Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2008
Authors
Hallvard Jensen Kimmo K. Kahilainen Per-Arne Amundsen Karl øystein Gjelland Anti Tuomaala Tommy Malinen Thomas BøhnAbstract
No abstract has been registered
Abstract
For subsurface solute transport, flux concentrations are key, while usually resident concentrations are measured. Flux concentrations are frequently estimated from resident concentrations by temporal moment analysis. We tested this approach by simulating transport of an injected tracer during steady flow in an aquifer with a heterogeneous saturated hydraulic conductivity. We constructed grid-cell scale breakthrough curves (BTCs) from flux concentrations and approximate BTCs from resident concentrations and estimated flux concentrations. We assembled these BTCs into spatio-temporal leaching surfaces at various aquifer cross-sections for subsequent analysis. Resident concentrations were unsuitable to assess solute movement in the aquifer. Temporal moment analysis worked well when the entire aquifer cross-section was considered, but performed poorer at the grid-cell scale because it approximates the local velocity by the trajectory average. The leaching surfaces served as valuable tools to demonstrate and quantify the limitations of temporal moment analysis.
Abstract
No abstract has been registered
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No abstract has been registered
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No abstract has been registered
Abstract
A major challenge in studies on the environmental fate of nanoparticles is to detect their presence and distinguish them from natural nanoparticles and the large variety of amorphous materials present in environmental media. Neutron activation of mineral particles enables the production of radio-labelled NPs without surface modification, and enabling both localisation and quantification within a matrix or organism. The method is extremely sensitive, allowing detection at parts per billion or lower. Thus, any such labelled NP can be detected in individual fractions or compartments in soil or sediments (associated to clay, colloids, humic material, etc) or localized within organisms and their specific tissues following dissection (fish gills, digestive tract, liver, brain, etc) or by autoradiography. An added advantage of gamma-emitting radionuclides is that they do not need separation from the matrix for counting, thus uptake and extraction can be followed on live animals. Thus time-course experiments in vivo may be conducted to study metabolism and exposure, two aspects that are currently lacking in the body of ecotoxicological knowledge about ENPs. This paper will report some of the conditions, advantages and experimental opportunities of using neutron activation as a tool to study ENPs in environmental samples, with demonstration of the application of the technique in studies on Ag and Co nanoparticle uptake and metabolism in the earthworm Eisenia fetida.
Abstract
A major challenge in studies on the environmental fate of nanoparticles is to detect their presence and distinguish them from natural nanoparticles and the large variety of amorphous materials present in environmental media. Neutron activation of mineral particles enables the production of radio-labelled NPs without surface modification, and enabling both localisation and quantification within a matrix or organism. The method is extremely sensitive, allowing detection at parts per billion or lower. Thus, any such labelled NP can be detected in individual fractions or compartments in soil or sediments (associated to clay, colloids, humic material, etc) or localized within organisms and their specific tissues following dissection (fish gills, digestive tract, liver, brain, etc) or by autoradiography. An added advantage of gamma-emitting radionuclides is that they do not need separation from the matrix for counting, thus uptake and extraction can be followed on live animals. Thus time-course experiments in vivo may be conducted to study metabolism and exposure, two aspects that are currently lacking in the body of ecotoxicological knowledge about ENPs. This paper will report some of the conditions, advantages and experimental opportunities of using neutron activation as a tool to study ENPs in environmental samples, with demonstration of the application of the technique in studies on Ag and Co nanoparticle uptake and metabolism in the earthworm Eisenia fetida.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered