| 1. |
- Erlandsson Lampa, Martin, et al.
(författare)
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Catchment export of base cations : improved mineral dissolution kinetics influence the role of water transit time
- 2020
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Ingår i: SOIL. - : Copernicus GmbH. - 2199-3971 .- 2199-398X. ; 6:1, s. 231-244
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Tidskriftsartikel (refereegranskat)abstract
- Soil mineral weathering is one of the major sources of base cations (BC), which play a dual role in forest ecosystems: they function as plant nutrients and buffer against the acidification of catchment runoff. On a long-term basis, soil weathering rates determine the highest sustainable forest productivity that does not cause acidification. It is believed that the hydrologic residence time plays a key role in determining the weathering rates at the landscape scale. The PROFILE weathering model has been used for almost 30 years to calculate weathering rates in the rooting zone of forest soils. However, the mineral dissolution equations in PROFILE are not adapted for the saturated zone, and employing these equations at the catchment scale results in a significant overprediction of base cation release rates to surface waters. In this study, we use a revised set of PROFILE equations which, among other features, include retardation due to silica concentrations. Relationships between the water transit time (WTT) and soil water concentrations were derived for each base cation, by simulating the soil water chemistry along a one-dimensional flow path, using the mineralogy from a glacial till soil. We show how the revised PROFILE equations are able to reproduce patterns in BC and silica concentrations as well as BC ratios (Ca2+/BC, Mg2+/BC and Na+/BC) that are observed in the soil water profiles and catchment runoff. In contrast to the original set of PROFILE equations, the revised set of equations could reproduce the fact that increasing WTT led to a decreasing Na+/BC ratio and increasing Ca2+/BC and Mg2+/BC ratios. Furthermore, the total release of base cations from a hillslope was calculated using a mixing model, where water with different WTTs was mixed according to an externally modeled WTT distribution. The revised set of equations gave a 50% lower base cation release (0.23 eqm 2 yr 1) than the original PROFILE equations and are in better agreement with mass balance calculations of weathering rates. Thus, the results from this study demonstrate that the revised mineral dissolution equations for PROFILE are a major step forward in modeling weathering rates at the catchment scale.
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| 2. |
- Haraldsson, Hördur V., et al.
(författare)
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Causal Loop Diagrams – Promoting Deep Learning of Complex Systems in Engineering Education (rev 2007-05-11)
- 2006
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- The use of systems analysis involving tools like Causal loop diagrams and stock and flow diagrams can be shown in practical tests to greatly enhance systems insight and understanding of the dynamic behaviour of complex systems. Whereas many students may have difficulty understanding what a coupled system of differential equations really do, systems analysis creates such insights even to those with differentiofobia. Within the systems analysis course given at LUMES, we have extensive experience in teaching systems analysis and the use of CLD and SFDs to people of different backgrounds, and also seen how technical problems in engineering have a great help in using CLD and SFDs to explain and communicate insight into complex systems to non-technical people
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| 3. |
- Ny, Henrik, et al.
(författare)
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Systems Dynamic Modeling within Sustainability Constraints
- 2005
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Konferensbidrag (refereegranskat)abstract
- In this study we are asking ourselves whether ■Systems Dynamic Modelling■ can be combined with ■Backcasting from Sustainability Principles■ to support strategic planning towards sustainability. From the perspective of a ■Backcasting Practitioner■, ■Systems Dynamic Modelling■ is a set of tools that help gaining insight into the detailed functioning of a given system, but lacks the ability to support strategic planning towards sustainability ■ unless complemented with a satisfactory goal definition. ■Backcasting from Sustainability Principles■, in the eyes of a ■Systems Modeller■, is the planning step of a learning loop that also includes action implementation and follow-up. Since no dynamic modelling takes place this methodology typically produces laundry lists of isolated problems and solutions, thereby missing potentially important feedback loops, delays, hidden problems and suitable intervention points in the system.
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| 4. |
- Sverdrup, Harald U., et al.
(författare)
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Developing an approach for Sweden, Switzerland, United States and France for setting critical loads based on biodiversity including management, pollution and climate change
- 2015
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800. ; 306, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- The integrated dynamic ecosystem model ForSAFE-VEG was used to estimate critical loads for nitrogen using different chemical and biological criteria, and attempting to account for possible effects of climate change. The study is based on a model application on sites used for critical loads assessments in Sweden and France, focusing on the ecological effect of nitrogen pollution. To assess critical loads for nitrogen to ecosystems, two criteria were used for the critical loads estimates, N leaching, and changes in plant community composition, and assessed using the models mentioned. We show that the models give results consistent with earlier results using other methods such as the simple mass balance method. We show that the new model system is operational over the whole of the territory and may be used for policy development and policy outcome assessments.
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| 5. |
- Sverdrup, Harald U., et al.
(författare)
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How large is the global population when limited by long term sustainable global metal-, energy-and phosphate supply ?
- 2020
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Ingår i: System Dynamics Society, International Conference Proceedings.
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Konferensbidrag (refereegranskat)abstract
- The WORLD7 model was used to make an assessment for the sustainable metal usage and the resources available within the planetary limits to human society, in order to estimate demands on recycling and maximum metal consumption per capita for different metals. The metals were selected for their importance in society. The calculations of critical metal use show that we have substantial metal usage above the sustainable rates, needing a reduction in net use of more than 95% for many metals. Alternatively, the issue was turned around, asking, if this is how much metals that is available, how many people for how long can we support with it? A sustainability gap can be determined, alternatively, that the global population needs to come down in size to somewhere between 1.5-2 billion people, combined with improved recycling efficiencies. How a global population contraction can take place is not discussed.
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| 6. |
- Sverdrup, Harald U., et al.
(författare)
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On modelling the global copper mining rates, market supply, copper price and the end of copper reserves
- 2014
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Ingår i: Resources, Conservation & Recycling. - : Elsevier BV. - 0921-3449. ; 87, s. 158-174
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Tidskriftsartikel (refereegranskat)abstract
- The world supply and turnover of copper was modelled using simple empirical estimates and a COPPER systems dynamics model developed for this study. The model combines mining, trade markets, price mechanisms, population dynamics, use in society and waste as well as recycling, into a whole world system. The degree of sustainability and resource time horizon was estimated using four different methods including (1) burn-off rates, (2) peak discovery early warning, (3) Hubbert's production model, and (4) COPPER, a system dynamics model. The ultimately recoverable reserves (URR) have been estimated using different sources that converge around 2800 million tonne, where about 800 million tonne have already been mined, and 2000 million tonne remain. The different methods independently suggest peak copper mine production in the near future. The model was run for a longer period to cover all systems dynamics and delays. The peak production estimates are in a narrow window in time, from 2031 to 2042, with the best model estimate in 2034, or 21 years from the date of writing. In a longer perspective, taking into account price and recycling, the supply of copper to society is estimated to run out sometime after 2400. The outputs from all models put focus on the importance of copper recycling so that society can become more sustainable with respect to copper supply. (C) 2014 Elsevier B.V. All rights reserved.
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