This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport. 相似文献
The concept of sustainable development has experienced great development and change at different levels of theoretical connotation and practical implementation since 1960s and 1970s when it was first proposed. People’s understanding of the relationship between economy, society, and environment has been continuously deepened over the years. When it came to the end of 2015, it is necessary to examine the results of the United Nations Millennium Development Goals on sustainable development, and at the same time, the post-2015 framework and guidance on sustainable development at the global level were to be made, including the ideas, action plans, key areas that would guide the global sustainable development. The 2030 Agenda for Sustainable Development has developed a 5P theoretical framework of being people-centered, global environmental security, sustained economic prosperity, social justice and harmony and partnership promotion, including a political declaration, 17 overarching goals and 169 specific targets, specific ways of implementation, as well as the follow-up. It is the road map to achieve global sustainable development and meet the requirements of the millennium development goals. This paper summarizes the understanding of the concept of sustainable development from its origin, its significant development, to the proposition and development of the 2030 Agenda for Sustainable Development, and its strategic impact on China. 相似文献
Leaching behavior and gastrointestinal bioaccessibility of rare earth elements (REEs) from hospital waste incineration (HWI) fly and bottom ash samples collected from Beijing and Nanjing Cities were assessed. In the same ash sample, the leaching concentrations of individual REEs determined by the Toxicity Characteristic Leaching Procedure (TCLP) were higher than those detected by the European standard protocol (EN-type test), thereby suggesting that the low pH value of leaching solution was an important factor influencing the leachability of REE. The REE bioaccessibility results, which were evaluated using the physiologically based extraction test (PBET), indicated that REEs were highly absorbed during gastric phase by dissolution; and subsequently precipitated and/or re-adsorbed in small intestinal phase. The relative amounts of the total REEs extracted by the TCLP method, EN-type test and PBET test were compared. In addition to the pH value of extraction solutions, the chelating role of REEs with organic ligands used in the PBET method was also an important parameter affecting REE adsorption in human body. Additionally, this study showed that REEs were extracted by these methods as concomitants of heavy metals and anions (NO3–, F–, SO42–, and Cl–) from HWI ash, which probably caused the remarkably complex toxicity on human body by the exposure pathway.
The diamondback moth, Plutella xylostella, is recognized as a widely distributed destructive insect pest of Brassica worldwide. The management of this pest is a serious issue, and an estimated annual cost of its management has reached approximately US$4 billion. Despite the fact that chemicals are a serious threat to the environment, lots of chemicals are applied for controlling various insect pests especially P. xylostella. An overreliance on chemical control has not only led to the evolution of resistance to insecticides and to a reduction of natural enemies but also has polluted various components of water, air, and soil ecosystem. In the present scenario, there is a need to implement an environmentally friendly integrated pest management (IPM) approach with new management tactics (microbial control, biological control, cultural control, mating disruption, insecticide rotation strategies, and plant resistance) for an alternative to chemical control. The IPM approach is not only economically beneficial but also reduces the environmental and health risks. The present review synthesizes published information on the insecticide resistance against P. xylostella and emphasizes on adopting an alternative environmentally friendly IPM approach for controlling P. xylostella in China. 相似文献
Environmental Science and Pollution Research - In the present study, heavy metal (HM)-tolerant phosphate solubilizing bacteria (PSB) were isolated and their performance during the remediation of Pb... 相似文献
Environmental Science and Pollution Research - Eco-ditches are being explored to maximize their capability of capturing pollutants and mitigate any harmful side effects in rivers. In this study,... 相似文献