نتایج جستجو برای: grained sediments are present
تعداد نتایج: 5723422 فیلتر نتایج به سال:
Abstract. In water-stressed regions of the world, managed aquifer recharge (MAR), process intentionally recharging depleted aquifers, is an essential tool for combating groundwater depletion. Many groundwater-dependent regions, including Central Valley in California, USA, are underlain by thick unsaturated zones (ca. 10 to 40 m thick), nested within complex valley-fill deposits that can hinder ...
the sorkheh deposit in northwestern iran exhibits several readily visible general characteristics of sediment-hosted stratiform copper (ssc) mineralization. it consists of fine-grained disseminated base-metal sulfides within gray sandstones (gray beds, the basal whitish miocene sandstone and shallow-water) that overlie a thick sequence of red beds (miocene upper red formation). the host gray be...
Exceptionally preserved fossil biotas of the Burgess Shale and a handful of other similar Cambrian deposits provide rare but critical insights into the early diversification of animals. The extraordinary preservation of labile tissues in these geographically widespread but temporally restricted soft-bodied fossil assemblages has remained enigmatic since Walcott's initial discovery in 1909. Here...
Many elements such as Arsenic (As), Cadmium (Cd), Copper (Cu), Chromium (Cr), Lead (Pb), Zinc (Zn), and others are major environmental problems due to their toxic nature, nonbiodegradability and accumulative behaviors. There are anthropogenic or geogenic sources that accumulate or rotate elements in sediments. Sediments served as excellent indicator of metal pollution in coastal environments as...
This study focused on the luminescence dating of sediments from Lake El’gygytgyn, a meteorite impact crater 100 km north of the Arctic Circle in northeast Siberia, formed 3.58 Ma ago. The sediment is principally eolian deposited in to a lake with nearly permanently ice. The fine-grained polymineral and quartz extracts taken from nine distinct levels from the upper 12.3 m of sediment core PG1351...
The polybrominated diphenyl ethers (PBDEs) are bioaccumulative, persistent, and toxic. They have a high risk of emission into the environment via volatile losses and diffuse sources, such as commercial product disposal or the use of sewage sludge. The PBDEs’ congeners were analyzed in municipal waste water treatment plant (WWTP) sludge, river and lake water, sediment, and fish samples, to inves...
Heterogeneity can boost biodiversity, as well as increase the resilience of an ecosystem to changing environmental conditions; therefore, it is important to understand how topographic heterogeneity in ecosystems is formed. Sandy tidal marshes have a repetitive pattern of higher elevated hummocks surrounded by lower elevated depressions, representing topographic heterogeneity at the scale of a f...
Evidences of highly localized methane fluxes are reported from the Arctic shelf, hot spots of methane emissions in thermokarst lakes, and are believed to evolve to features like Yamal crater on land. The origin of large methane outbursts is problematic. Here we show, that the biogenic methane (δ13C ≤ −71h) which formed before and during soil freezing is presently held in the permafrost. Field a...
Introduction Sand ramp is a kind of sand dune located on or in the foot of some mountains slopes of arid and semi-arid regions. Although these landforms does not differ from other types of sand dunes in these areas apparently, but, there are significant differences between them from the point of view of slope, sediment grain size, Morphology, sediment homogeneous, stratigraphy, laminatio...
In this research, the effects of a sedimentary basin, environmental conditions, and the passage of time were investigated on consolidation processes and engineering characteristics of fine-grained soils in Kerman city. For this purpose, the natural consolidation curves of soil samples extracted from different locations of Kerman city were compared with the Kerman city intrinsic consolidation li...
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