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
Authors
Nina Elisabeth NagyAbstract
No abstract has been registered
Authors
Wenche Dramstad Wendy Fjellstad Geir-Harald Strand Henrik Forsberg Mathiesen Gunnar Engan Jogeir N. StoklandAbstract
No abstract has been registered
Authors
Nicholas ClarkeAbstract
In natural waters, total organic carbon (TOC) is the sum of particulate and dissolved organic carbon. Dissolved organic carbon (DOC) is operationally defined, usually as organic carbon that passes through a 0.45 µm filter. Cellulose acetate or nitrate filters should not be used for this purpose due to contamination or adsorption problems. Glass fibre filters are preferable. Although the discussion below concerns DOC, much of it applies to TOC as well. Organic carbon is most often determined after oxidation to CO2 using combustion, an oxidant such as persulphate, UV or other high-energy radiation, or a combination of some of these. If only UV radiation with oxygen as oxidant is used, low DOC values may be obtained in the presence of humic substances. A variety of methods are used for detection, including infrared spectrometry, titration and flame ionization detection after reduction to methane. Always follow the instrument manufacturer’s instructions. For determination of dissolved organic carbon, dissolved inorganic carbon must be either removed by purging the acidified (for example with phosphoric acid) sample with a gas which is free from CO2 and organic compounds, or determined and subtracted from the total dissolved carbon. If acidification followed by purging is used, care should be taken as volatile organic compounds may also be lost. After acidification, remove CO2 by blowing a stream of pure carbon-free inert gas through the system for at least 5 minutes. Carbon is ubiquitous in nature, so reagents, water, and glassware cannot be completely cleaned of it. Method interferences (positive bias) may be caused by contaminants in the carrier gas, dilution water, reagents, glassware, or other sample processing hardware (for example a homogenization device). All of these materials must be routinely demonstrated to be free from interference under the conditions of analysis by running reagent blanks. Plastic bottles can bleed carbon into water samples, especially when they are new, or when they are used for low-level samples (less than 200 ppb C). Any new bottles (especially plastic) should ideally be filled with clean water for a period of several days or boiled in water for a few hours before use. The use of high purity or purified reagents and gases helps to minimise interference problems. It is very important to use ultra-pure water with a carbon filter or boiled distilled water just before preparing stock and standard solutions, in order to remove dissolved CO2. The stock solution should not be kept too long (about one week). For most DOC instruments a correction for DOC (due to dissolved CO2) in the dilution water used for calibration standards is necessary, especially for standards below 10 ppm C. The carbon in the blank should only be subtracted from standards and not from samples. For calibration, standard solutions are most often potassium hydrogen phthalate for total dissolved carbon and sodium bicarbonate for dissolved inorganic carbon. The DOC concentration should be within the working range of the calibration. If necessary the sample can be diluted. Sample DOC below about 50 ppb C can be affected by atmospheric exposure. In these cases, sampling bottles should be kept closed when possible, and autosampler vials should be equipped with septa for needle piercing by the autosampler.
Authors
Stig Strandli GezeliusAbstract
No abstract has been registered
Authors
Klaus MittenzweiAbstract
The growing concern about sub-national domestic support to agriculture is caused by the increased international monitoring of agricultural policies (through the WTO and the OECD) combined with the resulting problems of broadening the scope of agricultural policies to include rural development concerns. In this study, the term «sub-national» is defined as including any level of governance below a country’s (or a group of countries’) top level of governance. Australia, the EU, and the United States are selected as case studies in an attempt to describe and compare the evidence, significance, and reporting procedures of sub-national domestic support. These countries are major actors in world agricultural markets, possess considerable political power to influence international negotiation outcomes, and are able to set standards in the way sub-national domestic support is reported. The study shows that sub-national domestic support is evident in all countries investigated, but its significance varies considerably. Measured as a percentage of total domestic support, sub-national domestic support accounted for 5% and 15% in the US and the EU, respectively, while it reached 50% in Australia. The main reasons for the differences can be found in the historical development of the countries’ governance structure in general and the evolution of the countries’ agricultural policies in particular. […]
Authors
Kjell Andreassen Bernt-Håvard ØyenAbstract
Six experimental sites in the coastal spruce (Picea abies L. Karst.) forest of central Norway were investigated. A comparison of different silviculture systems was performed based on the present situation of mature stands, and a single tree selection system, a group system and a clearcutting system were studied. The diameter distribution shows the classical inverse J-shaped curve at five of six sites. The mean tree volume removed in the selection system was 0.6 m3, and about 0.3 m3 for the other two methods. The harvesting cost was about 14 Euro/m3 for clearcutting, and about 10% higher for the group and selection systems. In simulations of all future revenues and expenses based on the observed stand conditions, cutting and extraction costs, the net present value (NPV) was app. 15% lower for the group and selection systems compared to clearcutting. A lower stem volume production in uneven-aged stands and higher administration and harvesting costs had only a minor influence on the NPV. One percent higher interest rate lowered the NPV of the group and selection systems to 75% of the clearcutting method.
Authors
Inger Sundheim FløistadAbstract
No abstract has been registered
Authors
Vibeke LindAbstract
No abstract has been registered
Authors
Kjersti Holt HanssenAbstract
No abstract has been registered
Abstract
No abstract has been registered