Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China.
Institution of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China.
Int J Environ Res Public Health. 2019 Sep 23;16(19):3559. doi: 10.3390/ijerph16193559.
Anaerobic oxidation of methane (AOM) is a common biochemical process in the ocean and it plays an important role in global climate change, elemental circulation, and atmospheric evolution over geological time. In this paper, we analyzed of δS, Fe, Mn, Ca/Ti, and Sr/Ti ratios, and the date of carbon and sulfur from the site SH3 of Shenhu area. Result showed that (1) 0-6 mbsf (meter blow the sea floor) was mainly affected by OSR (anaerobic oxidation of organic matters) and 7-15 mbsf was a paleo-SMTZ (sulfate-methane transition zone) position. The modern SMTZ was mainly distributed at 19-25 mbsf. The barium sulfate precipitation above the modern SMTZ indicating that the current methane leakage was stable and lasted longer during geological history. (2) By studying the change of magnetic and the different carbonate minerals, results showed that there were two AOM stages. During the early stage, Fe were mainly produced by sulfide abiotic reductive dissolution. During the later stage, Fe were mainly produced by the metal-AOM. (3) Study of the mineral characteristics of the paleo-SMTZ and the modern SMTZ showed that the modern SMTZ carbonate minerals were mainly low-Mg calcite and aragonite, while the paleo-SMTZ carbon minerals were mainly high Mg minerals. The reason for this difference is that the modern SMTZ layer was only experienced the first stage of anaerobic oxidation of methane. In the paleo-SMTZ layer, it has experienced two stage of anaerobic oxidation of methane. During the last stage of metal-AOM, the low Mg carbonate minerals were converted into high Mg carbonate minerals. This research confirms the presence of metal-driven methane anaerobic oxidation at the bottom of sulfate-driven methane anaerobic oxidation and during the metal-driven methane anaerobic oxidation, methane and metal oxides or hydroxides would couple to convert the in situ metal oxides or hydroxides into metal ions, meanwhile the phosphorus adsorbed on the surface of the metal oxides is released into adjacent pore water, and convert to new P-bearing minerals under suitable conditions.
甲烷的厌氧氧化（AOM）是海洋中一种常见的生化过程，它在全球气候变化、元素循环以及地质时间内大气演化中起着重要作用。在本文中，我们分析了 SH3 站位的δS、Fe、Mn、Ca/Ti 和 Sr/Ti 比值以及碳和硫的年代数据。结果表明：（1）0-6mbsf（海底以下米数）主要受 OSR（有机物质的厌氧氧化）影响，7-15mbsf 为古 SMTZ（硫酸盐-甲烷过渡带）位置。现代 SMTZ 主要分布在 19-25mbsf。现代 SMTZ 上方钡硫酸盐的沉淀表明，当前的甲烷泄漏在地质历史时期是稳定且持续时间较长的。（2）通过研究磁性的变化和不同的碳酸盐矿物，结果表明存在两个 AOM 阶段。在早期，Fe 主要由硫化物的非生物还原性溶解产生。在后期，Fe 主要由金属-AOM 产生。（3）古 SMTZ 和现代 SMTZ 的矿物特征研究表明，现代 SMTZ 的碳酸盐矿物主要为低 Mg 方解石和文石，而古 SMTZ 的碳矿物主要为高 Mg 矿物。造成这种差异的原因是现代 SMTZ 层仅经历了甲烷厌氧氧化的第一阶段。在古 SMTZ 层中，它经历了甲烷厌氧氧化的两个阶段。在金属-AOM 的最后阶段，低 Mg 碳酸盐矿物转化为高 Mg 碳酸盐矿物。这项研究证实了在硫酸盐驱动的甲烷厌氧氧化底部存在金属驱动的甲烷厌氧氧化，并且在金属驱动的甲烷厌氧氧化过程中，甲烷和金属氧化物或氢氧化物会耦合，将原位金属氧化物或氢氧化物转化为金属离子，同时吸附在金属氧化物表面的磷会释放到相邻的孔隙水中，并在合适的条件下转化为新的含磷矿物。
