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171.
筑坝拦截阻断了河流连续体,改变了河流原始自然的生态系统。为了解河流筑坝对浮游植物功能群的影响,按季度对乌江流域支流猫跳河和三岔河的水库及入库河流进行调查,分析了浮游植物功能群及其相关环境因子。结果表明,河流出现频率大于20%的浮游植物功能群有6种,主要优势功能群均为B\MP;而不同水库中功能群组成各不相同,且出现频率大于20%的浮游植物功能群有11种,其中红枫湖水库以功能群S1\D为绝对优势功能群,平寨水库优势功能群为B\C,而普定水库和引子渡水库的优势功能群均为B\D\P\Lo。冗余分析(RDA)结合逐步多元回归分析显示,营养盐对河流浮游植物功能群组成影响并不显著,而库区浮游植物功能群动态变化主要受温度以及溶解无机碳(DIC)、NO_3~-、PO_4~(3-)等环境因子的影响,红枫湖水库优势功能群丰度与NO_3~-显著正相关,而三岔河流域的3座梯级水库优势功能群丰度均与DIC和PO_4~(3-)显著正相关。  相似文献   
172.
安青  陈德珍  钦佩  岳霞 《中国环境科学》2021,41(10):4720-4735
回顾了常用的生物炭活化方法,包括酸活化、碱活化、气体活化、等离子体活化以及金属浸渍活化等,并且针对不同的活化方法对生物炭的孔径分布、比表面积、活性基团和活性位点的密度等理化特征及其对生物炭催化活性的影响进行了比较.最后,进一步探讨了采用不同的活化方法获得的生物炭的应用场景,以期为定制型功能生物炭及生物炭的新应用提供参考.  相似文献   
173.
针对由总论、安全生产理念、战略目标、管理体系、运营机制、绩效考核、保障建设和附则8部分组成的企业安全生产发展战略的体系框架,系统阐述企业安全生产发展战略编制的核心内容,剖析了企业安全生产理念的内涵,并分析企业设立安全生产战略目标的层次和内容,在企业安全生产管理体系、运营机制、绩效考核、风险管理、保障建设等方面详细解析安全生产发展战略编制的路径。  相似文献   
174.
民窿空区群级联失稳评价   总被引:2,自引:0,他引:2  
民窿空区群已构成了许多矿山安全生产的极大隐患。针对民窿空区群的特点,运用重整化群方法,从整体的角度对民窿空区群系统的稳定性问题进行了研究,得到了空区群变尺度级联失稳迭代函数。给出了判别空区群系统整体失稳的临界概率,将空区群系统失稳的复杂判别转化为单元失稳概率与临界概率大小的比较问题,同时给出了计算实例,以供参考。所建立的方法可以为大规模民窿空区群范围内的工程施工以及民窿所在矿山空区群整体稳定性评价提供参考,同时也为认识一般空区群系统的失稳机理开辟了一条新的途径。  相似文献   
175.
Leaching of soils with water can be both beneficial and hazardous in the same instance, removing salts harmful to plants and contributing dissolved substances to groundwater. The leaching potential of a given soil is difficult to assess, even with complex instrumentation. This paper suggests that the final infiltration rates associated with the Hydrologic Soil Groups used by the USDA Soil Conservation Service in watershed planning may provide a useful guide in estimating quantities of leaching water moving through soil profiles.  相似文献   
176.
《组织行为杂志》2017,38(1):152-156
Teams are often described using the mean and variance of their member's characteristics. Recently, research has advanced this paradigm by beginning to explore the importance of patterns of team member perceptions regarding themselves, their teammates, and their teams. We highlight this work and suggest several directions for future research. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
177.
鸡粪厌氧消化接种物对沼气产气率的影响   总被引:4,自引:0,他引:4  
探讨鸡粪厌氧消化采用不同接种物时几个主要微生物生理群的相对数量对产气率的影响。结果表明,接种物中厌氧氨化细菌,产甲烷细菌含量皆较高不仅有利于缩短发酵启动期而且能提高产气率;如何利用葡萄糖的厌氧产酸细菌含量较高,氨化细菌和产甲烷细菌含量低,则发酵难以启动,产气率不高。  相似文献   
178.
179.
ABSTRACT: Artificial substrates were designed using rock filled polyethylene bags which were perforated with holes. The substrates trapped waterborne sediment and detritus which enhanced microhabitat complexity. Colonization was compared in side-by-side tests with multiple plate samplers in mountain streams ranging from second to seventh order. After 41 days the bag samples contained more sediment and detritus and more animals than did multiple plates. Plastic bags exceeded multiple plate samples by a factor of nearly 8 for individuals and 1.5 for taxa expressed as numbers/sampler. Although detritus amounts differed significantly between samplers, catch composition was similar in habitat preference and functional groups. Most taxa were “lotic erosional” or “lotic erosional-depositional” detritivores. The plastic bags better represented the streambed fauna judged by their greater similarity to dip net samples. Bag samplers had 4.5 × the colonization area of multiple plates, hence would be expected to support more species. Catch/m2 of colonization area was not significantly different between samplers. Functionally the plastic bags act as detritus retention devices, offering a diverse, highly dynamic microhabitat for colonization. Results are interpretable in terms of research on microdistribution of stream benthos and the river continuum model. This study supports the conclusion that stream benthos abundance and diversity are related to the amount of detritus. Maximum diversity and numbers of individuals occurred in samples from third and fourth order streams. Grazers reached peak abundances in the same streams where the continuum model predicts P>R Shredders reached maximum abundances in third and fourth order streams where the riparian canopy was greatest. Predator abundance changed little with stream size. Although bag samples required more sorting time, the samplers are catch effective, inexpensive, and adaptable.  相似文献   
180.
Since taking office 1 December 1988, Mexico's incumbent president, Carlos Salinas de Gortari, has introduced important innovations in environmental policy that distinguish his administration from those of his predecessors. Greater administrative continuity, improved regulatory capacity achieved through statutory change, focused priorities centering on pollution abatement in Mexico City, and an aggressive search for external financing for pollution control are hallmarks of Salinas' approach. The success of these environmental reforms depends heavily on economic recovery, however, and environmental policy still suffers from underfunding, bureaucratic fragmentation, and heavy reliance on voluntarist enforcement mechanisms. Recently, U.S. congressional debate on a proposed free trade agreement with Mexico has been a factor in spurring the Salinas government to take new antipollution and conservation measures. Mexico's growing environmental movement is also an important force behind the government's new responsiveness in environmental matters. The Salinas administration recognizes the issue's political salience and has sought to defuse environmental criticism using a large arsenal of resources at its disposal. Salinas' environmental policy strategy may thus be characterized as both proactive and reactive in nature. While the reforms are evidence that Mexico is beginning to take environmental matters more seriously, economic recovery and sustained environmental activism remain vital to further progress.  相似文献   
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