在这项工作中，研究团队发现沿汤加火山弧(南太平洋)喷出的流体，通过垂直扩散对光层中铁的浓度产生了很大的影响。这种富集刺激了生物活动，产生了大面积的叶绿素(36万平方公里)。富铁水域的固氮活性比邻近未施肥水域高2-8倍。碳输出通量高2-3倍。这些发现揭示了一种以前未描述过的海洋自然铁施肥化机制，这种机制为大气 CO2 的区域热点汇提供了燃料。
据悉，铁是一种必需的营养物质，在约30%的海洋中调节生产力。与向海洋内部提供铁的大洋中脊深层(大于2000米)的热液活动相比，浅层(小于500米)热液流体更可能影响海洋表面的生态系统。然而，它们影响的效果是未知的。
附：英文原文
Title: Natural iron fertilization by shallow hydrothermal sources fuels diazotroph blooms in the ocean
Author: Sophie Bonnet, Cécile Guieu, Vincent Taillandier, Cédric Boulart, Pascale Bouruet-Aubertot, Frédéric Gazeau, Carla Scalabrin, Matthieu Bressac, Angela N. Knapp, Yannis Cuypers, David González-Santana, Heather J. Forrer, Jean-Michel Grisoni, Olivier Grosso, Jérémie Habasque, Mercedes Jardin-Camps, Nathalie Leblond, Frédéric A. C. Le Moigne, Anne Lebourges-Dhaussy, Caroline Lory, Sandra Nunige, Elvira Pulido-Villena, Andrea L. Rizzo, Géraldine Sarthou, Chloé Tilliette
Issue&Volume: 2023-05-26
Abstract: Iron is an essential nutrient that regulates productivity in ~30% of the ocean. Compared with deep (>2000 meter) hydrothermal activity at mid-ocean ridges that provide iron to the ocean’s interior, shallow (<500 meter) hydrothermal fluids are likely to influence the surface’s ecosystem. However, their effect is unknown. In this work, we show that fluids emitted along the Tonga volcanic arc (South Pacific) have a substantial impact on iron concentrations in the photic layer through vertical diffusion. This enrichment stimulates biological activity, resulting in an extensive patch of chlorophyll (360,000 square kilometers). Diazotroph activity is two to eight times higher and carbon export fluxes are two to three times higher in iron-enriched waters than in adjacent unfertilized waters. Such findings reveal a previously undescribed mechanism of natural iron fertilization in the ocean that fuels regional hotspot sinks for atmospheric CO2.
DOI: abq4654
Source: https://www.science.org/doi/10.1126/science.abq4654