2. Lecture 8: Water Pollution
• Water: hydrologic cycle and watersheds
• Types of Water Pollutants
– Pathogens
– Organic Waste
– Chemical Pollutants
– Sediments
– Nutrients
• Eutrophication
• Anoxic Gulf Coasts Waters (a.k.a. The Dead Zone)
• Sewage
• Clean Water Act
• Safe Drinking Water Act
3. Water Pollution, Intro
• Any “bad” substance on the surface may
contaminate the hydrosphere, whether it is the
contamination of lakes, streams, and oceans or
whether it is the contamination of ground water.
• Water pollution has several environmental
consequences,
– Health hazards: many pathogens are waterborne and
are highly correlative to poor water quality..
– Loss of biodiversity = polluted water bodies or ones
with excess organic and/or nutrients become anoxic
and almost abiotic.
– Loss of aesthetic beauty
– Impact on leisure and other outdoor/sporting activities
4. Hydrologic Cycle
• Water migrates between
the atmosphere, the land,
underground, and so
forth.
• When examining the
different types of water
pollutants, I would like for
you to put them within
context of the Hydrologic
Cycle.
5. Review the Hydrologic Cycle
Water on the surface can do one of three (or four) things: a) evaporate back to the
atmosphere, b) percolate into the ground to become ground water, or c) run-off
downstream (alternatively d. become part of a glacier).
From McKnight, Physical Geography
6. Watersheds
• Watershed = area that shares a common drainage
network.
– Fluids (runoff, chemical spills, etc.) on the landscape move
downstream, aggregating in larger and larger channels.
– Pollution in one location, especially if released in the upland
areas, may contaminate the entire watershed due to the
interconnectivity.
• When examining the different types of water pollutants,
their source area, and their effect on the environment I
would like for you to keep the watershed concept in
mind.
• Please look at the watershed address locator webpage
from EPA to find your home watershed:
– http://www.epa.gov/win/address.html
8. Pollution
• Pollution = “the presence of a substance in the environment that,
because of its chemical composition or quantity, prevents the
functioning of natural processes and produces undesirable
environmental and health effects”- EPA definition printed in your
textbook.
• Pollution can be further subdivided into two sub-classes based on
the source:
– Point source = discharges of substances from factories, sewage,
industry, etc.. The source is easy to identify, and thus regulation of
point source pollutants is manageable.
– Non-Point source = the sources of this type of pollution is very difficult to
identify. Non-point pollution (NPS) often originates from agricultural and
urban runoff, rainfall and snowmelt, storm-water drainage, and
atmospheric deposition. Because the source regions are unidentifiable,
NPS are extremely difficult to manage.
9. Water Pollution
• Two basic strategies to managing the
pollution are:
– 1) to reduce or remove the source
– 2) to treat or purify the tainted water
11. Types of Water Pollutants
• The water pollutants that we will discuss in
this lecture include:
– Pathogens
– Organic Waste
– Chemical Pollutants
– Sediments
– Nutrients
12.
13. Pathogens
• “The most serious water pollutants are
the infections agents that cause sickness
and death” .
• Waterborne diseases kill thousands of
people per year. The majority of these
pathogens are a result of contaminated
water – unsanitary water associate with
poor hygiene.
14.
15. Source: Gleick, P. 2002: Dirty Water: Estimated Deaths from Water-Related Diseases, 2002 – 2020
Pacific Institute Research Report
16. Source: Gleick, P. 2002: Dirty Water: Estimated Deaths from Water-Related Diseases, 2002 – 2020
Pacific Institute Research Report
17. Pathogens (continued)
• Pathogens are related to poor sanitary conditions. In a
sense, they are often a result of organic pollution
• Human and animal excrement in water bodies creates a
suitable environment for these pathogens
– The fluid medium allows for quick transmitting
– People bathing or drinking in contaminated streams are exposed
to these pathogens
– Improved sanitation and hygiene education have saved more
lives than medicine. That is, the best way to mitigate the spread
of infectious waterborne diseases is to improve sanitary
conditions.
19. Organic Waste
• Human and animal waste creates “serious problems”
• Besides creating a pathogen-friendly environment,
excess organic wastes reduce the availability of
dissolved oxygen in water.
– aerobic bacteria and other decomposers breakdown organic
materials they consume oxygen through cellular respiration.
More organic waste results in more aerobic decomposition,
which ultimately lowers available oxygen.
• Biochemical Oxygen Demand (BOD) = measure of the
amount of organic material in water in terms of how
much oxygen will be required to break it down. The
higher the BOD the greater is the likelihood that
dissolved oxygen will be depleted.
