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forestsaintregisOil and Offshore

Nov 8, 2013 (3 years and 11 months ago)

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Water Pollution

G. Tyler Miller’s

Living in the Environment

13
th

Edition


Chapter 19





Key Concepts


Types, sources, and effects of water
pollutants


Major pollution problems of surface water


Major pollution problems of groundwater


Reduction and prevention of water pollution


Drinking water quality





What is 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 uses.





Major categories of water
pollutants

1.
Infectious Agents

2.
Oxygen
-
Demanding Wastes

3.
Inorganic Chemicals

4.
Organic Chemicals

5.
Plant Nutrients

6.
Sediment

7.
Radioactive Material

8.
Heat (Thermal Pollution)

Review
Table 19.1!!





Common Diseases Transmitted Through
Contaminated Drinking Water

Type of Organism

Disease

Bacteria

Typhoid fever

Cholera

Bacterial Dysentery

Enteritis

Viruses

Infectious hepatitis

Parasitic Protozoa

Amoebic Dysentery

Giardiasis

Parasitic Worms

Shistosomiasis





Effects


Premature death of 3.4 million
people worldwide each year


Diarrhea

alone kills 2.1 million
people





How do we measure water quality?

Fecal Coliform Test

Drinking
water

0 colonies
per 100 ml

Swimming
water


200
colonies
per 100 ml





How do we measure water
quality?


Measuring the
level of
D
issolved
Oxygen (DO)

Fig. 19
-
3 p. 485





Biological Oxygen Demand
(BOD):


the amount of
dissolved
oxygen

needed by aerobic
decomposers to break down
organic matter.





How do we measure water
quality?


Using
chemical analysis


Presence and concentration



Using
indicator species


Filter feeding mussels






Sources of Water Pollution


Point Sources


Discharge of pollutants
at specific
locations

through pipes, ditches, or
sewers into bodies of surface
water.


Easier to control


Non
-
Point Sources



pollutants cannot be traced to any
single source of discharge


Difficult to control





Point and Nonpoint Sources

NONPOINT SOURCES

Urban streets

Suburban
development

Wastewater
treatment
plant

Rural homes

Cropland

Factory

Animal feedlot

POINT
SOURCES

Fig. 19
-
4

p. 486





Pollution of Streams


Can recover rapidly from oxygen
-
demanding
waste

Fig. 19
-
5 p. 488





Oxygen Sag





Good New


Bad News
About Streams

Good News


Pollution control laws


Number of waste
water treatment
plants has increased


Industry required to
reduce or eliminate
point
-
source
discharges

Bad News


Large fish kills and
drinking water
contamination still
occur


Release of toxic inorganic
and organic chemicals


Malfunctioning sewage
treatment plants


Non
-
point runoff of
pesticides






Pollution of Lakes


Slow turnover


Flushing and changing of water



Thermal stratification


Little vertical mixing



Biological Magnification


Increase in the concentration of chemicals in
organisms at successively higher trophic
levels of a food chain



Eutrophication


Natural nutrient enrichment of lakes





Water

0.000002 ppm

Phytoplankton

0.0025 ppm

Zooplankton

0.123

ppm

Rainbow smelt

1.04 ppm

Lake trout

4.83 ppm

Herring gull

124 ppm

Herring gull eggs

124 ppm

Biomagnification





Pollution of Lakes


Cultural Eutrophication



Fig. 19
-
7 p. 491





Case Study: The Great Lakes

Fig. 19
-
8

p. 492





Solutions: Preventing and Reducing
Surface Water Pollution

Nonpoint Sources

Point Sources


Reduce runoff


Buffer zone
vegetation


Reduce soil erosion


Clean Water Act


Water Quality Act









Groundwater Pollution


Out
-
of
-
sight pollution


Low risk ecological problem
High risk health problem


Cannot get rid of degradable
waste


Low flow rates


Few bacteria


Cold temperatures





POLLUTION OF GROUNDWATER


It can take hundreds to thousand of
years for contaminated groundwater to
cleanse itself of

degradable wastes
.



Nondegradable wastes

(toxic lead, arsenic,
fluoride) are there permanently.



Slowly degradable wastes

(such as DDT)
are there for decades.





