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 for maximum 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 AEC’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 changes—simultaneous gains and losses—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.
ENVIRONMENTS—SINGULAR, YET PARTS OF A WHOLE
Each environment presents its own sets of conditions and unknowns. It is important to appreciate those that are characteristic of water, land, and atmosphere.
Aquatic Systems
The oceans are the basins into which are poured all the nutrients or wastes transported from the land by rivers and winds.