Most organic carbon delivered to the seafloor is degraded within the bioturbated layer. Theory and empirical evidence have shown that organic carbon reactivity relates to the age of a particle. However, due to particle mixing, the age-depth linear relation induced by sediment accretion is obfuscated. Here we combine a Lagrangian particle tracking model that resolves the age distribution of particles in the bioturbated zone and couple it to age-dependent organic carbon degradation. Depth profiles for organic carbon concentration, reactivity and degradation rate are presented for sediments receiving low and high reactivity organic carbon in coastal, continental slope and deep-sea environments. Our results show that a simple first-order kinetics model suffices for well-mixed sediments and systems receiving pre-processed materials. A reactive continuum approach is needed for poorly mixed sediments receiving highly reactive organic carbon and for sediments below the bioturbated layer.

中文翻译：

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生物扰动沉积物中的有机碳反应动力学


输送到海底的大部分有机碳在生物扰动层内降解。理论和经验证据表明，有机碳反应性与颗粒的年龄有关。然而，由于颗粒混合，沉积物吸积引起的年龄-深度线性关系被混淆了。在这里，我们结合了一个拉格朗日粒子跟踪模型，该模型解析了生物扰动区中粒子的年龄分布，并将其与年龄依赖性的有机碳降解耦合。介绍了在沿海、大陆斜坡和深海环境中接收低反应性和高反应性有机碳的沉积物的深度剖面。我们的结果表明，简单的一阶动力学模型足以用于混合良好的沉积物和接收预处理材料的系统。对于接收高活性有机碳的混合不良沉积物和生物扰动层以下的沉积物，需要一种反应连续体方法。