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  • Carbon credits  (1)
  • Micronutrient  (1)
Publikationsart
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Planta 198 (1996), S. 39-45 
    ISSN: 1432-2048
    Schlagwort(e): Chara ; Cell wall and zinc ; Micronutrient ; Triticum ; Zinc uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The mechanism of zinc influx was investigated using giant algal cells (Chara corallina Klein ex Will.esk. R.D. Wood), in which it was possible to discriminate clearly between tracer zinc bound in the cell wall and actual uptake into the cell. It was shown that despite lengthy desorption, retention of zinc in slowly exchanging zinc pools in the cell wall can invalidate tracer influx measurements. A comparative study of zinc desorption from isolated cell walls of wheat (Triticum aestivum L.) roots indicated exchange characteristics similar to that of Chara. Fractionation of Chara internodal cells taken directly from cultures showed that most of the cell-associated zinc was in the cell walls. The cytoplasmic and vacuolar zinc concentrations were 56 mmol·m−3 and 32 mmol·m−3, respectively, for cells grown in a zinc concentration of 0.1 mmol·m−3. Influx of 65Zn in Chara was linear over several hours, with rapid transfer to the vacuole, but only slow efflux. Influx occurred in a biphasic manner, which was tentatively attributed to the operation of two separate transport systems, a high-affinity system which is saturated at 0.1 mmol·m−3 and a low-affinity system which showed a linear dependence on concentration up to at least 50 mmol·m−3. Only the low-affinity system was examined in detail. Influx through this system showed a strong dependence on external pH with an optimum around 7 and was also stimulated by cytoplasmic acidification. Influx was sensitive to metabolic inhibition, but not to blockers of Ca2+ and K+ channels. Other characteristics included a slight sensitivity to Mn2+ and Fe2+ but little sensitivity to high concentrations of K+ or Na+. Influx was independent of membrane potential difference in cells voltage-clamped at − 65 to − 300 mV.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Pollution Bulletin 56 (2008): 1049-1056, doi:10.1016/j.marpolbul.2008.03.010.
    Beschreibung: The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.
    Beschreibung: This paper was developed under the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) core research project on HABs and Eutrophication and the GEOHAB regional focus on HABs in Asia. GEOHAB is supported by the International Oceanographic Commission (IOC) of UNESCO and by the Scientific Committee on Oceanic Research (SCOR), which are, in turn, supported by multiple agencies, including NSF and NOAA of the USA.
    Schlagwort(e): Urea dumping ; Ocean fertilization ; Carbon credits ; Sulu Sea ; Carbon sequestration ; Harmful algae ; Toxic dinoflagellates ; Cyanobacteria ; Hypoxia
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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