Chapter 19 Notes

busyicicleΜηχανική

22 Φεβ 2014 (πριν από 3 χρόνια και 7 μήνες)

126 εμφανίσεις

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 non
-
native 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

Fig. 19.3, p. 479

Clean Zone

Decomposition

Zone

Septic Zone

Recovery Zone

Clean Zone

Normal clean water organisms

(Trout, perch, bass,

mayfly, stonefly)

Trash fish

(carp, gar,

Leeches)

Fish absent, fungi,

Sludge worms,

bacteria

(
anaerobic
)

Trash fish

(carp, gar,

Leeches)

Normal clean water organisms

(Trout, perch, bass,

mayfly, stonefly)

8 ppm

Dissolved oxygen

Biological oxygen

demand

Oxygen sag

2 ppm

8 ppm

Concentration

Types of

organisms

Time of distance downstream

Direction of flow

Point of waste or

heat discharge

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

Fig. 19.4, p. 481

Rainbow smelt

1.04 ppm

Zooplankton

0.123

ppm

Phytoplankton

0.0025 ppm

Water

0.000002 ppm

Herring gull

124 ppm

Lake trout

4.83 ppm

Herring gull eggs

124 ppm

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 (CH
4,
H
2
S)

Fig. 19.5, p. 482

Discharge of untreated

municipal sewage

(nitrates and phosphates)

Nitrogen compounds

produced by cars

and factories

Discharge of treated

municipal sewage

(primary and secondary

treatment:

nitrates and phosphates)

Discharge of

detergents

( phosphates)

Natural runoff

(nitrates and

phosphates

Manure runoff

From feedlots

(nitrates and

Phosphates,

ammonia
)

Dissolving of

nitrogen oxides

(from internal combustion

engines and furnaces)

Runoff and erosion

(from from cultivation,

mining, construction,

and poor land use)

Runoff from streets,

lawns, and construction

lots (nitrates and

phosphates)

Lake ecosystem

nutrient overload


and breakdown of


chemical cycling

Fig. 19.6, p. 483

Fig. 19.7, p. 484

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

CANADA

WISCONSIN

MINNESOTA

IOWA

ILLINOIS

INDIANA

OHIO

PENNSYLVANIA

NEW YORK

MICHIGAN

MICHIGAN

Nipigon Bay

Thunder Bay

Silver Bay

St. Louis R.

Jackfish Bay

St. Mary’s R.

Spanish R.

Penetary Bay

Sturgeon Bay

Saginaw

Bay

Saginaw R.


System

St. Clair R.

Detroit R.

Rouge R.

Raisin R.

Maumee R.

Black R.

Rocky R.

Cuyahoga R.

Ashtabula R.

Thames R.

Grand R.

Niagara Falls

Niagara

R.

Buffalo

R.

St. Lawrence R.

Fig. 19.8a, p. 485

Industrial

pollution

Beaches

closed

Suffocated

fish

Low

dissolved

oxygen

Mercury
-

tainted fish

Decreased fish

population

Dead algae

Sewage

runoff

Fig. 19.8b, p. 485

Suburban

sprawl

Lower

water

levels

Clear

water

PCB’s in

sediment

Thriving fish

population

High

dissolved

oxygen

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


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


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


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.


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.


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

Fig. 19.9, p. 487

Waste lagoon,

pond, or basin

Mining

site

Pumping

well

Water

pumping

well

Sewer

Cesspoll,

septic

tank

Hazardous

waste

injection

well

Buried gasoline

and solvent

tanks

Landfill

Road

salt

Unconfined freshwater aquifer

Confined freshwater aquifer

Confined aquifer

Discharge

Leakage

from faulty

casing

Groundwater

Groundwater flow

Groundwater


IV. Groundwater = prime source of drinking water
and irrigation water. Groundwater cannot cleanse
itself like surface water does.


Reasons for pollution


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


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


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



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.