Marine Chemistry, Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany.
Ecology and Evolution in Microbial model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
Nat Commun. 2022 Aug 17;13(1):4837. doi: 10.1038/s41467-022-32457-z.
The deep terrestrial biosphere encompasses the life below the photosynthesis-fueled surface that perseveres in typically nutrient and energy depleted anoxic groundwaters. The composition and cycling of this vast dissolved organic matter (DOM) reservoir relevant to the global carbon cycle remains to be deciphered. Here we show that recent Baltic Sea-influenced to ancient pre-Holocene saline Fennoscandian Shield deep bedrock fracture waters carried DOM with a strong terrigenous signature and varying contributions from abiotic and biotic processes. Removal of easily degraded carbon at the surface-to-groundwater transition and corresponding microbial community assembly processes likely resulted in the highly similar DOM signatures across the notably different water types that selected for a core microbiome. In combination with the aliphatic character, depleted δC signatures in DOM indicated recent microbial production in the oldest, saline groundwater. Our study revealed the persistence of terrestrially-sourced carbon in severely energy limited deep continental groundwaters supporting deep microbial life.
深层陆地生物圈包括在光合作用驱动的地表以下的生命，它们在典型的营养和能量耗尽的缺氧地下水环境中得以生存。与全球碳循环相关的这个巨大的溶解有机物质（DOM）储层的组成和循环仍有待破译。在这里，我们表明，最近受到波罗的海影响的古老的全新世前咸芬诺斯堪的纳维亚盾状深基岩断裂水携带着具有强烈陆源特征的 DOM，并且受到生物和非生物过程的不同贡献。在地表水-地下水过渡处去除易降解的碳以及相应的微生物群落组装过程，可能导致在明显不同的水类型中具有高度相似的 DOM 特征，这些水类型选择了核心微生物组。结合脂肪族特征，DOM 中 δC depleted 的特征表明，在最古老的咸地下水中存在最近的微生物产生。我们的研究揭示了在严重能量受限的深层大陆地下水中，陆地来源的碳的持久性，这为深层微生物生命提供了支持。
