Water Pollution

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Water Pollutiondefinition

• Any chemical, biological, or physical change in water quality that

• has a harmful effect on living organisms

OR

• makes water unsuitable for desired uses

Infectious Agents

Examples:

bacteria, viruses, protozoa, &

parasitic worms

Major Human Sources:

human & animal wastes

Effects:

diseases (Typhoid Fever, Cholera,

Dysentery, Hepatitis)

Infectious Agents

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Oxygen-Demanding Wastes

Examples: decomposition of

animal & plant matter by aerobic

bacteria

Major Human Sources:

sewage, animal feed lots, paper mills

Effects: depletion of dissolved oxygen

leading to death of aquatic organisms

Inorganic Chemicals

Examples:

acids, toxic metals (Pb, As, Se), & salts (NaCl,

Fl-)

Major Human Sources: surface runoff, industrial

effluents, household cleansers

Effects: damage human systems (cancers), harm aquatic life, lower crop

yields, accelerate corrosion, make water

non-potable

Organic Chemicals

Examples:

gasoline, oil, plastics, pesticides, detergents

Major Human Sources: industrial effluents, household cleansers, surface runoff from

farms and yards

Effects:

threaten human health & harm wildlife

• Chemical water analysis and use of indicator species is used to determine presence and concentration of pollutants

• Example: Filter-feeding mollusks

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Sediment

Examples:

soil & silt

Major Human Sources:

land erosion

Effects: reduce photosynthesis, disrupt

aquatic food webs, destroy spawning

grounds of benthic species

Heat (Thermal Pollution)

Examples:

excessive heat

Major Human Sources:

water cooling of electric power plants

Effects: lowers dissolved oxygen

(DO) levels, causes thermal shock in

species

Forms of Water Pollution

•Point sources: discharge pollutants at specific locations through pipes, ditches, or sewers into bodies of surface water

•Easily identified, monitored, and regulated

•Nonpoint sources: sources that cannot be traced to a single site of discharge•Large areas of land that pollute water by runoff or atmospheric deposition •Agricultural runoff includes sediments, inorganic fertilizers, manure, salts from irrigation waters, and pesticides •Responsible for an estimated 64% of all water pollution in US

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Pollution of Streams & Rivers

• Streams and rivers have the potential to rapidly recover from wastes and excess heat

• Depends on volume, flow rate, temperature, and pH

• Developing nations deploy about 95% of all sewage directly into rivers and streams

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Pollution of Lakes

• Lakes are more vulnerable to pollution

• Often stratified with little vertical mixing

• Have little flow

Eutrophication:

• Natural nutrient enrichment of aquatic ecosystems leading to excessive algal growth

Cultural Eutrophication• Acceleration of

eutrophication in response to human activities such as

• sewage treatment plants

• runoff of fertilizers

• accelerated erosion of topsoil

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Ecosystem Impact of Cultural

Eutrophication

• Leads to a potential algal bloom

• Decreases light penetration

• Decreases DO levels due to the action of decomposers

• Disrupts nitrogen and phosphorus cycles

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Methods to Control Eutrophication

• Planting vegetation along streambeds to slow erosion

• Controlling application and timing of fertilizer

• Controlling runoff from feedlots, golf courses, and fields

• Use of biological control agents such as denitrification bacteria

Pollution of Groundwater

Groundwater supplies 75% of drinking

water in Europe and 51% in US

Pollution Sources

Storage Lagoons

Septic Tanks

Landfills

Hazardous Waste Dumps

Deep Injection Wells

Underground storage tanks filled with gasoline, oil, and solvents

Contamination

EPA estimates that 4.5 trillion liters of contaminated water seep into US groundwater each day

Easily polluted because water in aquifers is renewed very slowly

• recycling time is 1400 years compared to 16 days for rivers

• Degradable wastes do not break down due to slow flow of water, cold temperatures, and smaller populations of bacteria

Impossible to clean contamination so prevention is the only effective way to protect groundwater resources

Require leak detection devices for underground tanks

Banning disposal of hazardous wastes in deep injection wells & landfills

Storing hazardous wastes above ground

Ocean Pollution

• Coastal areas (wetlands, estuaries, coral reefs, etc.) • 40% of world’s population lives

within 160 miles of the coast

• 14 of the 15 largest metropolitan cities are coastal

• Dumping of untreated sewage directly into the ocean along SE Asia

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Red Tides

•Algal blooms

•Release toxins that kill marine life

•Poison seafood

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Oil in Ocean Ecosystems

• Oil enters ocean ecosystems through fossil fuel operations

• Operation of offshore wells, washing tankers, pipeline and storage tank leaks

• 50% of oil pollution comes from oil dumped on land making its way to sewers

Effects:• VOCs in oil kill aquatic

organisms immediately• especially larvae

• Accumulation of tars on feathers and fur of marine birds and mammals• reduce natural insulation

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Cleaning up Oil Spills

Floating booms to contain oil

spill

Absorbent pads to soak up oil on

beaches

Coagulating agents that cause oil to clump for easier pickup

Dispersing agents to break

up oil slicks

Biological cleanup—oil degrading microbes

Waterborne Disease

•The generic term for waterborne disease is ‘toilet to mouth’ disease, because of the mode of infection.

