Three-Dimensional Fluorescence Characteristic Of Dissolved Organic Matter Produced By Marine Algaes And Dissolved Organic Matter Sampled From The East China Sea

In this thesis, the three-dimensional fluorescence of dissolved organic matter in the mesocosm and micro-algaes culture experiment was determined by using excitation-emission matrix spectrum. The spatio-temporal characteristics of dissolved organic matter of the East China Sea were studied through directly sampling.Phytoplankton can produce protein-like and humic-like fluorescent matter at mesocosm experiment. The protein-like fluorescence is composed by tyrosine-like fluorescence and tryptophan-like fluorescence. The main position of protein-like fluorescent peak is Exmax/Emmax=270nm/290~310nm. The fluorescent intensity of the peak located in Exmax/Emmax=270~290/320~350 is less. The centers of humic-like peaks disperse at Exmax/Emmax=250~260/380~480nm(Peak A),Exmax/Emmax= 310~320/380~420nm(Peak C) and Exmax/Emmax=330~350/420~480nm (Peak M) in which peak A is the main peak. The fluorescent intensity of tyrosine-like is stronger than the intensity of humic-like. When the amount of phytoplankton decreased, the fluorescent intensity of tyrosine-like has negative relativity with the chlorophyll-a concentration. Tyrosine-like matter and Tryptophan-like matter have similar origin. Dinoflagellate can produce more protein-like fluorescent matter than diatom. The composition ratios of humic-like mixture are different in different environment. And it has a small A:C value in Dinoflagellate environment compared to diatom environment.Skeletonema costatum, Alexandrium tamarense, Alexandrium mimutum, Scrippsiella trochodea, Prorocentrum donghaiense and Prorocentrum can produce FDOM in the growth courses. Diatom such as Skeletonema costatum can produce humic-like FDOM. However dinoflagellate can produce protein-like FDOM at exponential growth phase. When the algae grow into decadency phase, the intensity of humic-like and protein-like fluorescence augment rapidly, which may be due to a mass of FDOM realeased by the old or dead cell fragmentation and the degradation of bacteria by using non-FDOM. The fluorescent intensity of Alexandrium tamarense, Alexandrium mimutum, Prorocentrum donghaiense and Prorocentrum micans can reduce at anaphase of decadency phase because of the degradation of bacteria and light. The same genus of algae can produce similar FDOM, for example: Alexandrium tamarense,and Alexandrium mimutum, Prorocentrum donghaiense and Prorocentrum micans, but the postions of the fluorescence peak are different. The Empirical Orthogonal Function method was used to analyse the main component of EEMs.The main fluorescent peaks of dissolved organic matter in Changjiangkou estuary were T peak, S peak. The tryptophan-like fluorescent matters of before wind and after wind were from respective similar matter. Before wind, at surface phytoplankton can produce protein-like, but at bottom protein-like has no direct relationship with phytoplankton, and at bottom Changjiang water can bring protein-like. Most of humic-like were brought by changjiang water. After wind, at bottom the fluorescent intensity of tryptophan-like has a positive relativity with chl-a concentration. Changjiang water can bring protein-like and humic-like.