| Combining sampling live in many voyages in sea area in Xiamen and lab analysis, this dissertation summarized and discussed problems in the study of light absorption and possible factors in fluorescence analysis. And utilizing the optical characteristic of CDOM, this dissertation studied its change between seasons and its distribution in offshore sea area such as entrance of Changjiang River, gulves of Wenzhou and Xiamen. Adopting means such as mathematical model and mixing simulation of experiment, this dissertation made a preliminary research on CDOM's source, move, transform and remove in the mouth of Jiulong River at the same time. The main result of study is as follows:(1). Questions mattered light absorption of CDOM: While determining the water sample, pure water after filtering should be regarded as the blank. Background parameter(K) was introduced in the equation a(λ)=a(λ0)exp(S(λ0-λ)) to evade raising and reducing of base-line which is not caused by organic matter, then the absorption coefficient of CDOM was calculated. When carrying on estimating S value of CDOM, this paper proposed to get S value by the non-linear regression technique instead of linear regression and select comparatively suitable wavelength rang between 300～650nm. When river mouthes mixed, S value not only depended on the S value of CDOM of the two end-members, but also the relative concentrations of their CDOM. The influence that membrane had on CDOM light absorption of inshore II water areas couldn't be neglected, so adoption of 0.2μm membrane filter to filtrate water sample was better.(2). Factors mattered in CDOM fluorogenic analysis: The fluorogenic determination of CDOM should be chosen to carry on at the room temperature. In the offshore sea area, small changes of pH of water body had little influence on fluorescence spectrum characteristic in CDOM. Excitation emission matrix fluorescence spectroscopy (EEMs) of CDOM in the river mouth district had no clear relation with ion intensity. The fluorogenic intensity of CDOM decreased with increasing multiple of physical dilution, but the impact that dilution had on EEMs only reflected on the fluorescence intensity too. In the mid and high salinity waters, 0.2μm filter could remove the interference that water body scattering had to EEMs, EEMs (0.2μm ) was more regular than EEMs (0.7μm ), the display of every peak was clearer and the division of different fluorescence groups was easier. Because the content of CDOM of the river was relatively high and the fluorescence signal was relatively strong, the membrane aperture had little effect on sample EEMs of the river sample.(3). Mixed sample EEMs of estuary showed: Samples of Jiulong River end member contained four kinds of fluorescence peaks: C(Ex=315～355nm;Em=415～445nm),A(Ex=235～250nm;Em=415～445nm),T1(Ex=225～235nm;Em=335～390nm),T2(Ex=260～285nm;Em=320～350nm). With the increase of the proportion of volume of oceanic end-member water in the mixed samples, the overall fluorogenic intensity of the sample was reduced, T2 Peak and M Peak representing marine humic-like(Ex=290～310nm;Em=370～420nm) appeared, and T1 Peak grew higher than Peak A gradually.(4). Every station location a355 range of Yangtze River downstream: 1.04-3.07m-1,S value range: 17.55～19.05×10-3nm-1 . High-Salinity station location a335 range of Wenzhou Bay: 0.54～1.10m-1, S value...
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