Lost Woods
Page 21
I should like to speak of that strange and seemingly hostile environment that, nevertheless, gave rise to an event possibly unique in our solar system: the origin of life. Of course, our thoughts on this must be speculative; but nevertheless there is fairly wide agreement among geologists, astronomers, geochemists, and biologists about the conditions that must have prevailed just before life appeared on earth. They were, of course, very different from those of the present day. Remember, for example, that the atmosphere probably contained no oxygen; and because of that there could be no protective layer of ozone in the upper atmosphere. As a result, the full energy of the sun’s ultraviolet rays must have fallen upon the sea; and there in the sea, as we know, there was an abundance of simple chemical compounds. These included carbon dioxide, methane, and ammonia, ready at hand for the complex series of combinations and syntheses that must have occurred. I shall not take time to describe the stages that presumably took place over long eons of time to produce, first, molecules capable of reproducing themselves; then some simple organisms, possibly resembling the viruses, and then doubtless much later organisms able to make their own food because of their possession of chlorophyll. Rather than stressing these details, I want to suggest two general thoughts: (1) So far as our present knowledge goes, nowhere else in the solar system have conditions equally hospitable to life occurred. This earth, then, presented an environment of extraordinary fitness; and life is a creation of that environment. (2) No sooner was life created than it began to act upon the environment. The early virus-like organisms must have rapidly reduced the supplies of nutrients adrift in that primitive ocean. But more important was the change that took place as soon as plants began the process of photosynthesis. A byproduct of this process was the release of oxygen into the atmosphere. And so, gradually, over the millions and billions of years, the nature of the atmosphere has changed; and the air that we breathe today, with its rich proportion of oxygen, is a creation of life.
As soon as oxygen was introduced into the atmosphere, an ozone layer began to form, high up; this shielded the earth from the fierce energy of the ultraviolet rays, and the energy needed for the creation of new life was withdrawn.
From all this we may generalize that, since the beginning of biological time, there has been the closest possible interdependence between the physical environment and the life it sustains. The conditions on the young earth produced life; life then at once modified the conditions of the earth, so that this single extraordinary act of spontaneous generation could not be repeated. In one form or another, action and interaction between life and its surroundings have been going on ever since.
This historic fact has, I think, more than academic significance. Once we accept it we see why we cannot with impunity make repeated assaults upon the environment as we now do. The serious student of earth history knows that neither life nor the physical world that supports it exists in little isolated compartments. On the contrary, he recognizes that extraordinary unity between organisms and the environment. For this reason he knows that harmful substances released into the environment return in time to create problems for mankind.
The branch of science that deals with these interrelations is Ecology; and it is from the viewpoint of an ecologist that I wish to consider our modern problems of pollution. To solve these problems, or even just to keep from being overwhelmed by them, we need, it is true, the services of many specialists, each concerned with some particular facet of pollution. But we also need to see the problem as a whole; to look beyond the immediate and single event of the introduction of a pollutant into the environment, and to trace the chain of events thus set into motion. We must never forget the wholeness of that relationship. We cannot think of the living organism alone; nor can we think of the physical environment as a separate entity. The two exist together, each acting on the other to form an ecological complex or an ecosystem.
There is nothing static about an ecosystem; something is always happening. Energy and materials are being received, transformed, given off. The living community maintains itself in a dynamic rather than a static balance. And yet these concepts, which sound so fundamental, are forgotten when we face the problem of disposing of the myriad wastes of our modern way of life. We behave, not like people guided by scientific knowledge, but more like the proverbial bad housekeeper who sweeps the dirt under the rug in the hope of getting it out of sight. We dump wastes of all kinds into our streams, with the object of having them carried away from our shores. We discharge the smoke and fumes of a million smokestacks and burning rubbish heaps into the atmosphere in the hope that the ocean of air is somehow vast enough to contain them. Now, even the sea has become a dumping ground, not only for assorted rubbish, but for the poisonous garbage of the atomic age. And this is done, I repeat, without recognition of the fact that introducing harmful substances into the environment is not a one-step process. It is changing the nature of the complex ecological system, and is changing it in ways that we usually do not foresee until it is too late.
This lack of foresight is one of the most serious complications, I think. I remember that Barry Commoner pointed out, in a masterful address to the Air Pollution Conference in Washington last winter, that we seldom if ever evaluate the risks associated with a new technological program before it is put into effect. We wait until the process has become embedded in a vast economic and political commitment, and then it is virtually impossible to alter it.
For example, surely it would have been possible to determine in the laboratory how detergents would behave once released into public water supplies; to foresee their nearly indestructible nature. Now, after years of use in every woman’s dishwasher and washing machine, the process of converting to “soft” detergents will be a long and a costly one.
