| 1. |
- Alveteg, Mattias, et al.
(författare)
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Developing a kinetic alternative in modeling soil aluminium.
- 1995
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Ingår i: Water, Air and Soil Pollution. - 1573-2932. ; 79:1-4, s. 377-389
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Tidskriftsartikel (refereegranskat)abstract
- Soil chemistry models often use gibbsite solubility and similar equilibrium models to predict Al concentrations in soil solution. A kinetic alternative was developed with the goal of finding universal rate constants instead of the site- and depth-specific solubility constants usually associated with the equilibrium approach. The behavior of the two approaches was studied within the framework of the steady-state soil chemistry model PROFILE using data from Solling, Germany and Gårdsjön, Sweden, two sites with different mineralogy and land use history. The kinetic alternative uses a mass balance to predict Al concentrations. The sources of Al in soil water are deposition, weathering and mineralization. The sinks are leaching and the formation of an aluminosilicate precursor. The precursor slowly transforms into an ordinary clay mineral. Both formation and transformation of the precursor are treated as irreversible processes. The kinetic model introduces a new relationship between pH and Al and produces a systematic pattern of different apparent gibbsite equilibrium constants at different depths. Results show that the kinetic model systematically underestimates Al concentration in the upper horizons, which indicates that there may be additional sources of Al in the upper horizons not accounted for in the model. Predicted values of pH and Al concentrations are comparable with field observations.
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| 2. |
- Alveteg, Mattias, et al.
(författare)
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Reconstructing historic atmospheric deposition and nutrient uptake from present day values using MAKEDEP.
- 1998
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Ingår i: Water, Air and Soil Pollution. - 1573-2932. ; 104:3-4, s. 269-283
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Tidskriftsartikel (refereegranskat)abstract
- A model, MAKEDEP, was developed for reconstructing historic atmospheric deposition and nutrient uptake for forests using present day values. Deposition is reconstructed by separation of wet deposition and throughfall into five different categories. Dry deposition is assumed to depend linearly on needle biomass. Non-marine deposition is scaled using general European emission and deposition trends for sulphur, nitrate and ammonia. Historic nutrient uptake is reconstructed using current biomass and nutrient content, a logistic forest growth curve and information on historic land use.
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| 3. |
- Alveteg, Mattias, et al.
(författare)
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Regional assessment of the temporal trends in soil acidification in Southern Sweden, using the safe model
- 1995
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Ingår i: Water, Air and Soil Pollution. - 1573-2932. ; 85:4, s. 2509-2514
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic soil acidification model SAFE was applied to 44 forested sites in Skåne, southern Sweden, using available Swedish databases on present soil status, vegetation and deposition. Time series of deposition were derived for each site from present deposition in a generalized fashion by dividing deposition into different classes and scaling with deposition trends from the literature. This study connects the current status of the soil and the soil development with critical load maps calculated with the steady-state model PROFILE. The model was calibrated against measurements of present base saturation from the Swedish Forest Inventory. Model output was compared with available measurements of soil water chemistry. Model output was used to assess the time delay between changes in acidic input and system response in terms of exchangeable base cations and pH. The model was also used for scenario analysis, applying the reductions agreed in the Oslo Protocol to assess the environmental benefits of the agreement.
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| 4. |
- Andersson, Roy, et al.
(författare)
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Developing a teaching and learning culture – the case of Faculty of Engineering at Lund University
- 2012
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Ingår i: Proceedings of Annual Conference.
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Konferensbidrag (refereegranskat)abstract
- The first chapter of this paper will give an overview of different ways of developing a university’s teaching and learning. There are many single activities that individually deal with the topic in a positive direction, such as teacher training, develop learning environments, develop teacher reward systems, etc. Traditionally educational development has been about these single activities focusing on individual teachers. But there has also been a change over time towards an increasingly focus on institutional strategies and even national policies. The second chapter sets the scene for the academic development work in the Faculty of Engineering at Lund University and the third chapter provides examples on aligned institutional activities and strategies, as well as an assessment of strong and weaker areas.
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| 5. |
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| 6. |
- Barkman, A, et al.
