Nanomagnetite Accelerates the Process of "Electron Driven Methanogenesis"
Effect of Nitrogen Deposition on Methane Emission from Coastal Wetlands in the Yellow River Delta
As a greenhouse gas, methane has a higher warming potential than carbon dioxide and plays a crucial role in the global carbon cycle and global climate change. Methane produced by natural activities has a considerable amount (about 250 million tons per year) and wetlands are its largest natural source. Various environmental factors can affect methane emissions from wetlands. Among them, conductive minerals that are widely present in nature (such as magnetite and other iron-bearing minerals) and nitrogen deposition due to human interventions are two important potential factors.
The Electromicrobiological Resources and Microbial Ecological Health Team of the Yantai Coastal Research Institute of the Chinese Academy of Sciences recently conducted a study on the influence and mechanism of nanomagnetite on the methane production pathway in the Yellow River Delta wetland. In order to more realistically simulate the natural in situ environment, unlike the previous use of a single carbon source, this study used reeds as the carbon source for the main wetland plant in the Yellow River Delta. The results show that nano-magnetite can significantly improve the wetland at the “hour†level. Methane production rate. The natural abundance carbon isotope fractionation and carbon tracer show that the increase in methane production is mainly related to the acceleration of carbon dioxide reduction. Researchers using a combination of thermodynamics, electrochemistry, model analysis, and other means have found that methane comes mainly from “electron-driven carbon dioxide reductionâ€, which is a new way of methane production. High-throughput sequencing analysis based on RNA levels showed that bacteria Geobacter, which has the ability to transport electrons out of cells, and Methanosarcina, a methanogenic archetype with methanogenic capacity, can promote the production of methane by coupling and acetic acid oxidation and electron reduction of carbon dioxide. . This study analyzes the impact of conductive minerals on methane production pathways in wetlands and provides new insights into the understanding of conductive methane emissions from wetlands.
In addition, the team used the Yellow River Delta Coastal Wetland Ecological Experiment Station of the Chinese Academy of Sciences and teamed up with Han Guangxuan to study atmospheric nitrogen deposition and intermittent flooding on coastal wetlands based on simulated nitrogen deposition for four consecutive years (2012 to 2016). Impact of emissions. Research shows that ammonium nitrogen increases methane emissions throughout the year. Although nitrate-nitrogen has a certain role in promoting the emission of methane during the flooding period, the impact is small. By analyzing the community structure of in situ archaea under different nitrogen deposition treatments, it was shown that ammonium nitrogen treatment increased the abundance of Methanocellaceae, which may be an important reason for the increase of methane flux. This helps to understand the response mechanism of methane emissions from coastal wetlands to increased nitrogen deposition and intermittent flooding, and provides theoretical support for accurately predicting the source and sink strength of methane in coastal wetlands under scenarios of nitrogen deposition increase.
Related research results are published in Environmental Science: Nano and Science of The Total Environment. The study was funded by the National Natural Science Foundation of China, the 100-person plan of the Chinese Academy of Sciences, the Shandong Provincial Natural Science Outstanding Youth Fund, and the Taishan Scholars Young Experts Program.
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