英国利兹大学Moore, Oliver W.及其团队成员在研究铁和锰增强有机碳的长期保存中取得进展。该研究于2023年8月2日发表于国际一流学术期刊《自然》杂志上。

研究提出了孵化实验，并发现铁和锰离子和矿物质在与大多数保存发生的大陆边缘相关的温度下，非生物催化美拉德反应高达两个数量级。此外，反应产物的化学特征与全球大陆边缘沉积物中发现的溶解和总沉积有机碳非常相似。借助于孔隙水模型，研究人员估计铁和锰催化的简单有机分子向复杂大分子的转化可能产生大约 4.1 Tg C yr^-1 的量级，以便保存在海洋沉积物中。在过去的 3 亿年的沉积有机保存中，大约只有 63 Tg C yr^-1的量级变化，研究人员认为，海洋中铁和锰的输入变化可能对地质时期全球沉积有机碳保存产生重大影响，但迄今为止尚未探索。

据悉，沉积有机碳(OC)是降解和保存之间的平衡对全球碳和氧循环非常重要。然而，促进海洋沉积有机碳保存的不同机制和环境条件的相对重要性仍然不清楚。尽管在海洋沉积温度下的反应动力学被认为是缓慢的，简单的有机分子可以通过美拉德反应被地质聚合成难分解的形式。最近在陆地系统中的研究表明，该反应可以被锰矿物催化，但在海洋沉积温度下，促进地质聚合沉积有机碳形成的可能性还不确定。

附：英文原文

Title: Long-term organic carbon preservation enhanced by iron and manganese

Author: Moore, Oliver W., Curti, Lisa, Woulds, Clare, Bradley, James A., Babakhani, Peyman, Mills, Benjamin J. W., Homoky, William B., Xiao, Ke-Qing, Bray, Andrew W., Fisher, Ben J., Kazemian, Majid, Kaulich, Burkhard, Dale, Andrew W., Peacock, Caroline L.

Issue&Volume: 2023-08-02

Abstract: The balance between degradation and preservation of sedimentary organic carbon (OC) is important for global carbon and oxygen cycles. The relative importance of different mechanisms and environmental conditions contributing to marine sedimentary OC preservation, however, remains unclear. Simple organic molecules can be geopolymerized into recalcitrant forms by means of the Maillard reaction, although reaction kinetics at marine sedimentary temperatures are thought to be slow. More recent work in terrestrial systems suggests that the reaction can be catalysed by manganese minerals, but the potential for the promotion of geopolymerized OC formation at marine sedimentary temperatures is uncertain. Here we present incubation experiments and find that iron and manganese ions and minerals abiotically catalyse the Maillard reaction by up to two orders of magnitude at temperatures relevant to continental margins where most preservation occurs. Furthermore, the chemical signature of the reaction products closely resembles dissolved and total OC found in continental margin sediments globally. With the aid of a pore-water model, we estimate that iron- and manganese-catalysed transformation of simple organic molecules into complex macromolecules might generate on the order of approximately 4.1 Tg C yr^-1 for preservation in marine sediments. In the context of perhaps only about 63 Tg C yr^-1 variation in sedimentary organic preservation over the past 300millionyears, we propose that variable iron and manganese inputs to the ocean could exert a substantial but hitherto unexplored impact on global OC preservation over geological time.

DOI: 10.1038/s41586-023-06325-9

Source: https://www.nature.com/articles/s41586-023-06325-9