Water Resources and Water Pollution — HS Environmental Science practice questions

Which sequence describes eutrophication?

1. Algal bloom → nutrients → oxygen rises → fish thrive
2. Oxygen falls → nutrients → algae die → algal bloom
3. Nutrients → algal bloom → algae die → decomposers use up oxygen
4. Nutrients → fish increase → algae die → oxygen rises

Answer: C — Nutrients → algal bloom → algae die → decomposers use up oxygen

C) Correct — Low oxygen kills fish, creating dead zones. A) Oxygen falls, not rises. B) Puts the steps in the wrong order. D) Fish die from low oxygen.

About what share of Earth's water is fresh water?

1. About 50%
2. About 30%
3. About 97%
4. About 3%

Answer: D — About 3%

D) Correct — Most of that is frozen in ice caps and glaciers. A) Most water is salty ocean water. B) Far too high. C) Is the share of salt water.

Which irrigation method wastes the least water?

1. Flood irrigation
2. Furrow irrigation
3. Drip irrigation
4. Overhead spray at midday

Answer: C — Drip irrigation

C) Correct — It delivers water directly to roots. A) Loses much water to evaporation and runoff. B) Loses water along the channels. D) Loses water to evaporation.

The U.S. Clean Water Act mainly regulates:

1. air emissions from factories and power plants
2. hazardous waste in landfills
3. pollution discharged into surface waters
4. endangered species habitats

Answer: C — pollution discharged into surface waters

C) Correct — It sets limits on what can be released into rivers and lakes. A) Is the Clean Air Act. B) Is mainly RCRA. D) Is the Endangered Species Act.

Which is point-source pollution?

1. Fertilizer runoff from many farms
2. Oil washing off city streets
3. Waste from a factory pipe
4. Pollution settling from the air

Answer: C — Waste from a factory pipe

C) Correct — Point sources come from one identifiable location. A) Is nonpoint-source pollution. B) Is nonpoint-source pollution. D) Is spread over a wide area.

The Ogallala Aquifer in the Great Plains is shrinking because:

1. water is pumped out faster than it recharges
2. acid rain dissolves the aquifer
3. rising sea level fills it with salt water
4. too much rain floods it

Answer: A — water is pumped out faster than it recharges

A) Correct — Irrigation draws it down far faster than rain refills it. B) Acid rain does not drain aquifers. C) It is far inland. D) Would add water, not remove it.

Large predatory fish such as tuna often have the most mercury because of:

1. eutrophication
2. bioremediation
3. photosynthesis
4. biomagnification

Answer: D — biomagnification

D) Correct — Mercury becomes more concentrated at each step up the food chain. A) Is nutrient overload. B) Uses organisms to clean pollution. C) Does not concentrate mercury.

Water pollution sources?

Sewage, agricultural runoff (fertilizer, pesticides), industrial waste, oil spills, plastics.