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[MA149]Pages 117-145
(It may take a while to download but I think it is worthy - John A. Keslick, Jr.)  A word from the webmaster - Within this article the word nutrient is misused at times where the true meaning is essential elements.  See my dictionary at www.treedictionary.com and look up nutrient as well as essential element.  The reason for the latter is to reduce misunderstanding of terms to better understand the message.  John A. Keslick, Jr.

Depletion of finite resources 
As the "Grand Exploiters," we now face a world soon to encounter shortages of its available minerals, metals, fossil fuels, and - if we do not act now - agricultural lands.

Agricultural land, forests, open space
Linked closely to the manipulation of the environment is the constant depletion of our most valuable finite resource -land.  It is necessary, of course, to change land uses as our population increases, but we must do this wisely.  Each year, in the name of "progress," we pave over, build on, or otherwise remove forever thousands of acres of productive land.  As was noted earlier, some activities- building on flood plains and filling of inland wetlands and salt marshes - produce adverse effects that are complex and far-reaching. 
    The removal of productive farms and forests, now proceeding rapidly in highly populated areas of the United States (fig. 46), may directly affect our well-being.  The current trend of concentrating food production in limited geographic areas that are often far from population centers may prove unsound as transportation and storage costs increase and as regional crops fail due to climatic disasters or disease. 
    How much land is needed for agriculture, forestry, or protective open space?  How should we ensure that sufficient amounts be maintained?  These questions are extremely difficult to answer.  It is often not recognized that much more space is demanded by each person in an affluent nation such as ours than is needed in poorer nations.  This is due to the foods we desire, the fiber we use, and the human services we demand to maintain our standard of living. 
    Some ecologists have recommended that at least one-third of all land be maintained as open space.  Whether or not this figure is the goal we should strive for, the current rate of land use changes and the projected doubling of our population in 25 to 45 years make it imperative that means be developed to ensure that the destruction of our productive agricultural lands is halted.

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Figure 47. - If rates of exploitation and "throwaway" practices continue to increase, the known reserves of nearly every essential metal and mineral may be depleted by 2100.

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Minerals and metals 
We in the United States have used more minerals and fossil fuels in the last three decades than have been used by humanity since time began!  Our mineral resources are running out (fig. 47).  If exploitation increases at its present rate, and if we continue our "throwaway" practices, those of us still alive in the year 2000 may see the last of the copper mines close-and before them, the last lead, tin, zinc, silver, mercury, and gold mines.  And the reserves of most of the other essential minerals and metals possibly could be depleted by 2100. 
    The hard truth is that the United States, Japan, and the affluent industrial nations of Western Europe import much of their key minerals from other countries-primarily the less developed nations. (Exceptions are the U.S.S.R. and mainland China.)  The dependence of the United States on other countries for necessary minerals will increase dramatically: within the next decade we will have to import more than half of the 12 key industrial minerals. 
    As we learned earlier, in natural ecosystems the Game of the Environment continues because all materials needed for production are cycled within the system.  But we have not yet learned this important lesson.  We play the Game as if our mineral resources were infinite.  Only a small fraction of the material we use is recycled.  Earthmanship - playing the Game well-must be improved so that all necessary materials are recycled as fully as possible. 
    But even if recycling were perfect, it still would not provide the answer to our growing needs.  Some mining would be required simply to replace materials lost to rust, corrosion, or wear.  Along with a total commitment to conservation and recycling, we must give priority to improving mining technology, locating new reserves, and developing substitute materials. 
    But the problems encountered in playing the Game will be far from solved even if all of these activities are successful.  While considerably less energy is required in recycling materials than in wresting them from virgin sources, the increasing rate of consumption means that ever increasing amounts of energy must be used.   And energy cannot be recycled - it is a noncyclic resource. 
    We do not have enough energy to extract resources, convert them to products, and then recycle them at increasing rates.
Energy reserves  
Is there really an energy crisis?  Are fossil fuel reserves being depleted?  How soon will we run out? 
    Although-coal has been burned as fuel for more than 800 years, it is only since the early 1800's that sizable amounts have been consumed.  Fantastic increases in coal consumption accompanied the Industrial Revolution (250 million tons in 1870 to 2.8 billion tons in 1970); this dramatic increase occurred at the same time that the importance of coal was declining sharply in favor of oil and natural gas.

