Transcript Water Pollution

Chapter 21
WATER & SOIL
POLLUTION
YOUR responsibilities for Ch 21
Read chapter opening (487-488)
 Enviro-brief

 Harmful algal blooms (pg 492)
 Something Fishy Near Sewage Treatment Plants (pg
505)

Case in Point
 Water pollution in the Great Lakes (pg 507-508)
Water pollution in other countries (pg 509- 511)
 Soil Pollution (pg 511-512)
 Meet the Challenge (pg 506)

Water pollution

Water Pollution:
any physical or chemical change in water that
adversely affects the health of humans and
other organisms.
 There are 8 categories
1.
2.
3.
4.
5.
6.
7.
8.
Sewage
Disease causing agents
Sediment pollution
Inorganic plant and algal nutrients
Organic compounds
Inorganic chemicals
Radioactive substances
Thermal pollution
1. Sewage

Sewage is the release of waste water from drains
or sewers and includes human waste, soaps and
detergents.
 Problems… What do you think???
○ Disease causing agents present
○ Enrichment: Fertilization of a body of water by presence of
high level of nutrients such as nitrogen & phosphorous

Sewage can be decomposed into CO2, water and
materials by microorganisms
 Process of cellular respiration (oxygen is required)
Sewage cont…

Oxygen has a limited ability to dissolve in water
and when sewage is present, the microorganisms
that break it down use up most of it
 BIOCHEMICAL OXYGEN DEMAND (BOD)
 The amount of oxygen needed by micoorganisms to
decompose the waste into CO2, water, and minerals
 Expressed as milligrams of dissolved
O2 per liter of water (mg O2/L)
 Large amounts of sewage  high BOD
 Robs the water of dissolved O2
 Anerobic miroorganisms produce
unpleasant odor..
bottom line…. High BOD =Poor water quality
2. Disease- Causing Agents

Infectious organisms that cause disease. They
come from the wastes of infected individuals.
Bacteria
Viruses
Protozoa
Parasitic Worms
Dysentery
Polio
 Diseases:
Typhoid
Cholera
Hepatitis

Our water systems are VULNERABLE!!!
 Milwaukee 1993
- Cryptosporidium contaminated the water supply
- 370,000 people developed diarrhea
- Several people died
 Ontario, Canada 2000
- Escherichia coli
- Several killed, thousands sick

Monitoring
 Water sources are constantly monitored for contamination
○ E. coli is used as it is an indication of the amount of sewage present
 Fecal Coliform Test
- Safe water should have no more that one coliform bacteria per 100 mL
- Most strains of coliform bacteria do not cause disease,
but coliform test is a reliable indication of the presence
of pathogens or disease causing agents in the water
Excessive amounts
of suspended soil
particles that settle
out and accumulate
on the bottom of a
body of water, due to
decrease in water
velocity.
3. Sediment Pollution
Causes:
Excess erosion
BRAINSTORM!
(what can cause that?)
Problems:
Reduces light penetration, bring pollutants into the water,
reservoir filling, channel changing (shipping)
Solution: Control the soil erosion
4. Inorganic Plant & Algal Nutrients

Chemicals such as Nitrogen & Phosphorus that
stimulate the growth of plants and algae.
 Necessary in small amounts, but overload is dangerous
 Sources: Human & animal wastes, plant residues, atmospheric
deposition, fertilizer runoff from agricultural and residential areas
 Problem: Excessive growth of algae and aquatic plants disrupting
the natural balance between producers and consumers. Also
causes enrichment, bad odors, and high BOD from excessive
numbers of algae dying and decomposition.
○ Dead Zone in the Gulf of Mexico
 Area the size of NJ is “dead” from the
seafloor up due to excess animal waste
moving downstream in spring & fall
HYPOXIA- oxygen free environment
5. Organic Compounds

Chemicals that contain carbon atoms (mostly synthetic)
Study: USGS found that 80% of waterways tested had at least one nonnative organic
compound present, and 1/3 of all streams tested had 10 or more…
…things like antibiotics, caffeine, birth control pills, oil residues, BPA, etc…

What are they?
 pesticides, solvents, plastics,
industrial chemicals

Where do they come from?
DDT
Acetone
 Seeping landfills, leaching, runoff, dumping

