Rochelle-Bates Nathan, Long Annabel, MacGilchrist Graeme A, Teske Andreas, Stüeken Eva E
School of Earth & Environmental Sciences, University of St Andrews, St Andrews, United Kingdom.
Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
Front Microbiol. 2025 Jul 16;16:1523696. doi: 10.3389/fmicb.2025.1523696. eCollection 2025.
Fluid-rock interactions in hydrothermal systems are capable of liberating ammonium (NH ) from sedimentary organic material and making it bioavailable for benthic and pelagic microbial communities. Hydrothermal systems in organic-rich sedimentary basins are therefore thought to have played a key role in supplying bioavailable nitrogen to the early biosphere. To place new quantitative bounds on this process, we examined sediments from active hydrothermal systems in the Guaymas Basin, a young oceanic spreading center in the Gulf of California. We analysed four shallow sediment cores that were taken in the Guaymas Basin's hydrothermally-active Southern Trough. We used a combination of isotopic tracers (δN, δC) and elemental abundances to explore nitrogen and metal mobility in buried sediments. We found that ca. 54% of the organically-bound nitrogen is remobilized by active seepage in the top 10 cm of the sediment package within as little as 27-83 yr. Extrapolating these findings over the hydrothermally-active area of the basin yields an ammonium seepage flux of ca. 1.3-4.1 mol/s. In addition, high temperature venting liberates ca. 156-187 mol/s, as estimated from previous data. Assuming biological uptake of hydrothermally recycled ammonium in the water column, these fluxes could support up to 1.3% and 58% of export productivity, respectively. Our data also reveal that the accumulation of micronutrients or potentially toxic metals is influenced by the presence of organic material in seep sediments. The Guaymas case study demonstrates that hydrothermal seepage in sedimentary basins can create a significant nutrient flux and is an efficient means of recycling nutrients from organic matter at shallow burial depths. Hydrothermal nutrient fluxes could therefore have enhanced microbial activity in Earth's history, in particular during time intervals when Earth's oceans are thought to have been nutrient-depleted. Our data also highlight the role of organic material in enhancing metal mobilization and accumulation in otherwise metal-starved hydrothermal seeps.
热液系统中的流体 - 岩石相互作用能够从沉积有机物质中释放铵（NH₄⁺），使其可供底栖和浮游微生物群落利用。因此，富含有机质的沉积盆地中的热液系统被认为在向早期生物圈供应生物可利用氮方面发挥了关键作用。为了对这一过程设定新的定量界限，我们研究了加利福尼亚湾一个年轻的大洋中脊——瓜伊马斯盆地活跃热液系统的沉积物。我们分析了在瓜伊马斯盆地热液活跃的南槽采集的四个浅沉积岩芯。我们使用同位素示踪剂（δN、δC）和元素丰度的组合来探究埋藏沉积物中氮和金属的迁移性。我们发现，在沉积层顶部10厘米内，多达54%的有机结合氮在短短27 - 83年内通过活跃渗漏被重新 mobilized。将这些发现外推到盆地的热液活跃区域，得出铵渗漏通量约为1.3 - 4.1摩尔/秒。此外，根据先前数据估计，高温排放释放约156 - 187摩尔/秒。假设水柱中热液循环铵被生物吸收，这些通量分别可支持高达1.3%和58%的输出生产力。我们的数据还表明，微量营养素或潜在有毒金属的积累受渗漏沉积物中有机物质的影响。瓜伊马斯案例研究表明，沉积盆地中的热液渗漏可产生显著的营养通量，是在浅埋藏深度从有机物质中回收营养物质的有效方式。因此，热液营养通量可能在地球历史上增强了微生物活动，特别是在地球海洋被认为营养匮乏的时间间隔内。我们的数据还突出了有机物质在增强原本金属匮乏的热液渗漏中金属迁移和积累方面的作用。 （注：原文中“remobilized”这个词在中文里不太好找到完全对应的准确词汇，这里暂且保留英文，你可根据实际情况进一步调整优化译文表述。）
