The Study On Characteristics And Distribution Of Chromophoric Dissolved Organic Matter (CDOM) In The Yellow Sea And The East China Sea

In this paper, both in situ measure and laboratory analysis were detailedly studiedfor Chromophoric Dissolved Organic Matter (CDOM) in the Yellow Sea and the EastChina Sea. Absorption and fluorescence characters of CDOM were utilized to analyseits source, horizontal and vertical distribution, seasonal change. The optical propertiesof CDOM in marine waters have been studied quantitatively and qualitatively. Whilethe environment influence factors to spatial and temporal distribution of CDOM havebeen discussed. The major results are showed as follows:(1) To understand the horizontal and vertical distribution, seasonal change ofCDOM’s absorption properties in the Yellow Sea and the East China Sea,absorption coefficient a(355)、 hydrological factors and the spectral slopesS275-295、S350-400、SRwere used. Slight absorption coefficient a(355) changes werefound in autumn and in the summer. The average values of a(355) in autumn andin summer were0.575m-1and0.578m-1, and values were decreased from inshoreto offshore in autumn, high a(355) values appearred in the middle of the YellowSea and the East China Sea in summer. In autumn, the spectral slopes S275-295、S350-400values were also decreased from inshore to offshore. SRappears oppositetrend, however the spectral slopes S275-295、S350-400values had no evidentregularity in summer. Most stations SRwere greater than one, which indicatedthat complex factors have been affecting the CDOM source, causing spectralslopes S diversities between different seasons.(2) Through the research on vertical distribution of the Yellow sea and East Chinasea, the absorption coefficient a(355) increased from surface to bottom of the eastChina sea. Spectral slope S275-295showed that is largest in the middle water,second in the bottom and minimum in the surface, which were obviously affected by biological activity, photochemical degradation and black tide of East ChinaSea in the autumn. The maximum SRvalue was present at the depth of D-30m,and then gradually decreasing trends for the center. Absorption coefficient a(355)values decreased from inshore to offshore, and lower values appeared the middlelayer of the C vertical in the Yellow sea. S275-295and S350-400had same regularity,and the values of the surface were higher than the bottom water values. Thismight mainly attribute to underlying sediments, water mass and trends. While thevertical profiles of S in the stations of Yangtze estuary in summer were observedthat minimum S275-295values were present at the depth of middle layer, and slightvalues changes in the inshore vertical profile, and minimum SRvalues showedhigher-lower-higher distribution in the offshore sites, which were obviouslyaffected by photochemical degradation and underlying sediments.(3) EEMs-PARAFAC method was applied to research the fluorescence character ofCDOM. Nine fluorescence components are identified in the Yellow Sea and theEast China Sea water samples. Respectively Cl, C2, C3, C6, C8and C9arehumic-like fluorophore, while C4, C5and C7are protein-like fluorophore.Complex environment factors influenced on CDOM fluorescence componentshorizontal distribution in the Yellow Sea and the East China Sea in summer andin autumn. On the whole, humic-like fluorescence intensity in summer werelower than in autumn. While opposite trend were appeared about protein-likefluorescence intensity. The vertical profiles in the stations of Yangtze estuary, theEast China Sea and the Yellow Sea in summer and autumn were also observed,which showed different characteristics in different vertical profiles, season andwaters.