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Water pollution.

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Presentation on theme: "Water pollution."— Presentation transcript:

1 Water pollution

2 What is Water Pollution?
Any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses can be considered pollution. There are two basic types of pollution Point Sources - discharge pollution from specific locations Factories, power plants, drain pipes, oil spill in the Gulf Non-Point Sources - scattered or diffuse, having no specific location of discharge Examples: Agricultural fields, Feedlots, Atmospheric Deposition contaminants carried by air currents and precipitated into watersheds or directly onto surface waters as rain, snow or dry particles Estimated 600,000 kg of the herbicide atrazine in the Great Lakes

3 Waterborne pathogens are mainly a product of improperly treated human waste At least 2.5 billion people in less developed countries lack adequate sanitation, and about half of these lack access to clean drinking water. Coli form bacteria - intestinal bacteria; used to detect water contamination

4 Sediment pollution Not just humans are affected by water quality
The living part of our planet---biosphere, needs certain things to support life Usually some form of gases CO2 for plants and O2 for animals Food source for energy to live Water—clean water Humans tend to forget about many of the other organisms that live with us. Sediment pollution has a profound affect on all living things. Sediment pollution is probably one of the most abundant type of water pollution. Because human activities have accelerated erosion rates in many areas, erosion and runoff contribute about 25 billion metric tons of sediment and suspended solids to world surface waters each year.

5 Aquatic animals are especially affected by sediment pollution and dissolved substances in the water. If the water is too polluted this can cause the oxygen content of the water to diminish and only certain organisms can survive. Water with an oxygen content > 6 ppm will support desirable aquatic life. Water with < 2 ppm oxygen will support mainly detritivores and decomposers. So if the water is so polluted that decomposers are the dominate species they will use up most of the oxygen—thus other organisms have no oxygen Thus testing the water for DO will help scientists know if a water system is not too polluted

6 Biochemical Oxygen Demand (BOD)
amount of dissolved oxygen consumed by aquatic microorganisms. Used as a test for organic waste contamination. Dissolved Oxygen Content (DO) measure of dissolved oxygen in the water Effects of oxygen-demanding wastes on rivers depend on volume, flow, and temperature of river water.

7 Remember that large bodies of relatively still water have different qualities
Oligotrophic - bodies of water that have clear water and low biological productivity Eutrophic - bodies of water that are rich in organisms and organic material Eutrophication - process of increasing nutrient levels and biological productivity Cultural Eutrophication - increase in biological productivity and ecosystem succession caused by human activities Algal blooms often result. Decomposing algae rob water of oxygen.

8 Oxygen Sag - oxygen levels decline downstream from a pollution source as decomposers metabolize waste materials

9 Red tides - dinoflagellate blooms - have become increasingly common in slow-moving and shallow waters. Dinoflagellates are single-celled organisms that swim with 2 whiplike flagella. Pfiesteria piscicida is a poisonous dinoflagellate recently recognized.

10 Inorganic Pollutants Metals
Many metals such as mercury, lead, cadmium, and nickel are highly toxic. Highly persistent and tend to bioaccumulate in food chains Most widespread toxic metal contaminant in North America is mercury (found in fish) 600,000 American children have mercury levels high enough to cause mental deterioration and 1 woman in 6 has levels high enough to harm fetus.

11 Nonmetallic Salts Many salts that are non-toxic at low concentrations can be mobilized by irrigation and concentrated by evaporation, reaching levels toxic to plants and animals. Leaching of road salts has had detrimental effect on many ecosystems. Arsenic in India and Bangladesh Arsenic in India

12 Acids and Bases Often released as by-products of industrial processes
Coal mining is an especially important source of acid water pollution. Many streams acidified by acid mine drainage are lifeless Combustion of fossil fuels releases sulfuric and nitric acids that are deposited in water. Thousands of lakes are empty of fish and support only a few mosses and fungi due to low pH.

13 Organic Chemicals Thousands of natural and synthetic organic chemicals are used to make pesticides, plastics, pharmaceuticals, pigments, etc. Two most important sources of toxic organic chemicals in water are: Improper disposal of industrial and household wastes Runoff of pesticides from fields, roadsides, golf courses, lawns, etc.

