Enhanced Terrestrial Carbon Export From East Antarctica During the Early Eocene
Enhanced Terrestrial Carbon Export From East Antarctica During the Early Eocene
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DOI：
10.1029/2021pa004348
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发表时间：
2022-01
影响因子：
3.5
通讯作者：
G. Inglis;J. Toney;Jiang Zhu;C. Poulsen;U. Röhl;S. Jamieson;J. Pross;M. Cramwinckel;S. Krishnan;M. Pagani;P. Bijl;J. Bendle
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作者：
G. Inglis;J. Toney;Jiang Zhu;C. Poulsen;U. Röhl;S. Jamieson;J. Pross;M. Cramwinckel;S. Krishnan;M. Pagani;P. Bijl;J. Bendle
陆地有机碳（TerrOC）是一种重要的CO2汇，通过河流输送到海洋，并被封存在沿海海洋沉积物中。这种机制可能有助于在短期和长期（103-106年）内调节大气中的二氧化碳水平，但其在过去温暖气候中的重要性仍然未知。在这里，我们使用陆地生物标志物保存在沿海海洋沉积物样品中威尔克斯，东南极洲（167 °S）量化TerrOC埋藏在始新世早期（154.4 -51.5 Ma）。陆地生物标志物分布表明植物、土壤和泥炭来源的有机碳（OC）进入海洋领域。植物（长链正构烷烃）和土壤来源的（藿烷）生物标志物的质量积累率在始新世早期（154 Ma）和始新世早期气候适宜期（EECO; 153 Ma）之间急剧增加。这与有机碳质量积累率的增加相吻合，表明EECO期间TerrOC埋藏增强。叶蜡δ 2 H值表明，EECO的特征是相对于最早的始新世更潮湿的条件，这表明水文气候对TerrOC输出施加了一级控制。我们的研究结果表明，TerrOC埋藏在沿海海洋沉积物中可以作为一个重要的负反馈机制，在始新世早期，但也在其他温暖的气候间隔。
Terrestrial organic carbon (TerrOC) acts as an important CO2 sink when transported via rivers to the ocean and sequestered in coastal marine sediments. This mechanism might help to modulate atmospheric CO2 levels over short‐ and long‐ timescales (103–106 years), but its importance during past warm climates remains unknown. Here we use terrestrial biomarkers preserved in coastal marine sediment samples from Wilkes Land, East Antarctica (∼67°S) to quantify TerrOC burial during the early Eocene (∼54.4–51.5 Ma). Terrestrial biomarker distributions indicate the delivery of plant‐, soil‐, and peat‐derived organic carbon (OC) into the marine realm. Mass accumulation rates of plant‐ (long‐chain n‐alkane) and soil‐derived (hopane) biomarkers dramatically increase between the earliest Eocene (∼54 Ma) and the early Eocene Climatic Optimum (EECO; ∼53 Ma). This coincides with increased OC mass accumulation rates and indicates enhanced TerrOC burial during the EECO. Leaf wax δ2H values indicate that the EECO was characterized by wetter conditions relative to the earliest Eocene, suggesting that hydroclimate exerts a first‐order control on TerrOC export. Our results indicate that TerrOC burial in coastal marine sediments could have acted as an important negative feedback mechanism during the early Eocene, but also during other warm climate intervals.