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93.
珊瑚礁工程地质研究进展 总被引:9,自引:0,他引:9
珊瑚礁是发育于热带海洋环境中由生物作用和地质作用共同形成的地质体,是一种特殊的岩土介质类型,有着独特的工程环境特性和工程地质性质。珊瑚礁工程地质研究是现代工程地质学的一个新课题,是近年来为适应珊瑚岛礁工程建设的需求而发展起来的。介绍了珊瑚礁工程地质研究的内容及意义,综述了国内外珊瑚礁工程地质研究的历史现状及其进展,指出应将珊瑚礁体作为工程岩体,进行工程地质环境区带划分及各区带工程地质条件评价;分析礁岩体结构特征和礁体稳定性及其影响因素;分析礁体工程适宜性、地基及其环境与工程活动相互关系。针对珊瑚礁岩土的土力学特点,加强珊瑚礁颗粒破碎机理及其对工程地质性质影响机制的研究;建立能够代表珊瑚礁应力—应变特性的本构关系。 相似文献
94.
An avenue to integrate theoretical, experimental and field research methods to forecast water quality in water bodies for different scenarios of water management is proposed. Exploration of the laws of organization, stability and controllability of laboratory "ideal" water microbial communities (model ecosystems) is the basis to build the following biophysical research chain:to formalize with primary field information a conceptual block-diagram of a water ecosystem →to real chemical and other density-dependent and population-growth-controlling factors → to find our limiting factors for natural ecosystems → to conduct experiments with isolated chemical factors and hydrobionts to derive kinetic dependencies and quantitative parameters→ to transfer regularities of operation and kinetic dependencies to the natural ecosystem→ retrospective verification of the model on the base of available field and derived theoretical-experimental data →prognostic calculations for the scenario. Efficiency of the approach is demonstrated in microalgal "blooming" models for Krasnoyarsk and Kantat reservoirs and in prognostication of radioecological state of great Yenisei river:1) radionuclide distribution in the Yenisei''s bottom sediment is nonuniform-"spotty"; 2) it is theoretically shown, that due to biological interactions and tro-phical radioniclide migration there is "spotive" type of space radionuclide distribution. The research is to make use of the novel methods of ecological biophysics:Monitoring:spectral analysis of surface waters (algal pigments), fluorescent techniques to evaluate productivity and condition of algae; rapid bioassays for water toxicity (bioluminescence, chemotaxis techniques). Kinetic experiments:microcosms on evaluating self-purification rates; special cultivators to evaluate the rates of growth of hydrobionts and radioactive engulfing, nutrition spectra; methods of finding growth limiting factors. Models:application of Bellman Principle to optimizing the river water use; theory and peculiarities of microbiological decomposition of pollutants in the river ecosystem. The composition of Prognostication Simulation Model is the next:1) hydrodynamical unit to calculate 2-dimensional space-time rate of stream on any depth; 2) hydrophysical unit to calculate:water temperature and level of solar radiation inside the water body; 3) ecosystem unit to calculate dynamic of concentration of phytoplankton, zooplankton, bacteria, major chemical matters and pollutants in water, content pollutants inside of hydrobionfs cells and dynamic of bentos; 4) radioe-cological unit to forecast the dynamic of radionuclides in the water body and bottom, their hydro-bont''s concentration; 5) database. Reservoirs and river models are provided by monitoring and kinetic experiments data. 相似文献
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96.
珊瑚颗粒形状不规则是其显著区别于陆源土的一大特征。为揭示珊瑚颗粒形状对钙质粗粒土压缩性能的影响,人工挑选出不同形状(块状、枝状、棒状、片状)的珊瑚颗粒,以块状颗粒为基础,与其他3种不同形状的粗颗粒任意一种混合,控制不同颗粒形状配比制成钙质粗粒土试样,完成室内压缩试验,对比分析试验前后珊瑚颗粒的圆度、长宽比、扁平度和凹凸度等形状参数,评价颗粒形状对压缩性能的影响。结果表明:(1)粒径为10~20 mm钙质粗粒土的压缩模量是4~5. 5 MPa,回弹系数为42~53;(2)随枝状、棒状或片状颗粒掺量的增加(0、10%、20%、30%),试样压缩模量呈小幅波状变化,回弹系数呈持续减小趋势;(3)各加载区间应力-应变曲线包括应力快速增长阶段、应力-应变同步增长阶段、应变增长阶段共3个阶段和1个稳定点;(4)随枝状颗粒掺量的增加,试样的长宽比和凹凸度逐渐增加,圆度和扁平度基本无变化;因颗粒破碎的影响,试验后试样的长宽比及扁平度有所增加,圆度及凹凸度则有所减小。选择钙质粗粒土地基时,应考虑其压缩性能,避免施工初期的快速加载。 相似文献
97.
