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1.
There is a growing demand for alternatives to Sweden’s current dominant silvicultural system, driven by a desire to raise biomass production, meet environmental goals and mitigate climate change. However, moving towards diversified forest management that deviates from well established silvicultural practices carries many uncertainties and risks. Adaptive management is often suggested as an effective means of managing in the context of such complexities. Yet there has been scepticism over its appropriateness in cases characterised by large spatial extents, extended temporal scales and complex land ownership—characteristics typical of Swedish forestry. Drawing on published research, including a new paradigm for adaptive management, we indicate how common pitfalls can be avoided during implementation. We indicate the investment, infrastructure, and considerations necessary to benefit from adaptive management. In doing so, we show how this approach could offer a pragmatic operational model for managing the uncertainties, risks and obstacles associated with new silvicultural systems and the challenges facing Swedish forestry.  相似文献   
2.
By combining digital humanities text-mining tools and a qualitative approach, we examine changing concepts in forestry journals in Sweden and the United States (US) in the early twentieth and early twenty-first centuries. Our first hypothesis is that foresters at the beginning of the twentieth century were more concerned with production and less concerned with ecology than foresters at the beginning of the twenty-first century. Our second hypothesis is that US foresters in the early twentieth century were less concerned with local site conditions than Swedish foresters. We find that early foresters in both countries had broader—and often ecologically focused—concerns than hypothesized. Ecological concerns in the forestry literature have increased, but in the Nordic countries, production concerns have increased as well. In both regions and both time periods, timber management is closely connected to concerns about governance and state power, but the forms that governance takes have changed.  相似文献   
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Two anticoccidial agents, salinomycin and robenidine, heavily used in the worldwide veterinary meat production, were investigated for their potential biotic degradation by cultured soil bacteria. The degradation-study was performed in lab-scale bio-reactors under aerobic and anaerobic conditions incubated for 200 h with a mixed culture of soil bacteria. Samples were analyzed by LC-MS/MS and potential transformation products were tentatively identified. Salinomycin was degraded under aerobic conditions and traces could be found after 200 h, however, seems more persistent under anaerobic conditions. Four transformation products of salinomycin were discovered. Robenidine was degraded under aerobic and anaerobic conditions, however, traces of robenidine were observed after 200 h. Five biotic transformation products of robenidine were discovered.  相似文献   
5.
If the release mechanisms during selective chemical extraction of persistent organic pollutants (POP) mimic release mechanisms in natural systems during biological uptake, then a selective non-exhaustive extraction could give a quantitative measure of the bioavailable POP fraction. Supercritical fluid extraction (SFE) is suggested as a possible technique to estimate the amount of bioavailable polychlorinated biphenyls (PCBs) at contaminated sites and hence serve as a new tool in risk assessment. The uptake of PCBs by earthworm (Eisenia foetida) was investigated. PCB contaminated soil was pre-extracted with selective non-exhaustive SFE (50 degrees C, 350 bar, 1h), which removed on average 70% of the individual PCBs. Earthworms were placed in this pre-extracted soil, as well as in untreated soil. After 10 days, the PCB uptake by earthworms in the two systems was compared. The bioaccumulation factor (BAF) was 83% lower in the pre-extracted system than in the untreated system, demonstrating that SFE extracts primarily bioavailable contaminants. From the data, the bioavailable fraction could also be calculated to be 75%, which is very close to the 70% removed by SFE under the applied conditions. This suggests that the chemical methodology is capable of measuring the bioavailable fraction very accurately in this system.  相似文献   
6.
Habermas's theory of communicative action is used in this paper to develop a cultural model for empirical studies of environmental policy processes. The model consists of three cultural ideal types: anthropocentric material; anthropocentric immaterial; and ecocentric immaterial. Obstacles to social learning and public participation, such as forms and styles of reasoning and the exclusion of citizens, are brought into focus. Finally, the model functions as a criticism of a pure liberal view of environmental problems.  相似文献   
7.
