Area IV: Pollution
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Transcript of Area IV: Pollution
Area IV: PollutionIVA3: Water Pollution
22-1 Types, Effects, Sources of Water Pollution
l water is polluted by infectious bacteria, inorganic and organic chemicals, and excess heat
water pollution: any chemical, biological, or physical change in water quality that has a harmful effect on living organisms
the WHO estimates that 3.4 million people/yr people die prematurely from waterborne diseases
an estimated 1.5 million people/yr in U.S. become ill from infectious agents
22-1 Types, Effects, Sources of Water Pollution
l scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms
number of colonies of fecal coliform bacteria present in a water sample
drinking water: 0 colonies/100 mL swimming water: < 200 colonies/100 mL
bacterial source tracking (BST) biological oxygen demand (BOD): the
amount of dissolved oxygen consumed by aquatic decomposers
Fig. 22-2 Fecal coliform bacteria
22-1 Types, Effects, Sources of Water Pollution
l scientists monitor water quality, cont. chemical analysis: inorganic and organic
chemicals present, sediment content, and turbidity of water
indicator species genetic techniques are being used to develop
organisms that will glow in the presence of specific pollutants such as toxic heavy metals in the ocean and carcinogens in food
Fig. 22-3 Water quality and dissolved oxygen
22-1 Types, Effects, Sources of Water Pollution
l water pollution can come from a single source or variety of dispersed sources
point sources discharge at specific locations examples: drainpipes, sewer lines easy to identify, monitor, and regulate
non-point sources are scattered and diffuse and can’t be traced to any single site of discharge
examples: runoff from croplands, livestock feedlots
difficult and expensive to identify and control these discharges
Fig. 22-4 Point and nonpoint sources
22-1 Types, Effects, Sources of Water Pollution
l sources of water pollution, cont. leading sources: agriculture, industries, mining
agricultural activities: erosion overgrazing fertilizers pesticides excess salt from irrigated soils
22-1 Types, Effects, Sources of Water Pollution
l too much rain and too little rain can increase water pollution
increased moisture with more intense rains can flush harmful chemicals, plant nutrients, and microorganisms into waterways
prolonged drought can reduce river flows so there is less dilution available
warmer water contains less dissolved oxygen
22-2 Pollution of Freshwater Streamsl streams can recover from moderate levels
of degradable water pollutants if the flows are not reduced
dilution and biodegradation can allow recovery of stream pollution if:
they are not overloaded do not have reduced flow due to damming,
agricultural diversion, or drought
22-2 Pollution of Freshwater Streamsl stream recovery, cont.
breakdown of pollutants by bacteria creates an oxygen sag curve
organisms with a high oxygen demand can’t survive in the curve
factors in size of curve: volume of the stream volume of wastes entering flow rate temperature pH levels
Fig. 22-5 Dilution and decay of wastes
22-2 Pollution of Freshwater Streamsl most developed countries have reduced
point source pollution, but toxic chemicals and pollution from non-point sources are still problems
the U.S. has avoided increases in pollution from point sources in most streams
cleanup of rivers: Cuyahoga River in Ohio and the Thames River in Great Britain
there are sometimes large fish kills, and contamination of drinking water from industry, mining, and non-point runoff of fertilizers and pesticides
22-2 Pollution of Freshwater Streamsl stream pollution in most developing
countries is a serious and growing problem half of the world’s 500 major rivers are heavily
polluted many run through developing countries where
waste treatment is minimal or nonexistent
22-2 Pollution of Freshwater Streamsl the Ganges River in India is severally
polluted ~350 million people live in the Ganges River
basin with little treatment of sewage Hindu beliefs compound problem
air pollution from cremated bodies water pollution from bodies thrown in river
government solutions: waste treatment plants in the 29 large cities
along the Ganges electric crematoriums on its banks introduction of snapping turtles as body
scavengers
22-3 Pollution of Freshwater Lakesl lakes are less effective at diluting pollutants
that enter them often stratified with little vertical mixing very little flow occurring may take from 1–100 years to flush and
change water in lakes and reservoirs much more vulnerable to runoff contamination
of all kinds of materials chemical concentrations build up as they pass
through the food webs in lakes
Fig. 22-6 Biomagnification of PCBs
22-3 Pollution of Freshwater Lakesl human activities can reduce dissolved
oxygen and kill some aquatic species natural eutrophication: nutrient enrichment of
lakes from runoff depends on composition of the surrounding
drainage basin can enrich abundance of desirable
organisms cultural eutrophication occurs due to runoff
usually near urban or agricultural areas and in coastal water, enclosed estuaries, and bays
can lead to serious pollution problems
Oligotrophic lake
Eutrophic lake
Fig. 22-7 Cultural eutrophication
22-3 Pollution of Freshwater Lakesl human activities, cont.
