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51.
Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain,Vietnam 总被引:1,自引:0,他引:1
52.
David P. Bacon Nash’at N. Ahmad Thomas J. Dunn Michael C. Monteith Ananthakrishna Sarma 《Natural Hazards》2008,44(3):317-327
By definition, a crisis is a situation that requires assistance to be managed. Hence, response to a crisis involves the merging
of local and non-local emergency response personnel. In this situation, it is critical that each participant: (1) know the
roles and responsibilities of each of the other participants; (2) know the capabilities of each of the participants; and (3)
have a common basis for action. For many types of natural disasters, this entails having a common operational picture of the unfolding events, including detailed information on the weather, both current and forecasted, that may impact on either
the emergency itself or on response activities. The Consequences Assessment Tool Set (CATS) is a comprehensive package of
hazard prediction models and casualty and damage assessment tools that provides a linkage between a modeled or observed effect
and the attendant consequences for populations, infrastructure, and resources, and, hence, provides the common operational
picture for emergency response. The Operational Multiscale Environment model with Grid Adaptivity (OMEGA) is an atmospheric
simulation system that links the latest methods in computational fluid dynamics and high-resolution gridding technologies
with numerical weather prediction to provide specific weather analysis and forecast capability that can be merged into the
geographic information system framework of CATS. This paper documents the problem of emergency response as an end-to-end system
and presents the integrated CATS–OMEGA system as a prototype of such a system that has been used successfully in a number
of different situations. 相似文献
53.
Riziki S. Shemdoe Frank M. Mbago Idris S. Kikula Patrick L. Van Damme 《GeoJournal》2008,71(2-3):107-115
This paper presents findings from a study that assessed influence of continuous application of a particular traditional tillage practice on weed species richness, diversity and composition and identifies weed species with positive benefits to the communities in semi-arid areas of Mpwapwa district, central Tanzania. In this area farmers apply three different traditional tillage practices which are no-till (NT), shallow tillage (ST) and Ridging System (RT). A total of 36 farm fields were surveyed in 2006/2007 cropping season where 63 weed species from 26 families were identified. Analysis of variance indicated significant differences between practices (p < 0.05), with NT practice having highest weed species richness and diversity. Among the five more prevalent weed species appearing, Bidens lineariloba was observed to exist in all the three practices. Community representatives during focus group discussions indicated 9 weed species out of 63 identified to have beneficial uses. These species are Cleome hirta, Amaranthus graecizans, Bidens lineoriloba, Bidens pilosa, Dactyloctenium aegyptium, Launaea cornuta, Heteropogon contortus, Tragus berteronianus and Trichodesma zeylanicum. Their main uses include leaf-vegetable, medicines, fodder and materials for thatching. From this study NT has highest weed species richness and diversity which therefore suggests that much more time is needed for weeding in this practice compared to other practice which was the farmers’ concern. It was also noted that although weed species have negative effects in crop production and production costs, they still play a vital role in food security and for the health of different people in marginal areas as well as for the complete ecosystem including micro and macrofauna. 相似文献
54.
Ramesh Sivanpillai X. Ben Wu R. Srinivasan Charles T. Smith Michael G. Messina 《GeoJournal》2008,71(4):211-220
Comparing satellite data derived map products are affected by differences in data characteristics, image acquisition dates,
processing techniques, and classification schemes used for assigning pixels to a thematic class. By comparing two forest maps
generated from Landsat Enhanced Thematic Mapper Plus (ETM+) and Advanced Very High Resolution Radiometer (AVHRR) images acquired
on the same day, and processed using identical classification scheme and methods these differences were minimized. The ETM+
derived map had higher classification accuracy values and more precise area estimates than the AVHRR derived map. In the ETM+
derived map, 87 of the 599 verification data were misclassified, whereas in the AVHRR derived map, 155 of the 469 verification
data were misclassified. Detailed error analyses by land cover class revealed that a land use based definition of forest accounted
for 74% (64 out of 87) and 57% (89 out of 155) of the classification errors in ETM+ and AVHRR derived maps, respectively. 相似文献
55.
Identifying China’s leading world city: a network approach 总被引:3,自引:0,他引:3
This paper reports our research on China’s world cities. Formal network analysis of air passenger linkages for recent years
among China’s most populous cities and among many of the world’s largest cities allows us to identify the country’s leading
world city from among the leading Mainland candidates, Beijing, Shanghai and Guangzhou. We theorize our findings about China’s
world cities in relation to both global forces (and China’s increasing entanglement with them) and the policies and actions
of the national state. We examine the national and global urban network through a longitudinal, two-level analysis of airline
passenger travel for four time points between about 1990 and 2005. We show that Beijing was China’s leading world city at
the beginning of the time period, a status it lost nationally in as early as 1995, and then globally 10 years later. On the
other hand Shanghai became China’s leading world city, and it acquired this status first nationally in 2000, and then globally
in 2005. The changing status of the Chinese capital corresponds to the country’s increasing involvement with the capitalist
world economy. Shanghai’s ascendance as the leading world city in China may indicate that global forces have come to play
an increasingly important role relative to that of the developmental state.
