Transcript Water Quality and Pollution

Water Quality and
Pollution
Water Pollution
Water Pollution is any chemical, biological, or
physical change in water quality that has a
harmful effect on living organisms and
makes water unsuitable for desired uses
Air and water pollution are closely related because
they mix together
Pollution Sources
1. Point Source: Specific site of pollution
dumping.
Ex: Pipes from factories and houses.
2. Nonpoint sources: are not easily determined.
No direct point of entry
Ex: runoff from a field or road, acid rain
Point Pollution
Non-point Pollution
3. STORM RUNOFF
- during heavy storms water mixes in the sewers
and the sewage treatment plants can not handle
the overload – excess is released
4. Agricultural runoff Open fields are especially
at risk because the excess water leaches down
into the ground water carrying phosphates and
nitrates. Farmers can reduce this by leaving a
zone of undisturbed land at the end or near
drains or streams.
5. Mining runoff: moves iron, copper, sulfuric
acid (from coal) sulfur and zinc = acid mine
drainage
This is an add-in. Yes, I know its not
in your packet. Find a space.
1. 2FeS2 + 7O2 + 2H2O  2FeSO4 + 2H2SO4
Iron Pyrite (Iron (II) Sulfide) reacts with water and oxygen
to form Iron (II) Sulfate and Sulfuric acid
2. 2Fe2+ + 1/2 O2 + 2H+  2Fe3+ + H2O
The Iron (II) ion dissociates and oxidizes to form Iron (III)
3. Fe3+ + 3H2O  Fe(OH)3 + 3H+
Iron (III) ion reacts with water to form the insoluble Iron
(III) Hydroxide which is a yellow orange color. Precipitates
out of solution and kills fish by clogging their gills. Also
makes the water more acidic.
Water Pollutants
1) Disease causing organisms
a) Bacteria i) Cholera - Vibrio cholerae - highly spreadable.
One fish packer in Equador died of Cholera and before
they could contain the fish that he packed, it went to 8
countries. 300,000 cases and 3000 deaths came from
that one person.
ii) E. coli - Bacteria associated with sewage causes
horrible stomach problems for many days.
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Cholera
E. coli
Good indicator for quality of drinking and
swimming water is the number of coliform
bacteria present in 100-mL sample
WHO recommends 0 colonies for drinking
EPA recommends max of 200 colonies for
swimming
Avg. person excretes 2 billion bacteria a day
iii) Bacterial dysentery - diarrhea, vomiting,
upset digestive tract for 4-5 days
b) Protozoans - Amoebic dysentery - vomiting,
diarrhea, and colon perforation causing death
c) Giardiasis - a problem in high mountain
springs. People think the water is safe and drink
it only to have 3-4 days of diarrhea and
vomiting. Dehydration is a problem as well as
fatigue.
Video
d) Parasitic worms
Video
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e) Viruses
2) Oxygen Demanding Wastes: organic wastes that
can be decomposed by aerobic bacteria which
depletes oxygen
- sewage, animal manure and some industrial
wastes.
- decomposition uses available oxygen and releases
excess phosphorous
- cause high level algal growth which blocks the
sunlight from other plants and they die – more
decomposition = less oxygen = fish death
Level of oxygen required for the break down of material is
called
Biological oxygen demand (BOD): amount of
dissolved oxygen needed by aerobic decomposers to
break down over 5 day period @ 20ºC (68ºF)
Test Procedure
1. Take 2 samples of water
2. Record the DO (DISSOVLED OXYGEN) level
(ppm) of one immediately using the method described
in the dissolved oxygen test.
3. Place the second water sample in an incubator in
complete darkness at 20 °C for 5 days.
4. After 5 days, take another dissolved oxygen reading
(ppm) using the dissolved oxygen test kit.
5. Subtract the Day 5 reading from the Day 1 reading
to determine the BOD level. Record
BOD Level (ppm)
Water Quality
Interpretation
1-2
Very Good
Little waste
3-5
Fair
Moderately Clean
6-9
Poor
10-99
Polluted
100 or greater
Very Poor
Bacterial
decomposition of
Organic Matter
present
Higher amounts of
waste
Very polluted
- High BODs indicate that too much organic
materials are in the water.
- oxygen is used and the anerobic bacteria begin to
produce chemicals that smell and have a
unpleasant taste.
