热带西太平洋古海水pH重建模型的参数修正与区域标定

项目名称： 热带西太平洋古海水pH重建模型的参数修正与区域标定

项目编号： No.41306055

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 吴晓丹

作者单位： 中国科学院海洋研究所

项目金额： 27万元

中文摘要： 大洋酸化是大气pCO2升高引发的全球性问题，pH是衡量大洋酸化程度的关键参数，以暖池为主体的热带西太平洋作为全球海气交换最活跃的区域，是探索大洋酸化机制的理想海区。由于缺乏海水pH的长期连续性观测，研究大洋酸化问题实质是以"示踪剂"反演为基础的古海水高分辨pH重建过程。海洋沉积物中生物碳酸盐硼同位素（δ11B）是古海水的理想"pH计"，但应用中尚未考虑早期成岩过程因溶蚀作用引起的二次分馏。基于此，本项目以热带西太平洋为研究靶区，外海调查与实验室模拟相结合，以表层沉积物中有孔虫为研究对象，模拟溶蚀作用所造成的硼同位素分馏程度，综合其他同位素和微量元素指标，确定表征二次分馏的化学参数，校准δ11B经验公式，修正δ11B-pH估算模型。利用大西洋标定方法，结合靶区古海洋和碳酸盐系统参数，区域标定δ11B，构建热带西太平洋海区的专属模型，为研究大洋酸化过程提供可靠依据。

中文关键词： pH重建；特点剖析；可靠性评估；方法改进和构建；模拟实验

英文摘要： Ocean acidification is a global concern caused by increasing atmosphere partial pressure of carbon dioxide (pCO2). The pH is the key parameter to investigate the level of ocean acidification and the tropical western Pacific, as the most active area for global air-sea exchange, is the ideal sea to explore the mechanism of ocean acidification. Due to the lack of long-term continuous observation of pH, researches on acidification heavily rely on tracers to precisely reconstruct pH of paleo-seawater. Although boron isotope (δ11B) in marine biogenic carbonates functions as desired proxy for calculating pH of paleo-seawater, the reconstruction process disregards the second fractionation caused by the dissolution of marine biogenic carbonates. Therefore, our project tries to simulate the degree of boron isotope fractionation from foraminifera in surface sediments in tropical western pacific in dissolution condition. Based on the simulated test in laboratory, the empirical formulas of δ11B will be calibrated by other isotopic and trace element. By the corrected δ11B values, a modified paleo-seawater pH mode can be established, which will be calibrated for regional applicability according to the calibration method applied in Atlantic and the paleoceanography and carbonate system parameters determined in the tropical wes

英文关键词： pH reconstruction；anatomy of the characteristic；estimation of reliability；improvement and construction of method；simulation experiment