ECOLOGY AND THE CONSERVATION OF NATURAL RESOURCES
|Pollution and Environmental Health
|Habits of Mind
||Science and Technology 3.5b
To develop an understanding of the interdependence of all organisms and the need for conserving natural resources
A relatively unpolluted environment is essential to maintain the quality of life on earth.
Ecology N4.00 To understand factors unique to the proper disposal of hazardous and radioactive wastes
INSTRUCTIONAL OBJECTIVES: The learner will:
4.01 explain the nature of radioactivity.
OUTLINE OF CONTENT:
4.02 identify the various sources of radioactive waste.
4.03 describe the effects of radioactive waste on living organisms.
4.04 describe the characteristics of hazardous waste.
4.05 identify the various sources of hazardous waste.
4.06 describe the effects of hazardous waste on living organisms.
4.07 describe the methods for proper handling and disposal of hazardous and radioactive waste.
I. Nature of radioactivity.
A. The structure of the atom
II. Sources of radioactive waste.
3. Atomic number
4. Atomic mass
a. Stable atoms
b. Unstable (radioactive) atoms
C. Half life
D. Types of radiation
1. Gems rays
E. Background radiation
2. Bets particles
b. Penetrating ability
c. Ionizing potential
3. Alpha particles
b. Penetrating ability
c. Ionizing potential
b. Penetrating ability
c. Ionizing potential
2. Naturally occurring ore
III. Effects of radioactive wastes an living organisms
1. Low level
2. High level
2. Biochemical research
3. Nuclear fuel cycle
4. Weapons industry
5. Weapons testing
6. Other industrial/manufacturing
A. The chemical (non-nuclear) activity of atoms
IV. Characteristics of hazardous wastes.
1. Recognition of radioactive isotopes by the body
B. The effects of ionizing radiation
2. Treatment of chemically similar atoms
1. On atoms and molecules
C. Concentration in the food chain
2. On cells and protoplasm
3. On DNA and genes - mutations
4. Large dosages
a. White blood vessels
5. Small dosages
b. Bone marrow
d. Lymph nodes
e. Lung tumors
f. Skin cancer
a. Somatic (body) cells
b. Germ (reproductive) cells
1. Strontium fallout
D. Circumstances of the greatest danger
a. Lichens, caribou, Eskimos
2. Iodine in the oceans
b. Grass, cow's milk, humans, mother's milk
1. Long term exposure
2. Short term exposure
V. identify the various sources of hazardous waste.
2. Duration of exposure
A. Chemical manufacturing
VI. Effects of hazardous wastes on living organisms.
B. Industrial processes
D. Household products
1. Paint thinners
E. Incinerator ash
2. Bug sprays
3. Cleaners and solvents
A. Methods of absorption
VII. Methods for proper handling and disposal of hazardous and radioactive waste.
B. Threshold limit value
4. Eyes and mucous membranes
A. Handling hazardous or radioactive waste
1. Containment during transfer and processing
B. Disposal of toxins
2. Protection of workers
1. "Isolation" from the environment
C. Source reduction - A management strategy
a. Toxic waste dumps - landfills
2. Destruction or conversion
b. Deep well injection
c. Deep burial or storage
a. Hazardous waste incineration
b. Conversion by biological agents
1. Using waste audits to pinpoint sources, process by process
D. Reduction at the household level by using alternative:
2. Preventive steps
a. Ray material substitution
a. Enhanced containment during transfer and processing
b. Process redesign
c. Product redesign
d. In-site recycling
3. Insect peat repellents
COMPONENT OF SCIENCE: Habits of Mind
To enable students to demonstrate ways of thinking and acting inherent in the practice of science; and to exhibit an awareness of the historical and cultural contributions to the enterprise of science.
3.5 SCIENCE AND TECHNOLOGY - Science and technology are separate but interdependent entities.
3.5b - Technology makes it possible for scientists to extend their research or to undertake entirely new lines of research.
