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71.
Søvik AK Alfnes E Breedveld GD French HK Pedersen TS Aagaard P 《Journal of environmental quality》2002,31(6):1809-1823
A lysimeter trench was established at the Gardermoen delta (50 km north of Oslo, Norway) to study the flow of water and transport and degradation of aromatic jet fuel components (toluene and o-xylene) in the undisturbed unsaturated zone. Site investigations with ground-penetrating radar revealed the presence of dipping sedimentary layers within the foreset unit. This study has shown that the foreset bed of the Gardermoen delta structure provided a preferential flow path for the transport of the solute plumes, but did not have dramatic effects on the degradation potential under the current conditions. The degradation potential for toluene and o-xylene in the unsaturated zone at Gardermoen was very high and almost all of the injected hydrocarbons were biodegraded before reaching the saturated zone. However, the horizontal displacement of the plume showed that knowledge about sedimentary structures in the unsaturated zone is important for a sufficient monitoring of contaminant transport and for remediation purposes. Carbon dioxide and O2 were measured in situ simultaneously with extraction of water samples, and indicated aerobic biodegradation of toluene and o-xylene. Overall, first-order degradation coefficients were calculated to be in the range of 0.19 to 0.21 d(-1) and 0.10 to 0.11 d(-1) for toluene and o-xylene, respectively. 相似文献
72.
Monte L Brittain JE Håkanson L Heling R Smith JT Zheleznyak M 《Journal of environmental radioactivity》2003,69(3):177-205
A variety of models for predicting the behaviour of radionuclides in fresh water ecosystems have been developed and tested during recent decades within the framework of many international research projects. These models have been implemented in Computerised Decision Support Systems (CDSS) for assisting the appropriate management of fresh water bodies contaminated by radionuclides. The assessment of the state-of-the-art and the consolidation of these CDSSs has been envisaged, by the scientific community, as a primary necessity for the rationalisation of the sector. The classification of the approaches of the various models, the determination of their essential features, the identification of similarities and differences among them and the definition of their application domains are all essential for the harmonisation of the existing CDSSs and for the possible development and improvement of reference models that can be widely applied in different environmental conditions. The present paper summarises the results of the assessment and evaluation of models for predicting the behaviour of radionuclides in lacustrine ecosystems. Such models were developed and tested within major projects financed by the European Commission during its 4th Framework Programme (1994-1998). The work done during the recent decades by many modellers at an international level has produced some consolidated results that are widely accepted by most experts. Nevertheless, some new results have arisen from recent studies and certain model improvements are still necessary. 相似文献
73.
The uptake of 109Cd and 65Zn and their stable isotopes by ryegrass (Lolium multiflorum Lam.), grown on two different soil types, was investigated in climatically controlled growth chambers at 9 and 21 degrees C. The soils were treated with 0 and 4% organic matter (pig [Sus scrofa] manure) and spiked with 109Cd and 65Zn before sowing. The organic matter addition resulted in increased uptake of the 109Cd, Cd, and Zn by ryegrass, but the uptake of 65Zn was decreased. The latter effect was ascribed to isotopic dilution of 65Zn as the amount of stable Zn in the plant tissues increased with the organic matter addition. The effect of temperature was more pronounced than that of organic matter addition, and the uptake of both 109Cd and 65Zn and their stable isotopes was higher in ryegrass grown at 21 degrees C than that grown at 9 degrees C. Results from fractionation and speciation analysis of soil cadmium and zinc were correlated with plant uptake, and there was a good consistency between observed plant uptake and the physico-chemical forms of cadmium and zinc in soil and soil solution presumed to be plant available. 相似文献
74.
A mechanistic sub-model predicting the influence of potassium on radiocesium uptake in aquatic biota
It is often argued that the quality of science is related to the possibilities of making accurate predictions. It has also long been argued that due to the complex nature of ecosystems, it will never be possible to predict important target variables, especially with more comprehensive dynamic models. New results in radioecology have, however, demonstrated that those arguments are no longer valid. The key to the predictive success lies in the structuring of the model. The accident at Chernobyl has, in fact, provided science with an intriguing opportunity to study how the pulse of 137Cs is transported through ecosystem pathways, thus revealing the basic structure of these ecosystems, i.e. which are the key and the less-important pathways. It is paradoxical to conclude that the Chernobyl accident is, perhaps, the most important factor behind the revolution in predictive ecosystem modelling which lies behind the decrease in the uncertainty factor from 10 to 0.25-0.5. The sub-model for the potassium moderator presented in this paper is an example of a mechanistically based sub-model used within the framework of a more comprehensive lake model for 137Cs. The K-moderator presented is derived from the existing knowledge on ion transport in biological membranes and takes into account ion equilibria modelled by the Nernst equation and the uptake kinetics quantified by the Michaelis-Menten model. It provides the type of structure to this overall lake model that helps to explain the excellent predictive power of this model. 相似文献
75.
