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Träfflista för sökning "hsv:(SAMHÄLLSVETENSKAP) hsv:(Annan samhällsvetenskap) hsv:(Tvärvetenskapliga studier) ;hsvcat:1;srt2:(2000-2004)"

Sökning: hsv:(SAMHÄLLSVETENSKAP) hsv:(Annan samhällsvetenskap) hsv:(Tvärvetenskapliga studier) > Naturvetenskap > (2000-2004)

  • Resultat 1-10 av 33
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  • Olsson, Johanna Alkan, 1968-, et al. (författare)
  • Setting Limits in Nature and the Metabolism of Knowledge : The Case of the Critical Load Concept
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • In the 1980s, the earlier understanding that environmental problems are relatively simple was questioned. In order to handle the perceived complexity, several responses emerged. The Critical Load concept is a prominent example of such a response, which was introduced in thesecond-generation Protocols of the Convention of Long Range Transport of Air Pollutants (CLRTAP). The aim of this thesis is to analyse the dynamics of the ideational content of the Critical Load concept, using a discursive approach on policy. At the centre of the analysis are theories, ideas and knowledge claims about nature and processes in nature. The empirical material consists of policy texts produced by the Swedish Environmental Protection Agency (SEPA) and interviews with SEPA employees.The Critical Load concept can be interpreted as a meeting place where perceptions of different pollutants, objects in nature and scientific disciplines, meet and interact under the common view of nature as being robust within limits. Chemical mass-balance calculations oftransboundary air pollution in soils and forests dominate the operationalisation of the concept. The dominating chemical perspective has two origins. The first is the acidification concept, which has been the central issue of CLR TAP and has mainly been identified and discussed as a chemical problem. The second is the perception that chemical processes can be exactly measured in nature just as they can in the laboratory. Consequently, it is also generally assumed that estimates based on calculations of chemical processes fit well into the larger discourse of economically and ecologically efficient environmental policy-making within which the Critical Load concept has been situated. A change in the Critical Load concept, from exact mass balance calculations to risk analysis, could be identified with the introduction of new pollutants into the CLRTAP policy agenda. For certain types of pollutants even the possibility defining limits is denied. The conceptual change is here interpreted as a shrinkinglegitimacy of the concept, which also encompasses a weakening of the dominant view of nature as being robust within limits. It is, however too early to judge if this change will lead to larger discursive changes and a general refutation of the ideas that nature's limits are calculable and that such limits provide suitable foundations for environmental policy.
  • Benyamine, Michelle, et al. (författare)
  • Multi-objective environmental management in constructed wetlands
  • 2004
  • Ingår i: Environmental Monitoring & Assessment. - 0167-6369. ; 90:1-3, s. 171-185
  • Tidskriftsartikel (refereegranskat)abstract
    • We examined multi-objective environmental management as applied to pursuing concurrent goals of water treatment, biodiversity and promotion of recreation in constructed wetlands. A case study of a wetland established to treat landfill leachate, increase biodiversity, and promote recreation was evaluated. The study showed that attempts to combine pollution management with activities promoting biodiversity or recreation are problematic in constructed wetlands. This could be because the typical single-objective focus of scientific research leads to contradictions when planning, implementing and assessing the multi-objective use of wetlands. In the specific case of wetland filters for landfill leachate treatment, biodiversity, and recreation, there is a need for further research that meet practical needs to secure positive outcomes.
  • Hassler, Björn, 1964- (författare)
  • The strategy of assistance : Swedish environmental support to the Baltic states 1991-1996
  • 2000
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Sweden has provided considerable amounts of environmental assistance to the Baltic States since their regained independence. To explain the existence and character of this support program, the rationales behind the Swedish policy have to be analyzed.This dissertation uses a rational choice approach, where it is assumed that the Swedish support to the Baltic States in the 1991-1996 period primarily was guided by self-interest. It is shown that there has been remarkable agreement among the political parties concerning the environmental support to the Baltic States during the whole period. This makes the unitary actor assumption reasonable. Swedish foreign aid history and earlier international environmental cooperation is provided as a background to the analysis of the support policy.It is shown that Sweden tended to favor support projects where the environmental impact had a trans-boundary character, thus implying that Swedish environmental interests were affected. This choice of policy introduced a bias in the allocation of environmental investments in the Baltic States, as they have been required to fmance the largest part of the investments with local funding. The consequence has been that issue-areas that have not been attractive to foreign aid providers have been neglected.