cultural eutrophication, cont. the EPA states that 85% of large lakes near
major population centers in U.S. have some amount of cultural eutrophication
can be reduced or prevented by: banning or limiting phosphates in
detergents advanced treatment methods to remove
nitrates and phosphates from wastewater use of soil conservation to reduce runoff
22-3 Pollution of Freshwater Lakesl human activities, cont.
hot weather or drought -> “blooms” of organisms -> reduction in lake productivity
reduced sunlight + decomposition -> increase in bacteria populations -> decrease in DO -> fish kills -> anaerobic bacteria take over
cleanup of lakes includes removing excess weeds, controlling plant growth, and pumping air through lakes and reservoirs to avoid oxygen depletion
pollution prevention is cheaper than cleanup
22-3 Pollution of Freshwater Lakesl Case Study in lake recovery: Lake
Washington, Seattle sewage diverted from the lake to Puget Sound,
where rapid water exchange dilutes sewage recovery took 4 years lake had not filled with weeds and sediment concern about Puget Sound due to increased
urban runoff and growing population What is the best way to deal with pollution?
Lake Washington
Lake Washington
22-3 Pollution of Freshwater Lakesl Case Study: pollution of the Great Lakes
has dropped but is still a problem the Great Lakes contain about 95% of the
fresh surface water in the United States, and 20% of the world’s fresh surface water
> 38 million people obtain drinking water from the lakes
vulnerable due to less than 1% outflow to the St. Lawrence River but lots of inputs
Lake Erie: shallowest; was the most polluted; high concentration of people and industry
Fig. 22-8 Great Lakes basin
Western Lake Eerie
22-3 Pollution of Freshwater Lakesl Case Study: Great Lakes pollution, cont.
since 1972, the U.S. and Canada have worked together to reduce pollution
there is still a large area of depleted oxygen that occurs in the center of the lake each August for unknown reasons
a 2000 survey by the EPA stated that more than ¾ of the shoreline is not clean enough for swimming or use as drinking water
non-point land runoff is now a greater problem than industrial pollution
22-3 Pollution of Freshwater Lakesl Case Study: Great Lakes pollution, cont.
biomagnification of the depositions from atmospheric contaminants means that one fish in four is unsafe for human consumption
EPA funding for cleanup has also dropped by 80% since 1992
environmentalists call for banning the use of bleach, building new incinerators, and stopping the discharge into the lakes of 70 toxic chemicals
22-4 Pollution of Groundwaterl groundwater is vulnerable to pollution
spilling gasoline, oil, paint thinners, etc. onto the ground can contaminate groundwater
low-risk ecological problem high-risk health problem contaminated water in the aquifer will slowly
flow, creating a plume of contaminated water contaminants in groundwater are not diluted or
dispersed because this water moves usually less than 0.3 meter per day
22-4 Pollution of Groundwaterl groundwater vulnerability, cont.
cleansing is slow; factors: lower oxygen content colder temperature of the water smaller populations of decomposing
bacteria it can take hundreds of years to cleanse
degradable wastes; nondegradable wastes are there permanently
22-4 Pollution of Groundwaterl the extent of groundwater contamination is
generally unknown EPA and U.S. Geological Survey figures state
that one or more organic chemicals contaminate about 45% of municipal groundwater supplies in the U.S.