How do we control organic compounds?
 Stewardship of our water sources, use of alternative
organic compounds, and tertiary water treatment.
6. Inorganic Chemicals
Contaminants that contain elements other than carbon:
Acids, Salts, Heavy Metals
1.
Lead
Sources: Paint, gas, incinerator ash dumped in ordinary
landfills, air pollution from factories, pesticides & fertilizer
residue on produce, food cans, serving plates & old pipes.
Medical Problems:
hypertension, miscarriages,
stillbirths, mental & physical
impairments, hearing loss, ADD,
lowered IQ, learning disabilities.
2. Mercury

Vaporizes at room temperature DANGEROUS!

Once mercury settles into sediment, it is converted by bacteria to
methyl mercury compounds which are more toxic.
- Mercury accumulates in the muscles of tuna, swordfish, sharks
- Methyl mercury compounds are very persistent and highly toxic
Sources: Coal burning power plants (33%), municipal waste
incinerators (18%), Medical waste incinerators (10%), smelting
metals (lead, copper, zinc), industrial waste water, household trash
(batteries, paints, plastics)
Medical Problems: mental impairments,
cerebral palsy, developmental delays in
children. Kidney disorders, nervous &
cardiovascular system damage,
headaches, depression
7. Radioactive Substances

Contain atoms of unstable isotopes that emit
radiation
 Sources: Mining & processing radioactive minerals,
nuclear plants, industries, medical & scientific facilities.
8. Thermal Pollution

Heated water produced during certain industrial
processes is released into waterways
 Produces chemical & biological effects
○ Chemical: decomposition of waste occurs faster depleting
water of oxygen. Less oxygen dissolves in warm water
○ Biological: less oxygen dissolved less animals or animal
stress, reproductive, digestion rates & respiration rates are
affected
http://www.crocodile-clips.com/absorb/AC4/sample/LR1105_mg.html
It’s HOT… & suddenly
I feel EXHAUSTED!
How do NUTRIENTS affect water
systems?
Eutrophic lake
Oligotrophic Lake



Slow flowing streams with
minimal nutrients
Clear water
Supports small
populations (pike, sturgeon,
whitefish cold )



Enrichment of water nutrients
causing algal blooms
High BOD
Fish populations
(catfish, carp use less O2)
Types of Pollution
Point Source:
Pollution is discharged into the
environment through pipes, sewers
or ditches from specific sites
Non-Point Source:
Pollution caused by land pollutants
that enter bodies of water over large
areas rather than at a single point.
Agricultural runoff, mining wastes,
municipal wastes, construction sediments
Discussion
What challenges do
Point & Nonpoint Source Pollution
present for management?
Sources of Water Pollution
1. Agriculture
Discussed in chapter 13
2. Municipal:
Contains salts, asbestos, chlorides,
copper, cyanides, grease, lead, zinc,
hydrocarbons, motor oil, organic
wastes, phosphates, sulfuric acid
Combined Sewer System: Human and
industrial wastes are mixed with urban
runoff or snowmelts that overpower
the treatment plant & raw sewage
flows into waterways without being
treated
3. Industrial
- High BOD, toxic compounds, sludge
- Some industries are cleaning water
before they discharge it
Groundwater Pollution
Improving Water Quality
Purification of Drinking Water

Water supplies include streams, rivers,
lakes, and reservoirs (dams)
1. Water is treated with aluminum sulfate
causing suspended particles to come out
2. Water is then filtered through sand
3. Some cities pump water through activated
carbon granules to remove organic cmpds.
4. Addition of chlorine to kill disease- causing
agents. Some cities use UV instead of Cl.
Should we use chlorine??
5.
Fluoridation – adding fluoride to municipal
water sources to prevent tooth decay.
Municipal Sewage Treatment
Waste water undergoes several treatments at
a sewage treatment plant to prevent
environmental and public health problems.
The treated water is then discharged into
rivers, lakes or the ocean.
Process:
1. Primary Treatment
A. Removes suspended & floating particles
B. Screening & gravitational settling
1.
2.
Solid material that settles out is known as primary sludge
Does not eliminate the inorganic & organic compounds
remaining in the wastewater.
2.
Secondary Treatment
A. Uses microorganisms to decompose the suspended
organic material
1.
2.
3.
Trickling filters: wastewater trickles through rock beds
containing bacterial which degrade the organic material
Activated sludge process: Wastewater is aerated and
circulated through bacteria rich particles.
Particles and microorganisms are allowed to settle out
forming Secondary Sludge
** Water is clear and free of organic wastes such as sewage**
Primary and Secondary Treatment
3.
Tertiary Treatment
A.
B.
C.
D.
Considered an advanced water treatment
Variety of biological, chemical & physical processes
Removes phosphorus & nitrogen
Can be used to purify wastewater so that it can be reused
in communities where water is scarce.
Question to think about-
What do we do with the
primary and secondary
sludge?
1. Anaerobic digestion
2. Fertilizer
3. Incineration
4. Ocean dumping
5. Sanitary landfill
Individual Septic Systems

