Identifying Sources of Radioactive and Heavy Metal Contamination in the Caspian Sea: Future Research Opportunities

Abstract

The interest to extend the knowledge in the field of the mechanisms regulating the behavior of radionuclides and heavy metals in different components of the environment has been raised in the second half of the 20th century. The use of nuclear energy for peaceful and military purposes, the radioactive fallout dispersed by nuclear weapon tests and, more recently, the contamination due to the Chernobyl accident have been the most important sources of radionuclides in terrestrial and aquatic ecosystems. As a consequence of industrial activity the environmental distribution of naturally occurring radioactivity and heavy metals was changed, and new areas of elevated levels of these contaminants appeared. The problems of environmental pollution by radionuclides and heavy metals appeared simultaneously. The first large-scale nuclear accident at Kyshtym (Russia) in 1957 caused heavy radioactive contamination of populated areas, soils and surface waters. For a rather long time this accident could not be studied exhaustively because of the Cold War situation; but now the data are accessible to scientists and they represent a source of invaluable information. The first detection of cases of heavy metal contamination in Japan appeared in 1956 (Minamata disease), resulting in extensive research concentrated on the food-chain transport and toxicity of heavy metals.