نتایج جستجو برای: seepage control
تعداد نتایج: 1331710 فیلتر نتایج به سال:
We have used new gel pore-water profilers and conventional seepage meters to determine the advective flux of water from an underwater saline seep into Lake Kinneret. The gel probes sampled pore waters from medium to coarse sands that could not be sampled by conventional coring methods. The anions Cl, Br, and SO4 were constant at levels just above those for the lake for 3–5 cm into the sediment ...
Trabeculectomy remains the standard surgery for intraocular pressure control for glaucoma. It involves a full thickness penetration of sclera, to allow aqueous seepage to subconjunctival space under a scleral flap. However, it carries the risk of serious bleb related complications like overfiltration, hypotony and consequent persistent choroidal detachment, shallow anterior chamber, cataract, p...
With decreases in acid deposition, nitrogen : phosphorus (N:P) ratios in lakes are anticipated to decline, decreasing P limitation of phytoplankton and potentially changing current food web dynamics. This effect could be particularly pronounced in the Adirondack Mountains of New York State, a historic hotspot for effects of acid deposition. In this study, we evaluate spatial patterns of nutrien...
Methane on Mars is a topic of special interest because of its potential association with microbial life. The variable detections of methane by the Curiosity rover, orbiters, and terrestrial telescopes, coupled with methane's short lifetime in the martian atmosphere, may imply an active gas source in the planet's subsurface, with migration and surface emission processes similar to those known on...
Engineers have worked for millennia to control natural flooding through dams and levees. While the fundamental principles and challenges of holding back water have not changed, the tools brought to the task continue to evolve. Among other tools being tested and implemented today are elaborate sensors to detect stresses and strains within structures, and impermeable lining materials known as geo...
Previous studies indicate that the local aquifer systems in the Mid-Levels, a highly urbanized coastal area in Hong Kong, have commonly been affected by leakage from water mains. The identification of leakage locations was done by conventional water quality parameters including major and trace elements. However, these parameters may lead to ambiguous results and fail to identify leakage locatio...
Acid mine drainage (AMD) was the main environmental problem facing the mining industry. For AMD had high heavy metals content and low pH, the compacted sewage sludge might be a barrier for tailings whose oxidation and weathering produced AMD, with its own carbon source, microorganism reduction ability and impermeability. To study the heavy metals environmental risk, under the simulate AMD, the ...
Widespread methane seepage along the continental margin off Svalbard - from Bjørnøya to Kongsfjorden
Numerous articles have recently reported on gas seepage offshore Svalbard, because the gas emission from these Arctic sediments was thought to result from gas hydrate dissociation, possibly triggered by anthropogenic ocean warming. We report on findings of a much broader seepage area, extending from 74° to 79°, where more than a thousand gas discharge sites were imaged as acoustic flares. The g...
Is the recently found seepage groundwater on Mars pure H2O, or mixed with salts and other antifreeze compounds? Given the surface conditions of Mars, it is unlikely that pure water could either exist in its liquid state or have shaped Mars’ fluid erosional landforms (gullies, channels, and valley networks). More likely is that Mars’ seepage groundwater contains antifreeze and salt compounds tha...
[1] Numerical models of bedrock valley development generally do not include weathering explicitly. Nevertheless, weathering is an essential process that acts in concert with the transport of loose debris by seepage and runoff to form many bedrock valleys. Here we propose a numerical model for bedrock valley development that explicitly distinguishes weathering and the transport of loose debris a...
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