~26,000 industrial waste ponds and lagoons in U.S. do not have a liner to prevent seepage
many underground storage tanks have leaks determining the extent of a leak is costly, and
the cost of cleanup is more costly yet
Fig. 22-9 Groundwater contamination
22-4 Pollution of Groundwaterl groundwater contamination, cont.
nitrates can contaminate groundwater, esp. in agricultural areas; form nitrites in the body
arsenic is released into drinking water when a well is drilled into arsenic-rich soils and rock
WHO estimates that more than 112 million people drink water containing 5–100 times the recommended level of 10 parts/billion
Bangladesh has a serious problem with arsenic, but the UN and several NGOs have begun to assess wells and tag them
22-4 Pollution of Groundwaterl prevention is the most effective and
affordable way to protect groundwater from pollutants
underground tanks in the U.S. and some other developed countries are now strictly regulated
old, leaky tanks are being removed, and the surrounding soils are being treated
Fig. 22-10 Groundwater pollution
22-5 Ocean Pollutionl oceans can disperse and break down large
quantities of degradable pollutants if they are not overloaded
raw sewage, sludge, oil, and some degradable industrial wastes can be degraded, especially in deep-water areas
some marine animals have been less affected by pollutants than expected
there is controversy as to whether this is a viable solution to the problem
22-5 Ocean Pollutionl pollution near heavily populated areas
~40% of the world’s population lives on or within 62 miles of the coast
in most coastal developing countries and some developed countries, sewage is dumped into the sea without treatment
human viruses (not removed by waste treatment) have been found in coastal waters
nutrient enrichment from nitrate and phosphate runoffs causes algal blooms, killing fish and fish-eating birds
Fig. 22-11 Pollution of coastal waters
22-5 Ocean Pollutionl pollution near populated areas, cont.
extensive non-point runoffs have caused seasonal, large oxygen-depleted zones in temperate coastal waters
the second largest of these zones forms each summer at the mouth of the Mississippi River in the Gulf of Mexico
scientists are investigating whether fine clay particles can pull algae out of the water
preventive measures: restore wetlands, reduce nitrogen inputs, sewage treatment
Fig. 22-
22-5 Ocean Pollutionl pollutants from six states contaminate the
shallow Chesapeake Bay estuary a huge drainage basin adds both point and
non-point pollutants to the waters point sources: 60% of phosphates nonpoint sources: 60% of nitrates
the bay is shallow, so only 1% of the waste that enters is flushed into the Atlantic Ocean
commercial harvest of oysters, crabs, and fish has fallen sharply since 1960 because of overfishing, pollution, and disease
Fig. 22-13 Chesapeake Bay
22-5 Ocean Pollutionl Chesapeake Bay estuary, cont.
in 1983, the U.S. started an integrated coastal management plan
reduction of runoff upgrading waste treatment plants better monitoring of industrial discharges banning phosphates from detergents
between 1985 and 2000, 27% decline in phosphorus levels, 16% drop in nitrogen levels, recovery of grasses on bottom of bay
reduction in funding has slowed progress
Fig. 22-14 Coastal water pollution
22-5 Ocean Pollutionl Chesapeake Bay estuary, cont.
introduction of disease-resistant oysters could greatly reduce water pollution because oysters filter algae and silt from water
oysters recycled the entire volume of the bay in 3–4 days
over-harvesting and two parasitic oyster diseases reduced the oyster population
several ways to reintroduce oysters into the bay are being considered
22-5 Ocean Pollutionl oceans as dump sites
dumping industrial wastes off U.S. coasts has stopped, dumping of dredge spoils continues
many countries dump sewage sludge (banned in U.S. since 1992)
50 countries with >80% of world’s merchant fleet agreed not to dump ship waste at sea
the London Dumping Convention of 1972: 100 countries agreed not to dump highly toxic pollutants, high-level radioactive wastes in open sea
22-5 Ocean Pollutionl oil pollution
crude petroleum and refined petroleum reach the ocean from a number of sources
day-to-day activities such as leaks from pipelines and storage tanks, tankers being washed out, loading and unloading
studies show that most ocean oil pollution comes from human activities on land
22-5 Ocean Pollutionl oil pollution, cont.
