Unit 3 Exam - Chapter 17

Question 1

Core Case Study: the Gulf of Mexico’s Annual Dead Zone

Answer 1

Spring and summer bring huge inputs of nutrients from the Mississippi River basin

Explosive growth of phytoplankton that eventually die and are
consumed by bacteria

Depletes oxygen in the Gulf’s bottom layer of water

Resulting dead zone contains little marine life

Winter storms redistribute oxygen

Question 2

CAUSES of water pollution

Answer 2

chief causes: agriculture, industry, and untreated wastewater

Question 3

EFFECTS of water pollution / things that it creates

Answer 3

Water pollution causes illness and death in humans and other species, and disrupts ecosystems

Question 4

Water pollution def

Answer 4

Change in water quality that can harm living organisms or make water unfit for human use

Question 5

Point Sources

Answer 5

Discharge pollutants at specific locations

Examples: factories, animal feedlots, underground mines, oil wells, and oil tankers

Question 6

Nonpoint Sources

Answer 6

Broad, diffuse areas

Rainfall or snowmelt washes pollutants from land into surface water

Examples: runoff of fertilizers and pesticides from croplands, logged forests, lawns, and golf courses

Question 7

Leading Causes of water pollution

Answer 7

Agricultural activities
(Sediment eroded from the lands
Fertilizers, pesticides, and bacteria from livestock and food)

processing wastes

Industrial facilities

Mining

Untreated human wastewater

Plastic

Question 8

Most serious threats to stream and lake water quality

Answer 8

Nutrients that cause oxygen
depletion

Mercury

Pathogens from broken sewer pipes

Sediment from land disturbance and erosion

Metals

Question 9

Infectious disease organisms in water

Answer 9

Contaminated drinking water
An estimated 1.6 million people die every year

Question 10

Major Pollution Problems in Streams or Lakes

Answer 10

Many streams and rivers around the world are polluted
—– Can cleanse themselves of biodegradable wastes if we do not overload them or reduce their flows

Adding excessive nutrients to lakes from human activities can disrupt ecosystems

Preventing pollution is more effective and less costly than cleaning it up

Question 11

In what here were lots of water pollution control laws passed

Answer 11

1970s: water pollution control laws

Question 12

Successful water pollution clean up

Answer 12

Cuyahoga River, Ohio, U.S.
Driven by bottom-up pressure from citizens

Question 13

EPA estimate on mining pollution

Answer 13

EPA estimate: mining wastes pollute 40 percent of headwaters of western watersheds

Question 14

Most polluted River in the US and why

Answer 14

Ohio River: most polluted river in the United States due to industrial wastes

Question 15

Why are half of the world’s 500 major rivers polluted

Answer 15

Untreated sewage
Industrial waste

Nearly half of China’s rivers too toxic to touch or drink
—- Liver and stomach cancer linked to water pollution among leading causes of death

Question 16

Critical Concept: Oxygen Sag Curves

Answer 16

Flowing rivers or streams can dilute organic pollutants and heated water unless overloaded

Does not eliminate heavy metals or slowly degradable pollutants

Oxygen sag curve is created when degradable pollutants are emitted and bacteria act to decompose the waste

Question 17

Pollution of Lakes and Reservoirs

Answer 17

Lakes and reservoirs are less effective at diluting pollutants than streams

Stratified layers with little vertical mixing

Little or no water flow

Can take up to 100 years to flush and change the water in a lake
Biological magnification of pollutants

Question 18

Eutrophication

Answer 18

Natural enrichment of a shallow lake, river mouth, or slow-moving stream

Caused by runoff of plant nutrients such as nitrates and phosphates

Question 19

Oligotrophic Lake

Answer 19

Low nutrients
Clear water

Question 20

Cultural Eutrophication

Answer 20

Nitrates and phosphates from human sources

Farms, feedlots, streets, parking lots, lawns, mining sites, and sewage plants

Question 21

Hot weather or drought : (cultural) eutrophication

Answer 21

Dense growths of algae and cyanobacteria

Oxygen depleted by bacteria that decompose the algae

Question 22

Prevent or reduce cultural eutrophication

Answer 22

Remove nitrates and phosphates

Recycle nutrients into the soil

Question 23

Methods to clean up lakes (cultural eutrophication)

Answer 23

Remove excess weeds

Use herbicides and algaecides

Pump in air

Most lakes will recover if
excessive input of nutrients is stopped

Question 24

Gulf of Mexico Dead Zone

Answer 24

Level of nitrates discharged from Mississippi River into Gulf of Mexico tripled since 1950s

Causes severe depletion of dissolved oxygen

Food web disruption

Many species cannot migrate away from area and die

Causes deaths of seabird and marine mammal species that depend on dying fish and shellfish

Human factors

Dredging and straightening of rivers increases flow of nutrients
Removal of wetlands that act as filters for pollutants

Question 25

Major groundwater pollution problems

Answer 25

Chemicals used in agriculture, industry, transportation, and homes spill and leak into groundwater

Question 26

Least expensive and most effective strategy against groundwater pollution

Answer 26

Protecting groundwater through pollution prevention

Question 27

Aquifers

Answer 27

drinking water source for about half the U.S. population

Question 28

Aquifers : common pollutants

Answer 28

Fertilizers and pesticides
Gasoline
Organic solvents
Fracking

Question 29

Slower chemical reactions in groundwater due to:

Answer 29

Slow flow–contaminants not diluted

Less dissolved oxygen

Fewer decomposing bacteria

Cold temperatures