.29. ̂ EPA (2006). "Construction Site Stormwater Runoff Control." National Menu of

Stormwater Best Management Practices.30. ^ a b EPA (1999)."Preliminary Data Summary of Urban Storm Water Best Management

Practices." Chapter 5. Document No. EPA-821-R-99-012.31. ̂ EPA. "Fact Sheet: Low Impact Development and Other Green Design Strategies."

October 9, 2008.

32. ̂ California Stormwater Quality Association. Menlo Park, CA. "Stormwater Best Management Practice (BMP) Handbooks." 2003.

33. ̂ New Jersey Department of Environmental Protection. Trenton, NJ. "New Jersey Stormwater Best Management Practices Manual." April 2004