Measurements and Interpretations

Taking a soil sample for the Project Chariot biological inventory to determine kinds and relative abundance of invertebrates and other soil organisms.

The program was an effort to make a model environmental inventory. Its significance was both in its assessment of the base for determining the â€œbiological costâ€ of the proposed operation and in the thoroughness of its documentation of the environmental features of a part of the world that previously had been virtually unexplored. It was a prototype for future studies.

Determination of the amounts and kinds of radioactivity in a biological sample is a process wholly dependent on instruments, since radiation usually cannot be detected by the senses.

A biological sample is any material of measurable biological significance. A sample of tissue or similar organic material usually is dried or reduced to ash in a muffle furnace before it is examined with a radiation counting device.

Improved instruments now permit the counting of radioactivity at levels so low as to have been imperceptible a few years ago. The samples, placed in lead chambers formaximum shielding from background radiations, are examined by multichannel analyzers capable of recording radiation emissions continuously over long periods of time.

Data-processing techniques have been employed in the handling and interpretation of information from long-range biological sampling and analysis programs. Analog computers have been used experimentally for theoretical projections of results.

Instruments record radiation, weather, sunlight, and other factors transmitted from remote sensors to this data center established for a long-range terrestrial ecology study program.

Scientists at the AECâ€™s Oak Ridge National Laboratory, for example, have developed experiments in which an analog computer is programmed to keep a running balance of the net changesâ€”simultaneous gains and lossesâ€”of radioactivity in the various compartments of a representative ecosystem. The computer becomes an electronic image of the biosphere, using known or assumed rates of energy transfer and photosynthesis to predict probable radiological results of tracer experiments of environmental contamination.

Each environment presents its own sets of conditions and unknowns. It is important to appreciate those that are characteristic of water, land, and atmosphere.

The oceans are the basins into which are poured all the nutrients or wastes transported from the land by rivers and winds.

The difficulty of determining the fate of radionuclides in aquatic systems is complicated by chemical and biological differences within the system and by the variety and scope of the circulatory mechanisms. In oceans the sheer immensity of the water volume usually makes observation superficial or fragmentary. Rivers present great differences in flow, and lakes vary in internal dynamics. Above all, an ocean, a river, or a lake is an area of constant physical and biological motion and change. In the ocean the surface waters form a theater of kaleidoscopic, and frequently violent, action. The presence of man-made radioactivity in water has made it possible to follow the disposition of nutrients and wastes in the restless aquatic ecosystem.

In a water environment the minerals necessary to life are held in solution or lie in bottom sediments. They become available to animal life after being absorbed by plants, both large floating or rooted plants and tiny floating ones called phytoplankton; because the phytoplankton are found everywhere in the sea, they play a larger role. The phytoplankton concentrate minerals and become food for filter-feeding fish and other creatures, including the smaller zooplankton,[14]which, in turn, are food for other organisms. Thus the minerals enter extremely complex food chains. The cycles of nutrition are completed when fish and plants die and decomposition again makes the minerals available to the phytoplankton.

RAIN FOREST. A giant fan pulls air through a plastic-enclosed portion of a Puerto Rico rain forest to study the metabolism rate of trees.

HARDWOOD FOREST. Technicians preparing to tag Tennessee trees with a solution containing a radioactive cesium isotope in the start of a 10-year project. Scientists will study movement of the radioactivity into insects and their predators.

FRESHWATER. Aquatic biologists emptying plankton traps to study concentrations of radioactivity in microscopic organisms in the Columbia River downstream from the Hanford atomic plant in Washington State.

MOUNTAINS. Weather station in a deer-forage area of the Rocky Mountains in Colorado provides environmental data and fallout samples that are correlated with levels of radionuclides found in the deer.

TUNDRA. This caribou was examined in detail as part of a study of transfer of fallout nuclides in food chains from plants to animals to man. Caribou is the principal meat animal of some Alaska Eskimos.

DESERT. Zoologist examines an animal trap as part of a field ecological study of a Nevada nuclear test site.

Some radionuclides that are introduced into an aquatic environment enter the food chains exactly as do the stable minerals essential to life, because the radionuclides are merely radioactive forms of the nutrients. Elements such as copper, zinc, and iron are less plentiful in the water environment than hydrogen, carbon, or oxygen, for example, but are concentrated by phytoplankton because they are necessary for life. Such elements are in short supply but in constant demand; thus, when their radioactive forms are deposited in water, they are immediately taken up by aquatic plants and begin to move through the food chains. Fission products such as strontium-90, for which there is little or no metabolic demand, are taken up by aquatic food chains to only a minor extent.