(författare)
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Regionalization of critical loads under uncertainty
- 1995
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Ingår i: Water, Air and Soil Pollution. - 1573-2932. ; 85:4, s. 2515-2520
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Tidskriftsartikel (refereegranskat)abstract
- The steady-state model PROFILE was used to perform Monte Carlo simulations of critical loads of acidity and exceedances of forest soils for 128 sites in the province of Scania, southern Sweden. Statistical tests showed that 100 sites had normal distributed critical loads and exceedances and that the variance of these parameters was statistically equal for all sites. Pooled estimates df the standard deviation was 0.19 and 0.31 kmol(c) ha(-1) yr(-1) for the critical loads and exceedances, respectively. Introduction of uncertainties, expressed as confidence intervals, in the cumulative distribution function for critical loads showed that overlaps between percentiles were substantial. The 5%-ile was systematically equal to the 57%-ile using a 67% confidence interval and equal to the 87%-ile when a 95% confidence level was chosen. The overlaps of percentiles cause a reduction of acidic deposition according to the mean value of the 5%-ile to protect only 68% of the ecosystem area with an 84% probability and not a guaranteed protection of 95% as if uncertainties did not exist. Thus, uncertainties make it possible to advocate reductions to levels of deposition below the 5%-ile of critical loads.
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| 7. |
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| 8. |
- Belanger, N, et al.
(författare)
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Simulation of soil chemistry and nutrient availability in a forested ecosystem of southern Quebec - I. Reconstruction of the time-series files of nutrient cycling using the MAKEDEP model
- 2002
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Ingår i: Environmental Modelling & Software. - 1364-8152. ; 17:5, s. 427-445
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Tidskriftsartikel (refereegranskat)abstract
- The MAKEDEP model is used to reconstruct the time-series input files of deposition, forest growth, uptake and litterfall needed to run the dynamic biogeochemical model SAFE. The amounts and timing of N made available for tree growth is what determines most of the model output. In this paper, the sensitivity Of MAKEDEP to various amounts and timing of N availability, including increased supplies of N prior to air pollution assuming increased biological N-2 fixation, was assessed in a small hardwood stand of southern Quebec. The scenarios of N cycling were validated for burned and unburned conditions based on the simulated tree growth and N leaching rates as well as the model's ability to recreate the trends in atmospheric deposition of major ions in northeastern North America. The N leaching rates were calculated as the residual component of all simulated processes acting as sources and sinks of N. The N availability scenarios that subtracted/added 5 mmol m(-2) yr(-1) of NH4 in the unburned and burned conditions, respectively, recreated N leaching rates and tree biomass with the most precision. Modifying the amounts of N made available prior to air pollution was also necessary for the trees to grow to reasonable values before 1900. Historical trends of deposition were linked to the changes in the continental emissions in northeastern North America. Observational data for 30 years at the Hubbard Brook Experimental Forest, New Hampshire, showed convergent trends for most ions with the deposition trends simulated with MAKEDEP.
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| 9. |
- Belanger, N, et al.
(författare)
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Simulation of soil chemistry and nutrient availability in a forested ecosytem of southern Quebec. Part II. Application of the SAFE model
- 2002
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Ingår i: Environmental Modelling & Software. - 1364-8152. ; 17:5, s. 447-465
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic soil model SAFE was calibrated and validated in a small hardwood forest of southern Quebec as a function of its ability to reproduce current soil chemistry and similar pre-industrial soil conditions despite the difference in forest history. SAFE was relatively accurate for reproducing soil chemistry, but comparison of pre-industrial soil conditions between unburned and burned stands casts doubt as to its applicability at sites where specific processes may be involved in nutrient cycling, e.g. the immobilization of N by microbes. Simulated soil chemistry in the unburned zone reinforced the conclusions of a few historical studies which support the hypothesis that acid-sensitive forest sites of northeastern USA underwent significant acidification when major inputs of acidity from the atmosphere occurred, i.e. during the 1930-1980 time span. Model projections in the mineral soil suggest that a new steady-state should be reached in the 21st century assuming no harvest, but that this equilibrium is broken if timber harvesting is done. Model output also suggests that cation nutrient deficiencies could occur in the long-term, but future Al phytotoxic responses are unlikely to occur due to a relatively high projected pH. Finally, it was demonstrated that the time-series files of nutrient cycling should be prepared with care as they can be the source of some abnormalities in model calibration.
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| 10. |
- Dérand, Per, et al.
(författare)
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Glomangioma: a case presentation.
- 2010
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Ingår i: Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. - : Elsevier BV. - 1531-5053 .- 0278-2391. ; 68:1, s. 204-7
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Forskningsöversikt (refereegranskat)
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