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.
2002
Abstract
The Norwegian intensive monitoring programme of forest condition has recorded rainfall, throughfall and soil water data from 1986 at 16 forest plots. Using covariance analysis, this study has examined short term and episodic influences on soil water ionic concentration at three of the plots, and identified both seasonal and long-term temporal trends. Acidity has decreased in bulk precipitation and throughfall, and the concentrations of base cations in the organic soil horizon have increased. Nevertheless, there is evidence of continued acidification in the organic and mineral soil horizons, though of a small scale. The influence of sea salt and drought effects on soil water chemistry are examined, but found to be unimportant in causing acidification effects such as increased soil aluminium concentration.
2001
Abstract
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.
Authors
Mehreteab TesfaiAbstract
No abstract has been registered
Authors
Mehreteab TesfaiAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Edward Tipping B. Michalzik Jan Mulder J.F. Gallardo Lancho E. Matzner Charlotte Bryant Nicholas Clarke S. Lofts A. Vicente EstebanAbstract
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.
Abstract
Materials and Methods: In the field, fresh samples were obtained from different sources. Lake samples were collected from Lake Årungen, which is located in Ås. Stream samples were collected from Ås and Birkenes in southern Norway. All the samples were filtered in the field through 0.45 um membrane filters using syringes. Then the samples were fractionated through Bond Elut SCX cartridges connected to a portable vacuum pump, based on the method of Wickstrøm et al. (2000). A portion of the sample was passed immediately through the cation exchange cartridge. After the fieldwork another portion of the sample was taken to the laboratory where the same fractionation procedure was applied. These two fractions were then analysed for non-labile aluminium. A portion of the unfractionated sample was also analysed for total dissolved aluminium. An additional laboratory fractionation with a time lag was also applied to observe storage effects. Subsequent determination of total elements was done using ICP-AES. Transport, pretreatment and storage can also have an effect on the pH and organic matter concentration of the samples and, through this, on the equilibrium between different Al fractions. To evaluate pH differences prior to analysis, pH values were also measured in the field and in the laboratory. DOC was also determined. Differences between fractionation in the field and fractionation in the laboratory: In this study, non-labile fractions of Al were compared instead of the labile fractions of Al (which can be removed from solution on passage through cation exchange column) that are believed to have the greatest toxic effect on organisms.
Abstract
Understanding sulfate transport and retention dynamics in forest soils is a prerequisite in predicting SO4 concentration in the soil solution and in lake and stream waters. In this study forest soil samples from the Grdsjn catchment, Sweden, were used to study SO4 transport in soil columns from the upper three soil horizons (E, Bs and BC).The columns were leached using a sequential leaching technique. The input solutions were CaSO4 equilibrated with forest floor material. Leaching behavior of SO4 and concentration in the effluent were measured from columns from individual horizons.SO4 was always retained in the Bs and BC horizons, while the pattern for the E horizon varied. Attempts were also made to model SO4 breakthrough results based on miscible displacement approaches and solute convection-dispersion equation (CDE) in porous media. Several retention mechanisms were incorporated into the CDE in order to account for possible reversible and irreversible SO4 reactions in individual soil layers.The model was not successful in describing the mobility of SO4 in the top (E) horizon. Moreover, a linear equilibrium approach was generally inadequate for describing sulfate mobility in the Bs and BC horizons whereas improved model descriptions were obtained when non-linear equilibrium and kinetic approaches were utilized.We conclude that sulfate retention during transport in this forest soil is most likely controlled by kinetic reactivity of SO4 by reversible and irreversible mechanisms.
Abstract
No abstract has been registered
Authors
Rolf D. Vogt E.T. Gjessing Dag Olav Andersen Nicholas Clarke T.C. Gadmar K. Bishop U.S. Lundström Michael StarrAbstract
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.