热带印度-太平洋浮游有孔虫Pulleniatina obliquiloculata的B/Ca和Cd/Ca指标：次表层海水碳化学参数计算的应用

Pulleniatina obliquiloculata shells from 16 core-top samples from the tropical Indo-Pacific Oceans are analyzed for the ratios of boron and cadmium to calcium(B/Ca and Cd/Ca). The B/Ca ratios show a very weak positive relationship with B(OH)_4~-] and the dissolved carbonate species at the apparent calcification depth of P.obliquiloculata. The boron partition coefficients(K_D) between P. obliquiloculata B/Ca and seawaterB(OH)_4~-]/HCO_3~-] distribute around 1.1×10~(-3)-1.3×10~(-3) with a mean value of(1.19±0.12)×10~(-3),and are significantly related to the nutrient concentration, especially phosphate. The lack of any clear correlation between the P. obliquiloculata B/Ca and seawater carbonate chemical parameters suggests that the physiochemical controls on boron incorporation are masked by the complexity of natural seawater condition. But the significant dependence of Ku on nutrient may likely be explained by a nutrient related growth-rate effect. Cd/Ca of P.obliquiloculata shows significant correlation with seawater phosphate concentration, and its partition coefficients(D_(cd)) are significantly related to temperature. A first-principle methodology of P. obliquiloculata B/Ca is applied;with the aid of Cd/Ca as a phosphate proxy and a constraint on K_D, to estimating sea water carbonate chemistry(e.g., pH). The results are fairly promising and allow us to propose the possibility to apply the combination of B/Ca and Cd/Ca proxies(and also Mg/Ca and δ~(18)O for estimating temperature and salinity) for the paleoreconstruction of seawater carbonate chemistry.

The B/Ca and Cd/Ca of a subsurface-dwelling foraminifera Pulleniatina obliquiloculata in the tropical Indo-Pacific Ocean: implications for the subsurface carbonate chemistry estimation

Pulleniatina obliquiloculata shells from 16 core-top samples from the tropical Indo-Pacific Oceans are analyzed for the ratios of boron and cadmium to calcium (B/Ca and Cd/Ca). The B/Ca ratios show a very weak positive relationship withB(OH)₄-] and the dissolved carbonate species at the apparent calcification depth of P. obliquiloculata. The boron partition coefficients (K_D) between P. obliquiloculata B/Ca and seawaterB(OH)₄-]/HCO₃-] distribute around 1.1×10-3-1.3×10-3 with a mean value of (1.19±0.12)×10-3, and are significantly related to the nutrient concentration, especially phosphate. The lack of any clear correlation between the P. obliquiloculata B/Ca and seawater carbonate chemical parameters suggests that the physiochemical controls on boron incorporation are masked by the complexity of natural seawater condition. But the significant dependence of K_D on nutrient may likely be explained by a nutrient related growth-rate effect. Cd/Ca of P. obliquiloculata shows significant correlation with seawater phosphate concentration, and its partition coefficients (D_Cd) are significantly related to temperature. A first-principle methodology of P. obliquiloculata B/Ca is applied, with the aid of Cd/Ca as a phosphate proxy and a constraint on K_D, to estimating sea water carbonate chemistry (e.g., pH). The results are fairly promising and allow us to propose the possibility to apply the combination of B/Ca and Cd/Ca proxies (and also Mg/Ca and δ18O for estimating temperature and salinity) for the paleo-reconstruction of seawater carbonate chemistry.