Production of radioactive particles for use in environmental studies

This paper presents an aerosol generation technique developed to produce dry aerosol particles of various sizes from aqueous solutions of salt. The technique was tested with sodium chloride, lithium carbonate and uranyl acetate at various aqueous concentrations which produced particles in the size range of 0.13-1.37 microm Mass Median Diameter (MMD). The generated aerosols were acceptably monodisperse with a geometric standard deviation of 1.4-2. Both MMD and Mass Median Aerodynamic Diameter (MMAD) increased significantly (p<0.001) with increased concentration of the salt in solution. The technique can also be used to generate aerosols of different chemical species. The results obtained indicate that the system is convenient for use with various aerosol-forming materials, with a stable particle size distribution being maintained for a long period of steady operation. The technique was successfully applied in wind tunnel studies to simulate the release of submicron radioactive particles and their interception by crops, grass and tree canopies. The relevance and application of the technique in other areas of environmental assessment studies is discussed.     

Ecotoxicological impact assessment of the brine discharges from a desalination plant in the marine waters of the Algerian west coast,using a multibiomarker approach in a limpet,Patella rustica

The aim of our study is to evaluate the impact of Bousfer desalination plant brine discharges on the Algerian west coast, on a natural population of the marine gastropod mollusc Patella rustica. The effects of a chronic exposure to such discharges are complex to understand due to the combined effects of environmental physico-chemical parameters (e.g., high salinity) and different pollutants that can modulate the physiological responses of this species to stress. In this context, we assessed the biological effects in a marine species P. rustica, by a multibiomarker approach that provided information on the health status of organisms in response to such an environmental stress. We measured biomarkers in the whole soft tissues of limpets as indicators of neurotoxicity (AChE activity), oxidative stress (CAT, SOD, GR, and GPx activities), biotransformation (GST), oxidative damage (LPO through TBARS levels), and genotoxicity (CSP 3-like activity). In parallel, hydrological parameters were measured in the Bay of Oran, at four selected sites: site H considered as a “hotspot,” located at Bousfer desalination plant; two other sites E and W, at the east and the west of H respectively; finally, site R “reference” located in Madragh, which is considered as a remote clean site. Our analyses revealed that the activities of antioxidant defense enzymes reached the highest levels in P. rustica collected from site H. The activation of antioxidant defense system in these organisms translated the alteration of their status health, reflecting a level of environmental disruption generated by the desalination plant brine discharges and the high salinity in this area. We also observed that the tissues of limpets collected from site H as well as the two other sites, E and W, had undergone molecular damage, confirmed by the high levels of CSP 3-like activity. This damage resulted from chronic exposure to environmental conditions, potentially genotoxic, due to the desalination plant discharges. The present results indicate the adverse impact of brine effluents from desalination plants on marine fauna and suggest the need for a more consistent approach to environmental management of brine discharges.

     

Dealing with uncertainty in the assessment of human exposure to radioactivity in food and the environment

This paper presents an overview of the approach used to assess radiation dose and risk to members of the public from radioactivity in food and the environment. It describes uncertainties in the process and suggests ways of dealing with them to improve the risk assessment process. It also explains how uncertainty in the assessed dose/risk can be communicated to non-expert audiences such as members of the public. The issues covered in this paper apply to risk assessment of any contaminant and not only radioactivity.