Ecology: Human Impact

Ecology: Human Impact

Station 2: Acid Rain

Watch the Video:

Acid Rain- Precipitation that has a pH below

Causes: Burning Fossil Fuels

Sulfur Dioxide (SO2)

Nitrogen Dioxide (NO2)

Effects of Acid Rain

Aquatic Ecosystems

The lower pH in surface water that occurs as a result of acid rain can cause damage to fish and other aquatic animals. At pHs lower than 5 most fish eggs will not hatch and lower pHs can kill adult fish. Acid rain has eliminated insect life and some fish species, including the brook trout in some lakes, streams, and creeks in geographically sensitive areas, such as the Adirondack Mountains of New York.

According to the table above, which aquatic organism would be least likely to survive in an acidic environment? ______

Terrestrial Ecosystems

Soil biology and chemistry in terrestrial ecosystems can be seriously damaged by acid rain. Some microbes are unable to tolerate changes to low pHs and are killed. Often the niches of these microbes include decomposition. Similarly, many species of plant life are slowly killed by the effects of acid rain. The trees pictured to the right are "standing dead" trees in Scandinavia.

How would an ecosystem be affected if soil bacteria were killed as a result of acid rain?

Why are organisms so sensitive to changes in pH?

What structures in cells only work at specific pHs? ______

Practice

Planctomycetes are single celled organisms that aid in decomposition of organic matter in aquatic ecosystems. A researcher had been monitoring the ecosystem in a lake over the course of several years. He noticed that on a few occasions the population of planctomycetes in the lake dramatically decreased. She formulated a hypothesis and the next time that the population dropped suddenly she tested the pH of the lake and found it to be 4.5. Normally the pH of the lake is about 6.

The table below lists a few of the enzymes in the Planctomycete, their functions, and the pH’s at which they work.

• State how the activity of peptidase in Planctomycetes would change following the acidic rainfall. Support your answer with data from the table.
• Identify the human activity that contributes to the sudden death of the Planctomycete population.

______

Use the information below to answer the questions.

Because of preventative measures that were taken in the United States, the problem of acid rain is not as severe today as it was 20 years ago. In 1989 the U.S congress passed the Clean Air Act, which forced industries to reduce their emissions of certain pollutants causing acid rain. However, in countries such as Russia and China, acid rain continues to become more frequent and more severe in recent years. This problem can be attributed to the increasing industrialization of these two countries. Both rely heavily on the burning of coal in particular, some samples of rain from those countries have pHs as low as 2.4!

According to the text, what is the source of the acid rain problem in Russia and China?

______

Though many areas in the United States continue to experience acid rain, the problem was significantly reduced by the Clean Air Act. Identify two pollutants that this law likely regulated.

______

Directions- Answer the questions that follow to the best of your abilities, using your notes and knowledge of Biology

1. In lakes in New York State that are exposed to acid rain, fish populations are declining. This is primarily due to changes in which lake condition?

(1) organic molecules(3) pH

(2) biotic factors(4) enzymes

2. A change in the acidity of mountain streams would most likely be the result of

(1) decreased enzyme activity in aquatic organisms (3) UV radiation entering the ecosystem

(2) deforestation of the area at the top of the mountain(4) sulfur dioxide being released miles away

3. A change in the acidity of mountain streams would most likely result in

(1) decreased enzyme activity in aquatic organisms (3) UV radiation entering the ecosystem

(2) deforestation of the area at the top of the mountain(4) sulfur dioxide being released miles away

4. Acid rain can be caused by

(1) An increase in CFC’s being released into the atmosphere

(2) Global warming

(3) The use of finite energy sources

(4) Direct harvesting