Scientists in many parts of the world have used both natural and intentionally injected radiation to study the coastwise movement of beach materials. British experimenters, for example, activate sand with scandium-46 and are thus able to follow its movement for up to four months. Pebbles (shingle) coated with barium-140 and lanthanum-140 are also used as tracers and are good for 6 weeks. Scientists at the University of California trace naturally occurring radioisotopes of thorium, which may be introduced from deposits of thorium sands along river banks. These studies are of immediate practical importance, for each year the ocean moves billions of cubic yards of sand, gravel, shingle, and rock to and from beaches and along shores. This action destroys recreational beaches, fills channels, blocks off harbors, and in general rearranges the terrain, often at considerable cost and inconvenience to mariners and other people who use the coast.
In another use of radioisotopes in marine research, studies at the AEC’s Oak Ridge National Laboratory in Tennessee have revealed radioactivity in the scales of fish taken from waters affected by the laboratory’s radioactive waste effluent. It was suggested that this phenomenon might be put to use as a tagging technique in fish-migration studies, and scientists are now working on a method using cesium-134 introduced into the fishes’ natural diet.
Isaacs-Kidd midwater trawl collects samples of oceanic animals off the Oregon Coast. These animals are then radioanalyzed to compare the quantity of radioisotopes associated with animals from various depths. The recorder at the trawl mouth indicates the volume of water filtered.
Some of the most extensive studies of a marine environment ever conducted are those by the AEC, the Bureau of Commercial Fisheries, and the University of Washington in the Columbia River system and the nearby Pacific Ocean. Operations at the AEC’s giant Hanford facilities some 300 miles upstream from the ocean result in the release of small amounts of radioactivity to the river and also in raising the river-water temperature. This downstream research is to determine any effects of these changes, including any that might be detrimental to man. The research encompasses studies of the variations and distributions of the freshwater “plume”—the outflow from the rivermouth—extending into the nearby Pacific, sediment analyses, studies of the population dynamics of phytoplankton, and the transport of radionuclides through the food chain.
This core sampler is used to obtain stream bed samples up to 5 feet long in the Columbia River. The samples are then analyzed for radioisotope content.
As so often happens with basic programs, this research has produced immediate benefits. New resources of marketable oceanic fish were discovered by the scientists at depths never before fished commercially (from the edge of the continental shelf to depths of 500 fathoms and greater). Similarly, commercial quantities of one species of crab have been discovered in the deeper ocean. Other findings indicate that crab populations may have seasonal up-and-down migrations that vary according to sex. It appears, in fact, that, except while mating and as juveniles, the male and female crab populations lead separate lives. This information is important both for more efficient fisheries and for improved conservation of the crab as a food resource.
The AEC is, in short, concerned with virtually every facet of basic oceanography, and with study of the sea as a whole, for radionuclides, like their nonradioactive counterparts, can and do become involved in every phase of the vast and complex ocean ecology. In the process of pursuing its research interests, it also provides oceanographers with a whole new family of tools for study. Let us now see how atomic instruments contribute to the growing knowledge of the sea.