Groundwater Pollution: Sources

Coal strip
mine runoff

Pumping
well

Waste lagoon

Accidental
spills

Groundwater
flow

Confined aquifer

Discharge

Leakage from faulty
casing

Hazardous waste injection well

Pesticides

Gasoline
station

Buried gasoline
and solvent tank

Sewer

Cesspool
septic tank

De
-
icing
road salt

Water pumping
well

Landfill





Fig. 21
-
8, p. 502

Water well

Migrating

vapor phase

Contaminant plume moves

with the groundwater

Free gasoline

dissolves in

groundwater

(dissolved

phase)

Groundwater

flow

Water

table

Gasoline

leakage plume

(liquid phase)

Leaking

tank






Groundwater Pollution
Prevention


Monitoring aquifers


Leak detection systems


Strictly regulating hazardous
waste disposal


Storing hazardous waste
materials above ground





Ocean Pollution

Fig. 19
-
12 p. 498





OCEAN POLLUTION


Harmful

algal

blooms

(HAB) are caused
by explosive growth of harmful algae
from sewage and agricultural runoff.





Oxygen Depletion in the
Northern Gulf of Mexico


A large zone of
oxygen
-
depleted water
forms for half
of the year in
the Gulf of
Mexico as a
result of HAB.





Case Study: Chesapeake Bay


Largest US
estuary


Relatively shallow


Slow “flushing”
action to Atlantic


Major problems with dissolved O
2

Fig. 19
-
14
p. 500





OCEAN OIL POLLUTION


Most ocean oil pollution comes from
human activities on land
.



Studies have shown it takes about
3 years
for many forms of marine life to recover
from large amounts of
crude oil

(oil
directly from ground).



Recovery from exposure to
refined oil

(fuel
oil, gasoline, etc…) can take
10
-
20 years
for
marine life to recover.





OCEAN OIL POLLUTION


Tanker accidents
and blowouts at
offshore drilling
rigs can be
extremely
devastating to
marine life
(especially diving
birds, left).





Oil Spills


Sources: offshore
wells, tankers, pipelines
and storage tanks



Effects: death of
organisms, loss of animal
insulation and buoyancy,
smothering



Significant economic
impacts



Mechanical cleanup
methods: skimmers
and blotters



Chemical cleanup
methods: coagulants
and dispersing
agents








Water
Break





Reducing Water Pollution
through Sewage Treatment


Septic tanks and various levels of
sewage treatment can reduce point
-
source water pollution.





Reducing Water Pollution
through Sewage Treatment


Raw sewage reaching a
municipal sewage
treatment plant

typically undergoes:



Primary sewage treatment
: a
physical

process
that uses screens and a grit tank to remove large
floating objects and allows settling.



Secondary sewage treatment
: a
biological

process
in which aerobic bacteria remove as much as 90%
of dissolved and biodegradable, oxygen demanding
organic wastes.





Reducing Water Pollution Through
Sewage Treatment


Primary and Secondary sewage
treatment.





Fig. 21
-
16, p. 511

Raw sewage

from sewers

Activated sludge

Disposed of

in landfill or
ocean or
applied to
cropland,

pasture, or
rangeland

Primary

Secondary

Grit chamber

Bar screen

Settling tank

Aeration tank

Settling tank


Chlorine

disinfection tank

Sludge drying bed

Sludge
digester

Air pump

To river,
lake,

or ocean

(kills bacteria)

Sludge





Reducing Water Pollution Through
Sewage Treatment


Advanced or
tertiary sewage treatment
:


Uses series of chemical and physical
processes to remove specific pollutants left
(
especially nitrates and phosphates
).



Water is
chlorinated

to remove
coloration and to kill disease
-
carrying
bacteria and some viruses (disinfect).





Technological Approach: Advanced
Sewage Treatment


Removes specific pollutants

Fig. 19
-
18

p. 505





Reducing Water Pollution
through Sewage Treatment


Natural and artificial wetlands

and
other ecological systems can be
used to treat sewage.



California created a 65 hectare wetland near
Humboldt Bay that acts as a natural wastewater
treatment plant for the town of 16,000 people.


The project cost less than half of the estimated price of
a conventional treatment plant.





Technological Approach:

Using Wetlands to Treat Sewage

Fig. 19
-
19

p. 506





Drinking Water Quality

Fig. 19
-
11 p. 495





DRINKING WATER QUALITY


Centralized water treatment plants
and watershed protection



can provide safe drinking water for city
dwellers in developed countries.



Simpler and cheaper ways can be used
to purify drinking water for developing
countries.


Exposing water to heat and the sun’s UV
rays

for 3 hours can kill infectious
microbes.






2 million plastic bottles,

dumped every 5 minutes.

Is Bottled Water the Answer?





Is Bottled Water the Answer?


Some bottled water is not as pure
as tap water and costs much more.



1.4 million metric tons of
plastic
bottles

are thrown away.



Fossil fuels

are used to make
plastic bottles.


The oil used to produce plastic bottles in
the U.S. each year would fuel 100,000 cars.