20. Organic Waste, Animals
• Animal Feeding Operations, colloquially referred
to as “Factory Farms” contain large quantities of
livestock.
• The high concentration of animals generates a
lot of waste. Some animals, such as hogs,
produce substantially more excrement per
pound than humans.
• The animal waste poses serious threats to the
environment. It is high in organic materials,
nutrients, heavy metals, and pathogens
22. EPA’s ‘Animal Feeding Operations’
• Animal Feeding Operations (AFO) are defined
as “a lot or facility (other than an aquatic animal
production facility) where the following
conditions are met” (epa.gov):
– “Animals have been, are, or will be stabled or
confined and fed or maintained for a total of 45 days
or more in any 12-month period, and
– Crops, vegetation, forage growth, or post-harvest
residues are not sustained in the normal growing
season over any portion of the lot or facility”
(epa.gov).
• AFO’s are treated as a point source of organic
and nutrient pollution
23. Waste Lagoons
• Waste from the AFO are
hosed into waste lagoons.
• Ideally within the lagoons
the solids become
concentrated as the water
evaporates. The manure
can then be used as a
fertilizer.
• These waste lagoons can
leak into the environment
contaminating surface and
ground water with organic
waste, nutrients, heavy
metals, and pathogens
Photo Source: Dairy Waste Pictorial, EPA Region 10 and Washington State Dairy Federation
http://lwcd.org/images/MCR_earthen_Waste_lagoon.JPG
24. Organic Waste and DO
• Typical Oxygen Depleting
Properties of Various Materials
• Type of Material Oxygen Demand (mg/l)
– Municipal Sewage, treated = 25
– Municipal sewage, untreated = 250
– Cattle feedlot runoff = 1,000
– Milk-house wastes = 1,500
– Silage stack leachate = 35,000
– Cattle or hog manure = 50,000Cattle or hog manure = 50,000
• Source: Minnesota Pollution Control Agency
• Note: cattle and hog waste is 200 times human waste!
25.
26. Hog Farms in North Carolina
• North Carolina is one of
the leading hog-producing
States. Most of the hog
farms are in the eastern
half of the state.
• The heavy rain from
Hurricane Floyd (1999)
flooded many of the waste
lagoons, and the organic
pollution washed out
across the landscape,
• Getting back to the
watershed concept, where
did all the flooded waste
lagoon materials go?
Source: North Carolina in the Global Economy
http://www.soc.duke.edu/NC_GlobalEconomy/hog/maps.php#map2b
27. •Famous photo from AP showing
flooded hog farms after Hurricane
Floyd.
•The waste lagoons were inundated
•There is a major concern about the
ramifications of this waste polluting
the local watershed and the nearby
coastal waters.
28. Human Waste, Hurricane Katrina
• We all remember the
images of a flooded New
Orleans. The water that
inundated the streets was
full of waste.
news.nationalgeographic.com/.../photo8.html
news.nationalgeographic.com/.../photo8.html
29. Fecal Coliform
• Organic material such as excrement is
decomposed by Fecal Coliform (FC) bacteria.
• FC (certain strains of E. coli and other bacteria)
pass through the digestive tracks of animals.
• Their presence in the water column indicates
contamination by excrement.
• The EPA measures FC concentrations as an
indicator of water quality.
• Other strains of E.Coli from organic waste are
more harmful, such as the recent outbreak of E.
coli in spinach.
30. Recent E.Coli (different strain than
the fecal coliform) Outbreak in
Spinach• FDA announced on September 29, 2006 that all spinach implicated in the current
outbreak has traced back to Natural Selection Foods LLC of San Juan Bautista,
California. This determination is based on epidemiological and laboratory evidence
obtained by multiple states and coordinated by the Centers for Disease Control and
Prevention (CDC). Natural Selection Foods issued a recall of all implicated products
on September 15, 2006. More specifically, Natural Selection Foods has recalled all
spinach products under multiple brand names with a date code of October 1 or
earlier. Five other companies have issued secondary recalls because they received
the recalled product from Natural Selections. See below for a complete list of brand
names that are subject to the recalls. Spinach processed by other manufacturers has
not been implicated in the outbreak. Processed spinach (e.g., frozen and canned
spinach) is not implicated in this outbreak.