BENCHMARKS Technological advances tend to extend the reach of our senses and to expand our ability to manipulate and to understand our environment.
An atom is the smallest unit that an element can be divided into and still be the element. Write down the names of six elements.
Atoms are made up of units called subatomic particles. The three primary subatomic particles are protons, neutrons, and electrons. Protons are positively charged and neutrons carry no charge. Both have about the same mass and are found in the atomic nucleus. Electrons are negatively charged and are about one-one thousandth the mass of a proton or neutron. Electrons are found in a "cloud" around the nucleus. The chemical properties of an atom are largely determined by the number of electrons it has. Atoms join, or bond, to other atoms to form molecules due to the activity of their electrons.
An element's atomic number is the number of protons in its nucleus. It is also the number of electrons usually found in the "cloud" around the nucleus. Some atoms have the tendency to give up some of their electrons. Others have a tendency to gain electrons. When this happens, the atom becomes charged, either positively or negatively because the number of protons in the nucleus is not the saw as the number of electrons in the cloud. In ordinary chemical reactions the number of protons in the nucleus remains the same. We call these charged atoms, ions. Ions are very chemically active.
An element's atomic mass, rounded to the nearest whole number is the sum of the number of protons and neutrons in its nucleus. It is possible that different atoms of the same element may have different atomic masses.
The difference in mass is due to different numbers of neutrons. Chemically, they behave in exactly the same manner because they have the same number of protons and electrons. These different forms of the same element are called isotopes. For example, carbon has the atomic number six. How many protons does carbon have in its nucleus? (Response) That is right, six. Most carbon atoms have six neutrons in the nucleus. That form of carbon is called Carbon-12. (6+6=12). However, some carbon atoms have eight neutrons in the nucleus. They have six protons there also; that is what makes it carbon. This carbon isotope is called Carbon-14. (6+8=14)
Practically all atoms that make up the matter on Earth are stable. This means that they remain the same element forever, with the same number of protons and neutrons in their nuclei. Some elements and isotopes are unstable, however. This means that over time, changes occur in the nucleus and they emit parts of the nucleus and energy. Such elements and isotopes are called radioactive and the stuff they emit is called radiation. Uranium-238 (U-238) is a radioactive element. U-238 undergoes radioactive transmutation. That is, its nucleus emits an alpha particle (a type of radiation) and becomes Thorium-234. This process is called radioactive decay.
The nuclei of some isotopes are such that when conditions are right, the atom splits roughly in half. This is called fission and the result of it is that one atom of an element changes into two atoms of entirely different elements and some neutrons and lots of energy are released. The two new elements may themselves be radioactive and undergo further decays until eventually a stable atom results. For example, when Uranium-235 is struck by a neutron it undergoes fission releasing two neutrons, lots of heat energy and the nucleus splits into one of Krypton-92 and Barium-141. It is this property of U-235 that makes it a suitable fuel for nuclear power plants or explosive for nuclear weapons. In each of these devices, nuclear fission is made to happen by concentrating the fissionable material such that the two neutrons released from one fission cause two more fissions which cause four fissions, then eight, sixteen, thirty-two, etc. This is called a chain reaction. With each increase in number of fissions more and more energy is released. Chain reactions do not occur in nature. Even in rich uranium ore there is not a high enough concentration of fissionable U-235 to sustain a chain reaction. Controlled, the energy from a chain reaction can be used as a source of heat to boil water and generate electricity. If made to happen at a fast enough rate it results in an explosion. In each case, vast amounts of deadly radiation are released.
The rate at which radioactive elements decay is unique to the element. It is measured in half-lives. A half life is the amount of time it takes for half of the atoms in a given
sample of a radioactive element to decay. For example, the half life of Carbon-14 is 5,730 years. This means that in 5,730 years half of a given sample of Carbon-14 will have decayed into another element (Nitrogen). In another 5,730 years, half of the remaining sample will have disintegrated. Only one fourth of the original amount will remain at that time. Some isotopes have short half lives (Iodine 181, eight days). Others have very long half-lives (U-238, four and half billion years).