14 Thermal Pollution Raising or lowering water temperatures from normal levels can adversely affect water quality and aquatic life. Oxygen solubility in water decreases as temperatures increase. Industrial cooling processes often use heat-exchangers to extract excess heat, and then discharge heated water back into original source as a thermal plume.

15 Groundwater Contamination
Landfills contaminate groundwater when rain water leaks into aquifers below the landfill. Many early landfills did not have liners to trap rainwater that percolates through the landfill, and some newer landfills have liners that leak. The percolating water leaches toxic chemicals from batteries, broken fluorescent bulbs, electronic equipment, discarded household chemicals, and paints and solvents. Although landfills now prohibit toxic waste, and they are carefully regulated to prevent leakage to groundwater, many older sites are unlined and leak. Extensive herbicide use in agricultural areas (accounting for about 70 percent of total national use of pesticides) has resulted in widespread occurrence of herbicides in agricultural streams and shallow ground-water.

16 Groundwater Pollution Continued…
EPA estimates 4.5 trillion liters (1.2 trillion gal) of contaminated water seep into the groundwater in the U.S. every day. Comes from septic tanks, cesspools, landfills, waste disposal sites, etc. In agricultural areas, fertilizers and pesticides commonly contaminate aquifers and wells. Contaminants remain for thousands of years Groundwater Pollution Continued… Some main causes of nonpoint pollution: Agriculture Urban runoff Construction sites Land disposal Generally, soil conservation methods also help protect water quality. In urban areas, reducing materials carried away by storm runoff is helpful.

17 Groundwater Contamination cont…
For decades, groundwater was assumed impervious to pollution and was considered the gold standard for water quality, but that is no longer true. Methyl tertiary butyl ether (MTBE) a suspected carcinogen found in gasoline, now contaminates groundwater. Groundwater Contamination cont… 1 gal of gasoline can make 1 million gal of water undrinkable.

18 About half the U.S. population, and 95% of rural residents, depend on underground aquifers for drinking water.

19 How Does Pollution Get to Groundwater?

20 Coastal Contamination
Coastal zones are often overwhelmed by contamination from heavy metals, toxic chemicals, oil, pathogens, sediment. These zones would otherwise be among most productive. Discarded plastics are non-biodegradable, last for years, and are carried by currents around the world. Few coastlines in the world remain uncontaminated by oil pollution. 3 to 6 million tons of oil are released into ocean each year, about half of which is due to marine transport. Major oil spills from transport, military conflict, oil drilling in risky locations such as the North Sea There are plans to drill in seismically active California and Alaskan coasts.

21 The Front Fell Off? On July 21, 1991, an oil tanker off the coast of Australia split in two, dumping nearly 20,000 tons of crude oil. Senator Collins, a member of the Australian Parliament appeared on a TV news program to reassure the Australian public that this was an isolated incident. Let’s watch the video and you decide whether you would be convinced . . . Australian Oil Spill Video

22 Water Pollution Control
The best solution is SOURCE REDUCTION – don’t create as much pollution and we won’t have to worry about cleaning it up! For Example: Salt on icy roads in the winter – we have found that we can use 90% less salt without affecting safety on the roads Industries can try to recycle materials rather than getting rid of it (Point Sources)

23 Controlling Nonpoint Sources
Agriculture – fertilizers, pesticides, animals, and excess nutrients Urban runoff – streets, parking lots, and industrial sites contain salts, oily residues, rubber, metals, and many industrial toxins. Yards and golf courses are often over-fertilized. Construction Sites – produce vast amounts of sediment

24 Controlling Nonpoint Sources
Agriculture Applying precisely determined amounts of fertilizer, water, and pesticides Intercropping Adding nitrogen-fixing bacteria to the soil Urban Runoff Clean streets with sweepers Divert runoff away from streams and lakes Similar to above for lawns, etc.

