晚更新世北极楚克奇陆架边缘有机碳的差异埋藏

Differential Burial of Particulate Organic Carbon at the Chukchi Continental Margin,Arctic Ocean since Late-Pleistocene

有机碳埋藏是评价北冰洋碳封存能力的关键因素,但其在轨道时间尺度上的埋藏特征目前还存在很大的争论.通过分析楚克奇陆架边缘M04孔和周边表层沉积物中总有机碳、稳定碳同位素和生物标记物等指标,进一步探讨了晚更新世楚克奇陆架边缘有机碳的组成、来源、埋藏速率及其与周边冰盖的协同演化.结果表明,陆源有机碳是楚克奇陆架边缘有机碳埋藏的主体,且在冰期‒间冰期旋回中表现出了显著的差异性,间冰期(MIS1和MIS3)埋藏速率低,冰期(MIS4和MIS2)埋藏速率急骤升高.结合楚克奇陆架边缘的地貌特征和沉积环境,东西伯利亚冰盖(ESIS)的扩张和冰下排水系统的输运可能是陆架有机碳二次搬运、并在陆架边缘高速埋藏的主要控制因素.M04孔的沉积记录为梳理北冰洋有机碳的埋藏特征提供了新的视角,进一步揭示了高速沉积区有机碳埋藏的驱动机制,有助于客观评价北冰洋碳埋藏对全球碳封存的推动作用,但仍需要更多、特别是来自北极加拿大一侧的数据才能有效刻画北冰洋碳埋藏与气候转型之间的耦合关系.

The burial of particulate organic carbon is a critical factor in assessing the Arctic Ocean´s carbon sequestration capacity,but its burial characteristics on orbital timescales remain highly debated.This study further explores the composition,source,and burial rate of organic matter in the Late Pleistocene and its co-evolution with the surrounding ice sheet by analyzing indicators such as total organic carbon,stable isotopes,and biomarkers in Core M04 at the Chukchi continental margin and the surrounding surface sediments.Results show that terrestrial organic carbon is the primary component of organic carbon burial at the Chukchi continental margin,with significant differences observed over glacial-interglacial cycles,with a low burial rate during the interglacial periods(MIS1 and MIS3)and a sharp increase in burial rate during the glacial periods(MIS4 and MIS2).Combined with the geomorphic features and depositional environment,the expansion of the East Siberian ice sheet(ESIS)and the transport of subglacial drainage systems may be the main controlling factors for the secondary transport of shelf organic carbon and its rapid burial at the continental margin.M04’s records provide a new perspective to unravel the characteristics of organic carbon burial,further revealing the mechanisms in the high-sedimentation-rate area of the Arctic Ocean,and help to objectively evaluate the role of Arctic Ocean carbon burial in promoting global carbon sequestration.However,further research,especially records from Arctic Canada,is needed to fully describe the coupling relationship between Arctic Ocean carbon burial and climate transition.