The effects of selected NOx reduction scenarios on long-term nitrogen deposition and episodic ozone levels in Europe

For computational reasons, evaluations of NO(x) emission controls usually concentrate on either episodic or annual impacts on pollution or deposition levels. However, previously published model results indicate that the consequences of NO(x) controls can be quite different on these different time scales. In this paper we analyse the impact of a consistent set of NO(x) control scenarios on both the episodic and annual time-scales. Using similar models, we compute levels of episode peak O(3) and NO(2) and annual NO(y)-N and total N deposition at three locations in Europe due to six emission scenarios derived from OECD estimates. An NO(x) control scenario which reduces European emissions by 63%, only results in total annual N deposition reductions of 19, 36 and 26% at the three locations examined because of the influence of ammonia-nitrogen deposition. The same scenario results in either increases or decreases in episode peak O(3) due to the influence of hydrocarbons. Emission reduction strategies should take into account not only NO(x) emissions, but emissions of other pollutants, such as hydrocarbons and ammonia.     

Movements of bluefin tuna (<Emphasis Type="Italic">Thunnus thynnus</Emphasis>) in the northwestern Atlantic Ocean recorded by pop-up satellite archival tags

Pop-up satellite archival tags were implanted into 68 Atlantic bluefin tuna (Thunnus thynnus Linnaeus), ranging in size from 91 to 295 kg, in the southern Gulf of Maine (n=67) and off the coast of North Carolina (n=1) between July 2002 and January 2003. Individuals tagged in the Gulf of Maine left that area in late fall and overwintered in northern shelf waters, off the coasts of Virginia and North Carolina, or in offshore waters of the northwestern Atlantic Ocean. In spring, the fish moved either northwards towards the Gulf of Maine or offshore. None of the fish crossed the 45°W management line (separating eastern and western management units) and none traveled towards the Gulf of Mexico or the Straits of Florida (known western Atlantic spawning grounds). The greatest depth recorded was 672 m and the fish experienced temperatures ranging from 3.4 to 28.7°C. Swimming depth was significantly correlated with location, season, size class, time of day, and moon phase. There was also evidence of synchronous vertical behavior and changes in depth distribution in relation to oceanographic features.Communicated by J.P. Grassle, New Brunswick     

Identification of metal toxicity in sewage sludge leachate

Sewage sludge is a source of organic matter and nutrients with the potential for being used as a fertilizer. However, metals in sewage sludge might accumulate in soil after repeated sludge applications, and metal concentrations might reach concentrations that are toxic to microorganisms, soil organisms and/or plants. This toxicity might change with time due to kinetic factors or abiotic factors such as freezing, drying or rainfall. The objective of this study was to determine toxicity of sewage sludge leachate from a lysimeter with 50 cm of sludge applied. Attempts were also made to identify the cause of toxicity of the sludge leachate by toxicity identification and evaluation (TIE) techniques. Sludge leachate was collected monthly during 1 experimental year (August 2001 to August 2002). Metal concentrations were analysed, and the toxicity was determined with Daphnia magna (48-h immobility). The effect of EDTA or sodium thiosulphate addition, filtration through a CM-resin or a Millex-resin on toxicity was also tested. The results showed that toxicity of the sludge leachate apparently varied during the year, and that filtration through the CM-resin reduced most of the toxicity followed by the addition of EDTA. None of the other treatments reduced the toxicity of the sludge leachate. This indicated that one or more metals were responsible for the observed toxicity. Further calculations of toxic units (TU) suggested that Zn contributed most to the toxicity. Results also indicated that Ca concentrations in the sludge leachate reduced the toxicity of Zn.     

Yield and arsenate uptake of arbuscular mycorrhizal tomato colonized by Glomus mosseae BEG167 in As spiked soil under glasshouse conditions

A glasshouse pot experiment was conducted to study the effect of arbuscular mycorrhizal (AM) colonization by Glomus mosseae BEG167 on the yield and arsenate uptake of tomato plants in soil experimentally contaminated with five As levels (0, 25, 50, 75 and 150 mg kg(-1)). Mycorrhizal colonization (50-70% of root length) was little affected by As application and declined only in soil amended with 150 mg As kg(-1). Mycorrhizal colonization increased plant biomass at As application rates of 25, 50 and 75 mg kg(-1). Shoot As concentration increased with increasing As addition up to 50 mg kg(-1) but decreased with mycorrhizal colonization at As addition rates of 75 and 150 mg kg(-1). Shoot As uptake increased with mycorrhizal colonization at most As addition levels studied, but tended to decrease with addition of 150 mg As kg(-1). Total P uptake by mycorrhizal plants was elevated at As rates of 25, 50 and 75 mg kg(-1), and more P was allocated to the roots of mycorrhizal plants. Mycorrhizal plants had higher shoot and root P/As ratios at higher As application rates than did non-mycorrhizal controls. The soil of inoculated treatments had higher available As than uninoculated controls, and higher pH values at As addition levels of 25, 50 and 75 mg kg(-1). Mycorrhizal colonization may have increased plant resistance to potential As toxicity at the highest level of As contamination studied. Mycorrhizal tomato plants may have potential for phytoextraction of As from moderately contaminated soils or phytostabilization of more highly polluted sites.     

