长链烯酮在古大气二氧化碳分压重建的应用

The Application of Alkenone-Based pCO_2 Reconstructions

大气二氧化碳浓度的变化与全球冰盖变化、温度、海平面变化密切相关,了解过去大气二氧化碳浓度的变化及对二氧化碳与气候之间关系的研究,是预测未来气候变化的重要手段。长链烯酮碳同位素是重建古大气二氧化碳分压(p CO2)的重要指标之一,广泛应用于新生代以来大气二氧化碳的重建。对长链烯酮重建大气二氧化碳的方法进行了综述,介绍了颗石藻长链烯酮的地球化学性质,回顾了二氧化碳被动扩散模型的发展、长链烯酮重建二氧化碳的指标的发展及其不确定性,颗石藻的碳浓缩机制以及新生代以来长链烯酮重建大气二氧化碳的地质记录。

The changing of atmospheric carbon dioxide concentration is closely related with the changing of global ice sheet,temperature and sea level.Knowledge of the past atmospheric carbon dioxide concentration and its relationship with climate is an important method of predicting the future climate change.Coccolith derived longchain alkenone carbon isotope is one of the important proxies to reconstruct past carbon dioxide,which is wildly applied in the reconstruction of the Cenozoic atmospheric carbon dioxide.In this paper,we focused on the method of alkenone-based atmospheric carbon dioxide concentration,including the geochemical properties of long-chain alkenone,carbon diffusive model and the carbon isotope fraction.Then,we introduced the development of alkenone-based carbon dioxide proxy and its uncertainty.Coccolith cell geometry and growth rate have great influence on carbon dioxide fraction.Besides,there are some uncertainties about carbon concentration mechanisms in coccolithes,which may have some influence on alkenone-based carbon dioxide method to reconstruct ancient carbon dioxide more accurately.At the end,we summarized the Cenozoic carbon dioxide record with various proxies including alkenone carbon dioxide,boron isotope,palaeosol carbonate nodules and stomatal indices of fossil leaves.