底栖有孔虫Δδ^(13)C定量重建海洋深水氧气含量的原理及应用

The principle and application of benthic foraminiferal Δδ^(13)C values to quantitatively reconstruct bottom water oxygen concentrations

海洋中的溶解氧是生物地球化学循环的重要参数。在全球变暖的背景下,海洋缺氧是当前面临的环境问题之一,定量重建海水氧气含量在预测未来气候和生态环境变化中尤为重要。以往常用的代用指标大多只能定性或半定量地重建海洋深水氧气含量,而近年来新发展的底栖有孔虫表生种Cibicidoides wuellerstorfi和内生种Globobulimina spp.的碳同位素梯度(Δδ^(13)C)被认为可以在20~235μmol/kg范围内定量重建海洋深水氧气含量。目前,底栖有孔虫Δδ^(13)C重建深水氧气含量的研究多集中于边缘海,对开阔大洋的关注不足。本文通过对比不同海洋深水氧气含量代用指标的异同,厘清底栖有孔虫Δδ^(13)C重建海洋深水氧气含量的原理及影响因素,归纳底栖有孔虫Δδ^(13)C在全球范围内的应用,这对约束地球系统模型的结果具有重要意义。

The dissolved oxygen is an essential parameter for the biogeochemical cycling in the ocean.Under the global warming background,the ocean deoxygenation is currently one of the critical environmental issues.To quantitatively reconstruct oxygen content of seawater is crucial in predicting changes of climate and ecological environment in the future.Most existing proxies can only qualitatively or semi-quantitatively reconstruct the bottom seawater oxygen concentrations,while the recently developed proxy,i.e.,the carbon isotope gradients of benthic foraminiferal epifaunal species Cibicidoides wuellerstorfi and the infaunal species Globulimina spp.(Δδ^(13)C)has been demonstrated to have the potential for quantitatively reconstructing bottom seawater oxygen concentrations varying from 20 to 235μmol/kg.However,researches for the reconstruction of oxygen content of the bottom seawater based on the benthic foraminiferal Δδ^(13)C values had mainly focused on the continental margin,with only limited attention paid to the open ocean.On the basis of comparing different proxies for the reconstruction of oxygen content of bottom seawater,in this paper,we have clarified the principle and influencing factors of the AsC proxy of the benthic foraminifera for reconstructing oxygen contents of the bottom seawater and have summarized the global application of the Δδ^(13)C proxy of the benthic foraminifera.The application of this method would be of great significance to constrain results of the earth system modelling.