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
Denitrification is a key ecosystem process which is essential to avoid massive enrichment of nitrate in surface and ground water. A rather narrow group of bacteria are able to carry out denitrification, and they are known to be sensitive to environmentally toxic pollutants like e.g. heavy metals. Since these microorganisms carry out a key ecosystem function, they are strong candidates for testing and monitoring environmental effects of toxic substances likely to reach the soil environment. We conducted a series of experiments where either a pure strain of a denitrifying bacterium (Paracoccus denitrificans) or intact soil microbial communities containing indigenous denitrifiers were subjected to different types of silver nanoparticles (average particle size 20 and 1 nm) at a wide range of concentrations. The results showed that the smallest particles were far more toxic than the larger ones on a mass basis and completely killed off denitrifying bacteria in vitro at concentrations as low as 100 ppb. When soil was present, this concentration had no effect on respiration and even the far more sensitive process of denitrification, measured as production of the gases NO, N2O and N2, was unaffected. Results from experiments that are under way will also be presented. Here threshold levels for inhibition of denitrification by P. denitrificans and intact microbial communities are established for the two types of silver nanoparticles and where toxicity is compared when expressed on a mass basis vs. a surface area basis. Also the sensitivity of the different steps in the denitrification process will be compared and related to corresponding data for dissolved metals. The perspectives for using denitrification impediment as a way to assess ecotoxicity at a functional level will be discussed.
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Authors
Holger Lange Lukas GudmundssonAbstract
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Lukas Gudmundsson Lena M. Tallaksen Kerstin Stahl Holger LangeAbstract
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Lukas Gudmundsson Holger Lange Lena M. Tallaksen Kerstin StahlAbstract
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