1. AP Environmental Science Review
Chapter 19: Water Pollution
Miller’s Living in the Environment

2. 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)

3. Major Water Pollutants and Their Effects

5. Major Water Pollutants and Their Effects
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.
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.

6. 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.

7. 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.

8. Unconfined freshwater aquifer Confined 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

9. 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.

10. Contaminant plume moves with the groundwater
Leaking
tank
Aquifer
Water
table
Bedrock
Figure 21.8
Natural capital degradation: groundwater contamination from a leaking gasoline tank. As the contaminated water spreads from its source in a widening plume, it can be extracted by wells used to provide water for drinking and irrigation.
Groundwater
flow
Free gasoline
dissolves in
groundwater
(dissolved
phase)
Gasoline
leakage plume
(liquid phase)
Migrating
vapor phase
Water well
Contaminant plume moves
with the groundwater

11. 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

12. 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

13. OCEAN POLLUTION
Harmful algal blooms (HAB) are caused by explosive growth of harmful algae from sewage and agricultural runoff.

14. 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.

15. 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

16. 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.

17. Reducing Water Pollution through Sewage Treatment
Primary and Secondary sewage treatment.

18. • 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