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41.
Fresh and mineral waters from the eastern margin of the Suez Rift Valley are described. They include a fair number of sources that resemble the mineral waters in the Jordan Rift Valley. The term Tiberias-Farun water is thus suggested to describe them. They are characterized compositionally by Cl > Na (in equiv.), the presence of NaCl and MgCl2, a Cl/Br ratio (by weight) around 150, elevated radium and H2S content, elevated temperature, a light stable-isotope composition and high carbon-14 age.
The Tiberias-Farun waters are suggested to have originated from entrapped seawater that gradually changed in composition by interaction with aquifer rocks. Such changes were demonstrated to take place in the laboratory experiments. 相似文献
42.
In Hungary loess has long been used for soil reclamation. The main steps of the method are: horizon A and B are removed from a suitable area and their material is stockpiled at the margins of the resulting pit. The loess (horizon C), this way exposed, is excavated and spread over the salt affected soils to be improved then mixed with their upper layer. The pit is named in Hungarian digó (pit). The name of the reclamation process is the digo method or spreading of yellow earth. Digó method is mainly used for the amelioration of salt affected soils with an acid A horizon and its benefits are as follows:
- The acidity of the horizon A is eliminated
- The soil structure is improved
- The amount of calcium (a plant nutrient) is increased
- Soil fertility is improved continuously
- The soil depth is extended which adds to the relative volume of the ground water table.
43.
Magda A. S. Duro Pierre Kaufmann Fernando C. P. Bertoni Emilio C. N. Rodrigues José Pissolato Filho 《Surveys in Geophysics》2012,33(5):973-989
High-voltage transmission networks represent a large electrical circuit just above the ground subjected to a number of transient overcharges of various kinds, some of which may lead to failures. Some failures might be related to anomalies of the geophysical environment. We have analyzed one unprecedented long series of transmission grid failures (9?years) on high-voltage networks located in S?o Paulo state, southeastern Brazil, from 1998 to 2006, which includes an important fraction of the past solar activity cycle 23. Ninety-five distinct failure causes were given by the power line operator to explain the transmission grid shut downs. Most failures were attributed to atmospheric discharges, corresponding to 1,957 failures out of a total of 4,572 for the whole period at 138?kV, and 170 out of 763 at 440?kV, respectively. They correspond to less than one ten thousandth of the actual number of atmospheric discharges recorded in the same area, demonstrating the grid’s high resilience to breakdowns due to lightning. A clear concentration of failures in the region’s thunderstorm season has been found. A significant 67 and 77?% reduction in the number of failure rates per year has been found for the 138 and 440?kV grids, respectively, for the period studied, in good correspondence with the decay in the sunspot numbers. No obvious correlation was found between power failures and the planetary index of geomagnetic activity or major geomagnetic storms in the period, either on short or on long time scales. Assuming that the dependence of the electrosphere/ionosphere-ground coupling on the external geophysical environment plays a major role in explaining the reduction in power failures as the solar cycle wanes, it is suggested that the increase in atmosphere conductivity caused by the larger cosmic ray flux then reduces the threshold voltage required to produce lightning strokes, so reducing their effectiveness in disrupting high-voltage power lines. 相似文献
44.
Cecilia Battocchi Magda Vila Samuela Capellacci Albert Reñé Antonella Penna 《Marine pollution bulletin》2010,60(7):1074-7059
A molecular PCR-based assay was developed and applied to macrophyte and seawater samples containing mixed microphytobenthic and phytoplanktonic assemblages, respectively, in order to detect toxic Ostreopsis species in Mediterranean Sea. The specificity and sensitivity of the molecular PCR assay were assessed with both plasmidic and genomic DNA of the target genus or species using taxon-specific primers in the presence of background macrophyte DNA. The PCR molecular technique allowed rapid detection of the Ostreopsis cells, even at abundances undetectable within the resolution limit of the microscopy technique. Species-specific identification of Ostreopsis was determined only by PCR-based assay, due to the inherent difficulty of morphological identification in field samples. In the monitoring of the toxic Ostreopsis blooms PCR-based methods proved to be effective tools complementary to microscopy for rapid and specific detection of Ostreopsis and other toxic dinoflagellates in marine coastal environments. 相似文献
45.
The increasing usage of sandy beaches as recreational resources has forced regional authorities of many tourist countries to remove all litter of fabricated origin and natural wrack from the beach. Consequently, a variety of heavy equipment has been developed during the last decades and is now used almost daily at many beaches. A field experiment, following a 'before-after-control-impact' (BACI) design, was conducted at the strandline of De Panne (Belgium) to investigate the impacts of mechanical beach cleaning on the strandline-associated meiofaunal assemblages, focussing on the free-living nematodes. Natural strandline assemblages were exposed to a one-off 5 cm deep mechanical beach cleaning and observed for 24 h. Differences between cleaned plots and those from control plots in terms of decreased percentage of organic matter, decreased total abundance and changed community structure were noticed from immediately after the experimental cleaning onwards and recovered to initial values after the following high water. Any impacts due to cleaning on species richness, Pielou's evenness and taxonomic diversity were shown to be minor in relation to the daily changes. Recolonization in the cleaned sediments is assumed to occur from the underlying sediments initiated by the elevated water table during the rising tide. 相似文献
46.
