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551.
本文简要分析了环境质量评价中目前广泛应用的各种评价方法与模型。在此基础上提出环境质量综合评判-灰色关联优势分析复合模型,应用于黄山风景区景观生态环境质量的综合评价,取得了满意的结果。  相似文献   
552.
本文针对目前环境保护的热点之一——全球和地区性生物多样性保护,对其中的一个基础理论问题,即区域生物多样性评价标准进行了探索;从理论上对制定这一标准的必要性、可行性、生物多样性的基本内涵、区域生物多样性中心标准的意义及标准制定的原则和依据进行了阐述,并在此基础上提出了我国区域生物多样性中心标准的基本框架。  相似文献   
553.
建立了包括生态资源、人类驱动和系统响应3方面17个指标在内的农业生态环境定量评价指标体系,结合广西柳城县的实际情况,运用模糊综合评价模型,对当地农业生态环境进行定量评价。结果表明,柳城县农业生态环境质量属于一般水平,当地自然生态条件较好,虽受人类活动影响较大,但生态系统运行依然正常。该评价结果与当地实际情况相符,表明该评价指标体系具有较强的科学性和实用性。依据评价结果,提出了改善柳城县农业生态环境的对策和建议。  相似文献   
554.
生态环境质量物元可拓评价及实例分析   总被引:15,自引:0,他引:15  
生态环境质量评价属于环境质量评价的重要方面。为了探索建立生态环境质量评价的方法,尝试运用物元可拓的方法来建立生态环境质量评价模型,并且通过用该方法对土壤生态环境质量评价实例验证物元可拓方法的可行性,得到该土壤生态环境质量评价等级值为3.73。从而为尚处在探索发展阶段的生态环境质量评价方法提供一种新思路。  相似文献   
555.
Examination of model predictions at different horizontal grid resolutions   总被引:1,自引:0,他引:1  
While fluctuations in meteorological and air quality variables occur on a continuum of spatial scales, the horizontal grid spacing of coupled meteorological and photochemical models sets a lower limit on the spatial scales that they can resolve. However, both computational costs and data requirements increase significantly with increasing grid resolution. Therefore, it is important to examine, for any given application, whether the expected benefit of increased grid resolution justifies the extra costs. In this study, we examine temperature and ozone observations and model predictions for three high ozone episodes that occurred over the northeastern United States during the summer of 1995. In the first set of simulations, the meteorological model RAMS4a was run with three two-way nested grids of 108/36/12 km grid spacing covering the United States and the photochemical model UAM-V was run with two grids of 36/12 km grid spacing covering the eastern United States. In the second set of simulations, RAMS4a was run with four two-way nested grids of 108/36/12/4 km grid spacing and UAM-V was run with three grids of 36/12/4 km grid spacing with the finest resolution covering the northeastern United States. Our analysis focuses on the comparison of model predictions for the finest grid domain of the simulations, namely, the region overlapping the 12 km and 4 km domains. A comparison of 12 km versus 4 km fields shows that the increased grid resolution leads to finer texture in the model predictions; however, comparisons of model predictions with observations do not reveal the expected improvement in the predictions. While high-resolution modeling has scientific merit and potential uses, the currently available monitoring networks, in conjunction with the scarceness of highly resolved spatial input data and the limitations of model formulation, do not allow confirmation of the expected superiority of the high-resolution model predictions.The U.S. Governments right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged.  相似文献   
556.
Data from a comprehensive field study in the Riviera Valley of Southern Switzerland are used to investigate convective boundary layer structure in a steep valley and to evaluate wind and temperature fields, convective boundary layer height, and surface sensible heat fluxes as predicted by the mesoscale model RAMS. Current parameterizations of surface and boundary layer processes in RAMS, as well as in other mesoscale models, are based on scaling laws strictly valid only for flat topography and uniform land cover. Model evaluation is required to investigate whether this limits the applicability of RAMS in steep, inhomogeneous terrain. One clear-sky day with light synoptic winds is selected from the field study. Observed temperature structure across and along the valley is nearly homogeneous while wind structure is complex with a wind speed maximum on one side of the valley. Upvalley flows are not purely thermally driven and mechanical effects near the valley entrance also affect the wind structure. RAMS captured many of the observed boundary layer characteristics within the steep valley. The wind field, temperature structure, and convective boundary layer height in the valley are qualitatively simulated by RAMS, but the horizontal temperature structure across and along the valley is less homogeneous in the model than in the observations. The model reproduced the observed net radiation, except around sunset and sunrise when RAMS does not take into account the shadows cast by the surrounding topography. The observed sensible heat fluxes fall within the range of simulated values at grid points surrounding the measurement sites. Some of the scatter between observed and simulated turbulent sensible heat fluxes are due to sub-grid scale effects related to local topography.  相似文献   
557.
