Environmental Science Water Resources 1 — Questions and Answers
Question 1: What percentage of Earth's water is freshwater available for human use (in rivers, lakes, and accessible groundwater)?
- About 70%
- About 30%
- About 10%
- About 1% (Correct answer)
Correct answer: About 1%
Only about 1% of Earth's water is accessible freshwater; the rest is saltwater, ice caps, or deep groundwater.
Question 2: Which U.S. law establishes the basic structure for regulating pollutant discharges into navigable waters?
- Safe Drinking Water Act
- Clean Water Act (Correct answer)
- Rivers and Harbors Act
- Water Resources Development Act
Correct answer: Clean Water Act
The Clean Water Act (1972) set the framework for regulating discharge of pollutants and established water quality standards.
Question 3: What is an aquifer?
- A type of water treatment plant
- A layer of permeable rock or sediment that stores and transmits groundwater (Correct answer)
- A surface water reservoir
- A water filtration membrane
Correct answer: A layer of permeable rock or sediment that stores and transmits groundwater
An aquifer is an underground geological formation of permeable rock or sediment that holds and transmits significant quantities of groundwater.
Question 4: What is the primary cause of saltwater intrusion into coastal freshwater aquifers?
- Storm surges during hurricanes
- Over-pumping of groundwater (Correct answer)
- Increased rainfall
- Sea turtle migrations
Correct answer: Over-pumping of groundwater
Excessive groundwater pumping lowers water table pressure, allowing denser saltwater from the ocean to move inland.
Question 5: Which watershed management concern arises when agricultural irrigation water evaporates, leaving minerals behind in soil?
- Eutrophication
- Salinization (Correct answer)
- Sedimentation
- Turbidity
Correct answer: Salinization
Salinization occurs when irrigation water evaporates and salts accumulate in topsoil, reducing agricultural productivity.
Question 6: What does BOD (Biochemical Oxygen Demand) measure in water quality assessment?
- The amount of dissolved oxygen in water
- The amount of oxygen consumed by microbes decomposing organic matter (Correct answer)
- The biological diversity of a water body
- The concentration of nitrogen compounds
Correct answer: The amount of oxygen consumed by microbes decomposing organic matter
BOD measures how much oxygen microorganisms use to decompose organic waste, indicating the level of organic pollution.
Environmental Science Water Resources 1
What percentage of Earth's water is freshwater available for human use (in rivers, lakes, and accessible groundwater)?