Home About us Contact
|
Home About us Contact | ||
|
|
||
Great Depth (great + depth)
Selected AbstractsContribution to the study of thermal waters in Greece: chemical patterns and origin of thermal water in the thermal springs of LesvosHYDROLOGICAL PROCESSES, Issue 2 2008N. J. Lambrakis Abstract The occurrence of thermal/spa waters on Lesvos Island is related to the presence of a major faulting system. Thermal waters are the result of mixing of meteoric and infiltrating seawater at great depth, and their total salinity depends on the percentage of seawater in their composition. According to the diagrams of main elements, trace elements and environmental isotopes, most of the components that determine the chemical composition of thermal waters such as sodium, chloride and sulphates originate from seawaters. On the other hand, the concentration of calcium, magnesium, boron, lithium, etc., was affected by water,rock interaction under high temperature conditions. Moving towards the surface, thermal waters may become polluted by influx of recent seawater, allowing their chemical composition to become similar to that of seawater. The thermal waters of Lesvos Island present relatively high concentrations of ammonia and redox sensitive metals because they are hosted in a reducing environment. They also exhibit low nitrate concentrations due to their mixture with recent fresh water. Finally, they show increased radon concentrations, ranging from 20 to 60 kBq m,3 in the eastern and southern parts of the island, and about 230 kBq m,3 in the north, in the area of Eftalou,Argenos. Copyright © 2007 John Wiley & Sons, Ltd. [source] The self-regulation of curiosity and interest during the information search process of adolescent studentsJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 7 2010Leanne Bowler In a world of increasing information and communications possibilities, the difficulty for users of information systems and services may not lie in finding information but in filtering and integrating it into a cohesive whole. To do this, information seekers must know when and how to effectively use cognitive strategies to regulate their own thinking, motivation, and actions. Sometimes this is difficult when the topic is interesting and one is driven to explore it in great depth. This article reports on a qualitative study that, in the course of exploring the thinking and emotions of 10 adolescents during the information search process, uncovered patterns of behavior that are related to curiosity and interest. The larger purpose of the study was to investigate the metacognitive knowledge of adolescents, ages 16,18, as they searched for, selected, and used information to complete a school-based information task. The study found that the curiosity experienced by adolescents during the search process was accompanied by feelings of both pleasure and pain and that both feelings needed to be managed in order to navigate a pathway through the search process. The self-regulation of curiosity and interest was a clear and distinct metacognitive strategy fueled by metacognitive knowledge related to understanding one's own curiosity and the emotions attached to it. [source] MYSTERIES OF ADAPTATION TO HYPOXIA AND PRESSURE IN MARINE MAMMALS The Kenneth S. Norris Lifetime Achievement Award LectureMARINE MAMMAL SCIENCE, Issue 3 2006Gerald L. Kooyman Presented on 12 December 2005 San Diego, California Abstract This paper reviews past and current work on diving behavior, effects of pressure, and the aerobic diving limit from the perspective of the Ken Norris Lifetime Achievement Award. Because of the influence of Norris to marine mammalogy in general, and to my career in particular, I want to emphasize the important tradition of mentors and colleagues as keystones to a successful career in science, and ultimately to the success of science itself. These two related activities are illustrated by studies on marine mammals that were conducted in an endeavor to understand: (1) the behavioral traits associated with deep diving, (2) the mechanical and physiological effects of pressure during routine dives to great depth, and (3) the degree of oxygen depletion that they routinely endure while diving. The search for answers has resulted in numerous physiological and ecological experiments, along with accompanying theoretical analyses. Currently it appears that some deep-diving mammals may suffer from bends, and some may resort more often than what seems physiologically possible to anaerobic metabolism while diving. Above all, the way divers manage their nitrogen and oxygen stores remains a mystery. [source] Urban,agricultural water appropriation: the Hyderabad, India caseTHE GEOGRAPHICAL JOURNAL, Issue 1 2010MATTIA CELIO With the urbanisation drive comes steady growth in urban water demand. Although in the past this new demand could often be met by tapping unclaimed water sources, this option is increasingly untenable in many regions where little if any unclaimed water remains. The result is that urban water capture, and the appropriation of associated physical and institutional infrastructure, now often implies conflict with other existing uses and users. While the urbanisation process has been studied in great depth, the processes and, critically, impacts of urban water capture and appropriation are not well researched or understood. This paper undertakes a critical examination of the specific case of Hyderabad, one of India's fastest growing cities, to shed light more generally on the process of water capture by