| Marine dissolved organic matter(DOM) is an important storage of the global carbon cycle,which plays an important role in water creatures and chemical process. However, the recognitionis limited because of its complex structure and composition. The wide applications ofthree-Dimensional Fluorescence Spectrum based on fluorescence properties of DOM, providesnew ideas for Marine research and new technological methods are used with multivariate dataanalysis.In this paper, fluorescence components of DOM were identified effectively in northernYellow Sea, South China Sea and East China Sea with the course of red tide dispersion, usingExcitation/Emission Matrix spectroscopy(EEMs) combined with Parallel FactorAnalysis(PARAFAC). The differences in composition and properties of fluorophore werediscussed, and the relationships with temperature, salinity, chlorophyll and other physical andbiochemical parameters were considered. Furthermore, cluster analysis was used to assess thesimilarities and dissimilarities of the EEMs data set. The result showed the sources and othermajor influential elements of the fluorescence components in different environments.(1) According to the three times aquatic researches in December, March, May in northernYellow Sea waters around Zhangzi Island, it indicated that DOM fluorescence components weregenerally consistent in different seasons, including humic-like component C1(265/440nm),C2(410-450/520-550nm) and protein-like component C3(230,280/330nm) and three had goodcorrelation. It showed that they had the same sources or some certain relationships between eachother. Further more, all of the3components in different layers and different seasons had higherfluorescence intensity around Zhangzi Island, which was relatively large in common. Throughthe research on the relationships among fluorescence components and chlorophyll-a andvariations in salinity, it surveyed the marine DOM was influenced by both phytoplankton and human activity.(2) Four fluorescent components were identified for the samples got from South China Seain January, including two protein-like components C1(280,230/335nm), C4(270/310nm), andthree humic-like components C2(255,320/415nm),C3(290,350/490nm), C4(270/480nm).Protein-like fluorescent matters were obtained from terrestrial inputs mainly. However, thefluorescent intensity of humic-like components only decreased with increase of salinity insurface layer, and high fluorescent intensity was found in the areas with low temperature andhigh salinity. Four clusters were obtained by cluster analysis, cluster1was distributed in thecoastal location, where human activities were extensive, cluster2was mainly composed ofsamples from the area little far away from the shore, while the most samples in cluster3weredistributed in the open ocean with low fluorescent intensity, and the samples of last cluster4wereobtained form the bottom open sea with low temperature and high salinity.(3) The distributions of fluorescent components of chromophoric dissolved organic matterfrom East Sea in April and May in the succession process of red tide dispersion were disscussed.Six individual fluorescent components were identified by PARAFAC, including three humic-likecomponents C1(265,335/470nm), C2(245,310/400nm), C6(300-310nm/510nm), protein-likecomponent C3(275/310nm), C4(235,290/330nm) and C4(305/345nm). The fluorescenceintensity in surface layers was higher than that in middle layers, and it was minimum in bottomlayers, conforming to biological activities. The compositions and properties of DOM in thesection of za, where red tide dispersion happened, were different from others, and hightyrosine-like intensity was observed, which was produced by the degradation of frond. Theprotein-like and humic-like components in other sections had good relationships, showing theyhad the same sources, and terrestrial inputs influenced mainly. No significant correlation wasfound with chlorophyll, suggesting that the living algal matter contributed little to thefluorescence intensity of the seawater.The results of the discuss for DOM in different sea areas demonstrated the capability of thecombination of EEMs and PARAFAC for characterizing fluorescence of DOM. Thecompositions and characterizations in different areas were different, influenced by thesurrounding environments. The terrestrial inputs were aggravated by human activities, which influenced the characterizations of marine DOM to a large extent, meanwhile phytoplankton canalso play a impotent role in the areas where they were active. The study in optical properties ofDOM have bright prospects in survey, exploitation and application of the ocean. |
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