Abstract: Optical properties of Chromophoric Dissolved Organic Matter (CDOM) have played an important role in quantitative water-color remote sensing retrieval. The optical properties of CDOM in coastal waters of Changjiang River Estuary were investigated in June of 2011. This area is affected by terrigenous factor strongly with different hydro-dynamic characteristics. CDOM absorption coefficient and spectral slope were got through sampling, laboratory measurements and subsequent data processing. Then, CDOM absorption cofficient and spectral slope were discussed. CDOM absorption coefficients at 440 nm [a(440)] varied between 0.21 and 0.85 m^-1, with an average value of 0.44 m^-1.In addition, the spectral slope, S_g varied between 0.013 3~0.016 7 nm^-1, with an average value of 0.014 nm^-1. Significant spatial difference in absorption cofficient and spectral slope was observed varied tremendously in the estuary and the offshore area. The higher absorption coefficients of the cruise appeared in the estuary area while the lower spectral slope of the cruise appeared in the area which is greatly influenced by the terrestrial sources; the lower absorption coefficients appeared in the offshore area while the higher spectral slope of the cruise appeared in the area which is greatly influenced by the mixing of terrestrial humic sources and seawater. A significant positive relationship between salinity and a(440) was found in the whole area showing conservative behavior of CDOM. There was a good correlative relationship between the spectral slope S_g and salinity in the whole area, which also reflected conservative behavior of CDOM.

Key words: CDOM, spectral absorption coefficient, spectral slope, Changjiang River Estuary