Southeast Environmental Research Center, and Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA.
Water Res. 2011 Jul;45(13):3836-44. doi: 10.1016/j.watres.2011.04.035. Epub 2011 Apr 28.
This study shows that light exposure of flocculent material (floc) from the Florida Coastal Everglades (FCE) results in significant dissolved organic matter (DOM) generation through photo-dissolution processes. Floc was collected at two sites along the Shark River Slough (SRS) and irradiated with artificial sunlight. The DOM generated was characterized using elemental analysis and excitation emission matrix fluorescence coupled with parallel factor analysis. To investigate the seasonal variations of DOM photo-generation from floc, this experiment was performed in typical dry (April) and wet (October) seasons for the FCE. Our results show that the dissolved organic carbon (DOC) for samples incubated under dark conditions displayed a relatively small increase, suggesting that microbial processes and/or leaching might be minor processes in comparison to photo-dissolution for the generation of DOM from floc. On the other hand, DOC increased substantially (as much as 259 mgC gC(-1)) for samples exposed to artificial sunlight, indicating the release of DOM through photo-induced alterations of floc. The fluorescence intensity of both humic-like and protein-like components also increased with light exposure. Terrestrial humic-like components were found to be the main contributors (up to 70%) to the chromophoric DOM (CDOM) pool, while protein-like components comprised a relatively small percentage (up to 16%) of the total CDOM. Simultaneously to the generation of DOC, both total dissolved nitrogen and soluble reactive phosphorus also increased substantially during the photo-incubation period. Thus, the photo-dissolution of floc can be an important source of DOM to the FCE environment, with the potential to influence nutrient dynamics in this system.
本研究表明，佛罗里达州沿海大沼泽地（FCE）絮体物质（floc）的光照暴露会通过光解过程导致大量溶解有机物质（DOM）的产生。floc 是在 Shark River Slough（SRS）的两个地点收集的，并接受人工阳光照射。生成的 DOM 采用元素分析和激发发射矩阵荧光结合平行因子分析进行表征。为了研究 DOM 从絮体中的光生成的季节性变化，本实验在 FCE 的典型旱季（四月）和雨季（十月）进行。结果表明，在黑暗条件下孵育的样品中溶解有机碳（DOC）的增加相对较小，这表明与光解相比，微生物过程和/或浸出可能是生成 DOM 的次要过程。另一方面，暴露于人工阳光下的样品的 DOC 增加了很多（高达 259 mgC gC(-1)），表明通过光诱导絮体的改变来释放 DOM。荧光强度也随着光照的增加而增加，不论是腐殖质类还是蛋白质类成分。发现陆源腐殖质类成分是发色溶解有机物质（CDOM）库的主要贡献者（高达 70%），而蛋白质类成分仅占总 CDOM 的相对较小比例（高达 16%）。在光孵育期间，DOC 的生成同时伴随着总溶解氮和可溶解反应磷的大量增加。因此，絮体的光解可以成为 FCE 环境中 DOM 的重要来源，有可能影响该系统中的养分动态。
