Tidal marshes as a source of optically and chemically distinctive colored dissolved organic matter in the Chesapeake Bay
Tidal marshes as a source of optically and chemically distinctive colored dissolved organic matter in the Chesapeake Bay
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DOI：
10.4319/lo.2008.53.1.0148
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发表时间：
2008-01
影响因子：
4.5
通讯作者：
M. Tzortziou;P. Neale;Christopher L. Osburn;J. Megonigal;N. Maie;Rudolf JaffÉ
中科院分区：
文献类型：
--
作者：
M. Tzortziou;P. Neale;Christopher L. Osburn;J. Megonigal;N. Maie;Rudolf JaffÉ
研究了切萨皮克湾罗德河河口附近潮汐沼泽作为溶解有机碳（DOC）和有色溶解有机物（CDOM）来源的作用。在几个半日潮周期中，每小时对排咸高海拔沼泽的潮沟中的水进行采样，以检查溶解有机物（DOM）的潮汐交换。水离开沼泽退潮期间一贯丰富的DOC相比，水进入沼泽涨潮期间。有一个净DOC输出从沼泽到河口在低和高沼泽植物生物量的季节。光学分析表明，除了有助于碳预算，沼泽河口的CDOM动态有很强的影响。沼泽出口CDOM的光学特性与邻近河口的CDOM一致且明显不同。具体而言，达信CDOM拥有：（1）明显更强的吸收，（2）更大的DOC特异性吸收，（3）更低的指数光谱斜率，（4）更大的荧光信号，（5）每单位吸光度更低的荧光，以及（6）在>400 nm波长处更高的荧光。这些光学特性表明了相对复杂、高分子量、富含芳香族的DOM，并且这通过分子量分布分析的结果得到了证实。我们的研究结果说明的重要性，潮汐沼泽的光学和化学独特的溶解有机化合物的来源，以及它们对CDOM动态，DOC预算，从而，光化学和地球化学过程的影响，在邻近的河口生态系统。
The role of tidal marshes as a source of dissolved organic carbon (DOC) and colored dissolved organic matter (CDOM) for adjacent estuarine waters was studied in the Rhode River subestuary of the Chesapeake Bay. Water in a tidal creek draining brackish, high‐elevation marshes was sampled every hour during several semidiurnal tidal cycles in order to examine the tidal exchange of dissolved organic matter (DOM). Water leaving the marsh during ebbing tide was consistently enriched in DOC compared to water entering the marsh during flooding tide. There was a net DOC export from the marsh to the estuary during seasons of both low and high marsh plant biomass. Optical analysis demonstrated that, in addition to contributing to the carbon budgets, the marsh had a strong influence on the estuary’s CDOM dynamics. Marsh‐exported CDOM had optical properties that were consistently and markedly different from those of CDOM in the adjacent estuary. Specifically, marsh CDOM had: (1) considerably stronger absorption, (2) larger DOC‐specific absorption, (3) lower exponential spectral slope, (4) larger fluorescence signal, (5) lower fluorescence per unit absorbance, and (6) higher fluorescence at wavelengths >400 nm. These optical characteristics are indicative of relatively complex, high‐molecular‐weight, aromatic‐rich DOM, and this was confirmed by results of molecular‐weight‐distribution analysis. Our findings illustrate the importance of tidal marshes as sources of optically and chemically distinctive dissolved organic compounds, and their influence on CDOM dynamics, DOC budgets, and, thus, photochemical and biogeochemical processes, in adjacent estuarine ecosystems.