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.
2009
Abstract
Silver nanoparticles constitute one of the most common nanomaterials used in consumer products today, and the volumes used are increasing dramatically. Silver is an element known for its acute toxicity to both prokaryotes and a range of aquatic organisms. While ecotoxicity studies on nano-sliver is being studied at species level for some aquatic organisms, corresponding studies on terrestrial organisms are lagging behind. Also, studies targeting functional endpoints rather than purely physiological aspects are lacking. We have compared two types of nano-silver differing in average particle size (1 and 20 nm) with respect to their inhibitory effects on a pure strain of the soil bacterium Paracoccus sp. Which is an efficient denitrifyer capable of transforming NO3 into N2. This process is an important step in the biogeochemical cycling of N, and one that may potentially produce large amounts of the potent green house gas N2O if impeded by environmental pollutants. The results show that nano-silver is highly toxic to denitrifying bacteria and that low amounts severely affect the process of denitrification. Studies using indigenous denitrifying bacterial communities incubated in the presence of different concentrations of nano-silver in soil slurries are under way and will provide data where soil constituents affect the bioavailability nano-silver in a close to realistic exposure scenario. The implications of the relationship between toxicity levels in pure cultures and soil slurries will be discussed regarding the bioavailability of nanoparticles as pollutants in terrestrial environments.
Abstract
Due to the exponential increase in production of engineered nanomaterials, concerns are raised about their inevitable spreading and fate in the environment. In this study we examined the uptake and excretion kinetics of cobalt and silver nanoparticles (NPs) in Eisenia fetida, as well as their internal distribution within earthworms. We hypothesised that the uptake, retention time and internal distribution of cobalt and silver depend on their speciation, i.e. whether they are absorbed as ions or nanoparticles. Nanoparticles were subjected to neutron activation prior to the experiment, in order to facilitate tracing and quantification in earthworms by gamma counting and autoradiography. Ions and NPs were added to the food, horse manure (HM). The treatments were Co2+ 0.70 µg/kg HM, CoNP 0.69 mg/kg HM, Ag+ 0.54 mg/kg HM, AgNP 0.45 mg/kg HM, and control. The experiment followed the OECD guidelines, with one month uptake and two months excretion for silver treatments, and four months excretion for cobalt treatments. The patterns of accumulation were highly different for cobalt and silver. The concentration ratios (Bq/g worm / Bq/g food) after one month uptake were 0.93 ± 0.36 and 2.02 ± 0.65 for CoNP and Co2+ respectively, and almost all absorbed CoNP and Co2+ remained within the worms after 4 months excretion. The Ag concentration ratios after one month uptake were 0.015 ± 0.016 and 0.054 ± 0.024 for AgNP and Ag+ respectively, with a subsequent excretion of almost all AgNP and Ag+ within a few days. In addition to information on uptake and excretion kinetics, gamma counting on individual organs, coupled to autoradiography on worm transects gave information on distribution of cobalt and silver NPs within the body, and the target organs for these NPs.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
2008
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
Authors
H. Dupré de Boulois Erik J. Joner C. Leyval I. Jakobsen B.D. Chen P. Roos Y. Thiry G. Rufyikiri B. Delvaux S. DeclerckAbstract
No abstract has been registered
Abstract
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.