ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 21 (1983), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The hydraulic properties of commercial well screens were investigated to determine which screen design features affected head loss. The test program began with laboratory experiments and continued as a field-scale experiment with the installation of a well field in the Thames Valley Gravel Aquifer.The laboratory experiments indicated that, for all practical purposes, the head loss attributable to all of the screens tested was negligible. The experimental head loss, however, did vary from screen to screen, particularly at high intake velocities, and the screens could be ranked on the basis of their hydraulic efficiencies. This efficiency hierarchy is explained tentatively in terms of the screen construction methods and slot geometry. The field experiments showed that the hydraulic performance of all well screens is independent of screen design provided that the open area of the screen is above about 10%. The field experiments also indicated that the development capacity of a screen in a gravel aquifer is not wholly dependent on screen design, but that progressive development does increase the hydraulic efficiency of a well.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 34 (1987), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Detailed studies of a new, complete Marl Slate core in South Yorkshire have provided information on isotopic (δ13C, δ18O, δ34S) and geochemical variations (trace elements and C/S ratio) which enable the formulation of a model for carbonate and sulphide precipitation in the Late Permian Zechstein Sea. Calcite and dolomite are intimately associated; the fine lamination, organic character and absence of benthos in the sediments are indicative of anoxic conditions. Lithologically the core can be divided into a lower, predominantly sapropelic Marl Slate (2 m) and an upper Transition Zone (0·65 m) of alternating sapropel and calcite-rich and dolomite-rich carbonates.C/S ratios are 2·22 for the Marl Slate and 1·72 for the Transition Zone respectively, both characteristic of anoxic environments. δ18O in the carbonates shows a large and systematic variation closely mirrored by variations in calcite/dolomite ratio. The results suggest a fractionation factor equivalent to a depletion of 3·8% for 18O and 1·5% for 13C in calcite. The δ34S values of pyrite are isotopically light (mean value = - 32·7%) suggesting a fractionation factor for the Marl Slate of almost 44%, typical of anoxic basins.The results are related to stratification in the early Zechstein Sea. Calcite was precipitated in oxic upper layers above the halocline. Below the oxic/anoxic boundary framboidal pyrite was precipitated, resulting in lower sulphate concentration and elevated Mg/Ca ratio (due to calcite precipitation). As a result of this, dolomite formation occurred below the oxic/anoxic interface, within the anoxic water column and in bottom sediments. Variations in calcite/dolomite ratios, and isotopic variations, are thus explained by fluctuations in the relative level of the oxic/anoxic boundary in the Zechstein Sea.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...