Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2008
Sammendrag
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.
Sammendrag
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Sammendrag
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Forfattere
H. Dupré de Boulois Erik J. Joner C. Leyval I. Jakobsen B.D. Chen P. Roos Y. Thiry G. Rufyikiri B. Delvaux S. DeclerckSammendrag
Det er ikke registrert sammendrag
Sammendrag
Studies regarding the environmental impact of engineered nanoparticles (ENPs) are hampered by the lack of tools to localize and quantify ENPs in water, sediments, soils, and organisms. Neutron activation of mineral ENPs offers the possibility of labeling ENPs in a way that avoids surface modification and permits both localization and quantification within a matrix or an organism. Time-course experiments in vivo also may be conducted with small organisms to study metabolism and exposure, two aspects currently lacking in ecotoxicological knowledge about ENPs. The present report explains some of the prerequisites and advantages of neutron activation as a tool for studying ENPs in environmental samples and ecologically relevant organisms, and it demonstrates the suitability of neutron activation for Ag, Co/Co3O4, and CeO2 nanoparticles. In a preliminary experiment with the earthworm Eisenia fetida, the dietary uptake and excretion of a Co nanopowder (average particle size, 4 nm; surface area, 59 m(2)/g) were studied. Cobalt ENPs were taken up to a high extent during 7 d of exposure (concentration ratios of 0.16-0.20 relative to the ENP concentration in horse manure) and were largely retained within the worms for a period of eight weeks, with less than 20% of absorbed ENPs being excreted. Following dissection of the worms, Co-60 was detected in spermatogenic cells, cocoons, and blood using scintillation counting and autoradiography. The experimental opportunities that neutron activation of ENPs offer are discussed.
2007
Forfattere
Arne Grønlund Tormod BriseidSammendrag
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Sammendrag
Leakage of tributyltin (TBT) to coastal environment is documented globally and represents environmental hazards because of long half lives in anaerobic environment and accumulation in biota. Concentrations below 1 ng/l influence marine organisms. Hence, pollution control authorities request abatements to mitigate toxic concentration levels. Dredging of contaminated sediments is one abatement strategy, but this approach requires safe landfill repositories. An alternative strategy is to cover contaminated sea bottom areas by cap layers of favourable composition and thereby reduce TBT exposure to the environment. Both abatement strategies require understanding of chemical and physical processes involved at the pore scale and at the field scale. In the present study pore scale processes are investigated by laboratory experiments on dredged sediments from contaminated sea bottom and integrated to field scale by numerical simulations. The distribution of TBT between solid and water phase is a function of several parameters viz texture; composition of clay minerals; content of organic matter; pH; and salinity in the pore water. The influences of these parameters on the mobility of TBT in sediments are studied with emphasize on variable salinity flux through the porous media. In our data the mobility of TBT increases as a function of decreasing salinity. Long term leakage of TBT is simulated in a typified near shore landfill with initial marine salt water concentration in the pore water. Initial TBT concentration in pore water is estimated to 30 ng/l, which is corresponding to a chemical equilibrium of 1 mg/kg of TBT in the sediments. Because sorption of TBT varies as a function of salinity, the transport of TBT has to be coupled to concentration of NaCl in the pore water. The pore water flow depends not only on the relation between infiltration of meteoric water and permeability of the sediments, but also on the concentration of NaCl, thus Darcy law has to be coupled to transport of NaCl. In this way transport of TBT require a coupling of three types of physics. First is Darcy pore water flow coupled to concentration of NaCl, and then concentration of NaCl is coupled to desorption of TBT.
Sammendrag
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Sammendrag
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Forfattere
Trine EggenSammendrag
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