- Food wastes are not as bad as detergent
wastes. Soap and detergent have phosphates in
them, which creates a problem
3) Water-Soluble Inorganic Materials: water-soluble
nitrates and phosphates
- excessive growth of algae and other aquatic plants that
die and deplete the O2 content (kills fish)
EX: acids
Salts: phosphate (X3PO4), nitrates (XNO3) and sulfur
(X2SO4)
Toxins/toxicants -- lead , arsenic salts
Can lead to Eutrophication:
Eutrophication
Eutrophication: natural enrichment of lakes
Cultural Eutrophication: process of human activities
accelerating the input of nutrients: farming, golf
courses
Prevention of cultural eutrophication = advanced waste
water treatment which bans/ limits the amount of
phosphates in detergents, soil conservation, and land
use control
Cleanup methods = dredging bottom sediments,
removing excess weeds, controlling plant growth with
herbicides and algaecides, pumping air thorough
lakes and reservoirs
4) Organic Chemicals: threatens human, animal and aquatic plant
life
EX: oil, gas, plastic, pesticides, detergents, ext.
a) Synthetic organic chemicals plastics, detergents, oil, solvents
and pesticides
Most of it comes from runoff.
Oil is highly toxic because it destroys the organisms ability
to swim, stay afloat and to feed. It is poisonous in small
amounts. It coats the water with a fine film to not allow O2or
CO2 movement to the air. It coats corals and other
underwater species with film so the air exchange is
impossible.
Oil
Tanker spills and blowouts, offshore drilling rig accidents,
Almost ½ of the oil reaching the oceans is waste oil dumped,
spilled, or leaked onto the land or into sewers by cities,
individuals and industries
The effects of oil on ocean depend on
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The type of oil (crude or refined)
amount released
distance of release from shore
time of year
weather conditions
average water temperature
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ocean currents
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Oil
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Research shows that most (but not all) forms of
marine life recover from exposure to large
amounts of crude oil within 3 years: Recovery
from exposure to refined oil take >10 yrs
Moderate oil spills can be cleaned up by
mechanical, chemical, fire, and natural
methods
Oil
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Mechanical methods include:
Floating booms to contain the oil spill or keep it
from reaching sensitive areas
 Skimmer boats to vacuum up some of the oil into
collection barges
 Absorbent pads or large feathered filled pillows to
soak up oil on beaches or in waters to shallow for
skimmer boats
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Oil
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Chemical methods include:
Coagulating agents to cause floating oil to clump
together for easier pick up or sink to the bottom
where is usually does less harm
 Dispersing agents to break up oil slicks
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Natural Methods:
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Oil digesting bacteria – spray on slick
5) Sediments or Suspended Matter: particles of
soil/solid that stay suspended in water and made the
water cloudy, reduces photosynthesis and disrupts
food webs and clogs harbors, reservoirs, channels and
artificial lakes
sediments - Sediments are not an immediate problem.
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take time to pollute
block the sunlight.
May have small amounts of toxins in them that build up
clog fish gills
cover and destroy the natural plants of a lake or reservoir.
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remove nesting sites of fishes.
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6) Water-Soluble Radioactive Isotopes: could
lead to cancer
7) Thermal Pollution: rise in water temp because
water used to cool power plants
- occurs when water is removed from a source,
heated to a high heat, driving off the oxygen
and placing the water back into the source
Ex: cooling electric generator and steam.
Thermal Pollution Prevention:
1) large pond that is not attached to any other water
- hot water is placed into one end and the cooled
water is used from the other.
2) cooling towers – water is sprayed in and cooled by
evaporation
3) cooling tower in which the water is moved into the
tower inside tubes and the heat is released, not the
water
4) Discharging the heated water into shallow ponds
or canals, and reusing it as cooling water
Problems with Thermal Pollution:
Affects fish spawns
Thermal shock: the effect of sharp changes in water
temperature (kills fish that can’t adapt)
Thermal enrichment: beneficial uses of heated water
- Lengthens the commercial fishing season, reduces winter
ice cover in cold areas, can extend the growing seasons,
help heat nearby buildings and greenhouses
8) Genetic Pollution: deliberate or accidental
addition of non-native species disrupts aquatic
systems and crowd out natives: reduces
biodiversity: principal way they are introduced =
intake and ballast from ships
Ex: Zebra mussels
9) GROUNDWATER POLLUTION
- due to percolation of pollutants to the water
table
- Typical Pollutants:
1. Pesticides
2. Fertilizers: farming and septic tanks
3. Gasoline: leaking underground tanks
MTBE – methyl-tert butyl ether –
oxygenate – enhance octane rating of gasoline
4. Toxins/toxicants: landfills
10) SALINIZATION
- Increasing salt in the soils creates salt in the
water.