利用有孔虫壳体B/Ca比值再造古海水pH值及[CO_3^(2-)]的潜力

Potential of Foraminiferal B/Ca Ratios for Reconstructing Paleo-seawater pH and CO_3^(2-) Concentrations

有孔虫壳体B/Ca比值是一个极具潜力并且受到广泛关注的古海洋学方法,适用于恢复古海水pH值及[CO23-]。对于表层水,在一定条件下可以再造大气CO2浓度;对于深层水,可以指示洋流变化及水团变迁。且与硼同位素方法相比较,B/Ca比值分析更简易、稳定性更好,受溶解及沉积埋藏作用影响小,因而更适合于高分辨率的古海洋学分析。但是,由于该分析方法较新,与之相关的有孔虫吸收B元素的生物过程不是很清楚,采用B/Ca比值恢复pH值及[CO32-]的机制也不是很了解,方法的建立主要基于经验公式基础之上,因而为该方法寻找理论基础是今后研究的一个重要方向。

The analysis of foraminiferal B/Ca ratios is a greatly potential and widely concerned paleoceanographic method, which is applicable to the reconstruction of the past pH and CO3^2- concentrations of sea water, and under certain situations also can also be used to reflect the changes of the atmospheric CO： concentration from surface water, and indicate changes of ocean current and water mass of deep water. Compared with the conventional method of boron isotopes, the B/Ca ratio method is relatively easier, more stable, and less affected less by dissolu- tion and post-deposition alternations. As a result, it is relatively suitable for high-resolution paleoceanographic studies. However, this method is comparably new. The foraminiferal biological processes to absorb boron element is still not very clear. Moreover, the mechanisms using B/Ca ratio to reconstruct pH and CO3^2- concentrations is not well accepted. As the method is constructed on the basis of empirical function, establishment of its theoretical basis will be the future and important development of this method.