海洋古pH重建的技术方法

重建海洋古pH对于海洋酸化进程研究具有重要意义。本文对海洋古pH反演的硅藻组合、硼同位素组成及B/Ca、brGDGTs及3-羟基脂肪酸等技术方法进行了归纳和总结。硅藻组合法系根据沉积物中保存的硅藻的种类和丰度重建水体的古pH，在湖泊研究中有较多成功的应用；硼同位素组成及B/Ca法基于海洋钙质生物中δ11B或B/Ca的变化重建海水pH，brGDGTs法是基于沉积物中brGDGTs的环化指数或异构化程度重建过去海水pH，3-羟基脂肪酸法是基于沉积物中3-羟基脂肪酸的支链比反演海洋古pH。这些海洋古pH的反演技术方法各有特点，就目前而言，仅硼同位素组成及B/Ca法是追溯海洋古pH变化较为成熟的方法。研发海洋古pH反演新技术方法至关重要，完善现有方法构建更加准确精密的海洋古pH重建指标体系任重而道远。

Methods for reconstruction of oceanic paleo-pH

Based on the significantly implication of marine paleo-pH reconstruction to ocean acidification study, different proxies including diatom assemblage, boron isotope composition (δ11B) and B/Ca, brGDGTs and 3-hydroxy fatty acid and their paleo-pH reconstructing methods were summarized in this study.The diatom assemblage, which has been successfully applied with lake sediments, could rebuild oceanic paleo-pH by extract information from the diatoms species and abundance record.Likewise, the δ11B and B/Ca records in marine calcareous organisms were widely used to reconstruct pH in seawater.Both the degree of cyclization or isomerization of brGDGTs and the branching ratio of 3-hydroxy fatty acids could be influenced by the pH level of ambient environment, so the sediment fingerprints of these indicators were used to reconstruct marine paleo-pH.All the approaches have their own merits and demerits, however, δ11B and B/Ca are the most mature indicators for tracing changes of oceanic paleo-pH.Consequently, exploring new methods and improving current techniques are necessary, also of crucial importance for producing more accurate index of oceanic paleo-pH rebuilding.