Identifying optimal agricultural countermeasure strategies for a hypothetical contamination scenario using the strategy model

A spatially implemented model designed to assist the identification of optimal countermeasure strategies for radioactively contaminated regions is described. Collective and individual ingestion doses for people within the affected area are estimated together with collective exported ingestion dose. A range of countermeasures are incorporated within the model, and environmental restrictions have been included as appropriate. The model evaluates the effectiveness of a given combination of countermeasures through a cost function which balances the benefit obtained through the reduction in dose with the cost of implementation. The optimal countermeasure strategy is the combination of individual countermeasures (and when and where they are implemented) which gives the lowest value of the cost function. The model outputs should not be considered as definitive solutions, rather as interactive inputs to the decision making process. As a demonstration the model has been applied to a hypothetical scenario in Cumbria (UK). This scenario considered a published nuclear power plant accident scenario with a total deposition of 1.7x10(14), 1.2x10(13), 2.8x10(10) and 5.3x10(9)Bq for Cs-137, Sr-90, Pu-239/240 and Am-241, respectively. The model predicts that if no remediation measures were implemented the resulting collective dose would be approximately 36 000 person-Sv (predominantly from 137Cs) over a 10-year period post-deposition. The optimal countermeasure strategy is predicted to avert approximately 33 000 person-Sv at a cost of approximately 160 million pounds. The optimal strategy comprises a mixture of ploughing, AFCF (ammonium-ferric hexacyano-ferrate) administration, potassium fertiliser application, clean feeding of livestock and food restrictions. The model recommends specific areas within the contaminated area and time periods where these measures should be implemented.     

"Reference Biospheres" for solid radioactive waste disposal: the BIOMASS methodology

The BIOMASS Theme 1 project has developed a methodology for the logical and defensible construction of 'assessment biospheres': mathematical representations of biospheres used in the total system performance assessment of radioactive waste disposal. The BIOMASS Methodology provides a systematic approach to decision making, including decisions on how to address biosphere change. The BIOMASS Methodology was developed through consultation and collaboration with many relevant organisations, including regulators, operators and a variety of independent experts. It has been developed to be practical and to be consistent with recommendations from ICRP and IAEA on radiation protection in the context of the disposal of long-lived solid radioactive wastes. The five main steps in the methodology are described in this paper. The importance of a clear assessment context, to clarify intentions and to support a coherent biosphere assessment process within an overall repository performance assessment, is strongly emphasised. A well described assessment context is an important tool for ensuring consistency across the performance assessment as a whole. The use of interaction matrices has been found to be helpful in clarifying the interactions between different habitats within the biosphere system and the significant radionuclide transfer pathways within the biosphere system. Matrices also provide a useful means of checking for consistency.     

Modelling and experimental studies on the transfer of radionuclides to fruit

Although fruit is an important component of the diet, the extent to which it contributes to radiological exposure remains unclear, partially as a consequence of uncertainties in models and data used to assess transfer of radionuclides in the food chain. A Fruits Working Group operated as part of the IAEA BIOMASS (BIOsphere Modelling and ASSessment) programme from 1997 to 2000, with the aim of improving the robustness of the models that are used for radiological assessment. The Group completed a number of modelling and experimental activities including: (i) a review of experimental, field and modelling information on the transfer of radionuclides to fruit; (ii) discussion of recently completed or ongoing experimental studies; (iii) development of a database on the transfer of radionuclides to fruit; (iv) development of a conceptual model for fruit and (v) two model intercomparison studies and a model validation study. The Group achieved significant advances in understanding the processes involved in transfer of radionuclides to fruit. The work demonstrated that further experimental and modelling studies are required to ensure that the current generation of models can be applied to a wide range of scenarios.     

Use of contaminated well water, example reference biospheres 1 and 2A

The BIOMASS programme's Theme 1 evaluated a number of scenarios, which assisted in the development of practical guidance. A total of four Example Reference Biospheres were fully developed, with the assumptions, data, and models thoroughly documented. These Examples display both the practicality and the transparency available through the use of the Reference Biosphere Methodology. While the methodology is designed to promote transparency and traceability, proper documentation and justification is still the responsibility of the user. The Examples can also be used as generic analyses in some situations. Although it is anticipated that each of the Reference Biospheres explored within BIOMASS Theme 1 should be a useful practical example, the quantitative results of the model calculations are not intended to be understood as prescribed biosphere 'conversion factors'. In choosing to implement an Example, careful consideration would need to be given to their relevance (including associated data) to the particular assessment context at hand. In general, the more complex the model is, the more limited applicability it has for generic purposes. For example, ERB1A (direct use of well water for drinking) can be used straightforwardly, with minor or no adjustments, at a number of generic sites. Example 2A, however, for which climatic conditions and agricultural practices need to be specified, would need to be implemented for each specific situation.