The precise paths of radioelements through aquatic ecosystems are almost unknown. In addition to their movement in food chains, radioelements also may be moved physically from place to place in the tissues of fish or other creatures. Some radionuclides for which there is no biological demand may sink into bottom sediments and remain there until they have lost their radioactivity. Or radioactivity actually may be transported â€œuphillâ€, from water to land, as when birds that feed on fish containing radioactivity leave their excretions at nesting areas. The routes and modes of transport seem numberless.

Movement of radioactive elements in a forest-lake ecological system. Most nutrient-flow is â€œdownhillâ€, but birds, migrating fish, and the evaporation-rainfall cycle may move them â€œuphillâ€.

The surface waters of the seas, down to depths of 200 meters, are areas of rapid mixing in which temperature, density, and salinity are almost uniform. Below the surface water is a zone in which temperature decreases and density and salinity increase with depth. This zone, known as the thermocline, may reach a depth of 1000 meters. Because density is increasing here, vertical motion is reduced, and exchanges between the surface and the deep waters are impeded. Knowledge of temperature, density, and salinity is important to understanding what happens to radionuclides in the ocean. Physical conditions affect the rates of physical movement of radioactivity in the mixed (surface) layer, the degree to which radionuclides are held at the thermocline, and the processes by which radionuclides pass the thermocline and enter the deep-water cycles and upwellings.

Men aboard the research vesselShimadapulling in plankton nets during sampling operations at sea.

The surface currents of the ocean are largely wind driven and their patterns generally well known. New conceptsof the vertical and horizontal diffusion of substances introduced into the ocean were developed, however, in studies of ocean-borne fallout during and after nuclear tests in the Pacific.

The first of these surveys was conducted near Eniwetok and Bikini. Scientists aboard a Navy vessel sampled water and plankton to depths of 300 meters at some 90 points spread over an area of 78,000 square miles to determine the disposition of early fallout from the nuclear detonations. Some weeks later another expedition voyaged from Eniwetok to Guam and returned, covering an area of 375,000 square miles to follow (by sampling) the mass of water-borne radioactivity resulting from the test and to note the intervening effects of diffusion, dilution, biological uptake, and decay. In 1958 two more surveys were conducted, the first to ascertain the spread and depthâ€”with samplings below the thermoclineâ€”of a radioactively tagged water mass immediately following an underwater detonation, and the second to follow the westward drift of the tagged water mass.

Significantly, it was found that plankton immediately take up large amounts of radioactivity. Planktonic forms, in fact, proved to be the most sensitive indicators of the presence of radioactivity in the marine environment. Further, the daily vertical migrations of planktonâ€”down in response to sunlight and up at nightâ€”seemed a part of the process by which radionuclides move from the upper waters to the deeps.

The expedition scientists noted that the masses of low-level radioactivity moved in the ocean significantly slower than the surface currents, a circumstance attributable in large measure to biological factors. The distribution of residual radioactivity in the sea a month after the close of a nuclear testing program could be determined by counting radioactivity in plankton samples.

It was established that strontium-90 and cesium-137, important in fallout on land, enter the marine cycles only in minute amounts. Practically no fission products are found in fish. Since strontium-90 is not concentrated strongly by marine organisms, the question of what happens to it in the ocean remains unanswered. Studies have suggested,however, that strontium moves in solution and thus indicates the movement of water. If this is true, strontium-90 may be contained in the deep currents and eventually will be brought again to the surface. Some observers believe this process has begun.

The freshwater environment differs from the marine in the greater variety of its minerals, among other things. As sites for radiobiological studies, rivers and lakes present problems of great complexity, but conditions at river mouths or estuaries are even more difficult because of the mixing by tidal action of fresh and salt water.

Rivers vary greatly in character and change radically from season to season because of rainfall and other factors. General understanding of their biological workings is difficult to formulate. But rivers are the routes by which minerals and wastes are transported toward the sea, and estuaries are significant because of the many forms of life that flourish there.

Studies of radioactivity in rivers and estuaries usually have been made in relation to the fate of effluents from nuclear plants. Among the longest and most intensive studies are those near Hanford, Washington. Observations were started in 1943, when the federal government was preparing to build plutonium-producing reactors to be cooled by waters of the Columbia River.

