Microanalysis of C and O isotopes of azooxanthellate and zooxanthellate corals by ion microprobe

摘要: We have determined the δ18O and δ13C values of azooxanthellate (Lophelia pertusa) zooxanthellate (Porites lutea) corals at a micrometer scale using an ion microprobe (SIMS—secondary mass spectrometry). In P. lutea, centers calcification are small (10 to 15 μm) difficult locate during measurements. L. pertusa, they large (50 arranged in lines calcification. Our results show that pertusa restricted range variation [-2.8±0.3‰ (PDB)], larger [14.3 10.9‰ (PDB)]. Surrounding skeletal fibers exhibit isotopic both for C O (up 12‰), positively correlated. The compositions center deviate from this linear trend lightest surrounding fibers. Ion on lutea demonstrate also 10‰). No correlation is found with isotopes exhibit, comparison (2‰). This probably result two processes: (1) equilibrium 1 pH unit fluid as indicated by direct measurements coelenteron coral Galaxea fascicularis (Al-Horani et al. 2003) (2) kinetic fractionation. apparent disequilibrium may be mixing between metabolic CO2 (respiration) dissolved inorganic carbon (DIC) coming directly seawater.