Environmental Science Exam 4 Water Quality

Q1. What contaminant categories are regulated under the SDWA?

A: Disinfectants, heavy metals, microorganisms

Q2. How does climate change exacerbate water scarcity?

A:

• Causes floods that damage infrastructure and spread contamination

• Causes droughts that reduce physical water availability

Q3. The Safe Drinking Water Act (SDWA) applies to:

A: Public water systems serving more than 25 people

Q4. Process where excess nutrients → algal bloom → decomposition → oxygen depletion

A: Eutrophication

Q5. Which is NOT a way that groundwater becomes contaminated?

A: Direct absorption of VOCs from the air

Q6. Why is plastic pollution dangerous?

A: Its durability allows it to persist and harm marine organisms

Q7. Difference between physical and economic water scarcity

A:

• Physical scarcity: Not enough water available

• Economic scarcity: Water exists but people lack access to it

Q8. Factory pipe discharging chemicals into a river is:

A: Point source pollution

Q9. Why do many people struggle to access clean water globally?

A: Economic water scarcity and lack of infrastructure

Q10. Fertilizer runoff from large agricultural fields is:

A: Non-point source pollution

What is physical water scarcity?

Lack of physically available freshwater due to drought, climate, or overuse.

What is economic water scarcity?

Freshwater exists but people lack access due to inadequate infrastructure, poverty, or political instability.

Why do people still lack clean drinking water even though Earth has enough freshwater?

Pollution, lack of infrastructure, treatment plant failures, economic barriers, and government policies.

How does climate change worsen global water issues?

• Increases drought frequency

• Causes more extreme floods that spread contamination

• Damages water treatment facilities

• Intensifies water-borne diseases (cholera, etc.)

Examples of water-related problems worldwide

• Water scarcity

• Water-borne diseases

• Flooding

• Chemical, biological, and physical pollution

What is point-source pollution?

Pollution from a single, identifiable source (e.g., factory pipe, oil spill).

What is non-point-source pollution?

Pollution from many diffuse sources (e.g., agricultural runoff, suburban lawns).

Chemical pollution example

Fertilizer runoff containing nitrate or phosphate.
Cause: Mostly anthropogenic.

Biological pollution example

Human or animal waste leading to E. coli or cholera.

Cause: Anthropogenic.

Physical pollution example

Plastic debris or sedimentation.
Cause: Mostly anthropogenic.

What nutrients most commonly cause eutrophication?

Nitrogen (N) and phosphorus (P)

Steps of eutrophication

• Excess nutrients enter water

• Algal bloom

• Algae die

• Decomposition uses oxygen

• Oxygen depletion (hypoxia/anoxia)

Primary source of nutrient pollution

Agricultural fertilizers

Other sources of nutrient pollution

• Sewage discharge

• Detergents

• Fossil fuel combustion (NOx)

• Animal farms

Solutions to reduce nutrient pollution

• Buffer zones around fields

• Wetland protection or restoration

• Improve wastewater treatment plants

• Reduce fossil fuel combustion

Common sources of biological pollution

Human and animal waste
Poor sanitation and sewage leaks
Flooding events that spread pathogens

Diseases linked to biological pollution

• Cholera

• E. coli infections

• Dysentery

• Typhoid fever

• Hepatitis A

Why are cholera cases increasing?

• Population growth

• Higher population density

• Limited healthcare access

• Climate-driven floods and droughts

• Humanitarian crises

Why is plastic’s durability both good and bad?

Good: Long-lasting material for human use
Bad: Persists in the environment for centuries, harming wildlife

How much plastic is produced worldwide, and what’s expected by 2050?

Plastic production is increasing rapidly and projected to triple by 2050.

What are ocean gyres?

Large circular ocean currents that trap plastic debris (e.g., Great Pacific Garbage Patch)

Findings from Dr. Jennifer Lavers’ seabird research

Seabirds ingest large amounts of plastic → injury, starvation, organ damage.

Why reduce plastic use?

To prevent long-term ecosystem damage and reduce marine pollution.

How can groundwater become contaminated?

• Infiltration of farm chemicals

• Recharge carrying pollutants

• Subsurface contamination (leaky tanks, septic systems)

• Surface water intrusion carrying pollution

Common groundwater contaminants

• Nitrate

• Pesticides and petroleum

• Heavy metals

• Pathogens

What does the SDWA regulate?

Public drinking water systems serving >25 people.

Who does not fall under SDWA protection?

Private wells.

What contaminant categories are regulated?

• Microorganisms

• Disinfectants

• Disinfection byproducts

• Inorganic chemicals

• Organic chemicals (20+)

Why is the SDWA important?

Ensures safe drinking water and sets maximum contaminant levels (MCLs).

Flint Water Crisis

Example of SDWA violation; lead levels reached 13,000 ppb (MCL = 15 ppb).

What does the Clean Water Act regulate?

Pollution in navigable surface waters (not groundwater).

Clean water act is most effective at regulating:

Point-source pollution.

Case study: Cuyahoga River

River caught fire multiple times due to oil and chemical pollution; led to EPA creation and CWA enactment.

Which water quality indicator is the only one that is good at high levels

Dissolved Oxygen

Infiltration

moves pollutants into soil → groundwater

Overland flow

carries nutrients/plastics → streams

Precipitation

washes contaminants into water bodies

Stream flow

transports pollution downstream

Groundwater recharge:

pulls pollutants downward long-term