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Oyster Bay, Australia

Airey P.,Australian Nuclear Science and Technology Organisation | Hinton T.,Institute for Radiological Protection and Nuclear Safety | Twining J.,Austral Radioecology
Radioactivity in the Environment | Year: 2012

Tropical radioecology is the study of the behaviour of radionuclides in tropical ecosystems and of their potential human and environmental consequences. The scientific bases include introductions to radioactivity and radiation science, the radiological protection of humans and the environment, and the sources of environmental radionuclides, both naturally occurring and anthropogenic. These sources include primordial radionuclides (U- and Th-series), cosmogenic radionuclides, and the fallout products from atmospheric nuclear testing programs. Information on the detection of radioactivity, measurement precision, and shielding is relevant to practitioners. Efforts are now made to minimise the dispersion of radionuclides through all environments because of their potential detrimental effects. However, it is recognised that careful studies of the dispersion of radionuclides have yielded invaluable information on ecosystem dynamics that would not otherwise be available. Examples relevant to tropical systems are presented. © 2012 Elsevier Ltd. Source

Prohl G.,International Atomic Energy Agency | Twining J.R.,Austral Radioecology | Crawford J.,Australian Nuclear Science and Technology Organisation
Radioactivity in the Environment | Year: 2012

Radiological consequences for humans, flora and fauna due to discharges of radionuclides into the environment are key issues in impact assessments prepared for nuclear installations. So far, radioecological studies have mainly focussed on temperate zones. Due to the foreseeable development of nuclear facilities in tropical and subtropical countries, the question arises whether radiological dose assessment in those regions needs special consideration. This chapter describes the radioecological processes affecting transport and migration from one environmental compartment to another. Since these mechanisms are generally universal, it could be concluded that no special tropical radioecological processes exist. However, it is also demonstrated that the degree of such environmental transfers is dependent on site-specific climatic and environmental conditions, the land use and habits of the people, as well as on endemic biota. From that, radiological outcomes may vary in tropical compared with temperate systems. To address specific features of the environmental transport of radionuclides in tropical areas appropriately, key processes and features needed for reliable radioecological assessments are identified. © 2012 Elsevier Ltd. Source

Tagami K.,Japan National Institute of Radiological Sciences | Twining J.R.,Austral Radioecology | Wasserman M.A.V.,Brazilian Nuclear Engineering Institute (IEN)
Radioactivity in the Environment | Year: 2012

In this Chapter we consider radionuclide uptake and translocation in tropical crops and ecosystems. There are many commonalities across all ecosystems because of the consistent, underlying mechanisms controlling the fate and behaviour of radioactivity in any environment. The basic radioecological concepts and models are described to cover these processes.However, the tropics and sub-tropics include much dissimilarity by way of soil types, agricultural methods, climate, plants and animals which give rise to different outcomes from those processes. Billions of people across the tropics and sub-tropics are supported by agricultural systems very different from those traditionally applied in more developed regions of the planet. Higher populations will do so in the foreseeable future. Given the push for nuclear developments in the region, the tropics will need greater attention now. Much of the science is under review but the available data, pertinent to tropical systems, has been summarised or the database identified for the reader.The conditions of tropical soil types and the factors influencing radionuclide biogeochemistry (which affects bioavailability and bioaccessibility) are discussed. Specific sections covering rice, tropical fruits and the limited data for tropical animals are included. © 2012 Elsevier Ltd. Source

Johansen M.P.,Australian Nuclear Science and Technology Organisation | Child D.P.,Australian Nuclear Science and Technology Organisation | Caffrey E.A.,Oregon State University | Davis E.,Australian Nuclear Science and Technology Organisation | And 8 more authors.
Journal of Environmental Radioactivity | Year: 2015

We examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife inhabiting the relatively undisturbed, semi-arid former Taranaki weapons test site, Maralinga, Australia. The accumulation of absorbed Pu was highest in the skeleton (83%±6%), followed by muscle (10%±9%), liver (6%±6%), kidneys (0.6%±0.4%), and blood (0.2%). Pu activity concentrations in lung tissues were elevated relative to the body average. Foetal transfer was higher in the wildlife data than in previous laboratory studies. The amount of Pu in the gastrointestinal tract was highly elevated relative to that absorbed within the body, potentially increasing transfer of Pu to wildlife and human consumers that may ingest gastrointestinal tract organs. The Pu distribution in the Maralinga mammalian wildlife generally aligns with previous studies related to environmental exposure (e.g. Pu in humans from worldwide fallout), but contrasts with the partitioning models that have traditionally been used for human worker-protection purposes (approximately equal deposition in bone and liver) which appear to under-predict the skeletal accumulation in environmental exposure conditions. © 2015. Source

Jeffree R.A.,University of Technology, Sydney | Markich S.J.,Aquatic Solutions International | Twining J.R.,Austral Radioecology
PLoS ONE | Year: 2014

Bony bream (Nematalosa erebi) and black catfish (Neosilurus ater) were sampled from the fresh surface waters of the Finniss River in tropical northern Australia, along a metal pollution gradient draining the Rum Jungle copper/uranium mine, a contaminant source for over five decades. Paradoxically, populations of both fish species exposed to the highest concentrations of mine-related metals (cobalt, copper, lead, manganese, nickel, uranium and zinc) in surface water and sediment had the lowest tissue (bone, liver and muscle) concentrations of these metals. The degree of reduction in tissue concentrations of exposed populations was also specific to each metal and inversely related to its degree of environmental increase above background. Several explanations for diminished metal bioaccumulation in fishes from the contaminated region were evaluated. Geochemical speciation modeling of metal bioavailability in surface water showed no differences between the contaminated region and the control sites. Also, the macro-nutrient (calcium, magnesium and sodium) water concentrations, that may competitively inhibit metal uptake, were not elevated with trace metal contamination. Reduced exposure to contaminants due to avoidance behavior was unlikely due to the absence of refugial water bodies with the requisite metal concentrations lower than the control sites and very reduced connectivity at time of sampling. The most plausible interpretation of these results is that populations of both fish species have modified kinetics within their metal bioaccumulation physiology, via adaptation or tolerance responses, to reduce their body burdens of metals. This hypothesis is consistent with (i) reduced tissue concentrations of calcium, magnesium and sodium (macro-nutrients), in exposed populations of both species, (ii) experimental findings for other fish species from the Finniss River and other contaminated regions, and (iii) the number of generations exposed to likely selection pressure over 50 years. © 2014 Jeffree et al. Source

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