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961.
We have developed a new version of the MERGE model, called MERGE-ETL, to analyse the dynamics of endogenous technological learning (ETL) in the energy system. This paper describes the basic formulation of MERGE-ETL, the solving techniques used for this model and some first numerical results in the context of policies designed to mitigate global climate changes. 相似文献
962.
Effects of initial iron corrosion rate on long-term performance of iron permeable reactive barriers: Column experiments and numerical simulation 总被引:2,自引:1,他引:2
Jin suk O Sung-Wook Jeen Robert W. Gillham Lai Gui 《Journal of contaminant hydrology》2009,103(3-4):145-156
Column experiments and numerical simulation were conducted to test the hypothesis that iron material having a high corrosion rate is not beneficial for the long-term performance of iron permeable reactive barriers (PRBs) because of faster passivation of iron and greater porosity loss close to the influent face of the PRBs. Four iron materials (Connelly, Gotthart-Maier, Peerless, and ISPAT) were used for the column experiments, and the changes in reactivity toward cis-dichloroethene (cis-DCE) degradation in the presence of dissolved CaCO3 were evaluated. The experimental results showed that the difference in distribution of the accumulated precipitates, resulting from differences in iron corrosion rate, caused a difference in the migration rate of the cis-DCE profiles and a significant difference in the pattern of passivation, indicating a faster passivation in the region close to the influent end for the material having a higher corrosion rate. For the numerical simulation, the accumulation of secondary minerals and reactivity loss of iron were coupled using an empirically-derived relationship that was incorporated into a multi-component reactive transport model. The simulation results provided a reasonable representation of the evolution of iron reactivity toward cis-DCE treatment and the changes in geochemical conditions for each material, consistent with the observed data. The simulations for long-term performance were also conducted to further test the hypothesis and predict the differences in performance over a period of 40 years under typical groundwater conditions. The predictions showed that the cases of higher iron corrosion rates had earlier cis-DCE breakthrough and more reduction in porosity starting from near the influent face, due to more accumulation of carbonate minerals in that region. Therefore, both the experimental and simulation results appear to support the hypothesis and suggest that reactivity changes of iron materials resulting from evolution of geochemical conditions should be considered in the design of iron PRBs. 相似文献
963.
964.
965.
I. A. Romanenko V. A. Romanenkov P. Smith J. U. Smith O. D. Sirotenko N. V. Lisovoi L. K. Shevtsova D. I. Rukhovich P. V. Koroleva 《Regional Environmental Change》2007,7(2):63-77
This study estimates the consequences of climate change on cropland with and without implementation of adaptation measures,
paying special attention to the maintenance of soil organic carbon (C) stocks. We examine the possibility for regional sustainable
agricultural management practice that combines both maintenance and gain in soil carbon level with profit maximization. Future
scenarios of Regional Agricultural Production Systems (RAPS) were constructed for 2000–2070 based on linking the effects of
global climate change, predicted change in productivity parameters for the main agricultural crops, land-use and soil database
parameters. The RAPS were used to examine profitability and feasibility of alternative agricultural scenarios, based on an
economic model. A number of recommendations for decision making were proposed based on an assessment of the efficiency of
adaptation in animal husbandry and in the crop production sector, after analysis of current percentage of perennial grass
in rotation in comparison with future economic scenarios.
Figures in color are available at 相似文献
966.
Reproduction and survival of tawny owls in relation to persistent organic pollutants 总被引:1,自引:0,他引:1
The potential effects of organochlorines (OCs) and brominated flame retardants on reproduction and survival were studied in tawny owls (Strix aluco) in Central Norway over a period of 19 years (1986-2004). Concentrations of 14 OCs and five polybrominated diphenyl ethers (PBDEs) were measured in eggs (n=104), and Principal Component Analysis was used to produce composite measurements of pollutants; i.e. PC1 and PC2, which accounted for 85% of the variation in contaminant concentrations. There was no evidence for adverse associations between pollutants (PC scores) and life-history traits such as clutch size, probability of producing fledglings and survival, when controlling for potentially confounding variables. Moreover, there was no evidence for interactions between pollutants and vole abundance suggesting no synergistic effects of food stress and pollutants on these life-history traits. There was, however, some evidence for a non-linear negative association between p,p'-DDE (1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene) and eggshell thickness. This suggests that the concentrations of pollutants in this ecosystem were too low to affect reproduction and survival in an owl predominantly consuming prey at low trophic levels, but may be sufficient to cause eggshell thinning at the highest concentrations. 相似文献
967.
The spatial distribution of coarse woody debris in pine forests has been studied in the Transvolga region of the Marii El Republic. For this purpose, 30 test plots have been established in pine (Pinus sylvestris) stands of the study region. The results are indicative of a tendency toward the spatial grouping (clustering) of woody debris by fractions, decomposition classes, and stocks along with increase in stand age. 相似文献
968.
R. W. Pohl E. Schmidt G. C. Hirsch H. Marquardt O. Harnisch 《Die Naturwissenschaften》1959,46(11):387-388
969.
970.
Mario Schirmer John W. Molson Emil O. Frind James F. Barker 《Journal of contaminant hydrology》2000,46(3-4)
Biodegradation of organic contaminants in groundwater is a microscale process which is often observed on scales of 100s of metres or larger. Unfortunately, there are no known equivalent parameters for characterizing the biodegradation process at the macroscale as there are, for example, in the case of hydrodynamic dispersion. Zero- and first-order degradation rates estimated at the laboratory scale by model fitting generally overpredict the rate of biodegradation when applied to the field scale because limited electron acceptor availability and microbial growth are not considered. On the other hand, field-estimated zero- and first-order rates are often not suitable for predicting plume development because they may oversimplify or neglect several key field scale processes, phenomena and characteristics. This study uses the numerical model BIO3D to link the laboratory and field scales by applying laboratory-derived Monod kinetic degradation parameters to simulate a dissolved gasoline field experiment at the Canadian Forces Base (CFB) Borden. All input parameters were derived from independent laboratory and field measurements or taken from the literature a priori to the simulations. The simulated results match the experimental results reasonably well without model calibration. A sensitivity analysis on the most uncertain input parameters showed only a minor influence on the simulation results. Furthermore, it is shown that the flow field, the amount of electron acceptor (oxygen) available, and the Monod kinetic parameters have a significant influence on the simulated results. It is concluded that laboratory-derived Monod kinetic parameters can adequately describe field scale degradation, provided all controlling factors are incorporated in the field scale model. These factors include advective–dispersive transport of multiple contaminants and electron acceptors and large-scale spatial heterogeneities. 相似文献