This lesson will increase your knowledge of concepts covered in the following TEKS for biology:

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

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

Previous LessonThe Water Cycle

Question: Where is most of the freshwater on earth and is it available for humans?

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

Question: What two key environmental factors can be used to predict the presence of biomes?

Temperature and precipitation predict the presence of biomes Based on: Mader, S., Inquiry into Life, McGraw-Hill

Question: Why will water potentially become a critical limiting resource to Texas in the next 30 years?

The population of North Texas will almost double by 2030 Population In North Texas

Today’s LessonAcid Rain and Fishless Lakes

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?

Controversies Over Acid Rain

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)

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

Changes in pH of rain from 1955 to 1979 over eastern U.S. From: Haines, Transactions of the American Fisheries Society, November 1981

Air movement patterns across U.S. Based on: Haines,Transactions of the American Fisheries Society, November 1981

Sulfur dioxide emissions in the eastern U.S. Based on: Driscoll et al., 2001. BioScience 51.

Nitrogen oxide emissions in eastern U.S. Based on: Driscoll et al., 2001. BioScience 51.

Amount of installed electricity production capacity in Ohio River Valley

Increase in stack height with time Based on: Patrick et al., Science Vol. 211, 30 January 1981

High smoke stacks inject sulfur and nitrogen emissions into upper atmosphere Photo courtesy of Texas Park and Wildlife Department

Rainfall with lowest pH or greatest acidity moves to the northeast

Fisheries biologists were the first to detect effects of acid rain on the biotic components of lakes

Lakes in N.Y. • Surveys of lakes in • 1930’s and 1970’s • pH of lakes declined • number of fishless • lakes increased • Hundreds of lakes • eventually had no fish

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

Number of fish species vs pH of lake Based on: Driscoll et al., 2001. BioScience, 51.

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

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

Effects of liming on pH are temporary and only treat the symptoms Based on: Verh. Internat. Verein. Limnol. 20, 1978, p. 852

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

Technology to remove sulfur dioxide is effective and sulfate deposition has declined. But would lakes respond? Based on: Driscoll et al., 2001. BioScience, 51.

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

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.

From Fort Worth Star-Telegram

pH of rainfall and acid-sensitive areas

Next LessonExotic Species and the Environment

This lesson will increase your knowledge of concepts covered in the following TEKS for biology: