Transcript Chapter 19 Notes - Rankin County School District

Chapter 19 Notes
Mrs. Sealy
Types and Sources of Water Pollution
• Water Pollution = any chemical, biological or physical change
in water quality that has a harmful effect on living organisms
or makes water unsuitable for desired use
Major Types of Water Pollution
• Disease causing agents (pathogens) – bacteria,
viruses, protozoa, and parasitic worms that
come from sewage and untreated human and
animal waste
• Indicator of water quality = # colonies coliform
bacteria
• 0-100=drinking water, max of 200 for
swimming water
Oxygen Demanding Waste
• Organic wastes that can be decomposed by
aerobic bacteria. Bacteria deplete water of
oxygen, which causes death to fish and other
aerobic aquatic life
• BOD = biological oxygen demand = amount of
oxygen needed by aerobic decomposers to
break down organic matter in a certain
volume of water over a five day period at
twenty degrees Celsius
Water Soluble Inorganic Chemicals
• Acids, salts, and compounds of toxic metals
(Hg, Pb)
• High levels of these make water unfit to drink,
harm fish, and other aquatic life, lower crop
yields and accelerates metal corrosion
Inorganic Plant Nutrients
• Water soluble nitrates and phosphates that
cause excessive growth of algae and other
aquatic plants, which die, decay and deplete
water of oxygen, killing fish.
• Excessive levels of nitrates lower the oxygen
carrying capacity of blood causing “Blue Baby
Syndrome”
Organic Chemcials
• Oil, plastic, gas,
pesticides, solvents, and
detergents
• Threaten human fish
and aquatic life
• Just downright
poisonous
Sediment or suspended matter
• Clouds the water and reduces photosynthesis,
which disrupts food webs and carries bacteria
and pesticides
• It clogs and fills lakes, streams and harbors
• Decreases the efficiency of chlorine to
disinfect water
Water Soluble Radioactive Isoptopes
• Can be biologically magnified in tissues and
organs
• Ionizing radiation can cause birth defects,
cancer and genetic damage
Thermal Pollution
• Heat absorbed by water to cool industrial and
power plants which lowers the water quality
by lowering dissolved oxugen leels making
aquatic organisms more vulnerable to disease,
parasites and toxic chemcials
• Causes fish kills
• Increases the growth rate of algae
Finland
Genetic Pollution
• When aquatic ecosystems are disruoted by
deliberate or accidental introduction of nonnative species, which reduces biodiversity and
causes economic loss.
• These species are usually introduced in the
ballast water of ships
Point source Pollution
•
1. Point sources = discharge pollutants
at specific locations (pipes, ditches, & sewers
at factories, sewage treatment plants, active
and abandoned underground mines, offshore
oil wells, & oil tankers). These are controlled in
developed countries and uncontrolled in
developing countries.
Non-point Source
• 2. Non Point Sources = pollutants that cannot
be traced to a specific site. These
include
large land areas that pollute due to runoff,
subsurface flow, & deposition from the
atmosphere. Agriculture produces non-point
pollution in the form of sediment, inorganic
fertilizers, manure, salts dissolved in irrigation
water and pesticides.
II. Pollution Of Streams and Lakes
• A. Stream and River Pollution
• 1. Streams and rivers usually recover rapidly
as long as streams are
not overloaded with pollutants and flow is not
reduced due to drought, damming, or
diversion for agriculture and industry
II. Pollution Of Streams and Lakes
• Oxygen Sag Curve = when bacteria reduces or
eliminates populations of organisms with high
oxygen requirements. This depends upon
stream volume, flow rate, temperature, pH
level and volume of degradable wastes. This
curve can also be done for thermal pollution
Types of
organisms
Clean Zone
Decomposition
Zone
Septic Zone
Normal clean water organisms
(Trout, perch, bass,
mayfly, stonefly)
Trash fish
(carp, gar,
Leeches)
Fish absent, fungi,
Sludge worms,
bacteria
(anaerobic)
Recovery Zone
Trash fish
(carp, gar,
Leeches)
8 ppm
Clean Zone
Normal clean water organisms
(Trout, perch, bass,
mayfly, stonefly)
8 ppm
Concentration
Dissolved oxygen
Oxygen sag
Biological oxygen
demand
2 ppm
Direction of flow
Point of waste or
heat discharge
Time of distance downstream
Fig. 19.3, p. 479
Reduction of Stream Pollution
•
•
require cities to withdraw drinking water
downstream rather than upstream, which
improves water quality
Water pollution laws of 1970 have increased
the number and quality of wastewater
treatment plants which in the US and other
developed countries has reduced or
eliminated point source pollution
Lake Pollution
• Dilution is less effective
• Lakes and reservoirs contain stratified layers that
undergo little vertical mixing. Stratification reduces
levels of dissolved oxygen (especially on the bottom)
• Ponds contain small volumes of water
• Lakes are more vulnerable to contamination by plant
nutrients, oil, pesticides, and toxic substances
(Pb,Hg,Se) and acid deposition
Water
0.000002 ppm
Herring gull
124 ppm
Phytoplankton
0.0025 ppm
Herring gull eggs
124 ppm
Lake trout
4.83 ppm
Zooplankton
0.123 ppm
Rainbow smelt
1.04 ppm
Fig. 19.4, p. 481
Eutrophication
• Natural nutrient enrichment
• Cultural Eutrophication=when human
activities near urban or cultural areas greatly
accelerate the input of nutrients to a lake.