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    Indeed, oil production has doubled every 10 years since about the turn of the century (fig. 48).  In the United States, oil production peaked around 1970, and we have been increasingly dependent on imports since.  It is projected that world consumption of oil in this decade (1970 to 1980) will equal that used during the previous 100 years!  Since we know that fossil fuel supplies are finite, the question of how long they will last is critically important. 
    The most optimistic estimates are that reserves of natural gas and "cheap" oil will be depleted (80 percent of total reserve used) by 2000 in the United States and about 30 years later in the rest of the world.

Figure 48. - Massive oil fields on land and offshore, refineries, tankers, and tank farms point to our great dependency on oil and natural gas as major energy sources.  It has been estimated that for all practical purposes, our reserves of natural gas and oil will be gone by the year 2000.

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The great hope for future sources of fuel seems to lie in our coal reserves (perhaps important for 200 to 300 years, but only 75 years if coal is the sole source of energy), and possibly in our vast deposits of western oil-bearing shales.  But "switching back to coal" signals a potential increase in air and water pollution.  Land reclamation, air pollution controls, safety measures, and shipping will generate additional costs. 
    And unlike its cost in the past, coal will be expensive. Gassification- producing synthetic natural gas (SNG) from coal-has been proposed as the answer to the high cost of shipping great quantities of coal from the West to the East.  But SNG is much less efficient than coal or natural gas, and the necessary increasing in mining will deplete coal reserves sooner. 
    Similar disadvantages are associated with the exploitation of shale oil.  The product that is sought, kerogen, is present in such low concentrations that huge quantities of rock must be ground and heated.  The great amount of energy required for extraction and shipping will result in a low net amount of energy.  And the impact on the environment is potentially very great.  Great tracts of land will be disrupted and vegetation and wildlife destroyed.  The quality of air and water will drop, as will water tables; and because the crushed spoils will occupy more than 10 percent more space than the solid rock, the waste disposal problem will be staggering. 
    These imminent shortages and escalating costs of fossil fuels have led us to focus on nuclear fuel for generating power.  But the process currently used- fission of a relatively rare resource, uranium-235 - is very wasteful.  Uranium- 235 makes up less than 1 percent of the uranium in natural ore.  In fact, proponents of nuclear power fear that medium-priced supplies of uranium-235 may be exhausted before breeder reactors are developed to "breed" or make fission- able plutonium-239 and uranium-233.  Either of these isotopes can be used as a catalyst to burn uranium-238 or thorium-232, which together represent an energy source millions of times larger than all known reserves of fossil fuel. 
    It would seem, then, that nuclear breeder reactors, and perhaps fusion reactors, offer the greatest hope for satisfying our insatiable appetite for energy.  Unfortunately, as with fossil fuel sources, there are potentially serious consequences associated with nuclear energy-most of which relate to environmental pollution. 
    The possibility that human or technological error will result in a serious malfunction will increase as the number of reactors increases.  This is perhaps sufficient reason to engage now in an integrated national energy program to develop technologies for alternative energy sources, especially solar, wind, tidal, and geothermal power.  While nuclear energy probably will be a major, if ;not the primary, source of power in the decades to come, it would be techno- logical insanity to put all our energy "eggs" in one basket-especially in the one that poses unparalleled potential for biological hazard.

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Page 122-123


Pollutants are materials injected into the biosphere in sufficient quantities to change the Game and to adversely affect the living Players, especially people (see picture on p.122).  For convenience, pollutants are often classified as soil, air, or water pollutants, as biodegradable or nonbiodegradable, or as threshold (damaging at some level) or nonthreshold (damaging at any concentration).  But pollution should be looked at as a whole, because what begins as an air pollutant often ends up in soil or water; and concentrations of substances damaging to one life stage of a Player organism may not be harmful to other stages or kinds of organisms. 
    Nature can be a polluter!  Volcanoes, earthquakes, dust storms, and salt spray from ocean storms are major sources of natural pollution.  Even wildfire and floods, whose effects may be beneficial, can contribute to air pollution or to undesirable siltation.  But the intermittent and dispersed nature of these natural Fouls lessens their impact on the environment.

Figure 49. - Too much phosphorus can trigger algal blooms in fresh water ecosystems, which, when extreme, can result in fish kills.

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    People are the primary cause of pollution.  Our actions as powerful biogeochemical agents-gathering, extracting, moving, concentrating, and dumping-have repeatedly swamped natural systems with too much material.  We also have introduced many compounds that are totally alien to natural systems.  Many of these substances are not biodegradable, and they accumulate or magnify in food chains until they become toxic.  The chlorinated hydrocarbons (DDT, PCB) and radionucleids (strontium-90, cesium-130) are examples of introduced synthetic materials that now are distributed in significant quantities throughout the atmosphere.  Thus, people can cause material cycles to "run amuck" by injecting into them excessive quantities of both natural and synthetic substances.

