Organic matter: Abiotic transformations and microbial interactions

DynaDeep将揭示高能海滩下海洋-陆地相互作用的功能和相关性，在那里，我们提出深层地下作为一个动态生物反应器和独特的微生物栖息地，影响到海洋的元素净通量。为了实现这一目标，六个次级项目将在联合实地运动、共享抽样方法和实验工作方面进行合作，并在综合方法中使用数学模型。P3子项目将研究深海地下河口生物地球化学过程的主要驱动因素——有机质的来源、组成和转化。我们假设深层地下的瞬态特征对于有机质通过相互作用的非生物和生物过程的周转和分子转化至关重要。本文将采用有针对性的实验室实验和实地工作相结合的方法，以确定和表征(1)深层地下河口供应的有机物的潜在端元，(2)在时空变化的氧化还原界面上发生的溶解有机质（DOM）数量和组成的非生物变化，以及(3)微生物群落对DOM的降解和转化。详细的分子信息将用于破译DOM与微生物群落组成和活性之间的联系。有机物组成将通过超高分辨率傅里叶变换离子回旋共振质谱（FT-ICR-MS）和超高效液相色谱等最先进的分子方法进行表征，并辅以稳定和放射性碳同位素的分析。将建立分子代用物，作为深层地下特定生物地球化学状态和由此产生的微生物生态位空间的诊断工具。P3的结果将用反应性术语填充耦合反应输运水文地质模型（P6），并提供DOM （P1）来源和年龄的信息。在P3中获得的分子数据将在微生物群落数据（P5）和关键微量元素分布（P4）的背景下进行解释，并将有助于理解微生物呼吸的机制（P2）。

DynaDeep will unravel the functionality and relevance of marine-terrestrial interactions below high-energy beaches, where we propose the deep subsurface to act as a dynamic bioreactor and unique microbial habitat affecting elemental net fluxes to the sea. To reach this goal, six subprojects will cooperate in joint field campaigns, shared sampling approaches as well as experimental work and use mathematical models in an integrative approach. Subproject P3 will study the sources, composition and transformations of organic matter as the main drivers of biogeochemical processes in the deep subterranean estuary. We hypothesize that the transient character of the deep subsurface is crucial for the turnover and molecular transformation of organic matter through interacting abiotic and biotic processes. A combination of targeted laboratory experiments and field work will be applied in order to identify and characterize (1) potential endmembers of organic matter supplied to the deep subterranean estuary, (2) abiotic changes of dissolved organic matter (DOM) quantity and composition occurring at temporally and spatially variable redox interfaces, and (3) degradation and transformation of DOM by microbial communities. Detailed molecular information will be used to decipher linkages between DOM and microbial community composition and activity. Organic matter composition will be characterized by state-of-the-art molecular approaches such as ultrahigh resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and ultra-performance liquid chromatography, and complemented by analyses of stable and radiocarbon isotopes. Molecular proxies will be established as diagnostic tools for specific biogeochemical states of the deep subsurface and the resulting microbial niche space. Results from P3 will populate the coupled reactive transport hydrogeological model (P6) with reactivity terms and provide information on sources and age of DOM (P1). Molecular data acquired in P3 will be interpreted in the context of microbial community data (P5) and distribution of key trace elements (P4), and will contribute to a mechanistic understanding of microbial respiration (P2).