On October 4, 2019,Science published a report by researchers of Tongji University and Eidgenössische Technische Hochschule Zürich (ETH Zürich), which found that soil-derived organic matter from land sources was stripped from the surface of montmorillonite during transportation and deposition in the ocean and replaced by marine-derived organic matter, but it is also rock-derived organic matter from land sources, which is closely combined with mica and chlorite without change in the marine environment. Results show that the long-term preservation of organic matter from land sources in marine sediments is controlled by the primary factor of layered silicate minerals.
Long-term preservation of organic matter has been a mystery for the earth science community. Despite the widely reported relationship between organic matter content and mineral surface area that is reported in numerous papers, there has been no clear explanation of the nature of this relationship. According to LIU Zhifei of State Key Laboratory of Marine Geology, Tongji University, co-author of this report, clay minerals are distributed in the South China Sea and its surrounding areas with high spatial diversity, which provides natural experimental conditions for quantitative verification of this relationship. After years of investigation, the research team has revealed that Luzon Island in the northern South China Sea only provides soil-derived montmorillonite, while Taiwan Island only provides rock-derived mica and chlorite. By setting up an anchor system observation system for deep sea sediment traps in the northern South China Sea, clay minerals from Luzon Island and Taiwan Island in time series and terrigenous organic matter carried by them are obtained. High-precision experimental analysis such as radiocarbon dating, stable isotope of organic carbon, surface area of layered silicate minerals and quantitative study of mineral content are carried out. It is clearly revealed for the first time that the types of clay minerals are the most important factor affecting the preservation of organic matter.
The research is an important landmark of the Comprehensive Observation System of Deep-sea Sedimentation Dynamic Processes supported by the key research program Evolution of Deep-sea Processes in the South China Sea sponsored by the National Natural Science Foundation. LIU's research team has previously published on this field in international journals. The publication of this article further expands the research space of the South China Sea as a natural laboratory for marine frontier scientific issues.
The preservation of terrigenous petrogenic and soil-derived organic matter after input into the ocean is controlled by the evolution model of layered silicate minerals.
About the authors:
Blattmann, T.M., Liu, Z., Zhang, Y., Zhao, Y., Haghipour, N., Montluçon, D.B., Plötze, M., Eglinton, T.I. Mineralogical control on the fate of continentally-derived organic matter in the ocean.Science, 3 October 2019 (DOI: 10.1126/science.aax5345). The first author of this paper is Dr. Thomas M. Blattmann, Institute of Geology, ETH Zürich, and the co-authors are Dr. Thomas M. Blattmann and Professor LIU Zhifei of Tongji University.
Full-text paper“Mineralogical control on the fate of continentally derived organic matter in the ocean” is available at https://science.sciencemag.org/content/early/2019/10/02/science.aax5345.
Source (in Chinese)：https://news.tongji.edu.cn/info/1003/71126.htm