Department of Earth and Planetary Sciences, Washington University in St Louis, St Louis, MO, 63130, USA.
Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA.
Nat Commun. 2018 Aug 24;9(1):3409. doi: 10.1038/s41467-018-05943-6.
Ocean Anoxic Event 2 (OAE2) was a period of dramatic disruption to the global carbon cycle when massive amounts of organic matter (OM) were buried in marine sediments via complex and controversial mechanisms. Here we investigate the role of OM sulfurization, which makes OM less available for microbial respiration, in driving variable OM preservation in OAE2 sedimentary strata from Pont d'Issole (France). We find correlations between the concentration, S:C ratio, S-isotope composition, and sulfur speciation of OM suggesting that sulfurization facilitated changes in carbon burial at this site as the chemocline moved in and out of the sediments during deposition. These patterns are reproduced by a simple model, suggesting that small changes in primary productivity could drive large changes in local OM burial in environments poised near a critical redox threshold. This amplifying mechanism may be central to understanding the magnitude of global carbon cycle response to environmental perturbations.
海洋缺氧事件 2（OAE2）是全球碳循环剧烈中断的一个时期，大量的有机物质（OM）通过复杂且有争议的机制被埋藏在海洋沉积物中。在这里，我们研究了 OM 硫化作用的作用，这种作用使 OM 更不易被微生物呼吸利用，从而在法国 Pont d'Issole 的 OAE2 沉积地层中驱动 OM 保存的可变性。我们发现 OM 的浓度、C:S 比、S 同位素组成和硫形态之间存在相关性，这表明随着化学梯度在沉积过程中进出沉积物，硫的硫化作用促进了碳埋藏的变化。这些模式被一个简单的模型所复制，这表明在接近关键氧化还原阈值的环境中，初级生产力的微小变化可能会导致局部 OM 埋藏的大量变化。这种放大机制可能是理解全球碳循环对环境干扰的响应幅度的核心。
