1. Water Pollution
APES: Ch. 14

2. Water Pollution
Is defined as the contamination of streams, rivers, lakes, oceans, or groundwater with substances produced by human activity that negatively affect organisms.
Has potential to impact both aquatic & terrestrial organisms
Pollution can either come from point sources or nonpoint sources

3. Point Sources vs. Nonpoint Sources
Point sources are:
Distinct locations like factories or sewage treatment plants that discharge pollution into a body of water.
Easier to pinpoint source of pollution
Nonpoint sources are:
Diffuse areas like an entire farming region, suburban community, or storm run-off from parking lots.
Harder to control pollution from these sources

4. NONPOINT SOURCES
Urban streets
Suburban development
Wastewater treatment plant
Rural homes
Cropland
Factory
Animal feedlot
POINT SOURCES

5. Human Wastewater This is produced by human activities including:
Sewage, gray water, bathing, washing clothes & dishes.
Biggest challenge?
To keep wastewater from contaminating drinking water.
Can be difficult because many use same water source for drinking, bathing, washing, and disposing of sewage.

6. Human Wastewater Three major reasons wastewater is a concern:
Wastewater naturally undergoes decomposition by bacteria, which creates a demand for dissolved oxygen (Oxygen Demand).
Nutrients in released in wastewater decomposition can make water sources eutrophic (Nutrient Release).
Wastewater can carry a wide variety of disease-causing organisms.

7. Oxygen Demand Oxygen-demanding waste:
Dissolved oxygen in water is used by many animals in respiration.
Organic matter that enters a body of water & feeds the growth of decomposers (microbes).
Microbes require oxygen to decompose waste
More waste More oxygen needed

8. Oxygen Demand Measured in terms of biochemical oxygen demand (BOD)
The amount of oxygen a quantity of water uses over a period of time at a specific temperature.
Lower BOD = body of water is less polluted by wastewater, whereas, higher BOD = body of water is more polluted by wastewater.
Normal = 5 to 20 mg of oxygen due to decomposition of leaves, twigs etc.
High = 200 mg of oxygen due to decomposition of domestic wastewater.

9. Oxygen Demand Dead Zones: High BOD due to decomposition
Dissolved oxygen is too low for other organisms to survive (lethal).
Some areas there is so little oxygen that life is absent.
These areas are called “dead zones”
Can be self-perpetuating due to dying organisms decomposing causing continued BOD
Mississippi delta in Gulf of Mexico
UN estimates 200 dead zones globally

10. Missouri River Mississippi River Basin Ohio River MS LA
Gulf of Mexico
Ohio River
Missouri River
Depleted oxygen
LOUISIANA
Mississippi
River Basin MS
Figure 21.A
Natural capital degradation: a large zone of oxygen-depleted water (less than 2 ppm dissolved oxygen) forms for half of the year in the Gulf of Mexico as a result of oxygen-depleting algal blooms. Evidence indicates that it is created mostly by huge inputs of nitrate (NO3−) and phosphate (PO43−) ions from farms, cities, and factories in the vast Mississippi River basin. The satellite image (bottom left) shows the inputs of such nutrients into the Gulf of Mexico during the summer of In the image, reds and greens represent high concentrations of phytoplankton and river sediment. This problem is worsened by loss of wetlands, which help filter plant nutrients. (NASA) LA TX
Fig. 21-A, p. 507

12. Nutrient Release Products of decomposition:
Include nitrates (NO3-2) & phosphates (PhO4-2)
Additional nutrient sources:
Soaps & detergents
Provides abundance of nutrients to a body of water
Called eutrophication
Anthropogenic inputs of nutrients is called cultural eutrophication
Produces algal blooms which die & decompose
Chain of events that leads back to low oxygen
Chesapeake Bay is an example

13. Pollution of Freshwater Lakes by Cultural Eutrophication1 2 3 4
Some lakes become eutrophic naturally but some do not, it depends on the conditions.
Overgrowth -> Breakdown -> Fish Kills -> Anaerobic Bacteria
Algae, cyanobacteria, water hyacinth, duckweed
Breakdown of these plants consumes oxygen
Less O2 causes organisms to die
Produce toxic HS and flammable CH4

14. Chesapeake Bay
Shallow estuary with slow flow. Caused problems with local fisheries and farms on the coast.
Point Source - Industry – 60% of phosphates, toxic waste
Non point Source – Agriculture/Municipal – 60% Nitrates, pesticides

16. Ocean Pollution DILUTE-DISPERSE-DEGRADE Can handle a lot of pollutants
Arguments over safety
Safer than burying
vs.
Delaying pollution prevention
Promotes degradation of ocean and connected wetlands
Red Tide – eutrophication in ocean
Release Toxins
Damage fisheries
Kills birds
Poison Seafood

