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首页> 外文期刊>Aquatic Sciences >Origin, enzymatic response and fate of dissolved organic matter during flood and non-flood conditions in a river-floodplain system of the Danube (Austria)
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Origin, enzymatic response and fate of dissolved organic matter during flood and non-flood conditions in a river-floodplain system of the Danube (Austria)

机译：多瑙河（奥地利）的河洪平原系统在洪水和非洪水条件下的起源，酶促反应和溶解有机物的命运

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摘要

Spectroscopic techniques and extracellular enzyme activity measurements were combined with assessments of bacterial secondary production (BSP) to elucidate flood-pulse-linked differences in carbon (C) sources and related microbial processes in a river-floodplain system near Vienna (Austria). Surface connection with the main channel significantly influenced the quantity and quality of dissolved organic matter (DOM) in floodplain backwaters. The highest values of dissolved organic carbon (DOC) and chromophoric DOM (CDOM) were observed during the peak of the flood, when DOC increased from 1.36 to 4.37 mg l~(-1) and CDOM from 2.94 to 14.32 m~(-1). The flood introduced DOC which consisted of more allochthonously-derived, aromatic compounds. Bacterial enzymatic activity, as a proxy to track the response to changes in DOM, indicated elevated utilization of imported allochthonous material. Based on the enzyme measurements, new parameters were calculated: metabolic effort and enzymatic indices (EEA 1 and EEA 2). During connection, bacterial glucosidase and protease activity were dominant, whereas during disconnected phases a switch to lignin degradation (phenol oxidase) occurred. The enzymatic activity analysis revealed that flooding mobilized reactive DOM, which then supported bacterial metabolism. No significant differences in overall BSP between the two phases were detected, indicating that heterogeneous sources of C sufficiently support BSP. The study demonstrates that floods are important for delivering DOM, which, despite its allochthonous origin, is reactive and can be effectively utilized by aquatic bacteria in this river-floodplain systems. The presence of active flood-plains, characterized by hydrological connectivity with the main channel, creates the opportunity to process allochthonous DOC. This has potential consequences for carbon flux, enhancing C sequestration and mineralization processes in this river-floodplain system.
机译：光谱技术和细胞外酶活性测量与细菌二次生产（BSP）评估相结合，以阐明维也纳（奥地利）附近河水平原系统中碳（C）源与相关微生物过程的洪水脉冲相关差异。与主要渠道的表面连接显着影响了洪泛区回水中溶解有机物（DOM）的数量和质量。在洪水高峰期，溶解态有机碳（DOC）和发色性DOM（CDOM）最高，DOC从1.36 mg·L〜（-1）增加到4.37 mg·l（-1），CDOM从2.94〜14.32 m〜（-1）增加。 ）。洪水引入了DOC，DOC由更多的异源芳香化合物组成。细菌酶活性作为跟踪DOM变化响应的代理，表明进口的异源物质利用率提高。基于酶的测量值，计算出新参数：代谢努力和酶指标（EEA 1和EEA 2）。在连接过程中，细菌葡糖苷酶和蛋白酶活性占主导地位，而在分离阶段，发生了木质素降解（酚氧化酶）的转换。酶活性分析表明，驱油调动了反应性DOM，然后它支持细菌代谢。在两个阶段之间未检测到总体BSP的显着差异，表明C的异质来源足以支持BSP。研究表明，洪水对DOM至关重要，尽管DOM是异源的，但它是反应性的，在此河洪平原系统中可以被水生细菌有效利用。活跃的洪泛区的存在（其特征是与主要河道的水文连通性）为处理异源DOC提供了机会。这可能会对碳通量产生潜在的影响，从而增强该河漫滩系统中的碳固存和矿化过程。

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