cities and the resultant impacts on pre-existing claims, particularly agriculture. It does this by examining the history and institutional response to Hyderabad's urban,rural water contest; how the results of that contest are reflected in surface and groundwater hydrology; and the eventual impacts on agriculture. The findings show that the magnitude, and sometimes even direction, of impact from urban water transfer vary in space and time and depend on location-specific rainfall patterns, the nature of existing water infrastructure and institutions, and farmers' adaptive capacities and options, notably recourse to groundwater. Broader consideration of the specific findings provides insights into policy mechanisms to reduce the possible negative impacts from the global, and seemingly inexorable, flow of water to the world's growing cities. [source] Hudson Strait ice streams: a review of stratigraphy, chronology and links with North Atlantic Heinrich eventsBOREAS, Issue 1 2003John T. Andrews We review the literature on the occupation of Hudson Strait (800 km long by 90 km wide) by late Quaternary ice streams, and the importance of Hudson Strait as the major source for sediments associated with the North Atlantic Heinrich (H-) events. Glacial erosion of the Paleozoic outcrop on the floor of Hudson Strait and Ungava Bay resulted in the export of detrital carbonate-rich sediments to ice-proximal locations on the slope and floor of the NW Labrador Sea, mainly in meltwater and turbidite plumes, and to ice distal sites thousands of kilometres away largely as iceberg-rafted detritus (IRD). Erosion of bedrock from the Precambrian Superior and Churchill provenances of the Canadian Shield is also indicated by the isotopic analyses of sediments. The major late Quaternary H-events (H-4, H-2 and H-1) are represented in southeast Baffin Island slope sediments as detrital carbonate-rich intervals up to 40 cm in thickness and appear to represent flow along the axis of the Strait. However, the late marine isotope stage #3 event, H-3 (,27 ka), and a younger event (H-0, ,11 ka), are not as dominant in the sedimentary record and probably represent a different glaciological regime with flow across Hudson Strait from eastern Ungava-Labrador. The freezing-on of sediments by supercooling in the rise from the 900 m deep Eastern Basin to the 400 m sill is proposed as the source of the abundant carbonate-rich glaciomarine sediments some 250 km from the outcrop in Eastern Basin. Sediment transport by meltwater and turbidity currents was the major process during H-events in ice-proximal settings. IRD was not a key diagnostic process at sites fronting Hudson Strait. A key feature in the instability of this ice stream might be the great depth (600 m) at the shelf break, and the deep basin, which lies seaward of the outer Hudson Strait sill. [source] The sedimentary structure of the Lomonosov Ridge between 88°N and 80°NGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2005Wilfried Jokat SUMMARY While the origin of the 1800-km-long Lomonosov Ridge (LR) in the Central Arctic Ocean is believed to be well understood, details on the bathymetry and especially on the sediment and crustal structure of this unique feature are sparse. During two expeditions in 1991 and 1998 into the Central Arctic Ocean several high quality seismic lines were collected along the margin of the ridge and in the adjacent Makarov Basin (MB). The lines collected between 87°36,N and 80°N perpendicular to and along the LR show a sediment starved continental margin with a variety of geological structures. The different features may reflect the different geological histories of certain ridge segments and/or their different subsidence histories. The sediments in the deep MB have thicknesses up to 2.2 km (3 s TWT) close to the foot of the ridge. At least in part basement reflections characteristics suggest oceanic crust. The acoustically stratified layers are flat lying, except in areas close to the ridge. Seismic units on the LR can be divided into two units based on refraction velocity data and the internal geometry of the reflections. Velocities <3.0 km s,1 are considered to represent Cenozoic sediments deposited after the ridge subsided below sea level. Velocities >4.0 km s,1 are associated with faulted sediments at deeper levels and may represent acoustic basement, which was affected by the Late Cretaceous/Early Cenozoic rift events. Along large parts of the ridge the transition of the two units is associated with an erosional unconformity. Close to the Laptev Sea such an erosional surface may not be present, because of the initial great depths of the rocks. Here, the deeper strata are affected by tectonism, which suggests some relative motion between the LR and the Laptev Shelf. Stratigraphic correlation with the Laptev Sea Shelf suggests that the ridge has not moved as a separate plate over the past 10 Myr. The seismic and regional gravity data indicate that the ridge broadens towards the Laptev Shelf. Although the deeper structure may be heavily intruded and altered, the LR appears to extend eastwards as far as 155°E, a consequence of a long-lived Late Cretaceous rift event. The seismic data across LR support the existence of iceberg scours in the central region of the ridge as far south as 81°N. However, no evidence for a large erosional events due to a more than 1000-m-thick sea ice cover is visible from the data. South of 85°N the seismic data indicate the presence of a bottom simulating reflector along all lines. [source] | ||||||||||