So our approach to the whole problem is shot through with fallacies. We have persisted too long in the kind of thinking that may have been appropriate in the days of the pioneers, but is so no longer – the assumption that the rivers, the atmosphere, and the sea are vast enough to contain whatever we pour into them. I remember not long ago, I heard a supposedly able scientist, the director of one of our agricultural institutions, talk glibly about the “dilution of the pollution,” repeating this magical phrase as though it provided the answer to all our problems. It does not, for several reasons.
One reason, as I expect Dr. Brown will tell us tonight, is that there are entirely too many of us; and so our output of pollutants of all kinds has become prodigious. Another reason is the very dangerous nature of much of the present-day pollution. Substances that are highly capable of entering into biological reactions with living organisms. The third very important reason is that the pollutant seldom stays where we put it, and seldom remains in the form in which it was introduced.
Let us look at a few examples. The most serious problem related to modern synthetic pesticides, in my opinion, is the fact that they are becoming long-term, widespread contaminants of the environment. Some of them persist in soil for ten years or more, entering into what surely is one of the most complex and delicately balanced of all ecological systems. They have entered both surface and ground waters; they have been recovered not only from most of the major river systems but in the drinking water of many communities. Their importance as air contaminants is only beginning to be recognized. I remember this past summer there was a freak mishap in the State of Washington, which provided a rather dramatic illustration: a temperature inversion kept a very dangerous chemical, which was sprayed from the air, from settling on the crops that were being sprayed. Instead, the chemical remained in a drifting cloud for some hours and before the incident was over several cows had died of poisoning and some thirty people had been hospitalized. Then there was the incident in Long Island last winter, when several schools had to be closed because of dust from the potato fields – dust that was carrying insecticides and blowing through the screens of the school windows.
Less dramatic than those examples, but probably more important
in the long run, is the fact, seldom remembered, that, for example, of all the DDT sprayed from the air less than half falls directly to the soil or to the intended target. The remainder is presumably dispersed in small crystals in the atmosphere. These minute particles are the components of what we know as “drift,” or the dispersal of pesticides far beyond the point of application. This is a subject of great importance and one on which few studies have been made. We don’t even know the mechanics or the mechanisms of drift. We certainly need to find out.
A few months ago, wide publicity was given to a release purporting to show that only a very small percentage of the land surface of the United States is sprayed with pesticides in any year. I don’t necessarily quarrel with the statement; it may or may not be correct. But I do quarrel very seriously with the interpretation, which implies that the pesticide chemicals are confined to very limited areas; to the areas where they are applied. There are a number of reports, from many different sources, which show how inaccurate that is. The Department of the Interior, for example, has records of the occurrence of pesticide residues in waterfowl, in the eggs of the waterfowl, and in associated vegetation in far arctic regions hundreds of miles from any known spraying. The Food and Drug Administration has revealed the discovery of pesticide residues in quite substantial amounts in the liver oils of marine fishes taken far at sea, fishes of species that do not come into inshore waters. How do those things happen? We do not know. But we must remember that we are dealing with biological systems and cyclic movements of materials through the environment.
Take, for example, some of the recent demonstrations of what happens when pesticides enter a natural food chain. They progress through it in a fashion that is really explosive. You have several examples here in the State of California, at the Tule Lake and Klamath National Wildlife Refuges. Water entering the refuges from surrounding farms is carrying in residues of insecticides. These have now become concentrated in food chain organisms and in recent years have resulted in a heavy mortality among fish-eating birds.
Then, at Big Bear Lake in San Bernardino County, toxophene was applied to the lake at a concentration of only 0.2 of 1 part per million. But notice how it was built up. Four months later it was concentrated in plankton organisms at a level of 73 parts per million. Later, residues in fish reached 200 parts per million. In a fish-eating bird, a pelican, 1700 parts per million.
And at Clear Lake, not far from here, efforts to control the gnat population have had a long and a troubled history. Beginning in 1949, the chemical DDD was applied to the lake in very low concentrations. It was later picked up by the plankton, by plankton-eating fish, and by fish-eating birds. The maximum application to the water itself was only 1/50 part per million; yet in some of the fishes the concentration reached 2500 parts per million. The western grebes which nested on the shore of the lake and are fish-eaters almost died out. When their tissues were analyzed they were found to contain heavy concentrations of the chemical. A very interesting phenomenon was that five years after the last application of the chemical, although the water of the lake itself was free of the poison, the chemical apparently had gone into the living fabric of the lake; all of the resident plants and animals still carried the residues and were passing them on from generation to generation.
One of the most troublesome of modern pollution problems is the disposal of radioactive wastes at sea. By its very vastness and seeming remoteness the sea has attracted the attention of those faced with the problem of disposing of the by-products of atomic fission. And so the ocean has become a natural burying-place for contaminated rubbish and for other low-level wastes of the atomic age. Studies to determine the limits of safety in this procedure for the most part have come after rather than before the fact, and disposal activities have far outrun our precise knowledge as to the fate of these waste products.
