The article "Oceanic Methane Biogeochemistry" by William S. Reeburgh provides a comprehensive overview of the biogeochemical processes involving methane in the ocean. The paper covers various aspects, including measurements of methane in the water column and sediments, distributions of methane in these environments, and the sources and sinks of methane in the ocean. Key points include: 1. **Measurements**: The first measurements of dissolved methane in the ocean were made in the 1950s, while measurements in sediments began in the mid-1950s. The ocean is a significant source of methane, but it is not a major contributor to atmospheric methane increases. 2. **Distributions**: Methane concentrations are typically nanomolar in the water column and micromolar in anoxic basins. The ocean has a mixed layer methane maximum, which is a paradox because it occurs in an oxygenated environment where methanogenesis is thermodynamically unfavorable. 3. **Production and Consumption**: Methane is produced in the ocean through diagenesis of organic matter and abiotic processes like serpentinization. Microbial oxidation of methane occurs under both oxic and anoxic conditions, with anaerobic oxidation being more effective. 4. **External Sources**: External sources of methane include coastal runoff, hydrothermal systems, and decomposition of methane clathrate hydrates. These sources contribute to the ocean water column through various pathways such as seeps, vents, and mud volcanoes. 5. **Microbial Oxidation**: The paper discusses the mechanisms and rates of microbial oxidation of methane, including aerobic and anaerobic processes. Recent advances in biomarker molecules, genomics, and benthic communities have provided new insights into methanotrophy. 6. **Future Research**: The paper outlines areas for future research, including natural 13C measurements, oxidation rate measurements, and the role of methane-consuming benthic communities. Reeburgh emphasizes the importance of understanding the balance between methane production and consumption in the ocean to better predict and manage global methane budgets.The article "Oceanic Methane Biogeochemistry" by William S. Reeburgh provides a comprehensive overview of the biogeochemical processes involving methane in the ocean. The paper covers various aspects, including measurements of methane in the water column and sediments, distributions of methane in these environments, and the sources and sinks of methane in the ocean. Key points include: 1. **Measurements**: The first measurements of dissolved methane in the ocean were made in the 1950s, while measurements in sediments began in the mid-1950s. The ocean is a significant source of methane, but it is not a major contributor to atmospheric methane increases. 2. **Distributions**: Methane concentrations are typically nanomolar in the water column and micromolar in anoxic basins. The ocean has a mixed layer methane maximum, which is a paradox because it occurs in an oxygenated environment where methanogenesis is thermodynamically unfavorable. 3. **Production and Consumption**: Methane is produced in the ocean through diagenesis of organic matter and abiotic processes like serpentinization. Microbial oxidation of methane occurs under both oxic and anoxic conditions, with anaerobic oxidation being more effective. 4. **External Sources**: External sources of methane include coastal runoff, hydrothermal systems, and decomposition of methane clathrate hydrates. These sources contribute to the ocean water column through various pathways such as seeps, vents, and mud volcanoes. 5. **Microbial Oxidation**: The paper discusses the mechanisms and rates of microbial oxidation of methane, including aerobic and anaerobic processes. Recent advances in biomarker molecules, genomics, and benthic communities have provided new insights into methanotrophy. 6. **Future Research**: The paper outlines areas for future research, including natural 13C measurements, oxidation rate measurements, and the role of methane-consuming benthic communities. Reeburgh emphasizes the importance of understanding the balance between methane production and consumption in the ocean to better predict and manage global methane budgets.