Fisheries biologists studying hatchery fish reared in water containing radioactivity from the Hanford plutonium reactors.

For more than two decades, observations have been made of the physical dispersion and biological disposition of low-level effluents in the Columbia. Concentration factors have been established for significant radionuclides in phytoplankton, algae, insects, and fish, and typical patterns of dilution and dispersion have been plotted.

Similar programs, in an entirely different freshwater system, have been conducted over a similar span of years near the Oak Ridge National Laboratory in Tennessee. One area of interest has been the biological disposition of trace amounts of strontium-90 released to the Tennessee River via tributary streams.

Among the few broad estuarial studies yet undertaken is one started in 1961 to plot the dissemination in the lower Columbia River, and in the Pacific Ocean, of radioisotopes transported by the river from the Hanford plant. Radiobiologists are studying biological distribution. Oceanographers are using the trace amounts of effluent radioactivity to verify the patterns of dispersion of river waters in the ocean.

Plant ecologists â€œtaggingâ€ experimental forest plots with radioactive cesium for long-term studies.

Natural radionuclides find their way into plantsâ€™ metabolic processes. Man-made radionuclides also are so incorporatedâ€”even some, such as uranium or radium, that have no known metabolic role. The man-made nuclides, whether they reach the earth in fallout or by other means,mix with the stable nuclides to which they are chemically related, increasing by small fractions the total amount of each element available to participate in plant growth cycles. Because artificial radionuclides behave so typically, they present, on the one hand, a possible long-term hazard and, on the other, the expectation that their detectability will reveal much about the biological courses of minerals and nutrients.

The disposition of man-made radioactivity on land is determined in part by such factors as topography and the presence or absence of water. Topography may influence the distribution by setting patterns of drainage and exposure of surface soils to wind and rain. Water may affect dilution, or it may leach radionuclides out of surface soils and thus remove them from the level in which plants are rooted. The leaching may carry radionuclides elsewhere, however, possibly causing mild contamination of the water table.

Trench dug on Rongelap Island to expose soil strata and root systems to determine penetration of radionuclides in coral-sand â€œtopsoilâ€.

Plants take up radionuclides through their roots or through their foliage. But the role of soils is significant. Some radionuclides are bound as ions to clays and thus are withheld in large measure from entry into the plant system. Cesium-137, for example, is held so tightly by soils that uptake through plant roots is slight, and thus a more significant mode of entry of cesium-137 into food chains is by direct deposit on plant leaves. Variables are introduced by the physical configuration of the plant itself, by seasonal differences in plant metabolism, and by the effects of rain and snow. In the case of iodine-131, a short half-lifeâ€”8 daysâ€”virtually precludes the possibility of extensive uptakethrough plant roots. But the half-life is not too short to prevent grazing cattle from ingesting radioiodine deposited in fallout and thus allow the appearance of radioiodine in milk.

Survey of pasture grasses to determine whether radioactive materials are present. If they are, they could be passed from the grasses to cows and then from the cowsâ€™ milk to humans.

Much attention has been devoted to strontium-90 and to its availability to man by deposit on plants and soils. Because strontium bears a close chemical relation to calcium, a unit expressing this relation, thestrontium unit(one picocurie[15][1 Ã— 10-12curie of strontium-90 per gram of calcium]) is used in following strontium-90 through food chains. Soils, however, present confusing factors. Experiments and fallout observations show that strontium-90 does not penetrate soils deeply. In typical instances it remains in the upper inch or two of the soil surface, where its availability to root systems is as variable as the conditions of mixing, leaching, and plant growth. Experiments have shown that plant uptake of strontium from soils can be reduced by introduction of calcium in available form into the soil.

Radiobiological developments on land result from combinations of environmental influences. Studies in the Rocky Mountains show that ecological conditions above the timberline, particularly in areas where snowbanks accumulate, are efficient in concentrating fallout radionuclides. Concentrations thus take place in the snow-packed heights that are the sources of mountain streams flowing to the plains far below.

The environment of the earth is a product of â€œweatherâ€â€”of the transport of moisture, of the actions between winds and oceans, of the cycling of energy through biotic systems. Understanding of biological potentials of atmospheric factors involves understanding of atmospheric motions affecting transport and mixing of contaminants and the processes of deposition of radionuclides from atmosphere to earth.

Network of towers on the Atomic Energy Commission reservation near Richland, Washington, used by atmospheric physicists in measuring quantity, concentration, and dilution of radioactive materials in the atmosphere.

