The impact of submarine hydrothermal systems on organic carbon in the ocean—one of the largest fixed carbon reservoirs on Earth—could be profound. Yet, different vent sites show diverse fluid chemical compositions and the subsequent biological responses. Observations from various vent sites are to evaluate hydrothermal systems' impact on the ocean carbon cycle. A response cruise in May 2009 to an on‐going submarine eruption at West Mata Volcano, northeast Lau Basin, provided an opportunity to quantify the organic matter production in a back‐arc spreading hydrothermal system. Hydrothermal vent fluids contained elevated dissolved organic carbon, particulate organic carbon (POC), and particulate nitrogen (PN) relative to background seawater. The δ¹³C‐POC values for suspended particles in the diffuse vent fluids (−15.5‰ and −12.3‰) are distinct from those in background seawater (−23 ± 1‰), indicative of unique carbon synthesis pathways of the vent microbes from the seawater counterparts. The first dissolved organic nitrogen concentrations reported for diffuse vents were similar to or higher than those for background seawater. Enhanced nitrogen fixation and denitrification removed 37%–89% of the total dissolved nitrogen in the recharging background seawater in the hydrothermal vent flow paths. The hydrothermal plume samples were enriched in POC and PN, indicating enhanced biological production. The total “dark” organic carbon production within the plume matches the thermodynamic prediction based on available reducing chemical substances supplied to the plume. This research combines the measured organic carbon contents with thermodynamic modeled results and demonstrates the importance of hydrothermal activities on the water column carbon production in the deep ocean.

中文翻译：

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东北NE Lau热液出气口田西马塔的有机生物地球化学

水下热液系统对海洋中的有机碳（地球上最大的固定碳储库之一）的影响可能是深远的。然而，不同的排气口显示出不同的流体化学成分和随后的生物学反应。从各个发泄点观察到的数据是为了评估热液系统对海洋碳循环的影响。2009年5月，对劳盆地东北部西马塔火山持续进行的海底火山喷发进行了响应航行，这为量化后弧扩展热液系统中的有机物产量提供了机会。相对于本底海水，热液排放液含有升高的溶解有机碳，颗粒有机碳（POC）和颗粒氮（PN）。该δ ¹³弥散排放流体中悬浮颗粒的C‐POC值（−15.5‰和−12.3‰）与背景海水中的C‐POC值不同（−23±1‰），这表明来自海水对应物的排放微生物的独特碳合成途径。据报道，扩散口的最初溶解有机氮浓度与背景海水相似或更高。增强的固氮和反硝化作用去除了热液喷口流动路径中补给本底海水中总溶解氮的37％–89％。热液羽流样品富含POC和PN，表明生物产量提高。羽流中总的“暗”有机碳产量与热力学预测相符，该预测基于提供给羽流的可用还原性化学物质。