A simple selective supercritical fluid extraction (SFE) method was developed for the determination of desorption behaviour of PCBs in sediments. This method was applied to determine the distribution of individual PCB congeners among sites of differing bonding strengths in two Swedish sediments (Lake J?rnsj?n and Baltic bay Orserumsviken). Four different PCB fractions were distinguished in each sediment by applying consecutively harsher supercritical fluid extraction conditions on the same sample. Even though the two sediments had completely different textures, they showed very similar extraction behaviour. It was shown that, in both sediments, a major part of the PCBs (58% and 65%, respectively) were located at "fast sites", from which they were extractable already with the mildest extraction conditions (60 min, 40 degrees C and 120 bar). Only a small fraction of the PCBs were so tightly bound to the sediments (located at "slow sites"), that they could be extracted only under the harshest conditions (60 min, 150 degrees C and 400 bar). Information of this kind should be of great value for the determination of bioavailability of pollutants in sediments and soils, and it is the author's belief that this technique has the potential to develop into a powerful tool in environmental risk assessment.  相似文献   
8.
Selective supercritical fluid extraction (SFE) at 40 degrees C, 120 bar and 60 min was utilised as a means to estimate the bioavailable fraction of PCBs to chironomid larvae in a naturally contaminated limnic sediment. This extraction methodology removed about 50% of the PCBs from the sediment. According to the equilibrium partitioning theory, organisms in that sediment should decrease their uptake from the sediment to the same extent, biota-to-sediment accumulation factors (BSAFs) thus remaining constant. Surprisingly, the BSAFs for 11 PCB congeners decreased some 40% for the selectively extracted sediment as compared to BSAFs for organisms dwelling in untreated sediment. The results were statistically significant at the 0.001 level using a paired t-test. This can only be interpreted so that selective SFE removed easily available PCBs preferentially, leaving more tightly bound PCBs behind. Hence, by fine-tuning extraction conditions, this methodology might be used to estimate bioavailable fractions by chemical means.  相似文献   
9.
A naturally contaminated sediment was partially extracted with selective supercritical fluid extraction (SFE) to remove a fraction of supposedly bioavailable PCBs from the matrix. Eels (Anguilla anguilla) were cultured in systems with untreated and pre-extracted sediment, respectively, and it was shown that the SFE treatment selectively removed bioavailable PCBs from the sediment, since relative biota-to-sediment accumulation factors (BSAFs) for the eight studied PCB congeners were much lower in the pre-extracted than in the untreated system at the end of the study. Relative BSAF values decreased with about the same relative amount for all eight congeners, independent of the degree of chlorination and the initial concentration in the sediment. The results demonstrate the ability of SFE to selectively remove sediment-bound PCBs that are available for uptake by the eels, thus demonstrating the feasibility of using selective SFE to estimate bioavailability of PCBs in sediments.  相似文献   
10.
In the vulnerable Arctic environment, the impact of especially hazardous wastes can have severe consequences and the reduction and safe handling of these waste types are therefore an important issue. In this study, two groups of heavy metal containing particulate waste materials, municipal solid waste incineration (MSWI) fly and bottom ashes and mine tailings (i.e., residues from the mineral resource industry) from Greenland were screened in order to determine their suitability as secondary resources in clay-based brick production. Small clay discs, containing 20 or 40% of the different particulate waste materials, were fired and material properties and heavy metal leaching tests were conducted before and after firing. Remediation techniques (washing in distilled water and electrodialytical treatment) applied to the fly ash reduced leaching before firing. The mine tailings and bottom ash brick discs obtained satisfactory densities (1669–2007 kg/m3) and open porosities (27.9–39.9%). In contrast, the fly ash brick discs had low densities (1313–1578 kg/m3) and high open porosities (42.1–51. %). However, leaching tests on crushed brick discs revealed that heavy metals generally became more available after firing for all the investigated materials and that further optimisation is therefore necessary prior to incorporation in bricks.  相似文献   
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