caa a22 4500 469045426 CHVBK 20180323132823.0 cr unu---uuuuu 170328e19921201xx s 000 0 eng 10.1007/BF02539795 doi (NATIONALLICENCE)springer-10.1007/BF02539795 Merz Martina Institut für Geologie und Paläontologie, Hans Meerwein Str., Lahnberge, D-3550, Marburg aut The biology of carbonate precipitation by cyanobacteria [Elektronische Daten] [Martina Merz] Summary: In the freshwater areas of the Everglades, Florida, U.S.A., carbonate is precipitated in dense cyanobacterial mats. Precipitation is linked with photosynthesis in the mats in a quantitative relationship. On ground of field observations and experiments a model for precipitation in the filamentous cyanobacteriaScytonema is proposed, which links precipitation to bicarbonate use in photosynthesis and subsequent release of OH− ions. Besides supersaturation of the water with respect to carbonate and photosynthetic bicarbonate use, precipitation requires a suitable sheath structure and composition. The characteristics of the sheath seem to be responsible for a distinct crystal morphology in the two generaScytonema andSchizothrix, as well as for the restriction of calcification to the outer sheath inScytonema. In the immediate vicinity of the trichom precipitation seems to be inhibited. Comparison of this form of calcifying cyanobacteria with calcification in calcareous algae shows many similarities and rises the question of the biological significance of calcification or precipitation. The precipitated carbonate shows equilibrium precipitation in its δ oxygen values, while it is enriched in13C relative to the ambient water. This agrees with a model of precipitation in which the carbonate derives from the water immediately surrounding the filament. There the water is depleted in12C which is preferably taken up for photosynthesis. No respiratory carbon is involved in precipitation. From measurements of the amount of precipitation in the field and in experiments the annual sedimentation rate is estimated to be 0.024 to 0.24 mm. These values fall within the range of laminae thicknesses in fossil algal laminites. Institut für Palaentologie, Universitat Erlangen, 1992 Cyanobacteria nationallicence Schizothrix, Scytonema nationallicence Calcification nationallicence Stableisotopes nationallicence Freshwater Carbonate nationallicence Everglades (Florida) nationallicence Recent nationallicence Facies Springer-Verlag 26/1(1992-12-01), 81-101 0172-9179 26:1<81 1992 26 10347 https://doi.org/10.1007/BF02539795 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02539795 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Merz Martina Institut für Geologie und Paläontologie, Hans Meerwein Str., Lahnberge, D-3550, Marburg aut NATIONALLICENCE 773 0- Facies Springer-Verlag 26/1(1992-12-01), 81-101 0172-9179 26:1<81 1992 26 10347 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer