1. Water Pollution

2. Core Case Study: Using Nature to Purify Sewage
Ecological wastewater purification by a living machine.
Uses the sun and a series of tanks containing plants, snails, zooplankton, crayfish, and fish (that can be eaten or sold for bait).
Figure 21-1

3. WATER POLLUTION: SOURCES, TYPES, AND EFFECTS
Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses.
Point source: specific location (drain pipes, ditches, sewer lines).
Nonpoint source: cannot be traced to a single site of discharge (atmospheric deposition, agricultural / industrial / residential runoff)

4. Table 21-2, p. 495

5. Major Water Pollutants and Their Effects
A fecal coliform bacteria test is used to indicate the likely presence of disease-causing bacteria in water.
Figure 21-2

6. Major Water Pollutants and Their Effects
Water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C.
Only a few fish species can survive in water less than 4ppm at 20°C.
Figure 21-3

7. Water Quality DO (ppm) at 20°C Good 8–9 Slightly polluted 6.7–8
Moderately
polluted
4.5–6.7
Heavily
polluted
Figure 21.3
Natural capital degradation: water quality and dissolved oxygen (DO) content in parts per million (ppm) at 20°C (68°F). Only a few fish species can survive in water with less than 4 ppm of dissolved oxygen at this temperature. QUESTION: Would you expect the dissolved oxygen content of polluted water to increase or decrease if the water is heated? Explain.
Below 4.5
Gravely
polluted
Below 4
Fig. 21-3, p. 496

8. POLLUTION OF FRESHWATER STREAMS
Flowing streams can recover from a moderate level of degradable water pollutants if they are not overloaded and their flows are not reduced.
In a flowing stream, the breakdown of degradable wastes by bacteria depletes DO and creates and oxygen sag curve.
This reduces or eliminates populations of organisms with high oxygen requirements.

9. Biological Oxygen Demand
Measures the amount of oxygen consumed by microorganisms in decomposing organic matter in stream water
Also measures the chemical oxidation of inorganic matter (extraction of dissolved oxygen (DO) via chemical reaction)
Directly affects the amount of DO in rivers and streams (the greater the BOD, the more rapidly oxygen is depleted in the stream)

10. Biological Oxygen Demand
Sources of BOD include debris; dead plants and animals; animal manure; wastewater treatment plants; feedlots; urban stormwater runoff
The consequences of BOD are the same as those with low DO (aquatic organisms become stressed, suffocate, and die)

11. Water Pollution Problems in Streams
Dilution and decay of degradable, oxygen-demanding wastes and heat in a stream.
Figure 21-4

12. POLLUTION OF FRESHWATER STREAMS
Most developed countries have sharply reduced point-source pollution but toxic chemicals and pollution from nonpoint sources are still a problem.
Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.

13. Global Outlook: Stream Pollution in Developing Countries
Water in many of central China's rivers are greenish black from uncontrolled pollution by thousands of factories.
Figure 21-5

14. POLLUTION OF FRESHWATER LAKES
Dilution of pollutants in lakes is less effective than in most streams because most lake water is not mixed well and has little flow.
Lakes and reservoirs are often stratified and undergo little mixing.
Low flow makes them susceptible to runoff.
Various human activities can overload lakes with plant nutrients, which decrease DO and kill some aquatic species.

15. Cultural Eutrophication
Eutrophication: the natural nutrient enrichment of a shallow lake, estuary or slow moving stream, mostly from runoff of plant nutrients from the surrounding land.
Cultural eutrophication: human activities accelerate the input of plant nutrients (mostly nitrate- and phosphate-containing effluents) to a lake.
85% of large lakes near major population centers in the U.S. have some degree of cultural eutrophication.

16. POLLUTION OF GROUNDWATER
Groundwater can become contaminated with a variety of chemicals because it cannot effectively cleanse itself and dilute and disperse pollutants.
The drinking water for about half of the U.S. population and 95% of those in rural areas comes from groundwater.

17. Unconfined freshwater aquifer
Polluted air
Pesticides
and fertilizers
Hazardous
waste
injection
well
Deicing
road salt
Coal strip
mine runoff
Buried gasoline
and solvent tanks
Pumping
well
Gasoline station
Cesspool,
septic tank
Water
pumping well
Waste lagoon
Sewer
Landfill
Leakage
from
faulty
casing
Accidental
spills
Figure 21.7
Natural capital degradation: principal sources of groundwater contamination in the United States. Another source is saltwater intrusion from excessive groundwater withdrawal (Figure 14-12, p. 315) (Figure is not drawn to scale.)
Discharge
Unconfined freshwater aquifer
Confined
aquifer
Confined freshwater aquifer
Groundwater
flow
Fig. 21-7, p. 501

18. 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, flouride) are there permanently.
Slowly degradable wastes (such as DDT) are there for decades.

19. Groundwater Pollution
Solutions
Groundwater Pollution
Prevention
Cleanup
Find substitutes for toxic chemicals
Pump to surface, clean, and return
to aquifer (very expensive)
Keep toxic chemicals out of the environment
Inject microorganisms
to clean up contamination (less expensive but still costly)
Install monitoring wells near landfills and underground tanks
Require leak detectors on underground tanks
Figure 21.9
Solutions: methods for preventing and cleaning up contamination of groundwater. QUESTION: Which two of these solutions do you think are the most important?
Pump
nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed)
Ban hazardous waste disposal
in landfills and injection wells
Store harmful liquids in aboveground tanks with leak detection and collection systems
Fig. 21-9, p. 504

20. OCEAN POLLUTION
Oceans, if they are not overloaded, can disperse and break down large quantities of degradable pollutants.
Pollution of coastal waters near heavily populated areas is a serious problem.
About 40% of the world’s population lives near on or near the coast.
The EPA has classified 4 of 5 estuaries as threatened or impaired.