25 Human Waste Disposal Since over 500 types of pathogenic (disease-causing) bacteria, viruses, and parasites can travel from human or animal excrement through the water, the U.S. does everything we can to prevent the spread of these diseases

26 Human Waste Disposal Human waste disposal occurs naturally when concentrations are low, just like “in nature” So, using the bathroom in your backyard is ok as long as populations are low (and your backyard is big) Some still use the bathroom in the backyard when populations are high …  Studies in Mexico City show that a significant portion of the airborne dust is actually dry, pulverized human feces

27 Collecting “Night Soil”
In poorer agricultural countries they collect “night soil” (human and animal waste) to spread on their field as a fertilizer While nutrients in the feces truly help the plants, the pathogens are not good! Crops must be surface sterilized before eating

28 Septic Tanks Water moves from the toilet to the septic tank where solid settle to the bottom and liquids move on The effluent (liquid) moves on to pipes where it percolates into gravel just below the soils surface Microorganisms metabolize nutrients Septic tank is pumped out periodically improvement/plumbing/sewer2.htm


30 Municipal Sewage Treatment
You guys are already pros! Just a little review: Primary Treatment – Solids are separated from liquids (the stinky part in that little shed) Secondary Treatment – Biological degradation of dissolved organic compounds with microorganisms Water flows from the top of the tank and sludge is removed from the bottom (at Central Davis Sewer the sludge is used for compost) Tertiary Treatment – Last steps Water is treated with chlorine to disinfect Nutrients are also removed at this step, especially nitrates and phosphates Without this step the excess nutrients could cause cultural eutropication

31 Primary Treatment - physical separation of large solids from the waste stream
Secondary Treatment - biological degradation of dissolved organic compounds Effluent from primary treatment transferred into trickling bed, or aeration tank Effluent from secondary treatment is usually disinfected (chlorinated) before release into nearby waterway. Tertiary Treatment - removal of plant nutrients (nitrates and phosphates) from secondary effluent

32 Low-Cost Waste Treatment
Wetlands Wetlands provide natural pollution control by removing nutrients, pesticides and bacteria from surface waters and can act as efficient, low cost sewage and animal waste treatment practices. Wetlands filter and collect sediment from runoff water, slow overland flow and store runoff water, they reduce both soil erosion and flooding downstream. Space can be a limiting factor – large cities don’t have space to dedicate to large wetland wastewater treatment This is referred to as phytoremediation

33 Sewage Goes Green




37 Water Remediation – Fixing Problems
Containment – confine or restrain dirty water or liquid in a place or cap the surface with an impermeable layer to divert surface water or groundwater away from the site and prevent further pollution Extraction – pump out polluted waters so they can be treated These pollutants are then destroyed, detoxified, neutralized, hydrolyzed, or changed in chemical composition

38 U.S. Clean Water Act (1972) Goal was to return all U.S. surface waters to “fishable and swimmable” conditions For point sources, discharge permits and best practicable control technology (BPT) are required. Set goals of best available, economically achievable technology (BAT) for zero discharge of 126 priority toxic pollutants In 1998, EPA switched regulatory approaches. Rather than issue standards on a site by site basis, the focus is now on watershed-level monitoring and protection. States are required to identify waters not meeting water quality goals and develop total maximum daily loads for each pollutant and each listed water body.

39 Areas of Contention Draining or filling of wetlands is regulated Farmers and developers consider this the taking of private land Underfunded Mandates State or local governments must spend monies to comply with regulations but are not repaid by Congress Agricultural runoff is largest source of surface water degradation, but regulation remains a problem. Some of the greatest impediments to achieving national goals in water quality are Sediment Nutrients Pathogens, especially from non-point discharges. About three-quarters of water pollution in the U.S. comes from soil erosion, air pollution fallout, and agricultural and urban runoff.

40 The Safe Drinking Water Act (SDWA)
is the main federal law that ensures the quality of Americans' drinking water. Under SDWA, EPA sets standards for drinking water quality and oversees the states, localities, and water suppliers who implement those standards. SDWA was originally passed by Congress in 1974 to protect public health by regulating the nation's public drinking water supply. The law was amended in 1986 and 1996 and requires many actions to protect drinking water and its sources: rivers, lakes, reservoirs, springs, and ground water wells. (SDWA does not regulate private wells which serve fewer than 25 individuals.) Drinking Water

41 The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA),
commonly known as Superfund, was enacted by Congress on December 11, This law created a tax on the chemical and petroleum industries and provided broad Federal authority to respond directly to releases or threatened releases of hazardous substances that may endanger public health or the environment. established prohibitions and requirements concerning closed and abandoned hazardous waste sites; provided for liability of persons responsible for releases of hazardous waste at these sites; established a trust fund to provide for cleanup when no responsible party could be identified

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