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• Waterborne disease is common in undeveloped nations, where water treatment is not advanced.

• Even in the United States occasional outbreaks are not unknown. • In 1993 there was an outbreak

of Cryptosporidium in drinking water that affected 400,000 people in Milwaukee.

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Fecal Coliform Test

Fecal coliforms (specifically E. coli) are bacteria that live in the digestive system.

When they are detected in water, then there is a possibility that disease organisms spread through fecal matter are also present.

Standards are used that recognize different levels of hazard depending on the concentrations of coliforms.

One significant problem with this test is that it does not distinguish between coliforms from humans and other vertebrate animals.

Water for Domestic Use: How Safe is it?

• Domestic water in the U.S. is either drawn from surface or ground water, depending on location.

• The water is first treated by chlorination, and sometimes with fluorine, and stored in a reservoir before distribution.

• Biologically the water is safe, though there have been rare instances of outbreaks of pathogens.

• The greatest concerns are taste, which is not a health issue, and with trace contaminants (toxic organics and heavy metals).

• The pipes in homes can be a source of lead pollution/poisoning.

• Also, the chlorine can react with dissolved organic matter to create chlorinated hydrocarbons that are suspected of causing cancer.

• People are opting to consume more bottled water, currently selling for more than the price of oil.

• Home treatment systems (activated charcoal filters) are effective in removing the organics and heavy metals, but the filters need to be routinely changed because they can become colonized by bacteria and lose their effectiveness over time.

• Water Treatment

•

• ¾First treatment of drinking water began in 1872 with sand filtration- this method is fairly good at removing bacteria; chlorination began in 1902 and is effective against most pathogens.

•

• Wastewater Treatment ¾Septic Tank Disposal Systems ¾Waste Treatment Plants zPrimary Treatment – removes solids that settles in the tank zSecondaryTreatment - biological process that removes much of the dissolved organic matter and BOD, and some of the nitrogen via denitrification (bacteria convert the organics to inorganics). zTertiary Treatment or Advanced Treatment - a chemical process that removes the inorganic nutrients, especially phosphorus (expensive and rarely practiced).

• zChlorine Treatment

•

• Wastewater Renovation and Conservation Cycle ¾Steps: z1. Return of treated wastewater to crops z2. Renovation or natural purification by slow percolation of the wastewater into soil to eventually recharge the groundwater resource with clean water z3. Reuse of the treated water

•

• Resource Recovery Wastewater Treatment Plant

•

• In-Home Treatment of Waste ¾Practiced in some countries using a device called a Clivus multrum. ¾This is basically an outhouse. ¾The waste accumulates in a holding bin, it is composted there and makes a rich fertilizer. ¾Modern design and ventilation prevent bad smell.

•

• Septic Tanks ¾Home waste treatment. ¾The waste flows into a tank where the solids settle, and the liquid flows into a leach field (the grass is normally greener over the leach field). ¾There are usually regulations about where septic tanks can be used and their design. ¾Periodically they must be cleaned, and this is accomplished by a commercial service, euphemistically called a honey wagon, that sends out a truck to pump out the tank. ¾Septic tanks are common in rural or outlying suburban areas where the population density is low. ¾They can cause problems when used around lakes and streams because of the leachate.

•

• Problems with Wastewater Systems ¾A problem that faces many wastewater systems is the effect of storm water runoff. ¾Sewersoften pick up storm water, which raises the volume of water entering the plant. ¾After a big storm, under these conditions rawsewage can pour into the river. ¾In New Haven, CT for example, after a rain storm you would find corn all over the mud flats in the harbor (the corn is undigested waste from the sewage treatment plant, the birds loved it). ¾There is a multitude of toxins that enter the waste stream (used motor oil, heavy metals, paint solvents, pharmaceuticals that include mercury compounds, in short everything that anyone disposes of down the drain or in some cases down the storm sewer)

• Land Application of Wastewater

•

• ¾Another method of treating domestic wastewater. ¾This is practiced in some areas of the U.S. and is the common means of water treatment in Dutch cities and elsewhere. ¾In theory it is a method of recycling the waste and nutrients back into an ecosystem, such as an agricultural ecosystem. ¾In The Netherlands waste water is pumped into sand dunes where a natural filtering and biological treatment occurs, and the water is recycled back into the ground water which is used for human consumption. ¾In rural China the waste is often used to generate methane, which is used for cooking, and is recycled back onto the agricultural fields from which the nutrients originated.

• Water Pollution and Environmental Law ¾Environmental Law zThe branch of law dealing with conservation and use of natural resources and control of pollution

• zAlthough a federal law designed to protect water resources is as old as 1899, prior to 1974 there were no enforceable national standards for drinking water. zIn 1974 the Drinking Water Act was passed. This law required the EPA to establish standards, called maximum contaminant levels, for any pollutant that may have adverse effects on human health. zThey have been slow, by 1986 the EPA had set maximum contaminant levels for 26 out of 700 potential toxins. See table 21.4.