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.
2001
Forfattere
Rolf D. Vogt E.T. Gjessing Dag Olav Andersen Nicholas Clarke T.C. Gadmar K. Bishop U.S. Lundström Michael StarrSammendrag
In the Total Organic Carbon (TOC) intercalibration sub-project a set of 10 synthetic and natural samples as well as non-labile reverse osmosis isolates were sent to 25 laboratories for the analysis of TOC and dissolved Organic Carbon (DOC).The outcome of the statistical treatment of the results from this intercalibration and the information regarding the participants instruments and standard operational procedures is that:Synthetic samples provide apparent better precision than natural samples. This fact, together with the good experience from the use of non-labile Reverse Osmosis (RO) and freeze dried isolates of dissolved organic carbon (DOM) in the intercalibration, lead us to recommend the use of RO isolates as material for the preparation of house standards and for determination of methods merits.The intra laboratory precision (relative standard deviation) varied from 5 to 16%.The fractionation of the DOC by 0.45um membrane filtering causes in some cases a contamination of carbon to the sample.A specific construction in a brand of the TOC analysers give poor results in samples with high TOC concentrations and that are of refractory material. The five selected sampling sites have proven, on the basis of their soil and water chemistry, to be well suited for studying the effect of climate and S-deposition on the characteristics of DOM. 163 water samples from two seasons (fall and spring) and 20 soil samples are collected and analysed.Most water samples are determined for all major charge contributing species, DOM fractions, and several other parameters. The DOM in the surface waters have been isolated both using reverse osmosis and hydrophobic resin (XAD8). The original surface water, reconstructed water by RO isolates as well as the XAD8 fractionated DOM have been characterized by a number of methods ranging from optical properties to pH and metal titration.The RO isolates have been provided to 14 scientific research groups in Europe and North America that are in the process of using their analytical technique to characterize the DOM.The soils have been determined for key explanatory variables as pH, cation exchange capacity and C/N ratio. The main findings from the characterisation of DOM is that:Generally the hydrophobic acid fraction (HPO-A) was the main DOM fractions in all water compartments and sites.Seasonal variation in the DOM fractionation is found to be greater than the variation between the sites and water compartments. The DOM fractionation is therefore not a fingerprint of the site.According to a batch titration experiment the aluminium complexing ability of the HPO-A and hydrophilics (HPI) DOM fractions (fractionated using only the XAD8 resin) was indistinguishable.The HPI fraction has generally a higher site density of weak acids (WA).The reverse osmosis (RO) isolates represent the total DOM in the original sample.NMR spectres of the RO isolates show that the main difference between the sites lie in the amounts of carbohydrates and aromatic compounds.The RO isolates produce reconstructed water with DOM that have similar optical properties.PCA analysis suggest that as the S-deposition is decreasing we should expect relatively more hydrophobic character of the DOM.The spring sample from Svartberget differs from the rest of the samples in that there was a small rainstorm causing a hydrologic episode during the sampling. This led to the lowest pH, highest TOC and organic charge (A-) among the surface water samples. In terms of DOM characteristics this temporal variation in flow regime led to the highest HPO-N DOM fractions, lowest intensity of the NMR spectre and low ash content and lower density of WA then expected. This expresses the importance of temporal variation during hydrologic episodes.
Forfattere
Rolf D. Vogt K. Bishop Nicholas Clarke T.C. Gadmar E.T. Gjessing Jan Mulder Michael Starr Dag Olav AndersenSammendrag
The main tasks of the NOMiNiC project (Natural Organic Matter in the Nordic countries; see http://www.kjemi.uio.no/envir/nominic/) is to study the physiochemical characteristics of dissolved organic matter (DOM) and provide reverse osmosis (RO) spring and fall isolates of surface water natural organic matter (NOM) from 5 Nordic forested sites that differ mainly in atmospheric S-loading and climate. Hydrophobic and hydrophilic fractions are hypothesized to be more easily defined and have distinct different chemical characteristics than the total sample. A XAD-8 fractionation may then be used as a simple proxy for the physico-chemical properties of NOM. Both XAD-8 fractions and the total DOM sample have been base and metal titrated. Enhanced understanding of the significance of the numerous operationally defined parameters describing NOM will be achieved through a common multi-dimensional characterisation of the same set of isolates, that span a large spectre of the variation found in DOM. 7 institutes are already collaborating in characterizing the RO isolates using a large range of techniques and new participants are invited. In this presentation the 5 sampling sites are described and some results of the characterisation of the RO isolates are presented.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Edward Tipping B. Michalzik Jan Mulder J.F. Gallardo Lancho E. Matzner Charlotte Bryant Nicholas Clarke S. Lofts A. Vicente EstebanSammendrag
DyDOC identifies three soil horizons with different properties. Within each horizon the transport of wter, metabolic transformations of organic matter, and sorption of potential DOC are simulated. The model is parameterised by fitting experimental laboratory and field data, including 14C signals. The outputs are quasi-steady state C pools, varying on long timescales (centuries) and daily DOC concentrations and fluxes.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Fire ulike komposter ble benyttet til å evaluere ulike kjemiske parameteres egnethet som stabilitetsindeks. Vannløselig TOC viste signifikant korrelasjon til biologisk aktivitet målt som respirasjonsrate, og foreslås som en mulig operasjonell parameter ved komposteringsanlegg.
Sammendrag
Det er ikke registrert sammendrag
2000
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
A small number of measuring points may inflict a bias on the characterisation of flow and transport based on field experiments in the unsaturated zone. Simulation of pure advective transport of a Gaussian plume through a setup of 30 regularly placed measuring points revealed regular temporal fluctuations about the real spatial moments. An irregular setup predicted both irregular fluctuations and larger discrepancies from the real value. From these considerations, a regular setup is recommended. Spatial moments were sensitive to the plume size relative to the distance between individual measuring points. To reduce prediction errors of the variance, the distance between the measuring points should be less than twice the standard deviation of the examined plume. The total size of the setup should cover several standard deviations of the plume to avoid mass being lost from the monitored area. Numerical simulations of a dispersing plume (comparing calculations based on 9000 nodes with 30 measuring points) revealed that vertical and horizontal centres of mass were predicted well at all degrees of heterogeneity, and the same was the case for horizontal variances. Vertical variances were more susceptible to prediction errors, but estimates were of the same order of magnitude as the real values.
Sammendrag
Våtkjemiske oksydasjon ved bruk av Fentons reagens viste å kunne bryte ned DDT i forsøk med oppgravde forurensede masser. Det ble i løpet av de første 5 minutter oppnådd ca. 50% reduksjon og ved å forlenge behandlingsprosessen opp til 12-24 timer ble rundt 80% nedbrytning målt. Hvitråtesopp viste en i størrelsesorden 31-37% nedbrytning i løpet av 4 ukers behandling. Forsøkene har demonstrert at metoden både med hensyn på oppnådd renseresultat og økonomi, kan anvendes for avhending av oppgravd forurenset jord fra skogplanteskoler.