At some thousands of feet above the earthâ€™s surfaceâ€”at 30,000 to 40,000 feet in the middle and polar latitudes and at 50,000 to 60,000 feet in the tropicsâ€”there is a level, the tropopause, at which air temperature, rather than decreasing, becomes constant or increases with height. Below this level is the troposphere, the turbulent zone of clouds, rain, and fog. Above it is the stratosphere, where there is noturbulence and only a slow mixing of dry and cloudless air. The stratosphere continues to a height of about 100,000 feet. Investigators have noted the importance of rain or snow in washing fallout particles from the air in the troposphere. There is disagreement on the precise modes of distribution of radioactive materials projected into the stratosphere.

In the detonation of low-yield nuclear devices, fission products are not projected beyond the troposphere, and fallout is washed down in periods of days or weeks. Because winds move principally in east-west directions, tropospheric fallout appears on the earth in bands centered approximately at the latitude of detonation. But when high-yield explosions propel contaminants into the stratosphere, the pattern of subsequent developments is less clear. It once was believed that fallout from the stratosphere was distributed more or less evenlyâ€”though over long periods of timeâ€”over the surface of the earth. The present view is that fallout debris placed in the stratosphere remains in that hemisphere in which the explosion occurs. This concept is based on an atmospheric circulation theory that air enters the stratosphere at the equator and descends again in temperate and polar latitudes each spring. The theory presumes a much shorter â€œresidence timeâ€ of stratospheric air and thus a quicker return of fallout particles to the turbulent troposphere.[16]

The presence of radionuclides in the atmosphere has provided clues to cyclical movements of biological importance. During the period of nuclear tests in the Pacific, observers noted spring â€œpulsesâ€, or increases, of strontium-90 deposition in the northern hemisphere, a phenomenon difficult to verify or explain satisfactorily while testing was proceeding. Later, when testing had been suspended, the spring peaks reappeared. The observation seemed to support the theory that nuclear debris injected into the stratosphere was descending years later through a gap in the tropopause.

Samplings of nuclear debris by balloon have been under way for several years at altitudes of 100,000 to 150,000feet, and rocket-borne air samplers and other systems have been developed for taking atmospheric samples up to 200,000 feet.

Programs for studying airborne contamination from industrial activitiesâ€”operated at the more accessible but equally difficult levels of the atmosphereâ€”have been sponsored by the Atomic Energy Commission near the Hanford Plant, Washington, and at the Oak Ridge, Argonne, and Brookhaven National Laboratories in Tennessee, Illinois, and New York. The Hanford studies were started before plutonium production was begun in 1943, and findings on industrial stack-discharge rates established patterns for meteorological programs at other sites.[17]

The range and variety of environmental studies now in progress make it almost impossible to provide any all-encompassing statement of results. Almost all places associated with nuclear programs have become focal points of research in environmental biology. Fallout, deposited in patterns determined by the mechanisms of the atmosphere, has created at certain points on the earthâ€™s surfaceâ€”the Arctic, for exampleâ€”ecological conditions that require investigation. New information of bioenvironmental significance has come in bits and fragments. We can, however, attempt to summarize what has been learned and to show, in broad terms, how radiobiological experience has extended appreciation of the earth as a single ecosystemâ€”a system comprised of an infinity of interactions of water, land, and atmosphere, and of all living things.

The spectrum of environmental investigationâ€”investigations using man-made radioactivityâ€”incorporates research in which:

1. Fallout radioactivity is assessed as a potential specific hazard to human populations.2. Conditions created by fallout are examined for their potential long-term ecological significance.3. Radionuclides introduced into the environment by nuclear tests, reactor operations, or other means are used as trace materials in basic studies in biological systems.4. Radioactive forms of minerals and nutrients are deliberately introduced into biosystemsâ€”in measured amounts and under conditions of controlâ€”for studies of metabolic cycles and rates of flow of energy and nutrition.

1. Fallout radioactivity is assessed as a potential specific hazard to human populations.

2. Conditions created by fallout are examined for their potential long-term ecological significance.

3. Radionuclides introduced into the environment by nuclear tests, reactor operations, or other means are used as trace materials in basic studies in biological systems.

4. Radioactive forms of minerals and nutrients are deliberately introduced into biosystemsâ€”in measured amounts and under conditions of controlâ€”for studies of metabolic cycles and rates of flow of energy and nutrition.

It will be useful to look in detail at some typical programs and results.

