Radioecology

Radioecology

The study of the fate and effects of radioactive materials in the environment. It derives its principles from basic ecology and radiation biology.

Responses to radiation stress have consequences for both the individual organism and for the population, community, or ecosystem of which it is a part. When populations or individuals of different species differ in their sensitivities to radiation stress, for example, the species composition of the entire biotic community may be altered as the more radiation-sensitive species are removed or reduced in abundance and are replaced in turn by more resistant species. Such changes have been documented by studies in which natural ecological systems, including grasslands, deserts, and forests, were exposed to varying levels of controlled gamma radiation stress. See Population ecology

Techniques of laboratory toxicology are also available for assessing the responses of free-living animals to exposure to low levels of radioactive contamination in natural environments. This approach uses sentinel animals, which are either tamed, imprinted on the investigator, or equipped with miniature radio transmitters, to permit their periodic relocation and recapture as they forage freely in the food chains of contaminated habitats. When the animals are brought back to the laboratory, their level of radioisotope uptake can be determined and blood or tissue samples taken for analysis. In this way, even subtle changes in deoxyribonucleic acid (DNA) structure can be evaluated over time. These changes may be suggestive of genetic damage by radiation exposure. In some cases, damage caused by a radioactive contaminant may be worsened by the synergestic effects of other forms of environmental contaminants such as heavy metals.

Because of the ease with which they can be detected and quantified in living organisms and their tissues, radioactive materials are often used as tracers. Radioactive tracers can be used to trace food chain pathways or determine the rates at which various processes take place in natural ecological systems. Although most tracer experiments were performed in the past by deliberately introducing a small amount of radioactive tracer into the organism or ecological system to be studied, they now take advantage of naturally tagged environments where trace amounts of various radioactive contaminants were inadvertently released from operating nuclear facilities such as power or production reactors or waste burial grounds.

An important component of radioecology, and one that is closely related to the study of radioactive tracers, is concerned with the assessment and prediction of the movement and concentration of radioactive contaminants in the environment in general, and particularly in food chains that may lead to humans. See Ecology, Food web, Radiation biology