Roger R. Torres David M. Lapola Jose A. Marengo Magda A. Lombardo 《Climatic change》2012,115(3-4):597-609
Brazil suffers yearly from extreme weather and climate events, which can be exacerbated in a warmer climate. Although several studies have analyzed the projections of climate change in Brazil, little attention has been paid to defining the locations that can be most affected, and consequently have a more vulnerable population, in a spatially-explicit form. This study presents a spatial analysis of summarized climate change data and a joint investigation combining these possible climate changes and social vulnerability indicators in Brazil. The Regional Climate Change Index (RCCI), which can synthesize a large number of climate model projections, is used for the climate analysis, and the Socio-Climatic Vulnerability Index (SCVI) is proposed to aggregate local population vulnerabilities to the climate change information. The RCCI results show climatic hotspots emerging in Brazil, covering the western portion of the Northeast (NE), northwestern Minas Gerais state and center-western (CW) and northern regions (N), except northeast Pará and Amapá states. The SCVI analysis reveals major socio-climatic hotspots in the NE and several localized hotspots in some of the major Brazilian metropolitan regions, namely Manaus, Belo Horizonte, Brasília, Salvador, Rio de Janeiro and S?o Paulo. The two novelties of this study are a spatially detailed analysis of the RCCI in Brazil and the development of an index that can summarize the large amount of climate model information available today with social vulnerability indicators. Both indices may be important tools for improving the dialogue between climate and social scientists and for communicating climate change to policymakers in a more synthetic and socially relevant form. 相似文献
47.
Annelies De Backer Stefanie Adam Jaak Monbaliu Erik Toorman Magda Vincx Steven Degraer 《Estuaries and Coasts》2009,32(6):1121-1129
The present study aims to test the application of remote sensing to address the impact of bioturbation on physical sediment
properties. Therefore, a laboratory experiment was developed, using microcosms mimicking a marine intertidal water–sediment
interface to test the influence of Corophium volutator densities on sediment properties. Three main variables (water content, clay content, and mean grain size) were measured in
three treatments (no Corophium, 5,000 Corophium per square meter, and 20,000 Corophium per square meter) after 16 days of bioturbation. Results obtained with conventional—destructive—techniques showed a significant
increase of water content and a significant, but small decrease of clay content in the presence of Corophium. The remote sensing technique detected the impact of Corophium on water content as an increase in absorption at 1,450 nm, but was not able to detect the animal impact on clay content.
This study demonstrates that remote sensing data could be significantly modified by bioturbation activities and that remote
sensing can be applied in the laboratory to address the impact of bioturbation on sediment properties. This possibly opens
new perspectives for long-term experiments concerning the role of bioturbation on sedimentary processes. 相似文献
48.
Ingrid KrönckeHenning Reiss Jacqueline D. EggletonJohn Aldridge Magda J.N. BergmanSabine Cochrane Johan A. CraeymeerschSteven Degraer Nicolas DesroyJean-Marie Dewarumez Gerard C.A. DuineveldKarel Essink Hans HillewaertMarc S.S. Lavaleye Andreas MollStefan Nehring Richard NewellEivind Oug Thomas PohlmannEike Rachor Mike RobertsonHeye Rumohr Michaela SchratzbergerRebecca Smith Edward Vanden Berghe Jan van DalfsenGert van Hoey Magda VincxWouter Willems Hubert L. Rees 《Estuarine, Coastal and Shelf Science》2011,94(1):1-15
The North Sea Benthos Project 2000 was initiated as a follow-up to the 1986 ICES North Sea Benthos Survey with the major aim to identify changes in the macrofauna species distribution and community structure in the North Sea and their likely causes.The results showed that the large-scale spatial distribution of macrofauna communities in the North Sea hardly changed between 1986 and 2000, with the main divisions at the 50 m and 100 m depth contours. Water temperature and salinity as well as wave exposure, tidal stress and primary production were influential environmental factors on a large (North Sea-wide) spatial scale.The increase in abundance and regional changes in distribution of various species with a southern distribution in the North Sea in 2000 were largely associated with an increase in sea surface temperature, primary production and, thus, food supply. This can be most likely related to the North Sea hydro-climate change in the late 1980s influenced by the variability in the North Atlantic Oscillation (NAO). Only one cold-temperate species decreased in abundance in 2000 at most of the stations. Indications for newly established populations of offshore non-native species were not found.Differences in macrofauna community structure on localised spatial scales were predominantly found north of the 50 m depth contour off the British coast along the Flamborough Head Front towards the Dogger Bank, off the coast of Jutland and at the Frisian Front. These changes were most likely attributed to stronger frontal systems in 2000 caused by the increased inflow of Atlantic water masses in relation to the hydro-climate change in the late 1980s. 相似文献
49.
Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of growth. The alga was cultured on BG11 growth medium and subjected to 0, 30, 100, and 200 mmol/L NaCl for a period of 20 d, during which algal cultures were harvested at 4-d intervals. The salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth phases. The sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to salinity. The concentrations of chlorophylls a and b, soluble sugars, proteins as well as those of K+ and Na+ in the alga exhibited peaks at the initiation of the exponential phase of growth, with increasing magnitude in proportion to the increase in the level of salinity. Nevertheless, whereas soluble sugars of the alga peaked at initiation of the exponential phase, starch concentration progressively increased with culture age, reaching saturation towards the stationary phase. Whereas the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for starch. The present results point to fast acclimation of S. obliquus to salt stress post a brief salt shock, utilizing soluble sugars, K+ and Na+ for osmotic adjustment. Increasing salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars, proteins, K + and Na + concentrations of the algal cells, particularly at the early stages of growth. However, the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth. 相似文献
50.