Characterizing Marine Chromophoric Dissolved Organic Matter Using Excitation-emission Matrix Spectrum Combined With Parallel Factor Analysis

Chromophoric dissolved organic Matter （CDOM） plays an important role in thebiogeochemistry of carbon, nitrogen and phosphorus. In this thesis, the fluorescent componentsfeature of CDOM was studied, sampled from the East China Sea （in spring, summer and autumn）and the seawater during the decomposing process of Ulva prolifera, using Excitation-emissionmatrix spectroscopy（EEMs）combined with Parallel Factor Analysis（PARAFAC）. The differencesin composition and properties and distribution of fluorophore were discussed, besides, therelationships with salinity, chlorophyll a and other parameters were considered to trace its origin.The main results are as fellows.（1）Three fluorescent components were identified for the samples got from the East ChinaSea in the summer and autumn using PARAFAC, including protein-like component C1（235,280/330）, marine-like and terrestrial-like humic component C2（255,330/400）andterrestrial-like humic component C3（275,360/480）. The good linearity of two humic-likecomponents showed the same source or some relationship between the chemical constitution. As awhole, the level of the fluorescence intensity in coastal ocean was higher than that of the openocean in different water layers in two seasons. The relationship of three components withchlorophyll-a and salinity showed the DOM in the study area almost not influenced by the livingalgal matter，but the fresh water outflow of the Yangtze River might be the source of them in theYangtze River estuary in Summer. （2）Sea water samples were collected in the East China Sea during dinoflagellate bloom after the8um algae bloom dispersion after the diatom bloom dispersion in spring,2011. There are threekinds of CDOM including tyrosine-like component C1（230,280/320）, tryptophan-like componentC2（240,305/355）and terrestrial-like humic component C3（270,340/480）.The fluorescenceintensities were not obvious difference between the surface and the middle layers, may resultedfrom degradation of the light, but it was minimum in the bottom layers in line with biologicalactivities. From the spatial and temporal distribution of the three components and its correlationwith salinity, we know that phytoplankton were the main source of the component C1. Tocomponent C2and C3, terrestrial input is the major contributor during diatom bloom dispersion, butphytoplankton became the main controlling factor when dinoflagellate bloom.（3）Four fluorescent components were identified during the decomposing process of Ulvaprolifera, including three humic-like components C1（260,355/420）、C2（310,380/490）、C3（245,320/380）and protein-like component C4（235,280/325）。The good linearity of threehumic-like components showed the same source or some relationship between the chemicalconstitution. In the early days of the degradation, the fluorescence intensities of C4were highest. Asthe solid matter were degraded to the dissolved organic matter, humic-like components increasedand then decreased with the dissolved organic matter further decomposed into inorganic. Theinfluence of PH on the COOM had no regularity. With the increased of temperature, fluorescenceintensity of humic-like components also increased, maybe caused by the temperature affect thedecomposition rate of the bacteria. The most likely reason why the fluorescence intensities ofcomponents increased with the increased of salinity was, adding concentrated seawater in order toincreased the salinity provided the bacteria more nutrients.