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.