Resumen de Modern calcite-precipitating experiment of algae and isotope imbalance
To understand the geochemistry effect of perplasmic carbonic anhydrase (pCA) during the sediment of calcium carbonate, Nosioc calcicola Breb. was studied. The photosynthetic carbon fixation in the obturator was enhanced by CA catalytically converting HCO3 - to CO2 and facilitating CO2 supply to the cell, which accelerated the sedimentation rate, reaching 22.4 mg/day/Lwater in the obturator and producing isotope fractionation. By testing[delta]13C and [delta]18O values of calcium carbonate affected by Nosioc calcicola Breb. and the corresponding contrast, the [delta]13C and [delta]18O values of calcium carbonate affected by Nosioc calcicola Breb. are 1.46 and -7.48%o, respectively, and the [delta]13C and [delta]18O values of contrast are -12.61 and -8.99%o, respectively, which means that isotope fractionation is influenced by the photosynthesis. Therefore, the results suggest that when isotope datum are used for paleoclimatic reconstruction by using stalagmites, local environment factors must be considered carefully to avoid the effect caused by metabolism.