harmful ecological and economic effects, but most disappear within 3–15 years
volatile organic hydrocarbons kill some aquatic organisms, especially larval forms
oil on birds and mammals causes drowning or fatal loss of body heat
bottom-dwelling organisms are killed when heavy components sink to the sea floor
recovery: 3 years from crude oil, 10-15 years from refined oil products
oil slicks on shore bad for local economy
22-5 Ocean Pollutionl oil pollution, cont.
only about 15% of the oil spilled can be recovered with current techniques
mechanical methods include floating booms, skimmers, and absorbent devices
chemical methods use coagulating agents for clumping oil and dispersing agents to break up slicks; fire to burn off floating oil
biological methods utilize bacteria that are able to degrade oil; probably best method
22-5 Ocean Pollutionl oil pollution, cont.
relevant laws the Oil Pollution Act of 1990 set up a trust
fund of $1 million per spill for cleanup by 2015, all oil tankers operating in U.S.
waters must be double hulledl preventing or reducing pollution from the
land and from streams is the key ocean pollution control must be linked with
land-use and air pollution policies to be effective
22-6 Preventing Surface Water Pollutionl reduce non-point pollution by preventing it
from reaching bodies of surface water agricultural non-point pollution can be reduced
by: reducing soil erosion reducing fertilizer use; slow-release fertilizer reforestation of watersheds keeping cover crops on farmland planting buffer zones between farmland and
surface water nearby relying more on bio controls than pesticides
EPA require 15,500 of the largest feedlots to apply for EPA permits
22-6 Preventing Surface Water Pollutionl most developing countries do not have
laws to set water pollution standards most cities in developing countries discharge
80–90% of untreated sewage water used for drinking, bathing, and washing clothes
in U.S., the Clean Water Act sets standards for allowed levels of key water pollutants and requires polluters to obtain permits to discharge pollutants into aquatic systems
EPA is experimenting with a discharge trading policy using credits
22-6 Preventing Surface Water Pollutionl septic tanks and sewage treatment can
reduce point-source water pollution ~1/4 of homes in U.S. served by septic tanks most urban areas served by sewage treatment
plants some 1,200 cities have combined storm runoff
and sewer lines because it is cheaper; can overflow
sewer systems in the U.S. are estimated to cost $10 billion a year for 10 years to install, expand, and repair the aging sewer network
Fig. 22-15 Septic tank system
22-6 Preventing Surface Water Pollutionl septic tanks and sewage treatment, cont.
raw sewage generally undergoes one or two levels of treatment
primary sewage treatment removes grit, floating objects, and suspended solids
removes ~60% of suspended solids and 30–40% of organic wastes
secondary sewage treatment is a biological process where aerobic bacteria remove up to 90% of O2-demanding organic wastes
tertiary sewage treatment: removing specific pollutants
Fig. 22-16 Primary and secondary treatment
22-6 Preventing Surface Water Pollutionl septic tanks and sewage treatment, cont.
raw sewage treatment, cont. a combination of primary and secondary
treatment removes 95–97% of the suspended solids and
oxygen-demanding organic wastes 70% of most toxic metal compounds 70% of P, 50% of N, 5% of dissolved
salts most U.S. cities have combined plants 34 East Coast cities screen out floating
objects and discharge sewage into coastal waters
22-6 Preventing Surface Water Pollutionl septic tanks and sewage treatment, cont.
water is bleached to remove colors and then disinfected (usually chlorination) to kill disease-causing bacteria and some viruses
ozonation and use of ultraviolet light are increasing as methods of disinfection
22-6 Preventing Surface Water Pollutionl sewage sludge
sludge is a thick, gooey mixture of bacteria, solids, chemicals, and metals when industrial and household wastes are combined
some sludge undergoes anaerobic digestion to decompose organics and produce compost
~36% of these biosolids are used as fertilizer; rest is added to landfills or incinerated
removing infectious bacteria, toxins, and metals is expensive, seldom done in the U.S.
health problems?
