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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Human Evolution 17 (1988), S. 597-614 
    ISSN: 0047-2484
    Keywords: Lainyamok ; Middle Pleistocene ; Olorgesailie ; butchery site ; hyena bone accumulation ; southern Kenya ; taphonomy
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2021-07-14
    Description: Dissolved organic carbon (DOC) in the oceans is one of the largest dynamic reservoirs of carbon on earth, comparable in size to the atmospheric reservoir of carbon (as CO2) in the atmosphere, or to the amount of carbon in all terrestrial and aquatic biota. The concerted efforts of earth scientists, atmospheric scientists, and biologists who study global biogeochemical cycles and the earth's climate have yielded a rather detailed understanding of carbon in the atmosphere and in biota. Marine dissolved organic matter (DOM) is far less well characterized, principally because it exists as a highly diluted mixture of perhaps millions of organic compounds in a highly saline aqueous solution. Prior to 2007, only around 1/3 of marine DOM was typically recovered from seawater for research purposes, regardless of the method of isolation. In 2007, reverse osmosis (RO) and electrodialysis (ED) were coupled to achieve recoveries of 64–93% of marine DOM. The level of residual salts in the concentrated samples, however, still precluded the characterization of marine DOM by solid-state NMR, mass spectrometry, or even elemental analysis. This paper describes a major improvement to the RO/ED method, in which pulsed ED is used (at sea) to reach roughly 100-fold greater removal of salts compared to non-pulsed ED while maintaining comparable recoveries of DOM.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2021-07-14
    Description: Dissolved organic carbon (DOC) in the oceans is one of the largest dynamic carbon reservoirs on earth. The composition and fate of this carbon reservoir is of great interest to earth scientists, atmospheric scientists, and biologists who study global biogeochemical cycles and global warming. Current techniques for the extraction and purification of dissolved organic matter (DOM) from seawater for research purposes recover at best only 30 wt% of DOC. A new technique for the recovery of DOM from seawater has been developed by combining electrodialysis and reverse osmosis. Here we present shipboard results and laboratory work to show the feasibility of our technique. DOC recoveries exceeding 60% and even exceeding 90% for one seawater sample have been found. Analysis of samples recovered using this technique will yield new insights into the cycling of DOC in the oceans.
    Type: Article , PeerReviewed
    Format: text
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  • 4
    Publication Date: 2020-02-12
    Description: Simultaneous removal of nitrogen and phosphorus by microbial biofilters has been used in a variety of water treatment systems including treatment systems in aquaculture. In this study, phosphorus, nitrate and sulfate cycling in the anaerobic loop of a zero-discharge, recirculating mariculture system was investigated using detailed geochemical measurements in the sludge layer of the digestion basin. High concentrations of nitrate and sulfate, circulating in the overlying water (∼15 mM), were removed by microbial respiration in the sludge resulting in a sulfide accumulation of up to 3 mM. Modelling of the observed S and O isotopic ratios in the surface sludge suggested that, with time, major respiration processes shifted from heterotrophic nitrate and sulfate reduction to autotrophic nitrate reduction. The much higher inorganic P content of the sludge relative to the fish feces is attributed to conversion of organic P to authigenic apatite. This conclusion is supported by: (a) X-ray diffraction analyses, which pointed to an accumulation of a calcium phosphate mineral phase that was different from P phases found in the feces, (b) the calculation that the pore waters of the sludge were highly oversaturated with respect to hydroxyapatite (saturation index = 4.87) and (c) there was a decrease in phosphate (and in the Ca/Na molar ratio) in the pore waters simultaneous with an increase in ammonia showing there had to be an additional P removal process at the same time as the heterotrophic breakdown of organic matter.
    Type: info:eu-repo/semantics/article
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