Figure 50. - Runoff from animal feedlots carries excessive amounts of phosphates and nitrates into waterways.

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Figure 51. - Sewage rich in detergents is a primary source of phosphate pollution.

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Some cycles run amuck 
- Phosphorus is usually the element in short supply - the limiting factor-for growth of algae in fresh water.  The rich green blooms of algae common in many of our rivers and lakes usually are signals that substantial amounts of phosphorus have been added to the system (fig. 49).  Most of this excess phosphorus enters the cycle in treated or untreated sewage rich in detergents, and in runoff from animal feedlots (figs. 50 and 51).
    The growth of algae Producers often proceeds unchecked until the excess phosphorus is used up and once again becomes limiting; then, a dieoff occurs.  Because the decomposition of large amounts of dead algae requires large quantities of dissolved oxygen, fish may be killed. 
    Once phosphates reach estuarine or coastal Arenas, they no longer contribute to algae blooms; in these systems, nitrogen is the limiting factor.  The suggestion that phosphate detergents be replaced with nitrogenous ones must be evaluated carefully because this substitution might seriously compound problems associated with explosions of phytoplankton and zooplankton in ocean ecosystems where nitrogen is the limiting factor.

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Figure 52.- As a result of human activities, the nitrogen cycle runs amuck {three boxes}: In the atmosphere when nitrogen oxides help to form ozone and smog; and in soil and water when nitrate-rich effluents speed eutrophication.

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Nitrogen. -Nitrogen monoxide (NO) and nitrogen dioxide (NO2) are the two of the eight nitrogen oxides that contribute to air pollution.  These gases are formed by the combustion of fossil fuels in automobiles and power plants (fig. 52).  Combustion at high temperatures and pressure converts gaseous nitrogen to nitrogen monoxide and this, in turn, is oxidized rapidly by ozone (O3) or slowly by oxygen to nitrogen dioxide.  Nitrogen dioxide is reduced by ultraviolet light to nitrogen monoxide and atomic oxygen (O).  The atomic oxygen can react with oxygen to form ozone or with unburned hydrocarbon emissions to form photochemical smog. 
    Nitrogen dioxide, ozone, and smog are harmful to plants and animals; they cause irritation of the eye, nose, throat, and respiratory tract, and they damage food crops and forests.  The interaction of these pollutants with others, especially with carbon monoxide and sulfur dioxide, can cause great damage at relatively low concentrations. 
    As is shown in figure 52, the nitrogen cycle is carried out not only in the atmosphere but also in soil and water.  As with phosphorus, excessive amounts of nitrogen in aquatic systems can result in overproduction-in cultural eutrophication.  And the polluting of aquatic systems with overloads of nitrogen is increasing.  Heavy losses of nitrate fertilizers from agricultural systems often result from runoff, especially in humid climates.  Animal manure is potentially a primary source of nitrate pollution, especially near feedlots (fig. 50); fortunately, most feedlots are located in regions with low rainfall.  One of the greatest sources of nitrate pollution is human effluent discharged directly from waste treatment facilities to waterways.

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Figure 53. - We disrupt the sulfur cycle by injecting great quantities of sulfur dioxide (SO2) into the atmosphere (box).  Sulfur dioxide combines with moisture in the atmosphere to form sulfuric acid-a compound that can be harmful to animals and plants.

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Sulfur dioxide. - We also are affecting the sulfur cycle by introducing great quantities of sulfur dioxide (SO2) into the atmosphere (fig. 53).  Sulfur dioxide usually is only a transitory step in the cycle, occurring in very low concentrations.  Additions through combustion and refining of sulfur-bearing fossil fuels and smelting account for only about 20 percent of the total global amount (80 percent is from natural sources); however, concentrations of SO2 in urban - areas are causing serious problems. 
    Once it is in the atmosphere, SO
2 reacts with moisture to form sulfuric acid.  When inhaled as a fine mist, or when attached to small particles, sulfuric acid can injure sensitive lung tissue; it is a major cause of bronchial asthma during air inversions.  Low concentrations of SO2 can injure and even kill many important crop plants, especially when it occurs with low concentrations of ozone. 
    Sulfur in the atmosphere produces acid precipitation in many areas.  Downwind from industrial centers, the acidity of rainfall has increased up to 200 times in recent years.  Sulfuric acid in the atmosphere damages paint, stone buildings, sculpture, and ancient artifacts.  And the acidity of streams, sometimes great distances from the industrial sources, has also increased, harming fish and other aquatic life.  Although the long-term effects of acid precipitation on terrestrial ecosystems are not well understood, this phenomenon emphasizes strongly that our activities in one location can adversely affect life processes many miles-even continents-away. 