17. and heavy metals in effluents flow into bays and estuaries. Cities
Industry
Nitrogen oxides
from autos and
smokestacks,
toxic chemicals,
and heavy metals in effluents flow into bays and estuaries.
Cities
Toxic metals and oil from streets and parking lots pollute waters;
Urban sprawl
Bacteria and viruses from
sewers and septic tanks contaminate shellfish beds
Construction sites
Sediments are washed into
waterways, choking fish and plants, clouding waters, and blocking sunlight.
Farms
Runoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus.
Red tides
Excess nitrogen causes
explosive growth of
toxicmicroscopic algae,
poisoning fish and
marine mammals.
Closed
shellfish beds
Closed
beach
Oxygen-depleted
zone
Figure 21.10
Natural capital degradation: residential areas, factories, and farms all contribute to the pollution of coastal waters and bays. According to the UN Environment Programme, coastal water pollution costs the world $16 billion annually—$731,000 a minute—due to ill health and premature death.
Toxic sediments
Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and
accumulate in the tissues of bottom feeders.
Oxygen-depleted zone
Sedimentation and algae
overgrowth reduce sunlight,
kill beneficial sea grasses, use
up oxygen, and degrade habitat.
Healthy zone
Clear, oxygen-rich
waters promote growth
of plankton and sea grasses,
and support fish.
Fig , p. 505

18. Disease-causing Organisms
Wastewater carries a variety of pathogens:
Viruses, bacteria, and parasites
Water-born diseases are:
Cholera, typhoid fever, stomach flu, diarrhea
Worldwide most common: cholera and hepatitis
In USA, hepatitis A & bacterium Cryptosporidium
Large-scale outbreaks are rare in US, but common in developing world.

19. Water Born Disease Statistics
1.1 billion do not have access to safe drinking water.
Diarrheal diseases can be prevented by:
Safe drinking water, proper sanitation, & proper hygiene
42% of world population lacks access to proper sanitation
Over half live in China & India
In sub-Saharan Africa only 36% have access

20. Disease-causing Organisms
Not feasible to test water for all pathogens
Scientists use indicator species –
An organism that indicates whether or not disease-causing pathogens are likely to be present.
Best indicator: fecal coliform bacteria
Generally harmless micro-organisms that live in human intestines
Most common is Escherichia coli or E. coli

21. Treatment of Wastewater
Two most widespread systems for treating human sewage is:
Septic systems – found in rural areas with low population density.
Sewage treatment plants – found in areas of high population density such as urban & suburban
System to treat wastewater from large livestock operations (feed lots) is a manure lagoon.

22. Septic Systems Septic system is a simple system with two components:
Septic tank (1,900 – 4700 L):
Buried underground near house
Three layers develop:
Scum layer (top): anything that floats & rises to the top
Sludge layer (bottom): anything heavier than water sinks
Septage (middle): layer of fairly clear water that contains bacteria, pathogenic organisms, and nutrients (PO4-2, NO3-2)

23. Septic Systems Leach field:
Septage moves by gravity out of tank to underground pipes which lie below the lawn
Septage slowly seeps out due to perforations in the pipe.
Septage is filtered by surrounding soil & changed into CO2 and nutrients.
Pathogens can:
Become part of the sludge
Be outcompeted by other micoorganisms
Be degraded by soil micoorganisms in leach field
Pro: no electricity needed to run septic system, but sludge needs to be removed periodically.

25. Sewage Treatment Plant
Managed by municipalities that are centralized.
Two steps to treating sewage-
Primary treatment:
Goal is for solids to settle out of wastewater
Solids are dried & exposed to bacteria that can digest pathogens; this material is called sludge.
Final product is either dumped in landfills, burned, or converted into fertilizer

26. Sewage Treatment Plant
Secondary Treatment:
Involves the remaining wastewater
Goal is to use bacteria to break down 85 – 90% of organic matter and convert it into CO2 and nutrients
Processes include –
Aeration to promote growth of aerobic bacteria (less odoriferous than anaerobic bacteria)
Secondary wastewater is left in settling ponds for several days to remove any remaining particles
Disinfection using chlorine, ozone, or UV light kills remaining pathogens
Final product is released into nearby river, lake, or ocean

28. Manure Lagoons Animal waste problems similar to human waste.
Only a problem when on a large scale like concentrated feed lots.
Manure from feed lots contains antibiotics & hormones
Large amounts of manure are handled in manure lagoons
Large, human-made ponds lined with rubber.

29. Manure Lagoons
Manure is broken down by bacteria (same as in sewage treatment plants)
Manure can be spread of farm fields
Risk of manure lagoons –
Leaks in rubber can contaminate groundwater
Overflow to adjacent water bodies
Application as fertilizer can runoff to nearby water bodies