| dc.description.abstract | Isotopic compositions of boron (δ11Bc value) and elemental concentrations of B, Ca, Mg, Fe and Al in growing corals from Sanya Bay, China and Kavaratti Lagoon, India along with δ11Bsw values and pH values of the coexisting sea water have been measured in this study using TIMS. The δ11Bc values of growing corals behave inconsistently and are not related to the concentrations of Fe and Al in corals. The higher δ11Bc values of corals imply additional amount of trigonal species of boron to be incorporated into corals. Based on the measured δ11B values of growing corals and coexisting sea water as well as the pH of co-existing sea water, a new isotopic fractionation factor α43 between two boron species, B(OH)4 – and B(OH)3, has been measured to be 0.980, consistent with the well accepted α43 of 0.981 established by earlier workers. The significance of α43 value established by recalculating the sea water pH considering the published δ11B values of marine carbonates and using the reported α43 values of 0.968, 0.981, 0.984 and one α43 of 0.980 observed in this study, gave the average pH values of sea water to be 8.85, 8.17, 7.76 and 8.22 respectively. This indicates the closeness of α43 value of 0.980 with that of the well-accepted reported α43 of 0.981 as the recalculated pH values of sea water obtained using these are nearly the same. The α43 value of 0.980 observed in this study can therefore be considered an acceptable value for reconstructing the past sea water pH values. | |
