Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland)
<p><em>In the course of a routine water-quality survey in meso-oligotrophic lake Geneva (Switzerland), suspended matter was collected by filtration on 0.2 μm membranes in July and August 2012 at the depth of maximal chlorophyll </em>a<em> (Chl </em>a<em>) concentr...
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| Format: | Article |
| Language: | English |
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PAGEPress Publications
2013-10-01
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| Series: | Journal of Limnology |
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| Online Access: | http://www.jlimnol.it/index.php/jlimnol/article/view/743 |
| _version_ | 1818116797213179904 |
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| author | Jean-Michel Jaquet Pascale Nirel Agathe Martignier |
| author_facet | Jean-Michel Jaquet Pascale Nirel Agathe Martignier |
| author_sort | Jean-Michel Jaquet |
| collection | DOAJ |
| description | <p><em>In the course of a routine water-quality survey in meso-oligotrophic lake Geneva (Switzerland), suspended matter was collected by filtration on 0.2 μm membranes in July and August 2012 at the depth of maximal chlorophyll </em>a<em> (Chl </em>a<em>) concentration (2 mg m<sup>–3</sup>). Examination by scanning electron microscopy revealed the presence of numerous dark and gelatinous patches occluding the pores of the membranes, containing high numbers of picoplanktonic cells and, in places, clusters of high-reflectance smooth microspheres (1-2 μm in diameter). Their chemical composition, determined by semi-quantitative, energy-dispersive X ray spectroscopy (EDS) showed magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) (alkaline earth metals) to be the dominant cations. Among the anions, phosphorus (P) and carbon (C) were present, but only the latter is considered here (as carbonate). The microspheres were subdivided into four types represented in a Ca-Sr-Ba ternary space. All types are confined within a domain bound by </em><em>Ca>45, Sr<10 and Ba<50 (in mole %). </em><em>Type I, the most frequent, displays a broad variability in Ba/Ca, even within a given cluster. Types II and III are devoid of Ba, but may incorporate P. Type IV contains only Ca. The Type I composition resembles that of benstonite, a Group IIA carbonate that was recently found as intracellular granules in a cyanobacterium from alkaline lake Alchichica (Mexico).</em><em>Lake Geneva microspheres are solid, featureless and embedded in a mucilage-looking substance in the vicinity of, but seemingly not inside, picoplanktonic cells morphologically similar to </em>Chlorella<em> and </em>Synechococcus<em>. In summer 2012, the macroscopic physico-chemical conditions in lake Geneva epilimnion were such as to allow precipitation of Ca but not of Sr and Ba carbonates. Favourable conditions did exist, though, in the micro-environment provided by the combination of active picoplankton and a mucilaginous envelope. </em><em>Further studies are ongoing to investigate the vertical distribution of the microspheres, their internal structure and their exact mineralogical composition, as well as the taxonomy of the picoplankton and the nature of the mucilage, in order to gain a proper understanding of this intriguing process of alkaline-earth metals sequestration.</em></p> |
| first_indexed | 2024-12-11T04:28:13Z |
| format | Article |
| id | doaj.art-9ab16a9dd7884d6e8922061a0688d566 |
| institution | Directory Open Access Journal |
| issn | 1129-5767 1723-8633 |
| language | English |
| last_indexed | 2024-12-11T04:28:13Z |
| publishDate | 2013-10-01 |
| publisher | PAGEPress Publications |
| record_format | Article |
| series | Journal of Limnology |
| spelling | doaj.art-9ab16a9dd7884d6e8922061a0688d5662022-12-22T01:20:56ZengPAGEPress PublicationsJournal of Limnology1129-57671723-86332013-10-01723e50e5010.4081/jlimnol.2013.e50585Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland)Jean-Michel Jaquet0Pascale Nirel1Agathe Martignier2Dept. of Geology Earth Sciences section University of GenevaUniversity of GenevaUniversity of Geneva<p><em>In the course of a routine water-quality survey in meso-oligotrophic lake Geneva (Switzerland), suspended matter was collected by filtration on 0.2 μm membranes in July and August 2012 at the depth of maximal chlorophyll </em>a<em> (Chl </em>a<em>) concentration (2 mg m<sup>–3</sup>). Examination by scanning electron microscopy revealed the presence of numerous dark and gelatinous patches occluding the pores of the membranes, containing high numbers of picoplanktonic cells and, in places, clusters of high-reflectance smooth microspheres (1-2 μm in diameter). Their chemical composition, determined by semi-quantitative, energy-dispersive X ray spectroscopy (EDS) showed magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) (alkaline earth metals) to be the dominant cations. Among the anions, phosphorus (P) and carbon (C) were present, but only the latter is considered here (as carbonate). The microspheres were subdivided into four types represented in a Ca-Sr-Ba ternary space. All types are confined within a domain bound by </em><em>Ca>45, Sr<10 and Ba<50 (in mole %). </em><em>Type I, the most frequent, displays a broad variability in Ba/Ca, even within a given cluster. Types II and III are devoid of Ba, but may incorporate P. Type IV contains only Ca. The Type I composition resembles that of benstonite, a Group IIA carbonate that was recently found as intracellular granules in a cyanobacterium from alkaline lake Alchichica (Mexico).</em><em>Lake Geneva microspheres are solid, featureless and embedded in a mucilage-looking substance in the vicinity of, but seemingly not inside, picoplanktonic cells morphologically similar to </em>Chlorella<em> and </em>Synechococcus<em>. In summer 2012, the macroscopic physico-chemical conditions in lake Geneva epilimnion were such as to allow precipitation of Ca but not of Sr and Ba carbonates. Favourable conditions did exist, though, in the micro-environment provided by the combination of active picoplankton and a mucilaginous envelope. </em><em>Further studies are ongoing to investigate the vertical distribution of the microspheres, their internal structure and their exact mineralogical composition, as well as the taxonomy of the picoplankton and the nature of the mucilage, in order to gain a proper understanding of this intriguing process of alkaline-earth metals sequestration.</em></p>http://www.jlimnol.it/index.php/jlimnol/article/view/743Bio-mediated carbonate precipitation, alkaline-earth metals, freshwater, picoplankton. |
| spellingShingle | Jean-Michel Jaquet Pascale Nirel Agathe Martignier Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland) Journal of Limnology Bio-mediated carbonate precipitation, alkaline-earth metals, freshwater, picoplankton. |
| title | Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland) |
| title_full | Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland) |
| title_fullStr | Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland) |
| title_full_unstemmed | Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland) |
| title_short | Preliminary investigations on picoplankton-related precipitation of alkaline-earth metal carbonates in meso-oligotrophic lake Geneva (Switzerland) |
| title_sort | preliminary investigations on picoplankton related precipitation of alkaline earth metal carbonates in meso oligotrophic lake geneva switzerland |
| topic | Bio-mediated carbonate precipitation, alkaline-earth metals, freshwater, picoplankton. |
| url | http://www.jlimnol.it/index.php/jlimnol/article/view/743 |
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