Composition of a protein-like fluorophore of dissolved organic matter in coastal wetland and estuarine ecosystems.
Composition of a protein-like fluorophore of dissolved organic matter in coastal wetland and estuarine ecosystems.
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DOI：
10.1016/j.watres.2006.11.006
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发表时间：
2007-02
期刊：
影响因子：
12.8
通讯作者：
N. Maie;N. Scully;O. Pisani;R. Jaffé
中科院分区：
文献类型：
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作者：
N. Maie;N. Scully;O. Pisani;R. Jaffé
本研究证明了亚热带河流和河口环境中溶解有机物(DOM)样品的类蛋白质荧光发射信号(T峰，最大激发/发射波长为280/325 nm)的成分不均一性。天然水样是从佛罗里达海岸大沼泽地生态系统采集的。样品经过超滤，得到了激发发射荧光矩阵。T峰强度与超滤DOM溶液的N浓度呈正相关，但相关系数很低(R2=0.140，p<；0.05)，表明蛋白质与其他类化合物共存。因此，T峰在尺寸排除层析中被分离。洗脱曲线表明，T峰由两个分子量不同的化合物组成，标称分子量分别为>；5×10~4(T1)和∼7.6×10~3(T2)，不同样品的相对丰度不同。T1峰的强度与[乌冬]有很强的相关性(R2=0.516，p<；0.001)，而T2峰没有相关性，这表明T峰是由具有不同化学结构和生态作用的化合物组成的混合物，即腐殖质类物质中的蛋白质物质和可能的酚类物质。后者的自然来源可能包括从衰老的植物材料中浸出的多酚，这些多酚是腐殖质的重要前体。多酚类物质，如可水解性单宁的重要成分没食子酸和从红树树叶中提取的缩合单宁在T峰附近(分别为260/346和275/313 nm)显示出荧光峰，这一事实支持了这一观点。根据这项研究，在有大量陆地DOM输入的沿海地区，T峰作为天然水域中[DON]的替代物的应用可能会受到限制。
This study demonstrates the compositional heterogeneity of a protein-like fluorescence emission signal (T-peak; excitation/emission maximum at 280/325nm) of dissolved organic matter (DOM) samples collected from subtropical river and estuarine environments. Natural water samples were collected from the Florida Coastal Everglades ecosystem. The samples were ultrafiltered and excitation–emission fluorescence matrices were obtained. The T-peak intensity correlated positively with N concentration of the ultrafiltered DOM solution (UDON), although, the low correlation coefficient (r2=0.140, p<0.05) suggested the coexistence of proteins with other classes of compounds in the T-peak. As such, the T-peak was unbundled on size exclusion chromatography. The elution curves showed that the T-peak was composed of two compounds with distinct molecular weights (MW) with nominal MWs of about >5×104(T1) and ∼7.6×103(T2) and with varying relative abundance among samples. The T1-peak intensity correlated strongly with [UDON] (r2=0.516, p<0.001), while T2-peak did not, which suggested that the T-peak is composed of a mixture of compounds with different chemical structures and ecological roles, namely proteinaceous materials and presumably phenolic moieties in humic-like substances. Natural source of the latter may include polyphenols leached from senescent plant materials, which are important precursors of humic substances. This idea is supported by the fact that polyphenols, such as gallic acid, an important constituent of hydrolysable tannins, and condensed tannins extracted from red mangrove (Rhizophora mangle) leaves exhibited the fluorescence peak in the close vicinity of the T-peak (260/346 and 275/313nm, respectively). Based on this study the application of the T-peak as a proxy for [DON] in natural waters may have limitations in coastal zones with significant terrestrial DOM input.