EMERGING APPLICATIONS OF NUCLEAR AND ISOTOPIC TECHNIQUES IN THE ENVIRONMENTAL SCIENCES

摘要

Nuclear techniques have many applications in environmental science, and new possibilities are provided by the instruments currently being developed and commissioned throughout the world. For example, the OPAL reactor at Lucas Heights in Australia has 13 operational and planned neutron beam instruments. Several of these techniques have already been applied in environmental science, including small-angle neutron scattering (SANS) and neutron radiography/tomography. The reactor also hosts advanced capabilities for the more traditional nuclear analytical technique of neutron activation analysis (NAA). This technique is being applied in biomonitoring and bioaccumulation research, with studies of a range of organisms including moss, crops, trees, bivalves, bird-feathers, human hair and marine species. Other related techniques available to environmental scientists include accelerator-based and synchrotron techniques, with 10 beam-lines currently available at the Australian synchrotron. Nuclear facilities have also been used to produce anthropogenic radioisotopes, which have been utilized in a range of environmental studies. Researchers have measured the distributions of radionuclides released by atmospheric weapons testing, reactor accidents and routine discharges from nuclear facilities. Isotopic techniques have been applied to research into atmospheric circulation, hydrology, oceanography, pollution, erosion, sedimentation, soil fertility, ecology, and plant uptake. In these studies, the unique attributes of radionuclides (low detection limits, ability to be distinguished from natural isotopes of the same elements whilst exhibiting nearly identical behavior, known timing of releases, etc) can often be exploited to elucidate environmental processes. Finally, environmental scientists have undertaken research aimed at the mitigation of environmental problems associated with releases from nuclear activities and radioactive waste disposal. These studies have had a high priority in recent decades, due to public concern over radioactivity in the environment, and, in particular, the Chernobyl and Fukushima events. Examples of many of these types of environmental research have been presented at the ICI-8 conference. The main themes have included effectively addressing the legacy problems from past nuclear activities, detecting clandestine operations involving nuclear materials; detection and minimization of airborne emissions from nuclear activities; uptake of radionuclides in vegetation at legacy radioactive waste sites; biomonitoring of airborne pollution using neutron activation analysis and addressing the unresolved issues of radioactive waste management.