Fig. 22-17 Problems with sludge
22-6 Preventing Surface Water Pollutionl preventing toxic chemicals from reaching
treatment plants would eliminate these from sludge and water that is discharged
require industries and businesses to remove toxic and hazardous wastes from water sent to sewage treatment plants
encourage reduction or elimination of toxic chemical use and waste
have households switch to waterless composting toilet systems maintained by professionals
22-6 Preventing Surface Water Pollutionl wetlands can be used to treat sewage
low-tech, low-cost alternative to expensive waste treatment plants
sewage -> sedimentation tanks -> oxidation ponds -> (1 month) artificial marsh
genetic engineering is developing a bioreactor where modified bacteria will consume pesticides
without large investments in building adequate sanitation facilities, more people will have inadequate sanitation
Fig. 22-18 Wastewater garden
22-6 Preventing Surface Water Pollutionl water pollution laws have significantly
improved water quality in U.S. improvements:
1992 to 2002, communities served by water systems meeting federal guidelines increased from 79% to 94%
fishable and swimmable streams increased from 36% to 60% of those tested
topsoil loss through runoff was cut by 111 billion metric tons annually (%?)
annual wetland losses decreased by 80%
22-6 Preventing Surface Water Pollutionl water pollution laws have significantly
improved water quality in U.S., cont. problem areas:
in 2000, 40% of streams and 45% of lakes surveyed were too polluted for swimming or fishing
animal waste and waste lagoons fish unsafe to eat (pesticides, Hg, etc.) in 2003, the EPA found that >50% of the
6,000 largest industrial facilities have been illegally discharging wastes into waterways
22-6 Preventing Surface Water Pollutionl a 2001 report by EPA’s inspector general
calls for strengthening the Clean Water Act increased funding, increased authority to
control non-point pollution, modernizing monitoring system, increasing compliance with the law
integrating watershed and airshed planning to protect ground and surface water sources
halt the loss of wetlands; increase standards for wetland restoration; and create new wetlands before filling existing ones
farmers feel they should be compensated for property value losses that result from federal regulations protecting wetlands
22-7 Drinking Water Qualityl 20% of people lack safe drinking water
95% of people in developed countries and 74% of people in developing countries have access to clean drinking water
the UN estimates $23 billion/yr for 8–10 yr to bring clean drinking water to those lacking it
l centralized water treatment plants can provide safe drinking water; water is settled, filtered, and chlorinated
22-7 Drinking Water Qualityl the U.S. is upgrading water purification and
delivery systems hard to secure also difficult to adequately poison both chemical and biological indicators are
being developed to indicate contamination
22-7 Drinking Water Qualityl several simple, inexpensive ways for
individuals and villages to purify drinking water have been developed
exposure of contaminated water to intense sunlight in a clear plastic bottle kills bacteria
filtering water through cloth reduces risk of cholera
a small amount of chlorine in a plastic or clay storage vessel cuts the rate of diarrheal disease in half
22-7 Drinking Water Qualityl about 54 countries have standards for safe
drinking water levels have been established called maximum
contaminant levels for any pollutants that may adversely affect human health
privately owned wells don’t have to meet these standards
some want the standards to be strengthened certain industries want to weaken the Safe
Drinking Water Act (which industries?)
22-7 Drinking Water Qualityl some bottled water is not as pure as tap
water and costs much more bottled water is vastly more expensive than tap
water 1/4 is tap water 1/3 is contaminated with bacteria 1/5 is contaminated with organic chemicals
creates lots of waste manufacture releases toxic gases and liquids have home water tested be wary of companies claiming EPA approval
22-7 Drinking Water Qualityl we need to shift priorities to preventing and
reducing water pollution bottom-up political pressure on elected officials
has reduced point-source water pollution a shift needs to be made to how we can
prevent water pollution in the first place prevention of water pollution will take action
from individuals and groups to pressure elected officials
Fig. 22-19 Solutions
Fig. 22-20 What can you do?