1: Environment and Ecosystems
Q1: What do we mean by environment?
Q2: What is an ecosystem?
The environment can be thought of as everything all around us. In studying the environment it is often helpful to concentrate on a space with specific boundaries.
An ecosystem is a space with specific boundaries. It includes all living and non living things within its limits. It could be small like a puddle or large like a biosphere.
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2: Energy Flow
Q1: What is energy?
Q2: How important is it?
Q3: Is energy found in nature?
Q4: Where does energy come from?
Q5: What does “energy flow” mean?
Q6: What does it mean to say that energy flows one way?
Energy can be defined as the capacity to do work. All life depends on energy for reproduction, growth and maintenance. All living things must work to live and therefore all living things are dependent on energy.
Almost all Earth’s energy comes from the sun. The sun sends us only one fifty-millionth of its total energy production and this equals 13 x 10 23 calories per year.
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3: Energy Flow (cont.)
The two basic kinds of energy are potential (stored) energy and kinetic (active) energy. Energy also assumes three forms—radiant, chemical and mechanical.
Energy operates under the first and second laws of thermodynamics. The first law states the energy can neither be created nor destroyed but it can change forms. The second law states that every time energy changes form, some energy is lost for further use.
An example of how solar energy functions is as follows. Energy comes from the sun in the form of light and heat and by the process of photosynthesis some of it is stored in plants as sugar. In the process of the energy going from the radiant form of light and heat to the chemical form of plant sugar, some energy is lost for further use.
4: Energy Flow (cont.)
The energy that comes from the sun and is stored in plants cannot go back to the sun. If an animal eats the plant, some of the energy from the plant could be stored in the animal. Once stored in the animal, it cannot go back to the plant.
Almost all energy that comes to Earth eventually leaves Earth again in the form of heat. Energy cannot retrace its path, and it cannot cycle. way. It flows to Earth, may flow through various forms—each time losing some of its force, and then continues its flow away from Earth as heat loss. It is a one way flow.
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5: The Hydrologic Cycle
Ql: What is the hydrologic cycle?
Q2: Why is it important to us?
The amount of water we have on Earth remains fairly constant and moves in a large cycle called the hydrologic cycle. The following is an example of how the hydrologic cycle works.
A particle of water falls to the Earth in the form of rain. It is absorbed by the soil and becomes part of the soil solution. The root of a near by tree absorbs the water, and it is transported up the tree to be come part of the moisture in a leaf.
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6: The Hydrologic Cycle (cont.)
The water evaporated from the leaf and rises to become part of a cloud. It can then fall to Earth and begin another cycle.
Water is essential to our lives. We need water to—drink, to clean, to grow food and for many other things. Without water we could not live. It is therefore important for us to understand the hydrologic cycle and be supportive of it.
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7: The Nutrient Cycle
Q1: What is the nutrient cycle?
Q2: Why is it important to us?
Nutrients are minerals and other things needed to support life. The nutrient cycle refers to the using and reusing of nutrients which, like water, is different from the one way flow of energy. Since nutrients and water cycle here on Earth, we do not need a continuing new supply from outer space—as is the case with energy,
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8: The Nutrient Cycle (cont.)
As an example of how the nutrient cycle works, consider the following. A tree root grew near a limestone rock. As the root grew it gave off carbon dioxide which entered the soil solution and combined with it to form carbonic acid. The carbonic acid in the soil solution caused the limestone rock to “weather” and release a calcium ion that had been held fast by it.
The calcium ion was carried in the soil solution and the tree root then absorbed the ion and carried it up to become part of one of the leaves.
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9: The Nutrient Cycle (cont.)
All season long the ion remained a part of the leaf. In the autumn the leaf turned color and dropped to the forest ground with all the other leaves.
Once on the ground, the leaf began decaying, releasing its elements. The calcium ion was freed from the leaf and became part of the soil from which it could again be absorbed by the soil solution and be ready to begin another cycle.
The nutrient cycle is important to us because we must eat to live, and all our food is dependent on this cycle. It is important that we understand the cycle so that we may support its proper functioning and not interfer with it.
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10: All Things Are Interrelated
Q1: What does it mean to say that all things are interrelated?
Q2: What has this to do with environmental issues?
All things are interrelated. An example of this is as follows.
The water from rain enters the soil and the roots of an oak tree absorb it and transport it up the tree to become part of an acorn. Energy from the sun is stored as sugar within the acorn. Energy from the sun also provided the power for the tree to produce the acorn.
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11: All Things Are Interrelated (cont.)
A squirrel comes and eats the acorn. Under the usual conditions of nature, eating an acorn provides the squirrel with nutrients needed to grow and live. Much of the energy, water and nutrients that were within the acorn are now stored within him. They are available for his use.
If, however, the rain or soil have been contaminated, that is, made impure by harmful things such as radioactive material or chemica1 wastes, then the acorn may be contaminated and instead of nourishing the squirrel, it may poison him.
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12: All Things Are Interrelated (cont.)
In a similar way the fruit from a tree or fish from the sea may grow in a healthy way and provide nourishing food for people. It could also, in a similar way, become contaminated and provide little or no nourishment, make them ill or even poison people.
The air we breath either is pure or has various degrees of impurities such as particles from industrial smoke, fumes from automobiles or smoke from cigarettes. One way the impurities in the air can cause us trouble is by depositing particles in our lungs which then can block the free exchange of oxygen and carbon dioxide, a process essential to life.
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13: All Things are Interrelated (cont.)
Impurities in the air can be picked up by the rain, be deposited in the soil, absorbed by the tree roots, transported up the tree and become part of its fruit. If you eat such a fruit, the impurities can then become part of your body cells.
All things, therefore, are interrelated, Energy, water air, nutrients, plants, animals—which includes people of course, all these things are linked together in the Earth’s ecosystem. What happens to one part of the ecosystem affects all other parts.
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