洱海生物群落的历史演变分析 总被引:20,自引:5,他引:15
根据1957-1997年期间对洱海水体进行的历次综合研究结果分析,由污染引起的氮,磷等营养元素含量升高促进藻类生长繁殖,40年来其密度和生物量上升近10倍;近5年的变化尤为明显,一度出现以螺旋鱼腥藻为主的“水华”。 相似文献
98.
《Marine Policy》2017
This paper assessed the socio-economic implications of climate change and vulnerability of fishing communities known as “Koli” living in Mumbai, India. The vulnerability indicators are derived from sustainable livelihood literature and use of multi-criteria analyses and are validated with expert opinions. A survey of two hundred fishermen from five fishing villages in Mumbai was conducted to collect data. The results demonstrate that vulnerability perpetuates due to physical and financial resource constraints among the fishing community. Fishermen from Madh and Worli villages are observed to be more vulnerable and less adaptive due to their inability to use efficient mechanized boats and advanced fishing implements, such as fish finders and GPS (Global Positioning System). The divergence in the vulnerability scores among fishing villages is attributed to the coping strategies, resource availability, knowledge and the benefit derived from the local government. Fishermen have been observing the negative impacts of climate change on their fishing livelihoods. Adaptation strategies to maximize fish catch are observed in such practices as targeting different species and fishing intensively for several days. However, these practices are leading to an imbalance in the common resource pool and biased resource sharing among different groups of fishermen. 相似文献
99.
《Marine Policy》2017
Global coral reef related tourism is one of the most significant examples of nature-based tourism from a single ecosystem. Coral reefs attract foreign and domestic visitors and generate revenues, including foreign exchange earnings, in over 100 countries and territories. Understanding the full value of coral reefs to tourism, and the spatial distribution of these values, provides an important incentive for sustainable reef management. In the current work, global data from multiple sources, including social media and crowd-sourced datasets, were used to estimate and map two distinct components of reef value. The first component is local “reef-adjacent” value, an overarching term used to capture a range of indirect benefits from coral reefs, including provision of sandy beaches, sheltered water, food, and attractive views. The second component is “on-reef” value, directly associated with in-water activities such diving and snorkelling. Tourism values were estimated as a proportion of the total visits and spending by coastal tourists within 30 km of reefs (excluding urban areas). Reef-adjacent values were set as a fixed proportion of 10% of this expenditure. On-reef values were based on the relative abundance of dive-shops and underwater photos in different countries and territories. Maps of value assigned to specific coral reef locations show considerable spatial variability across distances of just a few kilometres. Some 30% of the world's reefs are of value in the tourism sector, with a total value estimated at nearly US$36 billion, or over 9% of all coastal tourism value in the world's coral reef countries. 相似文献
100.
《Limnologica》2016
In order to assess the diversity and spatial distribution of bacterial and archaeal communities in a CO2-rich and meromictic lake, samples were collected along the water column of Lake Monoun and analyzed using PCR-DGGE and quantitative analyses of the 16S rRNA gene. The retrieved sequences were affiliated to 6 bacterial phyla and two archaeal phyla which plausible environmental functions map with the physico-chemical parameters of the lake. Unclassified sequences were also detected. This suggests heterogeneity in community composition and existence of potential candidate divisions. For instance, amongst the bacterial sequences, 18.2% matched with methanotrophic bacteria of the order methylococcales and amongst the archaeal sequences, 16.6% matched with methanogenic species of the order methanomicrobiales. Hence, evidencing the existence of methane-related prokaryotes in the lake, a finding that would play a key role in our understanding of the methane puzzle of Lake Monoun. Other groups capable of a wide range of metal and nutrients transformations were also detected, as well as those of unknown functions. The layering of microbial communities also appeared to directly or indirectly depend on oxygen availability. DGGE and qPCR analyses both suggested a scarcity of archaea in the surface samples. Furthermore, qPCR revealed that bacteria were numerically more important than archaea in all the samples. The general distribution along the water column indicated that archaeal abundance increases with depth. 相似文献