RAT. A lightly anesthetized, wild trapped rat is weighed and measured prior to marking it, taking a blood sample, and releasing it in a controlled ecosystem.

FISH. Fisheries biologist with a large jackfish caught off Engebi Island, Eniwetok Atoll.

COCONUT CRAB. Measuring the radioactivity of the shell of a coconut crab caught on Bikini Island.

GEESE. Banding wild geese to study environmental effects of radionuclides on wildlife and possible entry of radionuclides into the human food chain.

PLANKTON. An ingenious plankton trap is placed in a river as part of a long-range study of radionuclide uptake by aquatic organisms.

SKATE. A clear-nosed skate being monitored by fisheries personnel to gather data on accumulation of radionuclides in its blood and tissues.

At Oak Ridge National Laboratory, Tennessee, it was discovered in 1964 that two kinds of mud-dauber wasps were building their mud nests in equipment, cabinets, and electronic gear in the vicinity of a field station on the Oak Ridge reservation.

Some nests, investigation disclosed, were built of radioactive mud. It seemed obvious that the wasps were obtaining mud from radioactive waste pits or from the White Oak Lake bed, which is the site of a former 40-acre lake used for 12 years as a detention pool for radioactive wastes.[18]

The mud daubers were carrying mud as far as 650 feet from the contaminated sources. Almost 90% of 112 nests built by the yellow-legged mud-dauber species were radioactive, and the mud was delivering to the wasp eggs each hour a dose of penetrating radiation equal to that received by a man from all natural sources over a period of many years. The development presented no human health problems, but further observation revealed a fascinating circumstance.

At the same time, another variety of wasp, the pipe-organ mud dauber, was building nests only ofnonradioactive mud. Of 150 pipe-organ wasp nests examined, none was radioactive. The nests were found in similar locations, and it was apparent that the same sources of nest materials were available to both species.

Mud-dauber wasps, building nests of radioactive mud in a waste disposal area near an Oak Ridge, Tennessee, atomic plant, are the object of intensive environmental radiation study. A shows radioactivity reading from a nest. B is an enlarged view of the nest with two tiny dosimeters in place to measure radiation. In C an ecologist inspects new nests built in a laboratory flight cage from radioactive mud provided in pans at the bottom. In D wasps are anesthetized, marked with tiny plastic disks for future identification, and released.

The question, then, was why wasps of one species were using radioactive mud while the other species seemingly discriminated against contaminated mud. The muds appeared to be entirely alike. X-ray-diffraction studies showed no material differences, nor were there detectable differences in â€œfeelâ€, smell, or plasticity. Radioactive isotopes in the mud included cesium-137, cobalt-60, ruthenium-106, and zinc-65. Oak Ridge scientists began to try to find out whether the pipe-organ wasps actually were discriminating against muds containing all or some of these radioisotopes or against the ionizing radiation from them. If so, how could the wasps detect it? These investigations were continuing in 1965. There is no answer yet.

The case of Bikini already has been discussed as an example of a predominantly aquatic environment apparently recovering from association with nuclear experiment. Eniwetok offers an instance of the toughness of an animal population exposed both to direct and long-range radiological impact.

Engebi Island, on Eniwetokâ€™s northeast reef, is the home of a wholly self-contained colony of Pacific rats living in a network of burrows in the shallow coral sands. After 1948 Engebi was exposed repeatedly to atomic detonations, and in 1952 the whole island was swept clean of growth and overwashed by waves from the thermonuclear explosion of Operation Ivy. On each of these occasions, exposure of the rat colony to radiation was intense. In 1952, by later estimates, the animals aboveground received radiation doses of 2500 to 6000 roentgens per hour, and those in burrows doses of 112 to 1112 roentgens per hour.[19]The island environment was so altered by atomic forces and by contaminated water that radiobiologists believed it impossiblethat any of the rats had survived. Because there was no natural route by which the island could be repopulated, scientists even considered introducing a new rat colony for study of a population growth in a mildly radioactive environment.

Engebi Island, Eniwetok Atoll, home of a colony of rats living in radioactive surroundings.

Close-up shows one burrow in the soil.

Contrary to all expectations, however, the original colony had not been eliminated. Biologists visiting Engebi in 1953 and 1954 found the rats apparently flourishing. New generations of rats were being born and were subsisting on grasses and other plants in an environment still slightly radioactive. In 1955 analysis of the bones of rats revealed the presence of strontium-89 and strontium-90 in amounts approaching what was assumed to be the maximum amount that would not cause bodily harm. The ratsâ€™ muscle tissues contained radioactive cesium-137. But no physical malformations were found in the rats. All animals appeared in sound physical condition, despite these body burdens of radioactivity. By 1964 the rat population had so increased that it apparently had reached equilibrium with available food supplies.

