Acid Rain and Sediment (4/24-4/28)
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Bioindicators:
Bioindicators are living things that are sensitive to changes in an environment. Scientists study bioindicators to see it the environment is healthy. Water fleas are a type of bioindicator and are very sensitive. Water fleas ear algae, and many fish eat water fleas. Chlorine can kill water fleas, which can tell us if there is a chlorine pollution. A decrease in water fleas could mean that there is no dissolved oxygen in the water, the water is too acidic or basic, or there are unhealthy chemicals (like chlorine) in the water.
Acids:
Acids are a group of chemicals with certain properties. They taste sour, dissolve metals, and conduct electricity well. Some examples of acids are orange juice and vinegar. Though some acids are safe, many acids are dangerous.
Scientists use a pH scale to measure how acidic something is. The pH scale goes from 0 to 14. The pH number tells us if it is acidic, neutral, or basic. The smaller the number, the more acidic something is. A pH 7 is neutral, and pH 8 and above is basic. Normal rain is a little bit acidic and has a pH of 5.6-6. Acid rain can a pH below 5.6
Acid Rain:
The main types of acid rain are nitric acid and sulfuric acid. Car exhaust and factory smoke can chemically react with water in the clouds. Sulfuric acid is caused by sulfur oxides which come from power plants like coal. Factory smoke can cause acid rain, and to limit this, factories can put "scrubbers" on their smokestacks which limit pollution and acid rain.
When water becomes acidic, most fish die. Water plants such as algae cannot take in nutrients, so their growth is stunted, and they eventually die. A solution to make acid lakes less acidic would be to add limestone. Limestone neutralizes the acid because it is a base that can make acid rain neutral (pH7.) Clay is also a base and can neutralize acids. However, granite does not neutralize acid rain.
How Sediment Can Affect Water Life:
- Fish cannot dig holes for laying eggs because sediment can cover the bottoms of rivers.
- Sediment can crush the eggs of water insects and suffocate newly hatched insect larvae.
- Sediment can also harm fish gills so that they cannot breathe.
- Sediment can cover the light, making it hard for plants to produce photosynthesis.
- Lastly, it can darken the waters so that it receives more of the sun's heat.
Overgrazing Can Cause Erosion
Overgrazing can damage plant cover. Shrubs and grasses protect the soil and slow down water run-off that can cause erosion. When sheep overgraze, these shrubs and grasses are not there, which can cause erosion. Excessive trampling by grazing animals can also make it hard for plants to grow back.
Clear Cut Forests vs Selectively Cut forests
After a clear-cut, the forest is gone. Clear cut forests and heavy rains can cause erosion, habitat destruction, and water pollution. Once a forest is clear-cut, new trees may have trouble growing because of dry conditions and brush covering the ground. Selectively cut forests recover more easily, and wildlife habitat is saved. When forests are clear-cut because of unhealthy trees, it is called "salvage."
SP8: Obtain, evaluate and communicate information
In class, we obtained, evaluated, and communicated information. We used scientific text to find information, evidence, and ideas about acid rain and sediment. We took notes and answered questions about what we read. After, we communicated the information with the class by having a class discussion which helped us understand more about the topic.
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