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The three-dimensional fluorescence spectrum was used to detect the changes in dissolved organic substances from the cultured Skeletonema costatum , Alexandrium tamarense, Alexandrium mimutum, Scrippsiella trochodea, Prorocentrum donghaiense and Prorocentrum micans. The result indicates that all of the miroalgaes 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 grows into decadency phase, the intensity of humic-like and protein-like fluorescence augments 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 Alexandrinum mimutum, Prorocentrum donghaiense and Prorocentrum micans, but the positions of the fluorescence peaks are different.

The three-dimensional fluorescence of dissolved organic matter in the mesocosm with different nutrients enrichment experiments in Jiaozhou Bay was determined by using excitation-emission matrix spectrum. The result indicates that phytoplankton can produce protein-like and humic-like fluorescent matter. The protein-like fluorescence is composed of tyrosine-like fluorescence and tryptophan-like fluorescence. The main position of protein-like fluorescent peak is Ex(max)/Em(max) = 270 nm/290 - 310 nm. The fluorescent intensity of the peak located in Ex(max/ Em(max) = 270 - 290 nm/320 - 350 nm is less. The centers of humic-like peaks disperse at Ex(max)/Em(max) = 250 - 260 nm/380 - 480 nm (Peak A), Ex(max)/Em(max) = 310 - 320 nm/380 - 420 nm(Peak C) and Ex(max)/Em(max) = 330 - 350 nm/420 - 480 nm(Peak M) in which peak A is the main peak. The fluorescent intensity of tyrosine-like matter is stronger than the intensity of humic-like matter. When the amount of phytoplankton decreased, the fluorescent intensity of tyrosine-like matter 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.