Mostly nitrates and phosphates cause this.
Eutrophication
• During hot weather, dense growths of algae,
cyanobacteria, duckweed and hyacinths occur
and dissolved oxygen is depleted which kills
fish and other aquatic animals
• Excessive nutrients can cause anaerobic
bactria to take over and produce gaseous
decomposition products (CH4, H2S)
Discharge of untreated
municipal sewage
(nitrates and phosphates)
Nitrogen compounds
produced by cars
and factories
Discharge of
detergents
( phosphates)
Discharge of treated
municipal sewage
(primary and secondary
treatment:
nitrates and phosphates)
Lake ecosystem
nutrient overload
and breakdown of
chemical cycling
Dissolving of
nitrogen oxides
(from internal combustion
engines and furnaces)
Natural runoff
(nitrates and
phosphates
Manure runoff
From feedlots
(nitrates and
Phosphates,
ammonia)
Runoff from streets,
lawns, and construction
lots (nitrates and
phosphates)
Runoff and erosion
(from from cultivation,
mining, construction,
and poor land use)
Fig. 19.5, p. 482
Fig. 19.6, p. 483
CANADA
Nipigon Bay
Jackfish Bay
Thunder Bay
Silver Bay
St. Mary’s R.
St. Lawrence R.
Spanish R.
St. Louis R.
MICHIGAN
Penetary Bay
Sturgeon Bay
WISCONSIN
MICHIGAN
Saginaw
Bay
Niagara Falls
NEW
Saginaw R.
Grand R.
System
Niagara R.
St. Clair R.
Thames R.
Buffalo R.
Detroit R.
Rouge R.
Raisin R.
Ashtabula R.
PENNSYLVANIA
Cuyahoga R.
Maumee R.
Rocky R.
Black R.
MINNESOTA
IOWA
ILLINOIS
INDIANA
YORK
OHIO
Great Lakes drainage basin
Most polluted areas, according to the Great Lakes Water Quality Board
“Hot spots” of toxic concentrations in water and sediments
Eutrophic areas
Fig. 19.7, p. 484
Industrial
pollution
Beaches
closed
Suffocated
fish
Sewage
runoff
Dead algae
Low
dissolved
oxygen
Mercurytainted fish
Decreased fish
population
Fig. 19.8a, p. 485
Suburban
sprawl
Clear
water
PCB’s in
sediment
Lower
water
levels
High
dissolved
oxygen
Thriving fish
population
Fig. 19.8b, p. 485
Ways To Prevent Cultural Eutrophication
• Use advanced sewage treatment
• Ban or limit phosphates in household
detergents and other cleaners
• Practice soil conservation and land use control
to reduce nutrient runoff
Ocean Hypoxia
• The “Dead Zone” is an area
of the ocean that is severely
oxygen depleted due to
cultural eutrophication
• Caused by plant nutrients
that get washed down rivers
into the ocean causing algal
blooms and fish kills
• Examples: Chesapeake bay
and the Gulf of Mexico
Ocean Pollution
• How coastal areas are effected
1. wetlands, estuaries, coral reefs, mangrove swamps
bear the majority of the enormous wastes we ad to
the ocean
2. Most sewage in developing countries is dumped
directly into the ocean without treatment
* sewage and agricultural wastes
introduce
large quantities of nitrogen and phosphorus
to the water which causes algal blooms
Ocean Pollution
• Pollutants that are dumped into the ocean:
1. dredge spoils or materials full of toxic chemicals
scraped from the bottom of harbors and rivers to
maintain channels are dumped from barges and
ships at 110 sites in the Pacific, Atlantic and Gulf
Coasts
2. sewage sludge-gooey, mud like mixture of toxic
chemicals, infectious agents and settled solids
removed from wastewater at sewage treatment
plants (banned in the US since 1992)
Ocean Pollution
• Sewage and garbage from merchant marine
fleets
• Highly toxic pollutants and high level
radioactive wastes
Ocean Pollution
• Effects of oil on ocean ecosystems
• Crude petroleum (oil from ground) and refined
petroleum (fuel oil, gasoline, & other petroleum
products) pollution comes from normal operation of
offshore wells, washing tankers, & releasing oily
water and from pipeline and storage tank leaks onto
the land or into sewers by cities, individuals and
industry (1000X’s that spilled by the Exxon Valdez).
Ocean Pollution
– Tar like globs that float on the surface coat
feathers of diving and other birds and the fur of
marine mammals, which destroys their
insulation and buoyancy, which causes death
due to the loss of body heat.
– Oil that sinks to the bottom smothers bottom
dwelling organisms (crabs, oysters, mussels,
clams) and can kill coral reefs.
– Overall- it is a low risk ecological problem.
Prevention of Ocean Pollution
•
Reduce oil waste and shift to renewable energy
resourcesReduce flow of pollution from the land
& streams into the oceans.