Questions relating to the reestablishment of the colony are intriguing. Why are new generations of these warm-blooded animals continuing to thrive after the colony was exposed to devastating nuclear effects? Is there a differentdose-effect relation for these rats than for other animals? Even if it is assumed, as it must be, that some members of the colony survived the original nuclear heat and radioactivity because they were shielded by concrete bunkers or other man-made structures, how is it that there have been no observable effects among rats existing for years in an area that continually exposed them to radiation?

A native rat, captured alive on Engebi Island, being held by a scientist before having its toenails clipped as a means of identification. Note the animalâ€™s healthy appearance.

In Arctic regions lying on opposite sides of the North Pole, fallout has created conditions that are given continuous scrutiny by scientists of Scandinavia and the United States.

The two cases, one involving the Lapps of northern Finland and the other the Eskimos of Alaska, are essentially the same. Hemispheric fallout introduced quantities of long-lived radionuclides, particularly cesium-137, into the food chains and consequently into the diets of native peoples. In each instance there had occurred a slow accumulation of radionuclides in the lichens and mosses and in other plants that are the foods of the reindeer and caribou. The meat of these animals forms a substantial part of the human diets, and as a result the members of the native communities were found to have, on the average, body burdens of radioactivity approaching the acceptable limit for human populations.

A preliminary study of the Lapp environment was made in 1958-1959, and a Lapp dietary study was made in 1960.The results showed close correlation between the consumption of reindeer meat and the Lappsâ€™ body burdens of cesium-137. The Scandinavian investigators concluded that the levels of concentrated cesium approximated the maximum permissible dose range for large populations. They noted, however, that â€œthe final answer ... has to be given by the geneticistsâ€.

Placing equipment to measure fallout in precipitation north of the Arctic Circle in Alaska.

In Alaska, where studies of the native populations have been proceeding for several years, adult Eskimos living in the vicinity of Anaktuvuk Pass[20]were found in 1964 to have average body burdens of cesium-137 more than 20 times as great as the average for adults in the area of the original 48 states. There was an expectation that even without further nuclear testing the levels of cesium-137 would continue to rise slowly in Arctic regions until about 1968.

Bioenvironmental studies form a background against which all atomic energy research is conducted. The central objective of the Atomic Energy Commissionâ€™s environmental radiation studies is â€œto determine the fate and effect of radionuclides in the environmentâ€. This objective calls for hundreds of concurrent approaches to the interlocking problems of the air, the sea, and the land. The AEC alone, through its Division of Biology and Medicine, is supportingresearch costing about $75 million a year, about two-thirds of this amount going to biological and medical programs at AEC laboratories and the remainder to some 650 individual contract studies at universities, nonprofit institutions, and commercial research organizations. Additional programs, large and small, are supported by foundations or other agencies. Work goes on in other nations. Many programs are international. Although only a fraction of this total activity is specifically related to environmental problems, the concern throughout is with the effect, for good or ill, of radioactivity on man and his world. It is possible to suggest by example the lines of inquiry.

A University of Georgia Research Institute ecologist studying biological specimens in a controlled environment near the AEC Savannah River Plant, Aiken, South Carolina.

The Trinity site in New Mexico, scene of the first atomic detonation in history, was studied for a number of years after 1945, particularly in relation to the distribution and effects of residual radioactivity in the desert environment. In 1963 and 1964 scientists from the University of Missouri undertook to determine the state of revegetation of the original atomic bomb crater.

The Nevada Test Site, where nuclear programs have been conducted for a decade and a half, has invited investigations of revegetation. Project Sedan, an underground thermonuclear detonation in 1962, established conditions for one such study. The crater produced by this detonation was 320 feet deep and 1200 feet in diameter. Vegetation growing within 2500 feet of ground zero was almost completely destroyed, and the original soil was covered by radioactive throwout. Shrubs as far as 5000 feet away from ground zero were damaged by air blast, and, in the weeks after the detonation, plants within a two-mile radius were covered by radioactive sand and silt or by deposits of windblown radioactive dust.