相似文献
Michael F. TimberlakeEmail: |
56.
We test the hypothesis that flexural isostatic compensation of the mass removed by enhanced Quaternary erosion is responsible for uplift of the Western European Alps and their forelands. We use two well‐preserved and well‐dated (1.8 Ma) abandonment surfaces of foreland basin remnants in SE France (the Chambaran and Valensole plateaux) as passive benchmarks for tilting of the foreland. Estimating their initial slope from morphometric scaling relationships, we determine bulk post‐depositional tilting of 0.5–0.8% for these surfaces. The calculated isostatic response of the Alpine lithosphere to erosional unloading, using the method recently proposed by Champagnac et al. [Geology 35 (2007) 195–198] , yields a predicted tilting of 0.3–0.4% in the considered areas, explaining approximately half of the determined post‐depositional tilting. Such long‐term deformation being insensitive to cyclic loading/unloading because of glaciations, we suspect the other half to be related to as yet undetermined long‐wavelength and long‐lived tectonic process(es). 相似文献
57.
Ronald Osinga Arjen J. Kop Gerard C. A. Duineveld Rudolf A. Prins Fleur C. Van Duyl 《Journal of Sea Research》1996,36(3-4)
Benthic oxygen uptake, sulphate reduction and benthic bacterial production were measured at two contrasting locations in the southern North Sea: the shallow and turbulent Broad Fourteens area in the Southern Bight, and the deeper Oyster Grounds, a deposition area, where thermohaline stratification occurs during summer. Oxygen uptake and sulphate reduction showed a clear seasonal pattern in the Broad Fourteens area, indicating a supply of carbon to the benthic system that is closely related to the standing stock of carbon in the water column. This close benthic-pelagic coupling is probably due to the influence of the tide in this part of the North Sea, which keeps the water column permanently mixed. At the Oyster Grounds, no seasonal pattern was observed. Peaks in oxygen uptake and sulphate reduction were found in winter. Irregularly occurring events, such as storms and fishery-related activities, are likely to affect the benthic mineralization patterns in this area. Annual benthic carbon mineralization rates estimated from oxygen uptake rates were 44 gC·m−2 at the Broad Fourteens, and 131 gC·m−2 at the Oyster Grounds, of which 26 and 28%, respectively, could be attributed to sulphate reduction (assuming an annual sulphide reoxidation rate of 100%). Although sulphate reduction rates in the southern North Sea are higher than previously suggested, aerobic respiration is the most important pathway for benthic carbon mineralization at the stations visited. Production rates of benthic bacterial carbon measured with labelled leucine were much higher than carbon mineralization rates based on oxygen uptake or sulphate reduction. This may either imply a very high bacterial carbon conversion efficiency, or point to shortcomings in the accuracy of the techniques. A critical evaluation of the techniques is recommended. 相似文献
58.
59.
Crude petroleum was emulsified or degraded by marine microorganisms and physically altered by an artificial weathering process. Only the water-soluble fraction from emulsified crude petroleum inhibited glutamate uptake by marine microorganisms from South Carolina and Georgia coastal waters. Chloroform extraction recovered almost equal amounts of total hydrocarbon from each water-soluble fraction. Chromatographic data indicated that the composition of microbially emulsified petroleum was similar to that of microbially degraded petroleum. Emulsification of crude petroleum was only observed in summer water samples and did not consistently occur at a given location. Results of this study indicate that the process by which crude petroleum is altered will influence its toxicity to microbial heterotrophic activity. 相似文献
60.
Glauconitic minerals range from green smectite to 10Å glauconite, occur mainly in peloids (most of which were fecal pellets), and apparently were produced largely by neoformation replacing several kinds of substrate. Chamositic minerals, berthierine and chamosite, occur in Recent and ancient peloids, but mostly in ancient ooids, and they developed by alteration of a precursor Al-rich clay mineral. Ooid sheaths were built by rolling of cores on ue sea floor. Glauconitic greensands and chamositic oolitic ironstones are condensed sequences deposited as sandwaves during long periods of reduced influx of sediment. Some are associated with hardgrounds. 相似文献