    Heavy metals.
- The cycles of many elements that are not essential for growth also have been adversely affected by people.  The heavy metals -lead, mercury, and cadmium-that have always been present in low levels have been injected into the biosphere in large quantities by the burning of leaded gasoline, by smelting and other industrial processes, and by the use of pesticides.  These elements magnify in food chains and accumulate in the blood and tissues of Consumers (including humans) at higher trophic levels, where they can cause severe neurological symptoms, chromosome breakage, and death.

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Hydrocarbons (chlorinated). -The book Silent Spring by Rachel Carson alerted the public to the dangers of chlorinated hydrocarbon pesticides.  The global spread of DDT and its unsuspected and dramatic impacts on nontarget organisms in distant areas point out the dangers of injecting huge quantities of synthetic materials into the biosphere (fig. 54). 
    The very characteristics of toxicity, persistence, and stability that made DDT attractive as an insecticide account for its spread and adverse effects.  Insoluble in water but highly soluble in fats and oils, DDT accumulates in fatty tissues of organisms.  It does not break down easily, and it continues to magnify in food chains.  Indeed, a study along the northeastern Atlantic coast revealed the level of DOT in gulls to be a million times more concentrated than it was in the water!

Figure 54. -Synthetic compounds, like the chlorinated hydrocarbon pesticides, become incorporated into biological cycles.  When they magnify in food chains, they can be lethal to nontarget organisms great distances away.

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Death or impaired reproduction can result when organisms acquire high concentrations of DDT.  Small fish can be killed from large doses of DDT that are stored in their yolk sacs; DDT in birds alters their calcium metabolism, resulting in death directly or indirectly when calcium-deficient egg shells break during incubation. 
    The greatest danger from DDT and similar compounds may not be from direct exposure but from subtle changes in the structure and function of the Game of the Environment.  When beneficial nontarget organisms are killed by pesticides, food chains become shortened- simplified,- and the Game is weakened.  Materials that are substituted for chlorinated hydrocarbons are usually shortlived-they do not magnify in food chains.  But the extreme toxicity of some of these substitutes poses real dangers through mishandling by humans. 
    Other synthetic compounds have attracted attention in recent years.  Polychlorinated biphenyls (PCB's) used widely in industry are perhaps more dangerous than DDT.  PCB's-also persist and magnify in food chains and kill many predaceous organisms.

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Figure 55. - Oil spills are dramatic examples of pollution, but most oil pollution is not nearly as visible.

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Hydrocarbons (oil). -Oil pollution can be a dramatic event (fig. 55).  Headlines tell of jumbo tankers breaking up, of offshore well blowouts, and of the potential failure of newly constructed pipelines.  Such events reflect our increasing appetite for oil.  As dwindling supplies necessitate exploiting reserves in increasingly inhospitable Arenas, the likelihood of serious accidents increases.  But most oil pollution (80 to 90 percent) occurs during everyday shipping, refining, processing, and burning of hydrocarbons.  The most important form of oil pollution is fallout of airborne hydrocarbons. 
    When hydrocarbons reach the oceans, they are diluted and dispersed.  Eventually, they disappear through microbial degradation, evaporation, oxidation, and deposition.  Along the way, however, great damage may occur to ocean- life.  Sometimes this damage is obvious, sometimes it is subtle and indirect.  Thus, hydrocarbons can destroy vital parts of some food chains directly (for example, aquatic insects), can accumulate and magnify in food chains (for example, in large fish and birds near tops of food chains), and can interfere with the communication systems of organisms (for example, disruption of chemical "messages" from rivers to fish returning to spawn).

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Figure 56. - Today, the greatest threats of radiation pollution stem not from nuclear fallout, but from radioactive wastes created in atomic power plants.

