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981.
The paper presents a model for contaminant transport and flux through a consolidating subaqueous sediment and overlying cap. The formulation is based on the effect of consolidation and excess pore pressure dissipation on transient, nonlinear advective component of transport through sediment and the cap. The consolidation is induced by the buoyant weight of the cap when it is placed on the contaminated sediments. One equation is presented for advective-diffusive transport through the sediment that is dependent upon soil/contaminant properties and transient advective velocity, which is calculated from a second equation based on the Terzaghi consolidation theory. A third equation is provided to describe the transport of contaminants in the cap. The parameters, including advective velocity, and boundary conditions used for contaminant transport through the cap are derived from the solution of the first two equations. The finite difference method is used to solve the system of equations for consolidation and contaminant transport. A hypothetical case is analyzed to demonstrate the formulation, and the results show that advection due to consolidation can accelerate breakthrough of contaminant through the cap by orders of magnitude. The derivation and results show that consolidation should be included for cap design, and that reactive caps are essential for delaying and reducing dissolved contaminant flux. 相似文献
982.
Attraction of two lacewing species to volatiles produced by host plants and aphid prey 总被引:1,自引:0,他引:1
Zhu J Obrycki JJ Ochieng SA Baker TC Pickett JA Smiley D 《Die Naturwissenschaften》2005,92(6):277-281
It is well documented that host-related odors enable many species of parasitoids and predatory insects to locate their prey and prey habitats. This study reports the first characterization of prey and prey host odor reception in two species of lacewings, Chrysoperla carnea (Say) and Chrysopa oculata L. 2-Phenylethanol, one of the volatiles emitted from their preys host plants (alfalfa and corn) evoked a significant EAG response from antennae of C. carnea. Traps baited with this compound attracted high numbers of adult C. carnea, which were predominantly females. One of the sex pheromone components (1R,4aS,7S,7aR)-nepetalactol of an aphid species, Acyrthosiphon pisum (Harris) attracted only C. oculata adults. Single sensillum recordings showed that the olfactory neurons of C. carnea responded to both 2-phenylethanol and aphid sex pheromone components, but those of C. oculata only responded to the latter. 相似文献
983.
Janus T Kirkeby Harpa Birgisdottir Trine Lund Hansen Thomas H Christensen Gurbakhash Singh Bhander Michael Hauschild 《Waste management & research》2006,24(1):3-15
A new model has been developed for evaluating the overall resource consumption and environmental impacts of municipal solid waste management systems by the use of life cycle assessment. The model is named EASEWASTE (Environmental Assessment of Solid Waste Systems and Technologies) and is able to compare different waste management strategies, waste treatment methods and waste process technologies. The potential environmental impacts can be traced back to the most important processes and waste fractions that contribute to the relevant impacts. A model like EASEWASTE can be used by waste planners to optimize current waste management systems with respect to environmental achievements and by authorities to set guidelines and regulations and to evaluate different strategies for handling of waste. The waste hierarchy has for decades been governing waste management but the ranking of handling approaches may not always be the most environmentally friendly. The EASEWASTE model can identify the most environmentally sustainable solution, which may differ among waste materials and regions and can add valuable information about environmental achievements from each process in a solid waste management system. 相似文献
984.
In this study, we examined the role of organizational level as a moderator of the relationships of procedural and distributive justice with seven employee attitudes and behaviors. Based on social identity and resource allocation theories, we suggested an allocational model of authority in organizations. We posited that lower rank encourages a more process‐oriented perspective that emphasizes procedural concerns while higher rank imbues a more result‐oriented perspective that emphasizes distributive outcomes. We considered the cultural context that characterized work relationships in our sample of respondents from a Chinese state‐owned enterprise. Significant sets of interactions supported the predicted relationships of procedural justice with three outcomes at lower levels and distributive justice with four outcomes at higher levels. Implications and extensions of these findings are considered. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
985.
Adapting to climate variability: Pumpkins, people and policy 总被引:2,自引:0,他引:2
Understanding of how best to support those most vulnerable to climate stress is imperative given expected changes in climate variability. This paper investigates local adaptation strategies to climate variability, focusing on agricultural decision‐making in a communal irrigation scheme in Vhembe District, Limpopo Province, South Africa. Research done through interviews, surveys and participatory methods demonstrates that adaptation strategies within a community are socially differentiated and present differing objectives and priorities. These results highlight the need for intervention and policy that support a heterogeneous response to a wide range of stresses. Evidence for climate change is clear and the need for adaptation is urgent. However, adaptation measures have to be sensitively integrated with ongoing development pathways to ensure they are sustainable and relevant to local priorities. 相似文献
986.
Ross Marshall Thomas B. Fischer 《Journal of Environmental Planning and Management》2006,49(2):279-299
Since 21 July 2004, formal strategic environmental assessment (SEA) requirements are in place for certain plans and programmes in European Union member states. Many public plans and programmes have been identified to fall under these requirements, and there has been a range of research activities particularly in land use and transport planning. However, the way in which SEA is to be applied in the private sector has remained largely unclear. Furthermore, to date there has been comparatively little reported private sector experience and the concrete benefits that SEA may deliver to private companies have not yet been discussed to any large extent. In order to address this shortcoming, the paper looks at SEA application in electricity transmission planning, taking the specific case of the privatized company ScottishPower as an example. Based on the evidence obtained, it is suggested that a structured SEA process can strengthen the environmental component and improve private sector decision-making processes. Corporate governance can be improved, if SEA is applied in a tiered system, addressing different issues and tasks at distinct stages in a clearly defined decision making hierarchy. 相似文献
987.
Thomas M. Yanosky 《Journal of the American Water Resources Association》1984,20(2):241-250
ABSTRACT: Ash trees (Fraxinus americana L. and F. Pennsylvanica Marsh.) collected from the flood plain of the Potomac River near Washington, D.C., were studied for evidence of associations between known periods of above-average summer flows and changes in wood-growth anatomy. Concentric bands of latewood fibers with atypically large lumens and thin walls commonly developed in trees growing near the low-water channel. Discharge records indicate that roots of most trees with these “white rings” were flooded temporarily during the latewood-growth interval. Trees apparently were not damaged and a concomitant reduction of internal water stresses seems to have accelerated the rate of radial growth. The intra-ring position of anomalous fibers generally corresponded to the time of increased discharge within the estimated interval of latewood growth. Anomalous fibers occasionally formed in unflooded trees, but their position also coincided with episodes of increased discharge. The results of these studies may have applications for streamflow-reconstruction techniques where hydrologic data are incomplete or lacking. 相似文献
988.
989.
在厌氧环境下的有机物的分解过程中,硫酸盐还原和甲烷生成是对端电子移动起着十分重要作用的过程.许多研究人员指出,硫酸盐还原菌(SRB)和甲烷生物共存于富硫酸盐的海洋沉积物中,而且通常为共同基层的使用而竞争[1~6]. 相似文献
990.