Many private residences use individual septic
systems instead of municipal sewage treatment.
 Household sewage is piped into the septic tank
 Particles settle to the bottom
 Grease and oils form a scummy layer where bacteria
decomposes it
 Waste water containing suspended organic and
inorganic material flows into the drain field through a
network of perforated pipes set in trenches of crushed
stone
○ Purified wastewater then percolates into
the groundwater or evaporates from the soil
Septic
TANK
Septic
SYSTEM
What’s the problem here?
Discuss various approaches to pollution
management with respect to this diagram.
How can we manage the problem of
Eutrophication with respect to this diagram?
Describe and Evaluate various strategies.
How can we manage the problem of
Eutrophication with respect to this diagram?
• Altering the Human Activity Producing Pollution:
– Alternative methods of enhancing crop growth
– Alternative detergents
– Others?
• Regulating and Reducing Pollutants at the Point
of Emissions:
– Sewage treatment processes
– How does this help?
• Cleanup and Restoration:
– Pumping mud from eutrophic lakes
– Reintroducing plant and fish species
POLLUTION CONTROL THROUGH LEGISLATION
The United States has attempted to control water pollution
through legislation since the passage of the Refuse Act of
1899.
(reduced pollution of rivers)
Governments control point source pollution by
1. Imposing penalties on polluters
2. Taxing polluters to pay for the cleanup
SAFE DRINKING WATER ACT

(1974)
Set uniform federal standards
 before, states set their own standards

Required EPA to determine the maximum
contaminant level (MCL)
 maximum permissible amount of any pollutant that
might adversely affect human health.

Amended in 1996- requires municipal water
suppliers to tell consumers what contaminants
are present in their city’s water and if they
pose a health risk.
CLEAN WATER ACT
(1972)
Controls the quality of rivers, lakes, aquifers,
estuaries, and coastal water in the US.
Original name: Water Pollution Control Act of 1972
 Two basic goals:

 Eliminate discharge of pollutants in US waterways
 Attain water quality levels that make waterways safe to
fish and swim in.

EPA is required to set and monitor national limits
for point sources (like industrial and sewage treatment facilities).
Clean Water Act continued….

Results
 Overall the CWA has been effective at improving the
quality of water from point sources.
○ Point sources must obtain permits from the National
pollutant Discharge Elimination System to discharge
untreated water.
 Nonpoint Source Pollution is more difficult and expensive
to control
○ CWA expanded in 1987 to allow National Pollutant
Discharge System to include non point sources such as
sediment from erosion from construction sites.
○ NO real effective policy to address non-point source
pollution.
Laws that Protect Groundwater

Resource, Conservation and Recovery Act
deals with the storage and disposal of
hazardous wastes and helps prevent
groundwater contamination.

Safe Drinking Water Act contains provisions to
protect underground aquifers that are important
sources of drinking water.
 Also regulates underground injection of wastes.

Several laws related to pesticides, strip mining
and cleanup of abandoned hazardous waste
sites (brownfields & superfund sites) also
indirectly protect groundwater.
Effects of Salinized Soil on Plants
Normally, the water
concentration inside
plant cells is lower than
that in the soil resulting
in a net movement of
water into the root cell.
When soil contains a
high amount of salt, its
relative water
concentration can be
lower than the water
concentration inside
cells. This causes water
to move out of the roots
into the soil, even when
the soil is wet.