Water Sources and PollutionWater Sources and Pollution

Where does our water Where does our water come from?come from?

• It comes from 2 sources:1. Surface water: above ground in lakes and

rivers.

– Most large cities depend on surface water for their water supplies.

2. Groundwater

– When it rains, some water soaks into the ground. Plants use some of this water but the rest seeps underground and becomes “groundwater”

The entire area of land that is The entire area of land that is drained by a river is its drained by a river is its ““watershedwatershed””

• The amount of rain that falls on a watershed varies from year to year and with seasons. This changes the flow rates in river and the habitats around them.

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Pollution can also be picked- up throughout the watershed with then concentrates at the point where all waters meet. – Chesapeake Bay!!

What is your watershed?What is your watershed?

• We live in the Chesapeake Bay watershed.

South R. Shenandoah Potomac Chesapeake bay

Controversy over Rivers Controversy over Rivers • River water is a valuable

resource.• Arizona and California

have fought over rights to the Colorado river for a long time.

• http://www.smithsonianmag.com/multimedia/videos/Climate-Change-and-the-Colorado-River.html (3 minute video)

A boat casts a forlorn shadow in a dry river channel 25 miles from the river's historical end at the Gulf of California.

A Cocopah Indian surveys what was once the tribe's traditional fishing grounds.

GroundwaterGroundwater• Aquifers are spaces underground that

contain large amounts of ground water.• May take millions of years to form b/c

water percolates through the soil to get there.

• The “recharge zone” is the area of land that contributes to the groundwater.

• There are several huge aquifers in the U.S. that supply millions of gallons of water for homes and agriculture.

Aquifers are Running LowAquifers are Running Low

• People are pumping water out faster than it can be replaced naturally.• The Ogallala Aquifer (the largest in the United States) is quickly being

depleted.• Some communities are now using other sources of fresh water.

Solutions to Water Solutions to Water ShortagesShortages

1. Desalting the Sea (Desalinization) Distillation or Reverse Osmosis Expensive!

2. Towing Water Transport icebergs

Problems = melting, disrupting polar ecosystems

Sell bags of water from Alaska (float to places)

In Saudi Arabia, water costs more than oil!

3. Water Conservation

Water PollutionWater Pollution

• Main Sources– Agriculture– Sewage treatment– Industry– Urban Runoff– Mining Runoff– Construction runoff

Water pollution is the introduction of chemical, physical, or biological agents into water that degrades the quality of the water and affects the organisms that depend on it.

Water PollutionWater Pollution• The four most common water pollutants are

– Pathogens – parasites, bacteria, and viruses that cause disease in living things.

– Nutrients – materials need for organisms to grow. Examples: Nitrogen or Phosphorus

– Toxic chemicals – chemicals that can cause harm or death to living things.

– Sediments – minerals or organic matter deposited by water, air, or ice. . . This eventually settles to the bottom of a liquid

but will make water cloudy and hard to live in.

Source Pathogens Nutrients Sediments Toxic Chemicals

Agriculture Sewage treatment Industry Urban runoff Mining runoff Construction runoff

Where it comes fromWhere it comes from

Finding PollutionFinding Pollution

• Sometimes it is hard to determine the source of water pollutions.

• Water flows overland and underground so it is not always clear.

• Plume Mistake Town Pollution Activity!

Point PollutionPoint Pollution

• Point pollution: Pollution that is discharged from a single source.– Examples: from a factory, a wastewater treatment

plant, or an oil tanker.

• Relatively easy to regulate and control.• Easy to identify and trace.• Plume: measurable discharge of a

contaminant from a given point of origin• Sometimes difficult to enforce cleanup.

PlumePlume

Non-point PollutionNon-point Pollution

• Non-point pollution: Delivers pollutants indirectly through environmental changes. One way in, which this occurs is through runoff.

• Normally has multiple sources that are small.

• Cannot pinpoint direct source

Contamination in the U.S.Contamination in the U.S.

• The EPA (Environmental Protection Agency) determined that 96% of the polluted bodies of water in the United States were contaminated by nonpoint sources.

• Controlling nonpoint pollution depends on public awareness &

education.

Cleaning up Water Cleaning up Water PollutionPollution

• Federal and state laws have been passed to improve water-quality.

• Toxic metals are now removed from wastewater.

• Industrial wastes are treated before disposal.

• Point pollution has been decreased, but nonpoint pollution continues to be a problem.

Groundwater PollutionGroundwater Pollution• It is hard to clean up water pollution

because the water clings to sand and rocks around it.

– This has been a big problem with the South River Floodplain.

– Mercury was used by Du Pont Co. for fiber production (1929 and 1950). A serious contamination problem was discovered in the 1970s.

– 1984, Du Pont established a trust fund to support a 100-year monitoring program for mercury.

– However, information collected during the last 20 years indicates that levels are remaining stable, with no clear decreases over time.

– WHY? - one reason is that a lot of mercury is left in the soil and groundwater and every time it rains more washes into the river!