Spatio‐temporal changes in dissolved organic matter composition along the salinity gradient of a marsh‐influenced estuarine complex
Spatio‐temporal changes in dissolved organic matter composition along the salinity gradient of a marsh‐influenced estuarine complex
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DOI：
10.1002/lno.11857
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发表时间：
2021-06
影响因子：
4.5
通讯作者：
Maria L. Letourneau;Sylvia C. Schaefer;Huan Chen;A. McKenna;M. Alber;P. Medeiros
中科院分区：
文献类型：
--
作者：
Maria L. Letourneau;Sylvia C. Schaefer;Huan Chen;A. McKenna;M. Alber;P. Medeiros
位于格鲁吉亚（美国）的阿尔塔马哈河和邻近声音的相互连接的河口复合体作为有机物转化的热点，因为它被输送到大西洋。在这里，我们调查了溶解性有机物（DOM）的组成变化的空间和季节沿着河口，以及它如何影响细菌处理。于2017年4月、7月、10月和2018年1月在整个河口的15个站的涨潮期间收集了表面样品。在暗孵育前后对样品进行了批量、光学和分子分析，以评估系统中的DOM来源和转化模式。DOM组成变化的主要驱动力被认为是有机质来源的陆源-海洋梯度。六个不同的集群被确定的基础上的陆源签名的DOM池，解释45%的系统中的DOM组成的方差。溶解有机碳（DOC）的细菌消耗的DOM组成的强烈影响，增加DOM的降解速率与较大的陆源字符。然而，光学性质的变化表明，较少的芳香DOM，共变与陆源物质优先降解。2017年9月飓风“厄玛”的过境导致DOC含量增加了27% ± 7%，这可能是由于与风暴潮和当地降水增加相关的洪水造成的，DOC生物降解比夏季高出17% ± 8%。这些影响在风暴后持续了至少一个月，表明飓风可以对DOM的组成和沿海系统的循环产生很大的影响。
The interconnected estuarine complex of the Altamaha River and adjacent sounds located in Georgia (USA) functions as a hotspot for organic matter transformation as it is transported to the Atlantic Ocean. Here, we investigated how dissolved organic matter (DOM) composition changes both spatially and seasonally along the estuary and how it influences bacterial processing. Surface samples were collected during high tide at fifteen stations throughout the estuary in April, July, October 2017, and January 2018. Bulk, optical, and molecular analyses were conducted on samples before and after dark incubations to assess DOM sources and transformation patterns in the system. The dominant driver of change in DOM composition was found to be the terrigenous‐marine gradient in organic matter sources. Six distinct clusters were identified based on the terrigenous signature of the DOM pool, explaining 45% of the variance in DOM composition in the system. Bacterial consumption of dissolved organic carbon (DOC) was strongly influenced by DOM composition, with increased degradation rates for DOM with a larger terrigenous character. However, changes in optical properties suggested that less aromatic DOM that co‐varied with the terrigenous material was preferentially degraded. The passage of Hurricane Irma in September 2017 resulted in a 27% ± 7% increase in DOC content, likely due to inundation associated with storm surge and increased local precipitation, and DOC biodegradation was 17% ± 8% higher than during summer. These effects lasted for at least one month after the storm, revealing that hurricanes can have a large impact on DOM composition and cycling in coastal systems.