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871.
We develop a reserve design strategy to maximize the probability of species persistence predicted by a stochastic, individual-based,
metapopulation model. Because the population model does not fit exact optimization procedures, our strategy involves deriving
promising solutions from theory, obtaining promising solutions from a simulation optimization heuristic, and determining the
best of the promising solutions using a multiple-comparison statistical test. We use the strategy to address a problem of
allocating limited resources to new and existing reserves. The best reserve design depends on emigration, dispersal mortality,
and probabilities of movement between reserves. When movement probabilities are symmetric, the best design is to expand a
subset of reserves to equal size to exhaust the habitat budget. When movement probabilities are not symmetric, the best design
does not expand reserves to equal size and is strongly affected by movement probabilities and emigration rates. We use commercial
simulation software to obtain our results. 相似文献
872.
中国环境监测陆海统筹机制的分析与建议 总被引:2,自引:0,他引:2
建立环境监测陆海统筹机制是新形势下管理模式向环境质量控制转变的必然需求。通过对涉海环境监测网络建设、运行管理模式、标准规范和信息发布体系的调研,分析了环境监测陆海统筹机制面临的缺乏统一规划、管理职责不清、标准化滞后和信息发布混乱等问题,并剖析了其深层次原因。借鉴欧盟、美国和日本在环境监测陆海统筹实践中的经验,总结其对中国的启示:陆海统筹既是自然环境客观规律的内在要求,也是中国自下而上的环境管理需求;管理部门建立沟通协调机制是陆海统筹的基础,监测网络加强技术体系整合是陆海统筹的关键。遵照公正可信、分步推进的原则,提出中国环境监测陆海统筹机制的实施路线。 相似文献
873.
874.
875.
物元分析法是处理不相容问题的一种有效方法。以竺山湾2010年7月水质监测数据为例,利用物元分析法分析太湖竺山湾水质监测点位分布情况,并将分析结果与系统聚类法的分析结果相比较,发现物元分析法的分析结果是准确、可信的。综合使用物元分析法和系统聚类法,最终确定水质监测点位可由14个优化至11个。 相似文献
876.
Jitka Hilgert Martina Sura-De Jong Jiří Fišer Kateřina Tupá Miroslava Vrbová Miroslav Griga 《Journal of environmental science and health. Part. B》2017,52(5):338-345
A plant selection system based on the phosphomannose isomerase gene (pmi) as a selectable marker is often used to avoid selection using antibiotic resistance. Nevertheless, pmi gene is endogenous in several plant species and therefore difficult to use in such cases. Here we evaluated and compared Agrobacterium-mediated transformation of Linum usitatissimum breeding line AGT-952 (without endogenous pmi gene) and Nicotiana tabacum var. WSC-38 (with endogenous pmi gene). Transformation was evaluated for vectors bearing transgenes that have the potential to be involved in improved phytoremediation of contaminated environment. Tobacco regenerants selection resulted in 6.8% transformation efficiency when using a medium supplemented with 30 g/L mannose with stepwise decrease of the sucrose concentration. Similar transformation efficiency (5.3%) was achieved in transformation of flax. Relatively low selection efficiency was achieved (12.5% and 34.8%, respectively). The final detection of efficient pmi selection was conducted using PCR and the non-endogenous genes; pmi transgene for flax and todC2 transgene for tobacco plants. 相似文献
877.
Wan Zurina Wan Jaafar Dawei Han 《Journal of the American Water Resources Association》2012,48(4):698-706
Wan Jaafar, Wan Zurina, and Dawei Han, 2012. Calibration Catchment Selection for Flood Regionalization Modeling. Journal of the American Water Resources Association (JAWRA) 48(4): 698‐706. DOI: 10.1111/j.1752‐1688.2012.00648.x Abstract: There are two unsolved problems in flood regionalization model development related to the quantity and quality of calibration catchments: (1) how many calibration catchments should be used? and (2) how to select the calibration catchments? This study explores these two questions through a case study on the median annual maximum flood (QMED) model in the United Kingdom. It has been found that the chance of developing a good QMED model decreases significantly when the number of calibration catchments drops below a critical number (e.g., 60 in the case study). However, no significant improvement is achieved if the number of calibration catchments is above it. This number could be used as a benchmark for choosing randomly selected calibration catchments. Across a broad range of calibration catchment numbers, there are good and poor calibrated models regardless of calibration catchment numbers. High quality models could be developed from a small number of calibration catchments and also poor models from a large number of calibration catchments. This indicates that the number of calibration catchments may not be the dominating factor for developing a high quality regionalization model. Instead, the information content could be more important. The study has demonstrated that the standard deviation values between the best and poorest groups are distinctive and could be used in choosing appropriate calibration catchments. 相似文献
878.
Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions.Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples.The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts.Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks.Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5 mg d−1 kg−1 pig at swine finishing barns and from 2.3 to 45.2 g d−1 m−2 at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates.Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors. 相似文献
879.
Maryam Mirhadi Fard Charles J. Kibert Abdol R. Chini 《International Journal of Sustainable Engineering》2016,9(2):76-92
Site selection is a typical strategic decision for many industries that deals with specifying the most appropriate location for a facility. In the context of sustainable development, site selection decisions need to be improved by adopting environmental, economic and social requirements. This study aims to frame sustainable location decisions by conducting a case study of siting a new cement plant in the state of Florida. As a part of the study, a wide range of technical and sustainability criteria has developed. These criteria can help decision-makers in the cement industry evaluate the selection of a location with the requirements of sustainable development. The sustainability characteristics of alternative sites in the state of Florida are evaluated based on the criteria to identify the most appropriate ones. The analytical hierarchy processand geographic information system techniques are utilized to weight the criteria and evaluate the characteristics of site candidates. 相似文献
880.
低碳城市是当今世界城市发展的大趋势,国内外一些城市已经开始践行低碳理念并形成了各具特色的发展模式,较为成熟的可归纳为"哥本哈根模式"、"伦敦模式"、"伯明翰模式"、"东京模式""保定模式"、"上海模式"等。中国低碳城市的建设和发展目前正处于起步阶段,存在一定的盲目性。中国城市的多样性、差异性和复杂性决定了其低碳发展不能千篇一律的复制和模仿,而必须在工业化和城市化进程中探索适合自身的发展模式。本文将中国城市的类型和特征与其低碳发展模式的选择相结合,从人口规模、区位、资源禀赋及工业化阶段等角度对我国城市进行类型划分,并认为任何一类城市的低碳发展都必须依据自身特征选择适宜的发展模式。同时,对武汉市的案例研究表明,因地制宜的选择一条重化工集聚、中部特大型城市的综合低碳发展模式是武汉市实现低碳转型的必然选择。 相似文献