• Although the current outbreak may ultimately trace back to a specific field(s), there
has been a long history of E. coli O157:H7 outbreaks involving leafy greens from the
central California region. Spinach processed by other manufacturers has not been
implicated in this outbreak, however, based on discussions with the industry, and
given the past E. coli O157:H7 outbreaks, FDA and the State of California expect the
industry to develop a comprehensive plan which is designed to minimize the risk of
another outbreak due to E. coli O157:H7 in spinach grown in central California. While
this plan is under development, FDA and the State of California reiterate our previous
concerns and advise firms to review their current operations utilizing the FDA's
guidance for minimizing microbial food safety hazards.
• http://www.cfsan.fda.gov/~dms/spinacqa.html
31. Chemical Waste
• “Water-soluble inorganic chemicals constitute an
important class of pollutants that include”
– Heavy metals (lead, mercury, cadmium, nickel, Def
Leppard)
– Acids from mine drainage
– Road salts
– Petroleum
– Urban runoff
– Pesticides, fungicides, herbicides
32. Chemical Pollutants
• Any noxious substance spilled on the
landscape can contaminate the
watershed. Toxic pollutants sometimes
have very long residence time and can be
very problematic to manage.
• The worst type of contamination is of the
groundwater. Groundwater contamination
is very difficult to manage.
34. Sediments
• All streams transport some degree of sediments.
• Development or construction within the watershed can
increase the amount of sediment in streams.
• Excess sediment will “choke the stream”
• The environmental effect is loss of biodiversity, change
in hydrology, and ruining the aesthetic beauty of the
water body.
• Sediments also act as surface area for other pollutants,
like heavy metals. So greater concentrations of
sediments will directly result in higher concentration of
other pollutants.
35. Fish are all dead! No light = no vegetation and the
whole ecosystem dies.
36. Nutrients
• Naturally, nutrients are limited within many
aquatic ecosystems. Plants often have to
compete for nutrients.
• Phosphorus and Nitrogen are two very important
nutrients that are usually in high demand by
aquatic vegetation. Both these elements are in
the building blocks of biological molecules (DNA,
Protein, Fatty Acids).
• When there are too many nutrients, however, it
throws the entire aquatic ecosystem at of whack.
• Aquatic systems with too many nutrients
become eutrophic.
37. Eutrophication
• Phosphorus and nitrogen in many aquatic systems are usually
limiting.
• Aquatic vegetation exists in two general forms:
– Benthic = rooted in the substrate, usually multicellular vegetation
– Planktonic = free-floating in the water column, often single celled
algae
• In nutrient poor environments the benthic organisms have an
advantage over the planktonic. Because they are rooted they can
draw upon nutrients within the sediment.
• Nutrient-poor aquatic ecosystems are called oligotrophic, which
translates to “poorly fed”. It seems paradoxical that a poorly fed
environment is usually the most biologically diverse.
39. Eutrophication
• Eutrophication translates to “well fed”, and it
refers to an aquatic or marine ecosystem with
too many nutrients.
• The excess nutrients stimulate the growth of the
plankton at the expense of the benthic
vegetation. Being single-celled and having a
quicker lifecycle, planktonic algae can rapidly
respond to an influx of nutrients within the water
column.
• The algal populations explode (the carrying
capacity jumps dramatically).
• The abundance of algae decreases the
biological productivity of the aquatic ecosystem
40. Eutrophication Continued
• Planktonic algae can form a thick scum surface that
blocks out light to the benthic species. Aquatic
vegetation that is mostly submerged below the water
surface (submerged aquatic vegetation, SAV).
• In addition the algae blooms result in lots of dead algae .
The dead algae along with the dead fish and other
organisms creates an abundance of organic materials.
This is broken down aerobically, which depletes the
dissolved oxygen in the water.
• Once the dissolved oxygen is reduced very few
organisms can survive in this hypoxic environment.
43. Dead Zone
• The “Dead Zone” is an area of hypoxic
water that stretches along the Gulf Coast.
• The Mississippi River drains 31 US states
and 2 Canadian provinces. It is one of the
largest rivers in the world, and it drains the
world’s best agricultural lands. The runoff
of fertilizes from along the Mississippi
River watershed empties into the Gulf of
Mexico where it stimulates an algal bloom.
46. Sewage
• We all know what we flush down the toilet or what we
pour down the drain. What happens to all that stuff?
• In answering the above question, keep in mind the first
law of thermodynamics, the bit about neither being
created nor destroyed but changing from one form to
another.
• Just because you flush it doesn’t mean that it disappears
forever.
47. Historical Context of Sewage
• Important note: prior to the 1970’s most of the
raw sewage, the stuff coming out of the houses,
was simply dumped into the environment –
usually within rivers or oceans. The book
mentions that the mistreatment of sewage is one
of the main instigators of the Clean Water Act
(1972).