Studies in 1963 by scientists from the University of California at Los Angeles showed that native plantsâ€”Russian thistle and various annualsâ€”had become well established in the zone around the Sedan crater where the earth was thrown out. This area had remained barren for less than a year. Some of the shrubs most severely damaged by the blast, and exposed to cumulative gamma radiation doses of more than 4000 roentgens, had produced new growth. Populations of creosote bush, evergreen plants that in 1962 appeared to have been killed by heavy doses of radiation, were producing leafy branches in the summer of 1963. These developments permitted no conclusions, of course, for the possible radiation effects still needed to be identified. Studies were conducted, for example, of the effect of deliberately depositing nonradioactive dust on healthy creosote plants, and comparative studies of other phenomena were made.

Since 1959, ecological studies have been carried forward at the Nevada site by investigators from Brigham Young University who are interested in the abundance, seasonal occurrence, and ecological influences affecting the vertebrate and invertebrate animals in plant communities of the region. Surveys have been made in areas where nuclear explosions had obliterated natural ecological relationships and in similar areas undisturbed by nuclear effects. The investigations are concerned primarily with desert ecologyâ€”with the identification of biotic communities and of predominant animal species.

Among research programs in marine environments is that initiated in 1963 and 1964 by the University of Californiaâ€™s Institute of Marine Resources at La Jolla, where studies of marine food chains are conducted by a team of zoologists, chemists, botanists, and microbiologists. The program studies the interrelations among organisms at the lower levels of the food chains and the dynamics of marine phytoplankton cell division, photosynthesis, and excretion of organic matter as related to temperature, light intensity, and nutrient conditions. The work is conceived as a basic study of marine ecology. It is focused, however, on questions found to be significant in studies of radioactivity in the sea.

The University of Californiaâ€™s Lawrence Radiation Laboratory has launched a long-term investigation of the effects of the release of radionuclides on the biosphere, which encompasses the origins, transport, and final localization of radionuclides in all types of organs, tissues, cells, and subcellular constituents. The objective is â€œto develop the most complete understanding possible of the potential hazards to man that arise from the release of nuclear radiation and radionuclides into the biosphere and to apply this knowledge to the prevention of damage to living forms...â€.

In programs such as theseâ€”multiplied by hundredsâ€”the problems are being attacked.

Radiobiological studies that are environmental in scope became, with the release of atomic energy, a mandate on the twentieth century.

Environmental studies are not new. They have been implicit in thousands of biological research efforts, large and small, for generations. Atomic energy, however, is a new factor. Also new is the intensity of the approach. Not until the explosion of inquiry of this century has man brought together the necessary resourcesâ€”the time, the funds, the instruments, the ingenious technological devices, the ideas, and the organizational and management skillsâ€”to attack problems that are global in scale.

The atom as a tool of the environmental radiobiologist has, of itself, solved few problems. Its significance is that it has speeded upâ€”to a degree still not fully testedâ€”our ability to study ecosystems and their relations to each other.

Instruments for environmental research.

A radiation analyzer for laboratory examination of field samples.

Installing environmental research equipment in the field.

The first two decades of the Atomic Age have comprised a period of swift maturity. Much has been done to gain perspective. Atomic energy as a potential force for destruction has not been controlled. But there is a surer knowledge of the hazard inherent in the absence of control and a rational hope that the new power will be directed toward peaceful objectives. We know that:

1. The uninhibited release of nuclear products into the environment of the earth will create problemsâ€”fundamentally biological problemsâ€”of long duration and of still-unassessed ultimate effect.2. Use of atomic weapons in war could have a â€œbiological costâ€ beyond calculation.

2. Use of atomic weapons in war could have a â€œbiological costâ€ beyond calculation.

Yet, in terms of constructive employment of atomic resources, we also know that:

1. Atomic energy may help solve the very problems that the new age presents.2. Careful and controlled development of atomic forces will provide the reservoirs of energy that will be needed to sustain the worldâ€™s populations of the next century and beyond.

1. Atomic energy may help solve the very problems that the new age presents.

2. Careful and controlled development of atomic forces will provide the reservoirs of energy that will be needed to sustain the worldâ€™s populations of the next century and beyond.

In whatever case, the solutions lie in the direction of environmental knowledge.

Man, the human animal, will live in the environment he has the intelligence to understand and to preserve.

â€œ... All creatures are linked to each other ... in their dependence on limited environments that together form the whole of nature ...â€ (Page 3). (White-capped noddy tern nesting colony, Engebi Island, Eniwetok Atoll, photographed in 1965.)