  • Bjorn, H, et al. (författare)
  • Metabolic fate of C-14-labelled chlorinated and non-chlorinated fatty acids in goldfish (Carassius auratus)
  • 2004
  • Ingår i: Fish Physiology & Biochemistry. - Springer. - 0920-1742. ; 30:1, s. 13-20
  • Tidskriftsartikel (refereegranskat)abstract
    • In order to study the metabolic fate of chlorinated fatty acids in fish, goldfish were fed either 9,10-dichlorostearic acid or oleic acid, chosen as the unchlorinated analogue, both radiolabelled at either the carboxyl (1st) or the terminal (18th) carbon of the fatty acid chain. By keeping the fish in hermetically closed aquaria, all the respired, assimilated and excreted radioactivity could be accounted for. Fish fed 9,10-dichlorostearic acid labelled in the terminal end respired radioactive CO2 to a much lower degree than fish fed the other test compounds. As a consequence, the radioactivity bound in lipids was higher in the group of fish fed dichlorostearic acid labelled in the terminal end. It is suggested that the chlorine atoms in the middle of the carbon chain obstruct the metabolic turn-over of 9,10-dichlorostearic acid, which may have an impact on the residence time of these compounds in the ecosystem.
  • Andrén, Thomas, et al. (författare)
  • Evidence of the final drainage of the Baltic Ice Lake and the brackish phase of the Yoldia Sea in glacial varves from the Baltic Sea
  • 2002
  • Ingår i: Boreas. - 0300-9483. ; 31, s. 226-238
  • Tidskriftsartikel (refereegranskat)abstract
    • A clay-varve chronology based on 14 cross-correlated varve graphs from the Baltic Sea and a mean varve thickness curve has been constructed. This chronology is correlated with the Swedish Time Scale and covers the time span 11 530 to 10 250 varve years BP. Two cores have been analysed for grain size, chemistry, content of diatoms and changes in colour by digital colour analysis. The final drainage of the Baltic Ice Lake is dated to c. 10800 varve years BP and registered in the cores analysed as a decrease in the content of clay. This event can be correlated with atmospheric D 14 C content and might have resulted in an increase in these values recorded between 11565 and 11545 years BP. The results of the correlation between the varve chronology from the Baltic Sea, the Greenland GRIP ice core and the atmospheric D 14 C record indicate that c. 760 years are missing in the Swedish Time Scale in the part younger than c. 10 250 varve years BP. A change in colour from a brownish to grey varved glacial clay recorded c. 10 770 varve years BP is found to be the result of oxygen deficiency due to an increase in the rate of sedimentation in the early Preboreal. The first brackish influence is recorded c. 10 540 varve years BP in the northwestern Baltic Sea and some 90 years later in the eastern Gotland Basin.
  • Sohlenius, Gustav, et al. (författare)
  • Development of anoxia during the Holocene fresh-brackish water transition in the Baltic Sea
  • 2001
  • Ingår i: MARINE GEOLOGY. - ELSEVIER SCIENCE BV. - 0025-3227. ; 177:3-4, s. 221-242
  • Tidskriftsartikel (refereegranskat)abstract
    • One of the most pronounced environmental changes during the Holocene Baltic Sea history was the transition from the freshwater Ancylus Lake to the brackish water Litorina Sea. The establishment of brackish conditions during this transition (the A/L) was c
  • Grönlund, Andreas, et al. (författare)
  • Networking the seceder model : Group formation in social and economic systems
  • 2004
  • Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics : Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics. - 1063-651X. ; 70:3, s. 036108
  • Tidskriftsartikel (refereegranskat)abstract
    • The seceder model illustrates how the desire to be different from the average can lead to formation of groups in a population. We turn the original, agent based, seceder model into a model of network evolution. We find that the structural characteristics of our model closely match empirical social networks. Statistics for the dynamics of group formation are also given. Extensions of the model to networks of companies are also discussed.
  • Jonzén, Niclas, et al. (författare)
  • Seasonal herbivory and mortality compensation in a swan-pondweed system.
  • 2002
  • Ingår i: Ecological Modelling. - Elsevier. - 0304-3800. ; 147:3, s. 209-219
  • Tidskriftsartikel (refereegranskat)abstract
    • Many birds feed on submerged macrophytes during a temporally discrete period every year, for instance during migratory stopover or at the wintering grounds. Hence, seasonal herbivory is a common feature of the life cycle in many aquatic macrophytes. We are interested in the effect of Bewick's swans (Cygnus columbianus bewickii) feeding on the tubers of fennel pondweed (Potamogeton pectinatus) in the Netherlands every autumn. For that purpose, we developed a sequential macrophyte population model, including seasons of tuber production, herbivory and winter mortality as distinct and unambiguously defined events. The model is characterised and parameterised with both field and laboratory data. Tuber consumption inevitably decreases the density of ramets sprouting next spring, but it may actually increase the density of tubers produced in the following autumn. Hence, we can only understand the effect of grazing on the fennel pondweed population by recognising the seasonal structure of density-dependence. The mean density of fennel pondweed and the yield taken by swans are dependent on the foraging threshold below which no grazing takes place. Furthermore, the consumption has a stabilising effect for a wide range of parameter values.
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