吡虫清等4种新农药的水生态安全性评价   总被引:1,自引:0,他引:1  
以斜生栅列藻 (Scenedesmusobliquus)、大型 (Daphniamagna)和斑马鱼 (Brachydaniorerio)为试验生物 ,在实验室条件下测定了吡虫清、吡嗪酮、恶草酮和精喹禾灵 4种新农药对水生生物的急性毒性IC50值或LC50 值 ,并进行了安全性评价。结果表明 ,杀虫剂吡虫清对水极毒 ,对鱼类高毒 ,对藻类低毒 ;杀虫剂吡嗪酮对水和鱼类低毒 ,对藻类中等毒性 ;除草剂恶草酮对藻类高毒 ,对水和鱼类中等毒性 ;除草剂精喹禾灵对藻类高毒 ,对水中等毒性 ,对鱼类高毒。  相似文献   
558.
李鹏  赵忠  李占斌 《生态环境》2001,10(4):301-306
通过对渭北黄土高原地区沟坡地土壤理化性质的分析和对当地社会经济状况的调查研究,应用层次分析法对沟坡地土地自然生产力和现实生产力进行了分析和评价.在分析过程中,把当地主要造林树种根系垂直分布特征及其根系抗旱性特性纳入了分析评价体系.结果表明,嘴头村和西坡村不同树种沟坡地上刺槐(Robinia pseudoacacia)的自然生产力属于中等稍微偏上水平,而山杏(Prunus armeniacia var. ansu)、油松(Pinus tabulaeformis)和侧柏(Platycladus orientalis)的自然生产力水平则较低.两地沟坡地上的现实生产力计算结果则证明刺槐和山杏两个树种表现出了较高的水平,具有较好的发展前途;而油松和侧柏的现实生产力水平则较低,其发展推广受到了限制.群众对沟坡开发治理的态度和对开发方案的认可对沟坡开发的成功起到了重要作用.  相似文献   
559.
A Global Indicator for Biological Invasion   总被引:2,自引:0,他引:2  
Abstract:  "Trends in invasive alien species" is one of only two indicators of threat to biodiversity that form part of the Convention on Biological Diversity's (CBD) framework for monitoring progress toward its "2010 target" (i.e., the commitment to achieve by 2010 a significant reduction in the current rate of biodiversity loss). To date, however, there is no fully developed indicator for invasive alien species (IAS) that combines trends, derived from a standard set of methods, across species groups, ecosystems, and regions. Here we provide a rationale for the form and characteristics of an indicator of trends in IAS that will meet the 2010 framework goal and targets for this indicator. We suggest single and composite indicators that include problem-status and management-status measures that are designed to be flexible, readily disaggregated, and as far as possible draw on existing data. The single indicators at national and global scales are number of IAS and numbers of operational management plans for IAS. Global trends in IAS are measured as the progress of nations toward the targets of stabilizing IAS numbers and the implementation of IAS management plans. The proposed global indicator thus represents a minimum information set that most directly addresses the indicator objective and simultaneously aims to maximize national participation. This global indicator now requires testing to assess its accuracy, sensitivity, and tractability. Although it may not be possible to achieve the desired objective for a global indicator of biological invasion by 2010 as comprehensively as desired, it seems possible to obtain trend estimates for a component of the taxa, ecosystems, and regions involved. Importantly, current indicator development initiatives will also contribute to developing the mechanisms necessary for monitoring global trends in IAS beyond 2010.  相似文献   
560.
以WHO/FAO规定的日允许摄入量换算得到的标准评价了南京市郊主要蔬菜品种的NO-3污染状况。结果表明,双闸镇蔬菜基地的大白菜和青菜样品属重污染,菠菜属轻污染,萝卜污染程度居中,因而有必要采取有效的污染防治措施  相似文献   
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