21. 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

22. OCEAN POLLUTION
Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff.
Figure 21-11

23. 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.
Figure 21-A

24. Missouri River Mississippi River Basin Ohio River Mississippi River 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
LOUISIANA
Mississippi River TX
Depleted oxygen
Gulf of Mexico
Gulf of Mexico
Fig. 21-A, p. 507

25. Case Study: The Chesapeake Bay – An Estuary in Trouble
Pollutants from six states contaminate the shallow estuary, but cooperative efforts have reduced some of the pollution inputs.
Figure 21-12

26. 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 years for marine life to recover.

27. OCEAN OIL POLLUTION
Tanker accidents and blowouts at offshore drilling rigs can be extremely devastating to marine life (especially diving birds, left).
Figure 21-13

28. Coastal Water Pollution
Solutions
Coastal Water Pollution
Prevention
Cleanup
Reduce input of toxic pollutants
Improve oil-spill cleanup
capabilities
Separate sewage and storm lines
Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters
Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without
creating harmful by-products
(still under development)
Ban ocean dumping of sludge and hazardous dredged material
Protect sensitive areas from development, oil drilling, and
oil shipping
Figure 21.14
Solutions: methods for preventing and cleaning up excessive pollution of coastal waters. QUESTION: Which two of these solutions do you think are the most important?
Require at least secondary
treatment of coastal sewage
Regulate coastal development
Use wetlands, solar-aquatic,
or other methods to treat sewage
Recycle used oil
Require double hulls for oil tankers
Fig , p. 509

29. PREVENTING AND REDUCING SURFACE WATER POLLUTION
The key to reducing nonpoint pollution – most of it from agriculture – is to prevent it from reaching bodies of water.
Farmers can reduce runoff by planting buffers and locating feedlots away from steeply sloped land, flood zones, and surface water.

30. PREVENTING AND REDUCING SURFACE WATER POLLUTION
Most developed countries use laws to set water pollution standards, but such laws rarely exist in developing countries.
The U.S. Clean Water Act sets standards fro allowed levels of key water pollutants and requires polluters to get permits.
EPA is experimenting with a discharge trading policy similar to that for air pollution control.

31. Reducing Water Pollution through Sewage Treatment
Septic tanks and various levels of sewage treatment can reduce point-source water pollution.
Figure 21-15

32. 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.

33. Reducing Water Pollution through Sewage Treatment
Primary and Secondary sewage treatment.
Figure 21-16

34. 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).

36. Reducing Water Pollution through Sewage Treatment
Sewage sludge can be used as a soil conditioner but this can cause health problems if it contains infectious bacteria and toxic chemicals.
Preventing toxic chemicals from reaching sewage treatment plants would eliminate such chemicals from the sludge and water discharged from such plants.

37. Odors may cause illness or indicate presence of harmful gases.
Dust Particles
Particles of dried sludge carry viruses and harmful bacteria that can be inhaled, infect cuts or enter homes.
BUFFER
ZONE
Exposure
Children may walk or
play in fertilized fields.
Livestock Poisoning
Cows may die after grazing
on sludge-treated fields.
Sludge
Groundwater
Contamination
Harmful chemicals
and pathogens may leach into groundwater
and shallow wells.
Surface Runoff
Harmful chemicals
and pathogens may
pollute nearby
streams,lakes, ponds,
and wetlands.
Figure 21.17
Natural capital degradation: some potential problems with using sludge from sewage treatment plants as a fertilizer on croplands. The EPA says that sludge is safe to use if applied following its guidelines. Scientists and people who have gotten sick from exposure to sludge fertilizer claim that the guidelines are inadequate and not well enforced.
Fig , p. 513

38. 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.

39. Using Laws to Protect Drinking Water
While most developed countries have drinking water quality standards and laws, most developing countries do not.
The U.S Safe Drinking Water Act requires the EPA to establish national drinking water standards (maximum contaminant levels) for any pollutant that may have adverse effects on human health.

40. • Prevent groundwater contamination
Solutions
Water Pollution
• Prevent groundwater contamination
• Reduce nonpoint runoff
• Reuse treated wastewater for irrigation
• Find substitutes for toxic pollutants
• Work with nature to treat sewage
• Practice four R's of resource use (refuse,
reduce, recycle, reuse)
Figure 21.18
Solutions: methods for preventing and reducing water pollution. QUESTION: Which two of these solutions do you think are the most important?
• Reduce air pollution
• Reduce poverty
• Reduce birth rates
Fig , p. 517

41. • Minimize your use of pesticides.
What Can You Do?
Water Pollution
• Fertilize garden and yard plants with manure or compost instead of commercial inorganic fertilizer.
• Minimize your use of pesticides.
• Do not apply fertilizer or pesticides near a body of water.
• Grow or buy organic foods.
• Do not drink bottled water unless tests show that your tap water is contaminated. Merely refill and reuse plastic bottles with tap water.
Figure 21.19
Individuals matter: ways to help reduce water pollution. QUESTION: Which three of these actions do you think are the most important?
• Compost your food wastes.
• Do not use water fresheners in toilets.
• Do not flush unwanted medicines down the toilet.
• Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground.
Fig , p. 517