PART X — ENVIRONMENTAL CONTAMINANTS 



minute trace (about one part in two 

 billion parts of air) of sulfur diox- 

 ide. In spite of all the sulfur diox- 

 ide put into the air by burning high- 

 sulfur fuels, it is unlikely that any 

 of this human contribution reaches 

 Barbados. Instead, some natural, 

 probably maritime, source must be 

 responsible for maintaining the con- 

 centration at this level. 



It is possible to compute how much 

 carbon monoxide the industries and 

 automobiles of the world release into 

 the atmosphere, and it appears that 

 the worldwide concentration of this 

 gas is about one part in ten million. 

 Knowing these facts, it should be 

 possible to estimate how rapidly car- 

 bon monoxide is removed from the 

 air. However, it has recently been 

 discovered that the ocean also con- 

 stitutes a vast and diffuse source of 

 the gas; thus a much higher removal 

 rate must account for the known con- 

 centration. At present the removal 

 process is unknown, yet it must be 

 discovered if environmental manage- 

 ment is to be possible. A knowledge 

 of the lifetime of carbon monoxide in 

 air would be a valuable clue from 

 which to begin. 



Over-all, one fact is clear. Many 

 pollutants are also released naturally, 

 though at lower concentrations. If 

 there were no natural processes to 

 remove them, the atmosphere would 

 be far more heavily contaminated 

 than it is, even in the absence of 

 human contributions. Hence there 

 must exist an enormous complex of 

 processes which maintain the atmos- 

 phere at substantially its present 

 composition. Every component, even 

 most of the minor ones here called 

 contaminants, is present in the global 

 atmosphere as a result of closely bal- 

 ancing processes of generation and 

 removal. 



These processes are such that a 

 substantial increase or decrease in 

 generation will be rapidly counter- 

 acted, at least in part, by a corre- 

 sponding change in rate of removal. 

 However, this sort of feedback con- 



trol generally has its inherent limits. 

 A very simple example is the ability 

 of living vegetation to remove sulfur 

 dioxide from the air. Studies in 

 Panama show that a very small con- 

 centration of this gas is a natural 

 contaminant in the tropics, perhaps 

 emanating from decayed vegetation. 

 If this supposition is correct, then the 

 small natural concentration of sulfur 

 dioxide results from a balance of its 

 release from dead plants and its con- 

 sumption by living plants. 



The balanced system will accom- 

 modate a considerable input of sulfur 

 dioxide from pollutant sources, and, 

 in fact, the gas has been shown to 

 absorb rapidly into vegetation. If the 

 added input is too great, however, 

 plants perish, and the system fails. 



It is further obvious that all forms 

 of life release wastes to the environ- 

 ment. Wastes by definition are in 

 some degree toxic to the organisms 

 that excrete them; hence, man or any 

 other organism reaching an intoler- 

 able population density will pollute 

 the environment with respect to his 

 own survival. Man is far worse than 

 his numbers indicate because he aug- 

 ments his own energies by the syn- 

 thetic release of energy, thus gener- 

 ating additional wastes. The energy 

 generated in the United States alone 

 is equal to that of 100 billion humans. 

 These "equivalent energy slaves" are 

 a measure of our standard of living; 

 they are also a true measure of our 

 impact upon the environment. 



Clearly, no acceptable degree of 

 control is imminent for the human 

 population. If both world population 

 and the U.S. living standard were 

 frozen at present levels, and the rest 

 of the world raised to the U.S. stand- 

 ard, a tenfold increase in pollutant 

 emissions would result, assuming con- 

 stant technology. Yet population can- 

 not be stabilized overnight, and the 

 rest of the world does aspire to the 

 U.S. living standard; although con- 

 stant technology is a poor assump- 

 tion, the developing countries have 



shown little inclination to avoid the 

 environmental errors of our own past. 



These collective considerations de- 

 lineate the environmental problem. 

 The human impact has reached an 

 alarming level, and much of its force 

 is mediated by the atmosphere. (See 

 Figure X— 2) Beyond the above quali- 

 tative statement, what is the state of 

 our knowledge? 



State of Scientific Knowledge 



Frankly, our over-all knowledge is 

 extremely fragmentary. Pate, Lodge, 

 and their co-workers at the Na- 

 tional Center for Atmospheric Re- 

 search have reported on atmospheric 

 composition in the moist tropics in 

 regions far from pollution sources. 

 Keeling and several others continue 

 to measure worldwide distributions 

 of carbon dioxide. At the Stanford 

 Research Institute, Robinson and 

 Robbins have obtained apparently 

 reliable figures for the worldwide 

 concentration of carbon monoxide, 

 and have shown the presence of an 

 unsuspected natural source of this 

 gas in the ocean. Patterson and his 

 group at the California Institute of 

 Technology, by analyzing ice cores 

 from the Greenland Ice Cap and 

 from Antarctica, have documented 

 the worldwide secular increase in 

 atmospheric lead. All of this infor- 

 mation is necessary to assess the orig- 

 inal state of the system that mankind 

 is now disturbing. 



O'Keeffe and his colleagues in the 

 Environmental Protection Agency, 

 Axelrod, Lodge, and others at the 

 National Center for Atmospheric Re- 

 search, and numerous academic sci- 

 entists are gradually developing ana- 

 lytical methods of sufficient sensitiv- 

 ity, specificity, and reliability to 

 assess both the reputedly unpolluted 

 and polluted environment. At the 

 University of Washington, Charlson 

 has developed a nephelometer that 

 rapidly assesses local atmospheric 

 haziness and also makes possible 



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