Yesterday, we learned that the nuclei of some elements undergo change and emit radiation. What term do we use to describe these unstable elements? (Radioactive) If an element has a half life of twenty years and you start with eight ounces of it, how much of it is left after twenty years? (Four ounces) After forty years? (Two ounces) After sixty years? (One ounce) Today we are going to learn what three types of radiation. Radioactive element emit, something about the nature of these radiations and how radioactive elements are used.
All three types of radiation are invisible, odorless and tasteless. You can be exposed to them and not even know it. All three types ionize atoms and will expose photographic paper.
The first type is the game ray. It is a form of very high energy electromagnetic radiation. It is similar to X-rays. It will not turn you into the Incredible Hulk. Gamma rays, like X-rays pass right through your body. They can penetrate over three feet of concrete. As they pass through your body they ionize atoms, ripping electrons off, breaking chemical bonds in molecules.
The second type of radiation is the beta particle. Beta particles are actually high velocity electrons. They can be traveling nearly the speed of light and are also capable of ionizing atoms, with about the same ionizing potential as gamma rays. They can penetrate about one half an inch of flesh before they run into something and are stopped.
The third type of radiation is the alpha particle. Alpha particles consist of two protons and two neutrons stuck together. They are much slower moving than beta particles, traveling at about one tenth the speed of light. They are also much bigger than beta particles and run into something and are stopped sooner than beta particles.
Alpha particles can be stopped by a piece of paper, your clothes or even the outer layer of your skin. However, recall that protons and neutrons are about 1000 times as massive as electrons. So alpha particles pack a bigger ionizing "punch". In fact, they have an ionizing potential twenty times that of gamma rays. Alpha particles are extremely dangerous when emitted by radioactive elements inside the body.
Radiation is of three types. Write these three down in the order of their ionizing potential. (Alpha, beta, gamma) Write them down in the order of penetrating ability from most to least penetrating. (Gamma, beta, alpha)
Radioactivity is a natural phenomenon. We are constantly exposed to a certain amount of ionizing radiation from the sun and naturally occurring radioactive ore. This is called background radiation. Life has existed for millions of years in the presence of background radiation. All organisms have adapted to it. In fact, background radiation is the primary cause of the mutations that allow species to evolve.
In the last fifty years humans have begun to mine and concentrate the naturally occurring radioactive elements in ores. In some instances we have manufactured new elements or artificially transmitted elements to produce radioactive isotopes. These radioisotopes have many useful purposes.
They are used in medicine as both diagnostic and therapeutic tools. Certain elements are concentrated in specific organs or tissues. Iodine, for example, is concentrated in the thyroid gland. Low dosages of radioactive iodine taken orally may be used to make its tissue visible on diagnostic X-ray photographs. In higher doses, radioisotopes may be used to treat cancer of a particular tissue or organ not suitable or accessible for removal by surgery.
Radioisotopes are used in biochemical research to tag molecules. For example, from which reactant did the oxygen produced in photosynthesis originate was a mystery. Did it come from the water or the carbon dioxide? Algae were grown in water made of ordinary hydrogen and oxygen-18, a radioactive isotope. Carbon dioxide made with non-radioactive oxygen was dissolved in the water. The oxygen gas produced by the algae contained oxygen-18. This proved that the oxygen came from the water, not the carbon dioxide.
Today we've considered the three types of radiation emitted by radioactive elements; alpha, bets, and game. What term is used to refer to the naturally occurring radiation to which we've constantly exposed? (Background) On your paper list at least three beneficial uses for radioactive isotopes.
This classroom connector addresses Instructional Objective 4.03, 4.04, 4.05, 4.06, and 4.07.
We've been learning about radioactive materials the last few days. They have many useful purposes. However, they must be handled cautiously. Why are radioactive materials potentially dangerous? (They emit harmful radiation). Today we are going to learn about the types of radioactive wastes and where they come from.
