Exposure of biota in the cooling pond of Ignalina NPP: hydrophytes

The radiological assessment of non-human biota is now accepted by a number of international bodies. In this connection the scientific basis to assess and evaluate biota internal and external radiation exposure is required. This paper presents the comparison of freshwater biota (hydrophyte species) exposure due to discharged anthropogenic radionuclides with that due to natural background radiation. The radionuclides from Ignalina Nuclear Power Plant (Lithuania) are discharged into cooling pond – Druksiai Lake. Submerged hydrophytes were selected as biota exposure indicators because they represent the largest biomass in this lake and have comparatively high radionuclide activity concentrations. The detailed methodology evaluation of the submerged hydrophyte dose rate is presented. The ionizing radiation exposure dose rates to submerged hydrophyte roots and above sediment parts due to the major radionuclides (54Mn, 60Co, 137Cs, 90Sr) discharged into the INPP cooling pond – Druksiai Lake were 0.044 μGy h−1 and 0.004 μGy h−1, respectively. The internal exposure dose rate due to natural background α-emitters (210Po,238U, 226Ra) was estimated to be 1.24 μGy h−1, as compared with that of anthropogenic α-emitter 240Pu – 0.04 μGy h−1, whereas the external exposure was 0.069 μGy h−1. The presented data deeper the knowledge about the concentration of radionuclides and submerged hydrophytes' exposure dose rates in European freshwater ecosystems

Influence of 137Cs and 90Sr on vegetative and generative organs of Lepidium sativum L. and Tradescantia clone 02

The impact of 137Cs and 90Sr activity concentrations from 0.4 to 400 kBqźL-1 and from 1 to 200 kBqźL-1, respectively, on seed germination of Lepidium sativum was insignificant; however, all concentrations of 137Cs and 30 kBqźL-1 concentration of 90Sr slightly stimulated root growth. The accumulated 137Cs and 90Sr stimulated shoot and parenchyma cell growth; 137Cs suppressed RNA-polymerase II activity, and 90Sr, on the contrary, stimulated it. Different genotoxic effects on Tradescantia clone 02 stamen hair cells were observed with comparable 137Cs and 90Sr activity concentrations. Activity concentrations of 137Cs from 0.001 to 1.3 kBqźL-1 were more effective in Tradescantia clone 02 stamen hair cell reproduction, whereas the studied activity concentrations of 90Sr (from 0.002 to 640 kBqźL-1) induced more mutations. -------------------------------------------------------------------------------

The impact of storm water runoff on a small urban stream

Background, aim, and scope: In urban areas, storm water runoff often transports various pollutants, some of which settle and form sediments. In order to have the comprehensive view of the ecological state of storm water runoff recipients, both water and sediments of the stream must be assessed. In the Baltic Sea Area, the Water Framework Directive & HELCOM Recommendations aim to prevent or minimise pollution caused by harmful substances arising from storm water runoff, in order to promote the ecological restoration of the Baltic Sea—one of the most vulnerable seas. The aim of the study was to investigate the toxicity of bottom sediments of a small storm water runoff recipient focusing on the potential impact of successive discharges of urban storm water. Some storm water runoff quality parameters and the toxicity of bottom sediments of recipients was studied in this research. Materials and methods: During 9 years, at four discharge points, minimum four grab samples per year at each discharge point were taken for chemical characterisation. General parameters (pH, SS, BOD7, CODCr and TPH) in liquid phase samples were analysed according to standard methods. Annual limit values were taken from the Lithuanian EPA requirements for the management of storm water runoff with a focus on prevention and control of contamination. Eleven composite samples of stream bottom sediments, each consisting of ten sub-samples, were collected in 2006. Toxicity screening from sediments was performed using the plant Lepidium sativum according to modified I. Magone’s methodology (Magone I, Bioindication of phytotoxicity of transport emission. In: Kachalova O-L, Zinatne (eds) Bioindication of toxicity of transport emissions in the impact of highway emissions on natural environment. Riga, pp 108–116, 1989). The level of toxic impact of Lepidium sativum (compared to control) was assessed according to the modified method of Wang (Rev Environ Contam Toxicol 126:88–127, 1992). Results: The mean pH of urban storm water runoff does not vary much from neutral, but range values are quite different, from 4.0 up to 8.7. The highest concentration of SS reached 800 mg L−1, TPH—2.4 mg L−1, BOD7—300 mg O2 L−1 and CODCr—1,400 mg L−1. The SS was above the limit in 64% of total amount of grab samples, TPH—37%, BOD7—41% and CODCr—55%. The toxicity analysis of the bottom sediments showed varying toxicity of bottom sediments along the stream. From nine analysed samples of bottom sediments, 30% had weak toxicity, 30% medium and 30% strong toxicity on the test organism plant L. sativum. There was one single sample with no toxic effects, so that the results showed that urban storm water has an unacceptable environmental impact on recipients. It was also indicated that storm water runoff discharge alone is not the potential source of toxicity of bottom sediments. The litter demonstrated a weak toxicity of bottom sediments as well. Discussion: Most local authorities do not consider storm water runoff discharges to be a matter of great concern because they believe that surface runoff arising from rainfall is still relatively clean. The study showed that the current method of monitoring storm water runoff quality by chemical analyses is not the best tool for environmental impact assessment and must be combined with toxicity tests of bottom sediments of recipients. Recommendations and perspectives: To avoid the environmental impact of storm water runoff more attention should be paid to the development and implementation of storm water runoff pollution prevention measures. The study implies that future research concerning the relationships between storm water runoff deposit characteristics and biological activities must be developed to evaluate the contamination potential of stream sediment deposits for local aquatic ecosystems. Further studies should be developed to characterise the activities of the microbial community of storm water runoff sediments, and to monitor bioremediation in situ

Background and anthropogenic radionuclide derived dose rates to freshwater ecosystem - Nuclear power plant cooling pond - Reference organisms

The radiological assessment of non-human biota to demonstrate protection is now accepted by a number of international and national bodies. Therefore, it is necessary to develop a scientific basis to assess and evaluate exposure of biota to ionizing radiation. Radionuclides from the Ignalina Nuclear Power Plan(Lithuania) were discharged into Lake Druksiai cooling pond. Additional radionuclide migration and recharge to this lake from a hypothetical near-surface, low-level radioactive waste disposal, to be situated 1.5 km from the lake, had been simulated using RESRAD-OFFSITE code. This paper uses ERICA Integrated Approach with associated tools and databases to compare the radiological dose to freshwater reference organisms. Based on these data, it can be concluded that background dose rates to non-human biota in Lake Druksiai far exceed those attributable to anthropogenic radionuclides. With respect the fishery and corresponding annual committed effective human dose as a result of this fish consumption Lake Druksiai continues to be a high-productivity water body with intensive angling and possible commercial fishing