–
Prevent and control air pollution (33% of pollutants
come from emissions).
Prevention
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Discourage sludge dumping and hazardous dredged material.
Reduce or curtail development of oil drilling and oil shipping in
coastal areas.
Develop land use planning in coastal areas.
Require double hulls in oil tankers by 2002.
Recycle used oil
Reduce genetic pollution in ballast water.
Prevention and Reduction of Surface Water
Pollution
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Nonpoint pollution
1.Leading cause=agriculture. Farmers can reduce fertilizer
runoff onto surface waters and into aquifers by:.
Reducing or eliminating the amount of fertilizer use.
Use slow release fertilizers.
Alternate crops between row crops and nitrogen fixation
crops
Plant buffer zones between cultivated fields and nearby
surface waters.
Apply pesticides only when needed.
Use biological controls for pests.
Prevention and Reduction of Surface Water
Pollution
•
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Eliminate or reduce inorganic fertilizers and
pesticides for golf courses, lawns and public lands.
Livestock growers could manage animal density
(reducing manure). Planting buffers, and locating
feed lots.
Create detention basins for animal runoff and
reapply fertilizers to croplands or forestlands.
Reforest critical watersheds (reduces soil erosion
and the severity of flooding and slows global
warming and the loss of wildlife habitants.
Point Pollution and the Legal Approach
•
•
2% of the sewage is treated in Latin American, 15%
in China, and 30% in India The Clean Water Act of
1977 and the Water Quality Act of 1987 form the
basis of the U.S. effort to control pollution of the
country’s surface waters.
The main goal=safe waters for fishing and
swimming by 1983 and restore and maintain
chemical, physical, and the biological integrity of
the nation’s waters.
•
Discharge Trading Policy of 1995 uses market forces to reduce
water pollution. Credits can be sold for excess reductions- like
air pollution control and SO.
Sewage Treatment Plants
•
Primary sewage treatment= a mechanical
process to screen out debris (sticks, stones,
rages, etc.), and suspended solids which
settle out as sludge in a settling tank.
Sewage Treatment Plants
•
Secondary sewage treatment= biological process in which
aerobic bacteria are used to remove up to 90% of
biodegradable, oxygen demanding organic wastes.
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Trickling filters= aerobic bacteria degrade sewage as it seeps
through a bed of crushed stones covered which bacteria and
protozoa.
Activated sludge process=sewage is pumped into a large tank,
mixed for hours with bacteria and air to facilitate degradation by
microorganisms. Then suspended solids settle out as sludge.
Sludge from both primary and secondary treatment is broken
down in an anaerobic digester and then incinerated, dumped into
the ocean, or used as fertilizer.
Sewage Treatment Plants
•
Advanced Sewage Treatment= series of chemical and physical
processes that remove pollutants left in the water after primary
and secondary treatment.
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Advanced sewage treatment removes nitrates and phosphates
which contribute to eutrophication of lakes, slow moving streams,
and coastal waters.
These advanced plants cost twice as much to build and four times
as much to operate. Water from primary, secondary, and advanced
treatment plants is bleached and disinfected by chlorinating.
» Sewage Sludge (36% by weight) is applied to farmland as
fertilizer for crops used for animal feed and human food.
» 38% is dumped into landfills;16% is incinerated; 9% is
composted
Waste lagoon,
pond, or basin
Hazardous
waste
injection
well
Mining
site
Water
pumping
well
Pumping
well
Road
salt
Buried gasoline
and solvent
tanks
Sewer
Landfill
Cesspoll,
septic
tank
Leakage
from faulty
casing
Unconfined freshwater aquifer
Groundwater
Confined freshwater aquifer
Groundwater flow
Confined aquifer
Discharge
Fig. 19.9, p. 487
Groundwater
• IV. Groundwater = prime source of drinking water
and irrigation water. Groundwater cannot cleanse
itself like surface water does.
• Reasons for pollution
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groundwater flow is slow, not turbulent
contaminants are not effectively diluted and dispersed
groundwater has smaller proportions of decomposing bacteria
cold temperatures slow decomposition
Groundwater
– Reasons for Pollution
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underground storage tanks
landfills
abandoned waste dumps
deep well disposal of liquid hazardous waste
industrial and livestock waste storage lagoons located
near aquifers
industrial waste ponds without liners to prevent toxic
liquid wastes from seeping into aquifers
VI. Drinking Water Quality
•
Protection of drinking water
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U>S> Safe Drinking Water Act of 1974 tests fro 64
contaminants
Strengthening Safe water Act:
improving water treatment by combining smaller
water systems for larger ones
strengthening and enforcing public notification
requirements about violations
banning all lead in new plumbing pipes, faucets
and fixtures
Bottled Water
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International Bottled Water Association tests for 181
contaminants
National Sanitation Foundation = certification by this agency
requires tests for 200 chemical and biological contaminants
EPA does not test or approve water-filtering devices
One/fourth of it is tap water
40% is contaminated by bacteria and fungi
1.5 million tons of plastic thrown away
Oil used to make plastic would power 100,000 cars for a year.