Water Resources and Water Pollution

Module 9 (10/27–11/2) · Water Resources and Water Pollution · Blueprint Pillar 3 · PGCC Outcome 4 · Download .docx

Objectives

Describe the global freshwater distribution and the challenge of scarcity.
Distinguish point source from nonpoint source water pollution.
Explain aquifer depletion and its environmental consequences.
Identify the three stages of wastewater treatment.

Key terms

Aquifer: Underground layer of permeable rock, sediment, or soil that stores and transmits groundwater.
Water table: Upper boundary of the saturated zone in an aquifer.
Point source pollution: Water pollution from a single, identifiable, localized source — regulated by discharge permits.
Nonpoint source pollution: Water pollution from diffuse, dispersed sources such as agricultural or urban runoff.
Eutrophication: Excess nutrients in water causing algae blooms, oxygen depletion, and fish kills.
Hypoxic zone: Area of water with dissolved oxygen too low to support most aquatic life.
Primary treatment: Physical removal of large solids from wastewater through settling and screening.
Secondary treatment: Biological breakdown of dissolved organic matter in wastewater by microorganisms.
Desalination: Removal of salt from seawater or brackish water to produce fresh water; energy-intensive.
Clean Water Act (1972): U.S. law regulating discharge of pollutants into navigable waters and setting water quality standards.
Groundwater depletion: Declining water table due to extraction faster than natural recharge.
Reverse osmosis: Water purification technique forcing water through a semi-permeable membrane to remove dissolved salts and contaminants.

The concept

About 97% of Earth's water is salt water. Of the 3% that is fresh, most is locked in glaciers and ice caps. Less than 1% of all Earth's water is accessible surface water or groundwater — making freshwater one of the planet's most critical finite resources.

Groundwater is stored in aquifers — permeable rock formations. Aquifer depletion occurs when extraction exceeds natural recharge, lowering the water table. Point source pollution (a factory discharge pipe) is identifiable and regulated under the Clean Water Act. Nonpoint source pollution (agricultural runoff, urban stormwater) is diffuse, unidentifiable, and harder to regulate.

Wastewater treatment has three stages: primary (physical removal of solids), secondary (biological breakdown of dissolved organics by microorganisms), and tertiary (advanced removal of nutrients and pathogens). Desalination — particularly reverse osmosis — can convert seawater to fresh water but is energy-intensive and produces brine waste. The Gulf of Mexico dead zone, fed by fertilizer runoff down the Mississippi, is a major eutrophication example.

Self-check

Try each one before you look. A miss here costs nothing and tells you exactly what to reread.

1. Less than 1% of Earth's total water supply is accessible fresh water because:

2. Point source water pollution differs from nonpoint source pollution in that point source pollution:

3. Aquifer depletion occurs when:

4. Secondary wastewater treatment primarily accomplishes:

5. The Clean Water Act (1972) primarily regulates:

Canvas is the official record. This companion enhances the PGCC curriculum; it does not replace it. Last name and class year only. Students with a 504 plan or IEP: your accommodations apply.

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