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991.
水-岩化学作用对岩体变形破坏力学效应研究进展 总被引:45,自引:0,他引:45
水—岩化学作用对岩体变形破坏力学效应的研究涉及力学和化学两方面,也即为地球化学与岩体力学两个研究领域的交叉。针对水化学作用对岩体力学性质的影响机理,较系统地总结了该研究领域中的现状和研究新进展,分析了其研究方法,指出了今后的研究方向和主要研究内容,并认为此方面的研究将在工程地质学中占重要地位。 相似文献
992.
应用GPS探测的可降水水汽资料Pwv对上海地区2002~2005年强对流的水汽变化特征进行了分析。分析表明:每30分钟一次的GPS/Pwv资料能直观地、及时地反映大气中水汽的时间变化和空间变化;GPS/Pwv资料随时间的演变特征与降水有较好的对应关系,不同的季节及不同的降水类型有着不同的分布特征;GPS/Pwv的散度资料可以反映大气中水汽的辐合、辐散分布情况。文章还给出了不同季节产生强对流天气的GPS/Pwv阈值,表明GPS/Pwv资料在强对流天气预报方面有一定的应用价值。 相似文献
993.
夏季青藏高原水汽输送特征 总被引:13,自引:11,他引:13
使用GMS-5的6.7μm水汽图、云图及天气图等资料,综合分析了1995年6月中旬至7月上旬青藏高原上空的水汽输送过程,总结出中、高层水汽输送的三种环流型特征(脊东型、脊西型和反相型);并初步分析了它们与降雨的关系。 相似文献
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996.
R. Mook 《Pure and Applied Geophysics》1978,117(4):573-582
For the site of the astronomical observatory operated by The University of Tromsø in Skibotn, Northern Norway, the distribution of very small amounts of atmospheric water vapour is estimated from aerological data. For 5 winter months through a period of 11 years, during at least 6 per cent of the time, the precipitable water is likely not to exceed 3.0 mm, i.e. observations at wavelengths as long as 25 and a little short of 1 mm are possible. For a mountain site at 1250 m altitude, the corresponding amount is estimated to be 1.8 mm. The small amounts considered, were observed in the subsidence of tropospheric ridges. The Skibotn site is compared with other sites for infrared measurements in the Subtropics and in the Arctic. 相似文献
997.
The decline of water quality in Tolo Harbour in recent years is an example of eutrophication. This paper delineates a robust unsteady two-layered, 2D finite difference numerical model for eutrophication in coastal waters. The modelling is based upon the numerically generated boundary-fitted orthogonal curvilinear grid system and integrated with a hydrodynamic model. It simulates the transport and transformation of nine water quality constituents associated with eutrophication in the waters, i.e. three organic parameters (carbon, nitrogen and phosphorus), four inorganic parameters (dissolved oxygen, ammonia, nitrite + nitrate and orthophosphate), and two biological constituents (phytoplankton and zooplankton). Key kinetic coefficients are calibrated with the field data. The hydrodynamic, pollution source and solar radiation data in the model are real-time simulated. The computational results show that the present model mimic the stratification tendency for eutrophication phenomena during summer time in the Tolo Harbour successfully. The model running time for the long-term simulation is not excessive and it can be run on a microcomputer. 相似文献
998.
