| Performing both in situ measurement and laboratory analysis for ChromophoricDissolved OrganieMatter (CDOM) in surfaee, middle and bottom water in the YellowSea and the East China Sea, absorption and fluorescence charaeter of CDOM are usedto researeh its souree, horizontal and vertical distribution, transposition, seasonalchange, conservative actions and stability. The optical properties of CDOM arestudied quantitatively and qualitatively. The datas were statistieally evaluated byparallel factor analysis to investigate major factors and biogeochemical proeess whichcontrol CDOM’s distribution.The main results are as follows:1. Ten fluorescence components are identified by the EEMs-PRAAFAC methodin the Yellow Sea and the East China Sea water. Respectively Cl, C2, C3, C4, C6, C8and C9are humic-like fluorophore, and the C5and C10are protein-like fluorophore.Clustering analysis for the sample in surface layer is studyed, It is found that thesamples of the spring were mainly divided into five categories and four categories inautumn.The humic-like components (C1, C2, C3, C4, C6and C8) show the oppositedistribution patterns with salinity in spring and autumn, and they appear high value inthe coastal area, however they appear low value in the offshore area. Theprotein-likecomponents (C5and C10) and the humic-like component (C9) appear thehigh value in the coastal area and the offshore area; Biological product component(C7) is complex, indicating that it has the unique sources or forming process.According to different areas and different season, were studied correlationanalysis between salinity and components. It is found that five humic-likefluorescence components (C1, C2, C3, C4and C6) have a better linear negatively correlated with salinity in spring and autumn voyage with exception of autumnvoyage in Yellow Sea. The tryptophan-like component (C5) and humic-likecomponent (C8) have a certain related negatively with salinity. The humic-likecomponent (C9) and the tyrosine-like component (C10) and salinity show nocorrelation with salinity. These results indicated that terrigenous input is main originfor CDOM in the Yellow Sea and the East China Sea. Ten kinds of components havenot a well related correlation with chlorophyll-a concentration, showing that thebiological activities is relatively small in the Yellow Sea and the East China Sea. Andmicrobial degradation and phytoplankton are not main origin of CDOM in this areas.By combining correlation analysis between ten kinds of components and salinityand correlation analysis between the proportion of ten components of the totalcomponents and salinity, the conservative behavior and the conservative for the tencomponents are studied. The hnmic-like component (C3) keeps conservative behaviorin spring and autumn in the Yellow Sea and the East China Sea. The othercomponents in different areas and different seasons show the different behavior.In addition, The correlation analysis between other components and humic-likecomponent (C1) is researched in different waters and different season. It is found thatthe source of humic-like components (C1, C2, C4and C6) is similar. The othercomponents are effected bythe season and stusied areas.2. From the spatial and temporal variation characteristics of humification index(HIX) and Fluorescence index (FI), the HIX value is found to be higher in sprinf thanthe HIX value in autumn. The highest HIX value appears in bottom in spring, whilethe highest HIX value appears in surface layer in autumn. The high HIX value area isfound to be in the offshore sea, showing that the stability of the fluorescencecomponents in spring CDOM is higher than that in autumn. The stability of themarine CDOM is higher than the terrigenous CDOM. The distribution patterns ofhumic-like component (C9) and the tyrosine-like (C10) of HIX is constant withdistribution patterns of HIX, indicating that fluorescence components (C9and C10)have high stability. The FI value is higher in spring than the FI value in autumn.TheFI highest value appears in surface layer and the area of high FI value are found around the Yangtze estuary and in offshore sea, showing that the relative molecularweight of CDOM in spring is layger than the relative molecular weight of CDOM inautumn, and the relative molecular weight of marine CDOM is higher than therelative molecular weight of terrigenous CDOM. In addition, the further study of eachcomponent stability and source are researched.3. When absorption characteristics of CDOM are studied, it is found that theseasonal changes of absorption coefficient a280and the ratio of absorption slope Svalue show a corresponding relation, and the value in spring is higher than the valuein autumn. The seasonal changes of S value shows that relative molecular weight ofCDOM in spring is larger than that in autumn. These results may reflect influence ofphotochemical reaction for CDOM in late summer or early autumn. The a280concentration is found to be higher in surface layer than that in bottom in spring, andhigh value area appears around the Yangtze estuary and offshore area; And the a280concentration is found to be higher in middle higher than that in sarface and bottomlayers, and high value area appears in the inshore waters. These results indicate thatMarine plankton is main sources of CDOM in spring, while the terrigenous input ismain sources of CDOM in autumn. The S value is higher than in surface layer thanthat of middle and bottom layers, and high value appears around the changjiang riverestuary and in offshore areas, indicating that the relative molecular weight of marineorigin matter is higher than terrigenous organic matter.Through the correlation analysis between absorption coefficient a280and salinityand chlorophyll-a, it is found that their correlation is not well, indicating that thesource of CDOM is more complex. In addition to terrestrial input and marinebiological activities, the sources include Swater mass of the Yellow Sea, jiangsucoastal current, the coastal current from jiangsu and zhejiang and taiwan warmcurrent.In addition, the relationship between the absorption coefficient and variouscomponents is studied, and the results showed that the correlated relationshipbetween humic-like components and absorption coefficient a280is well, showing thatCDOM chromophores and the humic-like components have similar nature, especially terrestrial humuic-like fluorophores. In addition, the correlated relationship betweenhumic-like fluorescence group, tryptophan-like fluorescence regiment and a280is well,indicating that their source and forming process are similar, and thei variation trend ofthe tyrosine-like components and biological product components and is different fromhumic-like components, showing that they have a unique source and forming process. |
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