Water Pollution Quiz
Questions: 16 · 10 minutes
1. A factory releases wastewater into a river through one identifiable discharge pipe. How is this source classified?
A nonpoint source
A point source
Atmospheric deposition
Natural background pollution
2. Investigators suspect that a wastewater outlet is affecting a stream. Which sampling design best helps test that suspicion?
Collect one sample far downstream during a single season
Measure air temperature without testing the water
Sample only the wastewater before it enters the stream
Compare repeated samples upstream and downstream of the outlet
3. Two stream samples are tested for biochemical oxygen demand, or BOD. Sample A has a much higher BOD than Sample B. What does that usually suggest about Sample A?
It contains more biodegradable material driving microbial oxygen use
It is necessarily free of sewage or organic waste
It contains more oxygen available for fish over time
It must have a lower temperature than Sample B
4. A farmer wants to reduce sediment and nutrient runoff into a stream bordering a field. Which measure would most directly help?
Replacing soil with an impervious surface
Maintaining a vegetated buffer strip beside the stream
Clearing plants from the stream bank
Applying fertilizer immediately before heavy rain
5. A persistent pollutant is found at low concentrations in water, higher concentrations in small fish, and the highest concentrations in fish-eating birds. Which process best explains this pattern?
Dilution
Neutralization
Biomagnification through the food web
Groundwater recharge
6. How can a healthy wetland improve water quality as water moves through it?
By preventing every microorganism from living in the water
By converting all dissolved pollutants into harmless oxygen
By increasing the speed of runoff into nearby rivers
By trapping sediment and supporting plant and microbial nutrient removal
7. A household is told to boil tap water because disease-causing microorganisms may be present. What important limitation does boiling have?
It works only when the water is visibly cloudy
It removes dissolved oxygen but leaves all microorganisms alive
It does not reliably remove dissolved pollutants such as lead or nitrate
It converts bacteria into chemical fertilizer
8. A power plant releases unusually warm cooling water into a river. Why can this thermal pollution harm aquatic life?
Warm water always becomes strongly acidic
Warm water prevents all sunlight from entering the river
It immediately turns freshwater into saltwater
It can hold less dissolved oxygen and may stress temperature-sensitive organisms
9. A neighborhood replaces lawns and soil with roads, roofs, and parking lots. During storms, what change is most likely?
More rainwater infiltrates into the soil
All pollutants are filtered by the paved surfaces
More runoff carries pollutants rapidly toward drains and streams
Stormwater stops reaching local waterways
10. What are microplastics?
Plastic particles generally smaller than five millimeters
Plastic items that dissolve completely when placed in water
Microorganisms that consume discarded plastic
Naturally occurring mineral crystals visible only under a microscope
11. A buried gasoline storage tank develops a slow leak. Which water resource is most directly threatened first?
Water vapor in the upper atmosphere
Ocean water beyond the continental shelf
Groundwater in the surrounding soil and rock
Rainwater before it reaches the ground
12. Water draining from an abandoned mine is acidic, orange-stained, and contains elevated metals. What commonly causes this type of pollution?
Evaporation removing all minerals from the drainage
Excess dissolved oxygen turning directly into iron
Plastic waste releasing nutrients into the mine
Sulfide minerals exposed to air and water forming acidic drainage
13. A stream looks clear and has no noticeable odor. Why is appearance alone insufficient to show that it is unpolluted?
Pathogens and dissolved chemicals may be present without visible signs
Only saltwater pollution changes water's appearance
Visible debris is the only form of water pollution
Clear water always contains more nutrients than cloudy water
14. Which finding is commonly used as an indicator that water may have been contaminated by fecal material?
A high concentration of dissolved calcium
Elevated levels of indicator bacteria such as E. coli
The presence of harmless algae
A neutral pH reading
15. After heavy rain washes fertilizer from nearby fields into a lake, a dense algal bloom develops. Which input most likely fueled the bloom?
Excess nitrogen and phosphorus
Suspended sand and gravel
Dissolved oxygen
Calcium carbonate
16. Several days after a large algal bloom dies, fish begin gathering near the water's surface. What is the most likely explanation?
The dead algae have made the water too transparent
Decomposers are consuming dissolved oxygen as they break down the algae
The algae have permanently raised the water's salinity
The fish are feeding on newly formed mineral deposits