Sourcebook on Atomic Energy, Samuel Glasstone, D. Van Nostrand Company, Inc., Princeton, New Jersey, 1958, 641 pp., $4.40.What is Ionizing Radiation?, Robert L. Platzman,Scientific American, 201: 74 (September 1959).

Sourcebook on Atomic Energy, Samuel Glasstone, D. Van Nostrand Company, Inc., Princeton, New Jersey, 1958, 641 pp., $4.40.

What is Ionizing Radiation?, Robert L. Platzman,Scientific American, 201: 74 (September 1959).

The Effects of Nuclear Weapons, Samuel Glasstone (Ed.), U. S. Atomic Energy Commission, 1962 (revised edition), 730 pp., $3.00. Available from Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402.Fallout from Nuclear Weapons Tests, Hearings Before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, 86th Congress, First Session, Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402, 1959. Vol. I, 948 pp., $2.75; Vol. II, 1967 pp., $2.75; Vol. III, 2618 pp., $1.75. â€œSummary-Analysis of Hearingsâ€, 42 pp., $0.15, is available only from the Office of the Joint Committee on Atomic Energy, Congress of the United States, Washington, D. C. 20510.Bombs at Bikini, W. A. Shurcliff, William H. Wise & Co., Inc., New York, 1947, 212 pp., $3.50. Out of print but available through libraries.

Fallout from Nuclear Weapons Tests, Hearings Before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, 86th Congress, First Session, Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402, 1959. Vol. I, 948 pp., $2.75; Vol. II, 1967 pp., $2.75; Vol. III, 2618 pp., $1.75. â€œSummary-Analysis of Hearingsâ€, 42 pp., $0.15, is available only from the Office of the Joint Committee on Atomic Energy, Congress of the United States, Washington, D. C. 20510.

Bombs at Bikini, W. A. Shurcliff, William H. Wise & Co., Inc., New York, 1947, 212 pp., $3.50. Out of print but available through libraries.

Health Implications of Fallout from Nuclear Weapons Testing Through 1961(Report No. 3), Federal Radiation Council, Washington, D. C., May 1962, 10 pp., free.Estimates and Evaluation of Fallout in the United States from Nuclear Weapons Testing Conducted Through 1962(Report No. 4), Federal Radiation Council, Washington, D. C., May 1963, 41 pp., $0.30.Report of the United Nations Scientific Committee on the Effects of Atomic Radiation, General Assembly, Seventeenth Session, Supplement No. 16 (A/5216), United Nations, International Documents Service, Columbia University Press, New York, 1962, 146 pp., $5.00.

Health Implications of Fallout from Nuclear Weapons Testing Through 1961(Report No. 3), Federal Radiation Council, Washington, D. C., May 1962, 10 pp., free.

Estimates and Evaluation of Fallout in the United States from Nuclear Weapons Testing Conducted Through 1962(Report No. 4), Federal Radiation Council, Washington, D. C., May 1963, 41 pp., $0.30.

Report of the United Nations Scientific Committee on the Effects of Atomic Radiation, General Assembly, Seventeenth Session, Supplement No. 16 (A/5216), United Nations, International Documents Service, Columbia University Press, New York, 1962, 146 pp., $5.00.

Environmental Radioactivity, Merril Eisenbud, McGraw-Hill Book Company, Inc., New York, 1963, 430 pp., $12.50.Proving Ground: An Account of the Radiobiological Studies in the Pacific, 1946-1961, Neal O. Hines, University of Washington Press, Seattle, Washington, 1962, 366 pp., $6.75.Radioecology, Proceedings of the First National Symposium on Radioecology Held at Colorado State University, Fort Collins, Colorado, September 10-15, 1961, Vincent Schultz and Alfred W. Klement, Jr. (Eds.), published jointly by the Reinhold Publishing Corporation, New York, and the American Institute of Biological

Environmental Radioactivity, Merril Eisenbud, McGraw-Hill Book Company, Inc., New York, 1963, 430 pp., $12.50.

Proving Ground: An Account of the Radiobiological Studies in the Pacific, 1946-1961, Neal O. Hines, University of Washington Press, Seattle, Washington, 1962, 366 pp., $6.75.

Radioecology, Proceedings of the First National Symposium on Radioecology Held at Colorado State University, Fort Collins, Colorado, September 10-15, 1961, Vincent Schultz and Alfred W. Klement, Jr. (Eds.), published jointly by the Reinhold Publishing Corporation, New York, and the American Institute of Biological

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