• The Clean Water Act (CWA) helped establish
modern sewage treatment by appropriating
funds to local and state governments to build or
revise existing plants.
48. Sewage Treatment
• Modern Sewage Treatment = based on
the filtration and biological decomposition.
• The raw sewage contains at least these
four components:
– Debris (toilet paper, feminine products, other things that get
flushed)
– Particulate organic mater
– Colloidal dissolved organic mater (things in solution or partial
solution, like urine
– Dissolved inorganic mater
– Misc. Chemicals
49. Sewage Treatment
– Preliminary = the raw sewage flows out of
your house to a sewer line, which eventually
leads to a municipal treatment plant. In the
preliminary stage the raw sewage is filtered
through a 1” mesh. The solids and paper that
accumulates on the mesh screen is raked off
and transported to an incinerator or taken to a
landfill.
50. Sewage Treatment
• Primary Stage = after passing through the
preliminary filtration, the raw sewage flows to a
circulation chamber. Here the sewage is slowly
circulated – the change in the velocity causes
the courser materials, such as grit and other bits
of organics, to settle out. The stuff that settles at
the bottom is referred to as sludge; it is removed
and taken to a landfill by dump trucks. In
addition, grease, fats, and oils will float on the
surface. These fatty materials are siphoned off
and merged with the sludge.
51. Sewage Treatment
• Secondary Treatment = in this stage of sewage
treatment the remaining dissolved organics and nutrients
are broken down via aerobic decomposition. The
sewage is aerated with oxygen and decomposing
bacteria are added. The bacteria “feed” on the organic
materials left in the water and utilize the remaining
nutrients.
• After biological decomposition, the water is then
sterilized, by either chlorine or ozone gas. Then it is
released back into the environment. Usually municipal
treatment facilities pump the treated sewage into a river
or pump it out into the ocean. Water exiting the sewage
treatment facility (gray water) in many places is cleaner
than that which comes out of your tap.
56. Gray Water
• In many cities the water exiting the
sewage treatment plant is reused. Some
cities use gray water to water lawns..
However in major metropolitan areas
where water is scarce – the desert west –
gray water might be an option for drinking
water?
57. Septic System
• Waste leaving the home flows through a septic
tank. In the tank the solids settle towards the
bottom. Here the organics breakdown through
aerobic and anaerobic decomposition. The
colloidal and dissolved inorganics flow out into
the yard via a drain field. The effluent is
supposedly filtered naturally by the lawns,
gardens, and soil microbes.
59. Septic Tank Problems
• Septic tanks have to be cleaned out about every
5 years depending on usage. If there are more
solids than the system can handle, the tank will
backflow and the sewage treatment becomes
ineffective. Leaking septic systems or poorly
working ones can leak too much raw sewage
into the environment. If too much water passes
through the septic system, it will turn the yard all
mushy.
• Also if there are too many septic systems built
within too small of an area, the sewage will not
be properly filtered or broken down. The excess
nutrients and organics will contaminate the
groundwater.
60. Sewage Ponds
• Many newer communities are using
sewage ponds to treat their waste. The
sewage ponds also employ biological
decomposition. In this case the raw
sewage is pumped into a containing pond.
The solids accumulate at the bottom of
the pond. The organic materials are
feasted on by decomposers. Aquatic
vegetation is also planted. The vegetation
uses the organics and nutrients as
fertilizers.
61. Clean Water Act 1972
• The Clean Water Act is the sister of the
Clean Air Act. It was the first legislation of
its kind to protect the Nation’s waters and
to create safe drinking water.
62. Clean Water Act
• During the Environmental Movement there
was a push to clean up polluted water.
This was in large part due to:
– Accumulating sewage
– Factory effluents from the Chemical
Revolution
– People getting sick from polluted water (see
the movie A Civil Action).
– The Cuyahoga River caught fire in 1967
63. Clean Water Act 1972
• The Clean Water Act:
– Gave the EPA the power to set regulations on
sewage effluent
– Appropriated funds to local governments to retool
poorly working sewage treatment
– Gave power to the EPA to regulate the amount of
pollutants emitted by factories
– Protected the US waterways (“Navigable
Waterways”). Under this definition wetlands are
designated “navigable waterways”, and the CWA
gave power to the Army Corp of Engineers to protect
wetlands.
• The Safe Drinking Water Act 1974 (from the same vein
as the CWA) authorized EPA to regulate the quality of
public drinking water and to set drinking water standards
