8 Water Pollution (Chp 4).notebook

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Warm­UpNov. 13th, 2007

What types of things could you expect to see in a Aquatic Ecosystem?

8 Water Pollution (Chp 4).notebook

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Intro

Why is the Earth called a Blue Planet?

Water.

Water• Covers more than two thirds of our planet. 97% of that water is saltwater which we cannot drink without filtering with special technology.

Where do you think most of the freshwater is stored?

Most freshwater gets stored in snow and ice.

8 Water Pollution (Chp 4).notebook

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Water Pollution

Water Pollution ­ Any physical or chemical change in surface water or ground water that can harm living things.

What are some ways that water pollution can occur?

Water pollution can occur through:• Human Sewage • Animal Wastes• Decaying Plant Life• Industrial Wastes• Acids from combustion and refining of fossil fuels • Fertilizers from farms and gardens entering aquatic systems through runoff• Oil and grease from roads• Electricity generating plants and other industries

8 Water Pollution (Chp 4).notebook

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Water quality is usually defined by its intended use.

Too polluted to drink ­­­­­­­> Acceptable for the lawn

Too polluted for swimming ­­­­­­­­­­­­> Acceptable for fishing

There are 3 main indicators of water quality:1. Bacteria Count2. Concentration of dissolved oxygen3. Biological Oxygen demand

8 Water Pollution (Chp 4).notebook

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Bacteria Count ­ expensive and complicated to find out the amount of bacteria.

Dissolved Oxygen ­

A cool lake with fewer pollution has dissolved oxygen levels between 8 and 14 mg/L

A good way to determine the dissolved oxygen levels would be to examine the living things found in the water.

A healthy trout ­­­­­­> High levels of dissolved oxygen

Carp and catfish ­­­­­­> Low levels of dissolved oxygen

A complete absence of fish may indicate very low levels of dissolved carbon.

8 Water Pollution (Chp 4).notebook

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Biological Oxygen Demand ­ a measure of the amount of dissolved oxygen needed by decomposers (bacteria) to break down the organic matter in a sample of water over a five day period at 20o C.

The BOD indicates the amount of available organic matter in a water sample. As the number of organisms in an ecosystem increase, so does the BOD.

The more organisms however, the more oxygen that is being used. This causes the level of dissolved oxygen to decrease.