1. What is Water Pollution? Any physical, biological, or chemical change in water quality that...
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1. What is Water Pollution? Any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable
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 2
Slide 3
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 Waterborne pathogens 3
Slide 4
Not just humans are affected by water quality The living part
of our planet---biosphere, needs certain things to support life
(1)Usually some form of gases CO 2 for plants and O 2 for animals
(2)Food source for energy to live (3)Waterclean water Humans tend
to forget about many of the other organisms that live with us. 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.
Sediment pollution 4
Slide 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 oxygenthus other organisms have no oxygen
Thus testing the water for DO will help scientists know if a water
system is not too polluted 5
Slide 6
Biochemical Oxygen Demand (BOD) 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. amount of dissolved oxygen consumed by
aquatic microorganisms. Used as a test for organic waste
contamination. 6
Slide 7
Remember that large bodies of relatively still water have
different qualities Eutrophic - bodies of water that are rich in
organisms and organic material Eutrophication - process of
increasing nutrient levels and biological productivity Oligotrophic
- bodies of water that have clear water and low biological
productivity Algal blooms often result. Decomposing algae rob water
of oxygen. Cultural Eutrophication - increase in biological
productivity and ecosystem succession caused by human activities
7
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Oxygen Sag - oxygen levels decline downstream from a pollution
source as decomposers metabolize waste materials 8
Slide 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. 9
Slide 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. 10
Slide 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 11 Arsenic in India
Slide 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. 12
Slide 13
Runoff of pesticides from fields, roadsides, golf courses,
lawns, etc. Thousands of natural and synthetic organic chemicals
are used to make pesticides, plastics, pharmaceuticals, pigments,
etc. Organic Chemicals Two most important sources of toxic organic
chemicals in water are: Improper disposal of industrial and
household wastes 13
Slide 14
Raising or lowering water temperatures from normal levels can
adversely affect water quality and aquatic life. Oxygen solubility
in water decreases as temperatures increase. Thermal Pollution
Industrial cooling processes often use heat- exchangers to extract
excess heat, and then discharge heated water back into original
source as a thermal plume. 14
Slide 15
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. Groundwater
Contamination 15
Slide 16
In agricultural areas, fertilizers and pesticides commonly
contaminate aquifers and wells. Contaminants remain for thousands
of years 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. 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.
Groundwater Pollution Continued 16
Slide 17
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. 1 gal
of gasoline can make 1 million gal of water undrinkable.
Groundwater Contamination cont 17
Slide 18
About half the U.S. population, and 95% of rural residents,
depend on underground aquifers for drinking water. 18
Slide 19
How Does Pollution Get to Groundwater? 19
Slide 20
Coastal zones are often overwhelmed by contamination from heavy
metals, toxic chemicals, oil, pathogens, sediment. These zones
would otherwise be among most productive. 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. Discarded plastics are non- biodegradable, last for
years, and are carried by currents around the world. Coastal
Contamination 20
Slide 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. Lets watch the video and you
decide whether you would be convinced... Australian Oil Spill Video
21
Slide 22
Water Pollution Control The best solution is SOURCE REDUCTION
dont create as much pollution and we wont 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) 22
Slide 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 23
Slide 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. 24
Slide 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 25
Slide 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 26
Slide 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 27
Slide 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 http://home.howstuffworks.com/home-
improvement/plumbing/sewer2.htm http://home.howstuffworks.com/home-
improvement/plumbing/sewer2.htm 28
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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 30
Slide 31
Primary Treatment - physical separation of large solids from
the waste stream Secondary Treatment - biological degradation of
dissolved organic compounds 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 Effluent from primary
treatment transferred into trickling bed, or aeration tank 31
Slide 32
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 dont have space to dedicate to large wetland wastewater
treatment This is referred to as phytoremediation Wetlands Low-Cost
Waste Treatment 32
Slide 33
Sewage Goes Green 33
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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 37
Slide 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.
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Slide 39
Areas of Contention Draining or filling of wetlands is
regulated Farmers and developers consider this the taking of
private land Some of the greatest impediments to achieving national
goals in water quality are 1)Sediment 2)Nutrients 3)Pathogens,
especially from non-point discharges. 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. About
three-quarters of water pollution in the U.S. comes from soil
erosion, air pollution fallout, and agricultural and urban runoff.
39
Slide 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.) 40 Drinking Water
Slide 41
The Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA), commonly known as Superfund, was enacted by
Congress on December 11, 1980. 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 41