If disposal of radioactive wastes at sea is to be safe, the material must remain approximately where it is put, or else it must follow predictable paths of distribution, at least until the decay of the radioactive substances has reduced them to relatively harmless levels. The more we know about the depths of the sea, the less do they appear to be a place of calm where deposits may remain undisturbed for centuries. There is far greater activity at deep levels than we formerly suspected. Below the known and charted surface currents there are others which run at their own speeds, in their own directions, and with their own volume. There are powerful turbidity currents that rush down over the continental margins. Even on the ocean floor, at great depths, moving waters are constantly sorting over the sediments, leaving the evidence of their work in ripple marks.
All of these activities, plus the long recognized upwelling of water from the depths and the opposite, downward sinking of great masses of surface water result in a gigantic mixing process. When we dump radioactive wastes in the sea we are introducing them into a dynamic system. But this transport by the sea is only part of the problem, because marine organisms also play an important part in concentrating and distributing radioisotopes. We still need to learn a great deal about the processes involved when radioactive materials are introduced, through fallout, into the marine environment. The studies that have been made reveal movements of great complexity between sea water and the hordes of plankton creatures, between the plankton and the organisms higher in the food chain, between the sea and the land and from the land to the sea.
The most important fact about this is that the marine organisms bring about a marked distribution, both vertical and horizontal, of the radioactive contaminants. As the plankton make regular migrations, sinking into deep water in the daytime and rising to the surface at night, with the organisms go the radioisotopes they have absorbed, or that may adhere to them. As a result, the contaminants are made available to other organisms in new areas; and as they are taken up by larger, more active animals, they are subject to transport over long horizontal distances; migrating fishes, seals, and whales may distribute radioactive materials far beyond the point of origin.
All these facts have important meaning for us. They show that the contaminant does not remain in the place deposited, or in its original concentration, but rather becomes involved in biological activities of an intensive nature.
It is surprising, then, that so little thought seems to have been given to the biological cycling of materials in one of the most crucial problems of our time: the understanding of the true hazards of radiation and fallout. There have been situations in the news in recent months that are perfect illustrations of our lack of application of the ecological understanding that we have. I think one of the best examples of what I mean is taking place now in the arctic regions in both eastern and western hemispheres. Only two or three years ago it was reported that both the Alaskan Eskimos and the Scandinavian Lapps are carrying heavy burdens of both Sr90 and Ce137. This is not because fallout is especially heavy in these far northern regions; indeed, it is lighter there than in areas of heavier rainfall somewhat farther south. The reason is that these native peoples occupy a terminal position in a unique food chain. This begins with the lichens of the arctic tundras; it continues through the bones and the flesh of the caribou and the reindeer, and at last ends in the bodies of the natives, who depend heavily on these animals for meat. Because the so-called “reindeer moss” and other lichens receive nutrients directly from the air, they pick up large amounts of the radioactive debris of fallout. Lichens, for example, have been found to contain 4 to 18 times as much Sr90 as sedges, and 15 to 66 times the Sr90 content of willow leaves. They are long-lived, slow-growing plants; so they retain and they concentrate what they take out.
Cesium137 also travels through this arctic food chain, to build up high values in human bodies. As you remember, cesium has about the same physical half-life as Sr90, although its stay in the human body is relatively short, only about 17 days. However, its radiation does take the form of the highly penetrating gamma rays, thus making it potentially a hazard to the genes. About 1960 it was
reported that Norwegians and also the Finnish and Swedish Lapps were carrying heavy body burdens of Ce137. Then, during the summer of 1962, a team from the Hanford Laboratories in Washington went up into the arctic and measured the levels of radioactivity in about 700 natives in 4 different villages above the arctic circle. They found that the averages for Ce137 were about 3 to 80 times the burden in individuals who had been tested at Hanford. In one little village, where caribou is a major item of diet, the average burden of Ce137 was 421 nanocuries;* the maximum burden was 790. The counts for 1963, which extended over a wider geographic area in Alaska, are said to have been still higher.
This situation almost certainly existed from the beginning of the bomb tests; yet somehow it does not seem to have been anticipated, or at least it was not widely discussed and acted upon, though the Scandinavian countries have been rather active in their investigations.
Another example which has become familiar to many of us in recent months is provided by radioactive iodine. This must always have been an important constituent of fallout, so we wonder why its significance has been largely ignored until very recently. Probably the answer lies in its very short half-life, which is only about 8 days, and in the assumption that decay would have rendered it harmless before it could affect human beings. But the facts, of course, are otherwise. Radioactive iodine is a component of the lower atmospheric fallout and so, depending upon weather conditions it may reach the earth so early that much of its radioactivity is retained. Its distribution may be spotty, also, because of wind, rain, or other weather conditions. So we have the occurrence of the so-called “hot spots.”