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    Radioactive materials. -Atomic bombs and the testing of nuclear weapons ushered forth the atomic age and the threat of radiation pollution (fig. 56).  This threat is very great.  The terrible radioactive fallout from massive atomic explosions is well known.  But the dangers from radioisotopes that may enter biological cycles are also potentially great. 
    Radiostrontium, the product of uranium fission, is a good example of a material that can cause a cycle to subtly run amuck.  Strontium "mimics" calcium and it can eventually become incorporated with calcium in human bones.  Here, it is in close contact with blood-forming marrow-tissue that is especially sensitive to radiation damage. 
    Genetic damage to reproductive cells, with the threat of passing on mutations to unborn generations, can also occur from radiation.  "Safe" levels are difficult to establish; the harmful effects of chronic exposure to low levels of radiation are still being studied. 
    There is little doubt that the greatest threat of pollution originates in transporting, storing, and reprocessing spent radioactive wastes.  Large quantities of these wastes are now being stockpiled for reprocessing.  They are a major liability; this material must be maintained-with no mistakes-for thousands of years.  Wastes of other kinds, although posing less imminent threats, nevertheless affect our well-being as they interfere with biogeochemical cycling.

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Figure 57. - Disposing of billions of tons of solid waste each year is costly in terms of land, money, and mineral resources.

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Solid Waste. -Solid waste is increasing, especially in urban areas (fig. 57).  Billions of tons are produced each year, and billions of dollars are spent in collecting and disposing of it.  And disposing of solid waste is becoming more and more difficult.  Poorly designed landfills can pollute land, water, and air, and the incineration of this material can contribute significantly to air pollution.  Space is often unavailable for landfills near urban areas where huge quantities of trash must be disposed of each day.  But the most serious and important aspects of disposal by burning or burial are the drain on our mineral resources and the loss of "waste" land such as wetlands and marshes. 
- The treatment of wastes by most of our sewage treatment plants involves only the primary or secondary phases or both.  In primary systems, solids are screened and sedimented from waste water and then burned or buried.  Secondary treatment consists of biological degradation of organic matter.  The cheapest secondary system is a shallow oxidation pond where algae provide the aeration; mechanical aeration can speed up this process. 
    However, secondary treatment does not remove nutrients from sewage.  When nutrients, such as phosphorus and nitrogen, discussed previously under "Some cycles run amuck," are transported back to natural Arenas, there must be sufficient space and food chains to handle them or pollution will result. 
    The expensive tertiary or advanced treatment includes the removal of phosphates, nitrates, organics, and other substances.  More and more interest is being expressed in using terrestrial ecosystems as tertiary treatment systems.

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Figure 58. - When too much heat, liberated into air or water, causes adverse effects, it is a pollutant.

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Messing up the flow of energy

Heat. -In figure 58, the cooling towers of an atomic power plant dominate the scene.   This is appropriate because one of the greatest pollutants created by human activities is heat. 
    We learned earlier that energy flows only in one direction through ecosystems; each time it is transformed from one form to another, or passes from one organism to another, a portion of the energy is converted to heat and is dispersed into space.  The biosphere must tolerate this heat.  Too much heat produced in a local Arena becomes a thermal pollutant. 
    Over cities, thermal inversions occur when heat radiates upward on clear nights and the ground layer cools.  Over valley cities, or when high-pressure air masses stagnate over the city, the cool air layer is trapped by the warm air above.  Gaseous pollutants (nitrogen oxides, sulfur dioxide, smog) collect in the cool air.  Thus, thermal air pollution can augment the adverse effects of other air contaminants. 
    The most serious thermal pollution stems from the use of water to cool industrial installations, especially fossil fuel and nuclear generating plants. 
    Water taken from lakes, rivers, or estuaries to cool reactors is sprayed into the air in cooling towers or is returned to the water body.  If this water is too hot, it becomes a pollutant.  Tremendous quantities of water are now used to cool power plants, and it has been estimated that at least 25 percent of all fresh water flow in the United States will be used for this purpose by the year 2000.

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Too much heat in aquatic Arenas can be harmful to the living Players. They can be:

Killed directly by a sudden change in temperature.
Rendered susceptible to parasites and diseases.
Starved for oxygen.
Starved for food because lower levels of their food chains were destroyed.
Disrupted in their patterns of migration.

    Overall, aquatic ecosystems can be degraded as eutrophication is speeded up, and as species composition changes to fewer and less desirable species.

The picture on pages 144 and 145 shows an ideal system where we, as the central Players of the Game of the Environment, have attuned ourselves and our actions to accommodate the Rules.  Only a few of the myriad ways to improve the Game are shown -"but all of these methods are available now or are easily within technological reach, and many of them are economically feasible (perhaps even profitable). 
    This illustration provides a sharp contrast to those that precede it.  It presents the view that cities will remain the focal points of human culture, and that we will continue to dominate and exploit our environment.  But it also points out the hope that this exploitation will take place within the Rules that govern our environment.

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Compare the illustration on page 144 with illustrations on pages 106,114, and 122; list the similarities and differences between this illustration and each of the others.

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Page 144-145

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