Borja A Barbone E Basset A Borgersen G Brkljacic M Elliott M Garmendia JM Marques JC Mazik K Muxika I Magalhães Neto J Norling K Rodríguez JG Rosati I Rygg B Teixeira H Trayanova A 《Marine pollution bulletin》2011,62(3):499-513
In recent times many benthic indices have been proposed to assess the ecological quality of marine waters worldwide. In this study we compared single metrics and multi-metric methods to assess coastal and transitional benthic status along human pressure gradients in five distinct environments across Europe: Varna bay and lake (Bulgaria), Lesina lagoon (Italy), Mondego estuary (Portugal), Basque coast (Spain) and Oslofjord (Norway). Hence, 13 single metrics (abundance, number of taxa, and several diversity and sensitivity indices) and eight of the most common indices used within the European Water Framework Directive (WFD) for benthic assessment were selected: index of size spectra (ISS), Benthic assessment tool (BAT), Norwegian quality index (NQI), Multivariate AMBI (M-AMBI), Benthic quality index (BQI), (Benthic ecosystem quality index (BEQI), Benthic index based on taxonomic sufficiency (BITS), and infaunal quality index (IQI). Within each system, sampling sites were ordered in an increasing pressure gradient according to a preliminary classification based on professional judgement. The different indices are largely consistent in their response to pressure gradient, except in some particular cases (i.e. BITS, in all cases, or ISS when a low number of individuals is present). Inconsistencies between indicator responses were most pronounced in transitional waters (i.e. IQI, BEQI), highlighting the difficulties of the generic application of indicators to all marine, estuarine and lagoonal environments. However, some of the single (i.e. ecological groups approach, diversity, richness) and multi-metric methods (i.e. BAT, M-AMBI, NQI) were able to detect such gradients both in transitional and coastal environments, being these multi-metric methods more consistent in the detection than single indices. This study highlights the importance of survey design and good reference conditions for some indicators. The agreement observed between different methodologies and their ability to detect quality trends across distinct environments constitutes a promising result for the implementation of the WFD’s monitoring plans. Moreover, these results have management implications, regarding the dangers of misclassification, uncertainty in the assessment, use of conflicting indices, and testing and validation of indices. 相似文献
999.
Rivers and streams are unstable environments in which estimation of energetic costs and benefits of habitat utilization are the daunting exercise. Empirical models of food consumption may be used to estimate energetic benefits based on abiotic and biotic conditions in patches of habitat. We performed thirty daily surveys of fish stomach contents to estimate the consumption rates for juvenile Atlantic salmon (Salmo salar) in a river. The data were used to assess whether variations of daily consumption rates existed within the river, and to develop empirical models that could predict fish consumption rates using abiotic and biotic conditions as independent variables. Daily consumption rates based on stomach content surveys in the field (range: 0.15–1.49 g dry/(100 g wet day)) varied significantly depending on habitat patch (500–1000 m2), summer period, and sampling year. Variables such as water temperature, numerical density of salmon, water depth and moon phase explained 83–93% of the variations in daily food consumption rates. Daily consumption rates tended to increase with water temperature and depth, and were also higher near a full moon. However, they tended to decrease with the numerical density of salmon. Our work suggests that empirical models based on independent variables that are relatively simple to estimate in the field may be developed to predict fish consumption rates in different habitat patches in a river. 相似文献
1000.
Type-specific and indicator taxa of phytoplankton as a quality criterion for assessing the ecological status of Finnish boreal lakes 总被引:6,自引:0,他引:6
Key issues in the implementation of the Water Framework Directive are classification of lakes using biological quality parameters and type-specific reference conditions. This work is one of three studies considering different metrics of phytoplankton in the classification of ecological status. Phytoplankton was studied in a total of 55 Finnish boreal lakes, including 32 reference lakes. We tested the suitability of taxonomic composition and abundance of phytoplankton groups for biological classification. We also preliminarily determined the type-specific taxa for the studied lakes. The type-specific taxa for reference conditions are coincidently the indicator species/taxa for high ecological status. Interestingly, some taxa type-specific for impacted oligo-humic lakes proved to be the type-specific taxa for humic reference lakes. The pressure of human impact was observed not only as increase of biomass but also as changes in the species composition. The phytoplankton composition indicated the ecological status of impacted lakes moderately well. There was some variation in the indications given by different algal groups, probably due to the preliminary class boundaries used. However, the preliminary combination of indicative parameters to estimate the ecological status of the studied impacted lakes was in general in accordance with earlier classification of water quality in Finnish lakes. 相似文献