In the last fifty years humans have begun to mine and concentrate the naturally occurring radioactive elements found in ores and in some instances, like with Pu-239, manufacture others. These mining, manufacturing and handling processes contaminate tools and materials, creating huge volumes of radioactive wastes.
Uranium mining, like all mining creates mine tailings which contain trace amounts of uranium. At one time considered safe, we now know that these tailings emit radon, a radioactive gas that is a product of uranium decay. Low level wastes are radioactively contaminated tools, gloves, aprons, lab costs, and various dilute solvents from the processing and enrichment of uranium are. Low level waste also includes radioactive garbage from hospitals, research labs, and industry. Low level wastes must be kept isolated from the environment for decades or centuries.
High level wastes are extremely radioactive, long lived contaminated materials. Spent nuclear fuel, solvents containing plutonium-239 or uranium-235 and other long lived radioactive elements must be kept isolated from the environment for hundreds of thousands of years. Plutonium-239, for example, is the most lethal substance an earth. One pound of plutonium, dispersed as a powder, has the potential to kill nine billion people. It has a half life of 24,400 years. In the course of operating one year an average sized (1000 NW) nuclear power plant produces 400 to 500 pounds of plutonium-239.
By far the greatest producer of both high and low level red waste (radioactive waste) is the nuclear power/nuclear weapons industry. These industries have coexisted for each other since the early 1950's. The Atomic Energy Commission, the government agency that directed the development of these industries, was responsible for both setting standards for nuclear power and promoting nuclear power. History has shown that the AEC and the nuclear power industry downplayed the hazards of nuclear power. How many of you would tell potential customers of a candy sale that your chocolate bars would promote tooth decay or make them fat? (response) Sure you wouldn't, they will probably not buy the candy. This is the situation the AEC was in during the 50's, 60's and early 70's. They had a conflict of interest (write on board); they are responsible for both regulating, setting guidelines, and promoting nuclear power.
Less than one percent of the uranium in ore is fissionable (U-235) and therefore suitable for fuel. Through the enrichment and breeding process U-238 can be artificially transmitted into Pu-239, which can be used as a fuel. The fact that there is such a limited supply of U-235 means that a decision to pursue a nuclear power program is a decisions to make more plutonium, generating more radwaste. Each average (1000 MW) nuclear plant produces enough low and high level radwaste every year to cover a four lane highway one foot deep for twenty-seven miles, remember mine tailings are radwastes, too. Particularly uranium mine tailings. Why? (responses) The wastes of the nuclear power/weapons program are not the only source of radioactive pollutants. During the operation of nuclear plants, there are routine, legally permitted releases of radioactive isotopes into the environment, as well as accidental spillages. In the nuclear fuel cycle from mine to mill to fuel fabrication to reactor there are at least seven points where radioactive wastes are routinely emitted into the environment.
On a piece of paper write down how much radioactive waste is produced by an average nuclear power plant in one year. (Enough to cover a four lane highway one foot deep for twenty-seven miles)
Think for a moment about nuclear energy and nuclear power. (pause) Now, write down what is your greatest fear about nuclear issue. (Responses will vary but most fears include accidents, contamination, explosion, waste storage, or pollution.) Most people fear some sort of accident could happen releasing deadly radiation making people sick or even killing them. We are going to consider a risk with nuclear energy not many think about.
(If "Horses of the Atom" is not available read aloud the following scenario and use the
questions after it to stimulate discussion)
(adapted from "Horses of the Atom" by Jacques Cousteau)
The year is one in the not to distant future. A few years before, growing concern about global warming from the greenhouse effect, acid rain and American dependence on foreign oil coupled with the development of a new type of nuclear reactor guaranteed not to melt down caused a renewed interest in nuclear power. The public, leery at first, came to accept the arguments of the nuclear industry and approved the development of nuclear power production. Over a period of years fossil fuel plants were shutdown and replaced by the new inherently safe nuclear plants. In order to supply the ever growing number of nuclear power plants, sometimes changing into different elements)
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