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
Authors
Holger Lange Nicholas Clarke O. Janne Kjønaas Wenche Aas Kjell Andreassen Isabella Børja Harald Bratli Susanne Eich-Greatorex Toril Drabløs Eldhuset Kjersti Holt Hanssen Tonje Økland Ingvald Røsberg Trine Aulstad Sogn Tomasgaard Volkmar TimmermannAbstract
No abstract has been registered
2008
Abstract
No abstract has been registered
Abstract
Recent in situ 13C studies suggest that lignin is not stabilised in soil in its polymerised form. However, the fate of its transformation products remains unknown. The objective of the present research was to provide the first comprehensive picture of the fate of lignin-derived C across its transformations processes: (1) C remaining as undecomposed lignin molecules, (2) C in newly formed humic substances, i.e. no longer identifiable as lignin-polymer C, (3) C in microbial biomass, (4) C mineralised as CO2, and (5) dissolved organic C. To achieve this objective, we designed an incubation experiment with 13C-labelled lignin where both elementary and molecular techniques were applied. Lignin was isolated from 13C labelled maize plants (13C-MMEL) and incubated in an agricultural soil for 44 weeks. Carbon mineralisation and stable isotope composition of the released CO2 were monitored throughout the incubation. Microbial utilisation of 13C-MMEL was measured seven times during the experiment. The turnover rate of the lignin polymer was assessed by 13C analysis of CuO oxidation products of soil lignin molecules. After 44 incubation weeks, 6.0% of initial 13C-MMEL carbon was mineralised, 0.8% was contained in the microbial biomass, and 0.1% was contained in dissolved organic C form. The compound-specific 13C data suggest that the remaining 93% were overwhelmingly in the form of untransformed lignin polymer. However, limited transformation into other humic substances potentially occurred, but could not be quantified because the yield of the CuO oxidation method proved somewhat variable with incubation time. The initial bacterial growth yield efficiency for MMEL was 31% and rapidly decreased to plateau of 8%. A two-pool first-order kinetics model suggested that the vast majority (97%) of MMEL lignin had a turnover time of about 25 years, which is similar to field-estimated turnover times for soil-extractable lignin but much longer than estimated turnover times for fresh plant-residue lignin. We conclude that natural lignin structures isolated from plants are rather unreactive in soil, either due to the lack of easily available organic matter for co-metabolism or due to enhanced adsorption properties. The data also suggest that fairly undecomposed lignin structures are the main reservoir of lignin-derived C in soils.
Authors
Karsten Raulund-Rasmussen Inge Stupak Nicholas Clarke Ingeborg Callesen Helja-Sisko Helmisaari Erik Karltun Iveta Varnagiryte-KabasinskieneAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Nicholas Clarke Nathalie Cools John Derome Kirsti Derome Bruno De Vos Alfred Fuerst Anna Kowalska Rosario Mosello Gabriele A. Tartari Erwin Ulrich Nils KönigAbstract
Over the past years considerable efforts have been made to improve the quality of laboratory analyses in the various monitoring programmes within the framework of the ICP Forests programme. The Soil and Soil Solution, Deposition and Foliage and Litterfall expert panels have carried out a number of ring tests and held discussions on quality control. The expert panels’ subgroup, \"Working Group on QA/QC in Laboratories\", has extended its activities from the quality control of water analyses to encompass all forms of laboratory analysis, and now also includes experts in the fields of soil, foliage and litterfall. This paper presents all the quality control methods that have been devised for the relevant fields of analytical chemistry. The aim is to provide those laboratories carrying out analyses within the ICP Forests programme with a complete overview of the possibilities of applying quality control in their laboratories.
Authors
Rosario Mosello Tiziana Amoriello Sue Benham Nicholas Clarke John Derome Kirsti Derome Gerrit Genouw Nils Konig Arianna Orrù Gabriele Tartari Anne Thimonier Erwin Ulrich Antti-Jussi LindroosAbstract
No abstract has been registered
Authors
Rosario Mosello Tiziana Amoriello Sue Benham Nicholas Clarke John Derome Kirsti Derome Gerrit Genouw Arianna Orrù Gabriele A. Tartari Anne Thimonier Erwin Ulrich Antti-Jussi Lindroos Nils KönigAbstract
A Working Group on Quality Assurance/Quality Control of analyses in laboratories active in the chemical analysis of atmospheric deposition and soil water has been created within the framework of the Integrated Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (UN-ECE/ICP Forests) and the EU/Forest Focus Programme (Regulation 2152/2003). This paper is a follow up to an earlier paper dealing with the validation of chemical analyses, in which validation techniques (ion balance, comparison between measured and calculated conductivity, Na/Cl ratio and relationship between different forms of N) were tested on a set of real analysis data obtained from different laboratories. This paper focuses on the validation of chemical analysis of samples containing high dissolved organic carbon (DOC) concentrations ( 5 mg C L-1), where the ion balance criterion fails because of the presence of weak organic acids. About 6000 chemical analyses of bulk open field, throughfall and stemflow samples, which contained complete sets of all ion concentrations, conductivity and DOC, produced in 8 different laboratories, were used to calculate empirical relationships between DOC and the difference between the sum of cations and the sum of anions, with the aim to evaluate a formal charge per mg of organic C...
Authors
Jihong Liu Clarke Carl Jonas Jorge Spetz Sissel Haugslien Shaochen Xing Merete Dees Roar Moe Dag-Ragnar BlystadAbstract
Agrobacterium-mediated transformation for poinsettia (Euphorbia pulcherrima Willd. Ex Klotzsch) is reported here for the first time. Internode stem explants of poinsettia cv. Millenium were transformed by Agrobacterium tumefaciens, strain LBA 4404, harbouring virus-derived hairpin (hp) RNA gene constructs to induce RNA silencing-mediated resistance to Poinsettia mosaic virus (PnMV). Prior to transformation, an efficient somatic embryogenesis system was developed for poinsettia cv. Millenium in which about 75% of the explants produced somatic embryos. In 5 experiments utilizing 868 explants, 18 independent transgenic lines were generated. An average transformation frequency of 2.1% (range 1.2-3.5%) was revealed. Stable integration of transgenes into the poinsettia nuclear genome was confirmed by PCR and Southern blot analysis. Both single- and multiple-copy transgene integration into the poinsettia genome were found among transformants. Transgenic poinsettia plants showing resistance to mechanical inoculation of PnMV were detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Northern blot analysis of low molecular weight RNA revealed that transgene-derived small interfering (si) RNA molecules were detected among the poinsettia transformants prior to inoculation. The Agrobacterium-mediated transformation methodology developed in the current study should facilitate improvement of this ornamental plant with enhanced disease resistance, quality improvement and desirable colour alteration. Because poinsettia is a non-food, non-feed plant and is not propagated through sexual reproduction, this is likely to be more acceptable even in areas where genetically modified crops are currently not cultivated.
Abstract
No abstract has been registered