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This lesson will increase your knowledge of
concepts covered in the following TEKS for
biology
3.a Analyze, review, and critique scientific
explanations, including hypotheses and theories,
as to their strengths and weaknesses using
scientific evidence and information 3.c
Evaluate the impact of research on scientific
thought, society, and the environment 11.b
Investigate and identify how organisms respond to
external stimuli 11.c Analyze the importance of
nutrition and environmental conditions on
physical exercise and health 11.d Summarize the
role of microorganisms in maintaining and
disrupting equilibrium and diseases in plants and
animals and decay in an ecosystem
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This lesson will increase your knowledge of
concepts covered in the following TEKS for
biology
12.b Interpret interactions among organisms
exhibiting predation, parasitism, commensalisms,
and mutualism 12.e Investigate and explain the
interactions in an ecosystem including food
chains, food webs, and food pyramids
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Previous LessonThe Water Cycle
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Question Where is most of the freshwater on
earth and is it available for humans?
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Global Water Cycle
15 cu km
110 cu km / yr
70 cu km / yr
40 cu km / yr
40 cu km / yr
100 cu km
15,000,000 cu km
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Question What two key environmental factors can
be used to predict the presence of biomes?
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Temperature and precipitation predict the
presence of biomes
Based on Mader, S., Inquiry into Life,
McGraw-Hill
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Question Why will water potentially become a
critical limiting resource to Texas in the next
30 years?
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The population of North Texas will almost double
by 2030
Population In North Texas
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Todays LessonAcid Rain and Fishless Lakes
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Overview of Lesson

• What is acid rain?
• What causes acid rain in North
• America?
• What are the effects of acid rain
• on lakes?
• How can we combat acid rain?
• Is acid rain a problem in Texas?

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Controversies Over Acid Rain
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pH of Rain

• Natural Rain Water in rain combines
• with carbon dioxide to form carbonic
• acid (a weak acid that causes normal
• rain to be slightly acidic or below a
• pH of 7)
• Acid Rain Sulfur and nitrogen
• oxides from the burning of fossil
• fuels combine with water in rain to
• form sulfuric and nitric acids
• (strong acids that cause rain to have
• pH below 5.6 or be acid rain)

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pH Scale
Acid rain is rain with a pH below 5.6
Based on Campbell et al., Biology Concepts
and Connections, Benjamin Cummings
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Overview of Lesson

• What is acid rain?
• What causes acid rain in North
• America?
• What are the effects of acid rain
• on lakes?
• How can we combat acid rain?
• Is acid rain a problem in Texas?

16
Changes in pH of rain from 1955 to 1979 over
eastern U.S.
From Haines, Transactions of the American
Fisheries Society, November 1981
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Air movement patterns across U.S.
Based on Haines,Transactions of the American
Fisheries Society, November 1981
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Sulfur dioxide emissions in the eastern U.S.
Based on Driscoll et al., 2001. BioScience 51.
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Nitrogen oxide emissions in eastern U.S.
Based on Driscoll et al., 2001. BioScience 51.
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Amount of installed electricity production
capacity in Ohio River Valley
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Increase in stack height with time
Based on Patrick et al., Science Vol. 211, 30
January 1981
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High smoke stacks inject sulfur and nitrogen
emissions into upper atmosphere
Photo courtesy of Texas Park and Wildlife
Department
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Rainfall with lowest pH or greatest acidity moves
to the northeast
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Overview of Lesson

• What is acid rain?
• What causes acid rain in North
• America?
• What are the effects of acid rain
• on lakes?
• How can we combat acid rain?
• Is acid rain a problem in Texas?

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Fisheries biologists were the first to detect
effects of acid rain on the biotic components of
lakes
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Lakes in N.Y.

• Surveys of lakes in
• 1930s and 1970s
• pH of lakes declined
• number of fishless
• lakes increased
• Hundreds of lakes
• eventually had no fish

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Ages of fish in acidified lakes of Canada

• only older fish
• were present
• fish had not
• spawned for
• years

Based on Harvey, Acid Rain / Fisheries, AFS,
1982
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Number of fish species vs pH of lake
Based on Driscoll et al., 2001. BioScience,
51.
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So how did lakes become fishless without
biologists knowing it?

• Gamefish are not killed directly
• by acid rain
• Declines in pH first affect the
• reproduction of fish and
• invertebrates in the food chain
• Gamefish reproduction stops
• and food chain collapses,
• eventually leading to loss of all fish

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Overview of Lesson

• What is acid rain?
• What causes acid rain in North
• America?
• What are the effects of acid rain
• on lakes?
• How can we combat acid rain?
• Is acid rain a problem in Texas?

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Liming of lakes
One of the most common ways to combat the effects
of acid rain in lakes Basic material which
neutralizes the acidity of a solution and raises
pH
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Effects of liming on pH are temporary and only
treat the symptoms
Based on Verh. Internat. Verein. Limnol. 20,
1978, p. 852
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In 1990, Congress amended the Clean Air Act to
require polluters (electric companies) to reduce
emissions of sulfur dioxide
Photo courtesy of Texas Park and Wildlife
Department
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Technology to remove sulfur dioxide is effective
and sulfate deposition has declined. But would
lakes respond?
Based on Driscoll et al., 2001. BioScience,
51.
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Studies in Europe and North America

• In the European
• lakes, the acidity has
• declined
• But some lakes in
• North America (like
• Adirondacks) have
• not had a decline in
• acidity

Based on Stoddard, et al., Nature ,Vol. 401, 7
Oct. 1999
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Heart Lake in the Adirondacks is still suffering
from the effects of acid rain. It has lost its
natural buffering capacity.
From U.S. News World Report, November 1, 1999
Prolonged exposure to acid rain may have leached
calcium and magnesium from the soils. It may
take decades to recover.
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Overview of Lesson

• What is acid rain?
• What causes acid rain in North
• America?
• What are the effects of acid rain
• on lakes?
• How can we combat acid rain?
• Is acid rain a problem in Texas?

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From Fort Worth Star-Telegram
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pH of rainfall and acid-sensitive areas
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Next LessonExotic Species and the Environment