Concentrations of Pb in livers of willow grouse (Lagopus lagopus), black grouse (Tetrao tetrix), and hare (Lepus timidus) were determined in samples collected during the period 1990-92 from 77 locations distributed across Norway. Our objective was to elucidate the impact of long-range atmospheric transport on the Pb exposure of the animals. The moss Hylocomium splendens was measured for atmospheric Pb deposition and Pb in soil at 60-cm depth was determined to reflect the natural geochemical background at the study locations. Strong positive relationships were found between Pb in liver and atmospheric deposition of Pb for all species and age groups studied. Results indicate that long-range atmospheric transport was the main source of Pb in the animals studied. This conclusion was supported by Pb analysis of typical food plants for the animals. Correlation between Pb in liver and Pb in soil mineral matter was observed only when considering sites with very low impact of atmospheric deposition. Even though the observed liver Pb concentrations may seem low (< or =12 microg g(-1) dw) they approach levels where sub-lethal effects cannot be ignored. 相似文献
76.
Harald Sverdrup Salim Belyazid Bengt Nihlgård Lars Ericson 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):163-179
The ForSAFE model, designed for modelling biogeochemical cycles (water, acidity, base cation, nitrogen and carbon) in terrestrial
ecosystems, was modified with a vegetation response module (VEG), incorporating the effects of: nitrogen pollution, acidification,
soil moisture, temperature, wind chill exposure, light and shading by trees, grazing by animals, competition between plants,
above ground for light and below ground for water and nutrients. The model calculates the response of number ground vegetation
plant groups. The integrated model was tested and validated at integrated level II forest monitoring sites across Sweden,
four have been shown here, and used to assess the effect of acidification and nitrogen pollution in relation to factors such
as climate change, forest management and changing grazing pressure. The response functions have been derived from single-factor
experiments and integrated through the model structure for use on whole systems. The tests with the model suggest that the
ground vegetation composition is reasonably well predicted, that much research remains before the model is fully tested and
operational, and that the model may serve as a tool for assessing impacts of climate change, acid rain and forest management
on plant biodiversity in forested areas. 相似文献
77.
78.
Per Angelstam Kjell Andersson Matilda Annerstedt Robert Axelsson Marine Elbakidze Pablo Garrido Patrik Grahn K. Ingemar Jönsson Simen Pedersen Peter Schlyter Erik Skärbäck Mike Smith Ingrid Stjernquist 《Ambio》2013,42(2):254-265
Translating policies about sustainable development as a social process and sustainability outcomes into the real world of social–ecological systems involves several challenges. Hence, research policies advocate improved innovative problem-solving capacity. One approach is transdisciplinary research that integrates research disciplines, as well as researchers and practitioners. Drawing upon 14 experiences of problem-solving, we used group modeling to map perceived barriers and bridges for researchers’ and practitioners’ joint knowledge production and learning towards transdisciplinary research. The analysis indicated that the transdisciplinary research process is influenced by (1) the amount of traditional disciplinary formal and informal control, (2) adaptation of project applications to fill the transdisciplinary research agenda, (3) stakeholder participation, and (4) functional team building/development based on self-reflection and experienced leadership. Focusing on implementation of green infrastructure policy as a common denominator for the delivery of ecosystem services and human well-being, we discuss how to diagnose social–ecological systems, and use knowledge production and collaborative learning as treatments. 相似文献
79.
Marine Elbakidze Per Angelstam Nikolay Sobolev Erik Degerman Kjell Andersson Robert Axelsson Olle Höjer Sandra Wennberg 《Ambio》2013,42(2):201-214
Protected area (PA) is an indicator linked to policies on ecological sustainability. We analyzed area, size, and categories of PAs in the European boreal forest biome in Norway, Sweden, Finland, and Russia from 1900 to 2010. The PA increased from 1.5 × 103 ha in 1909 to 2.3 × 107 ha in 2010. While the total PA in the boreal biome was 10.8 %, the figures ranged from 17.2 % in the northern, 7.9 % of the middle, and 8.7 % of the southern boreal sub-regions. The median size of PAs varied from 10 to 124 ha among countries. The categories of less strictly PAs increased over time. The proportion of area occupied by PAs is an important response indicator for conservation efforts. However, the use of PA as an indicator of ecological sustainability needs to consider ecosystem representation, functional connectivity and management categories. 相似文献
80.
Niwagaba C Nalubega M Vinnerås B Sundberg C Jönsson H 《Waste management (New York, N.Y.)》2009,29(2):585-589
In urine-diverting toilets, urine and faeces are collected separately so that nutrient content can be recycled unmixed. Faeces should be sanitized before use in agriculture fields due to the presence of possible enteric pathogens. Composting of human faeces with food waste was evaluated as a possible method for this treatment. Temperatures were monitored in three 78-L wooden compost reactors fed with faeces-to-food waste substrates (F:FW) in wet weight ratios of 1:0, 3:1 and 1:1, which were observed for approximately 20 days. To achieve temperatures higher than 15 degrees C above ambient, insulation was required for the reactors. Use of 25-mm thick styrofoam insulation around the entire exterior of the compost reactors and turning of the compost twice a week resulted in sanitizing temperatures (>or=50 degrees C) to be maintained for 8 days in the F:FW=1:1 compost and for 4 days in the F:FW=3:1 compost. In these composts, a reduction of >3 log(10) for E. coli and >4 log(10) for Enterococcus spp. was achieved. The F:FW=1:0 compost, which did not maintain >or=50 degrees C for a sufficiently long period, was not sanitized, as the counts of E. coli and Enterococcus spp. increased between days 11 and 15. This research provides useful information on the design and operation of family-size compost units for the treatment of source-separated faeces and starchy food residues, most likely available amongst the less affluent rural/urban society in Uganda. 相似文献