Study On The Characteristics Of Chromophoric Dissolved Organic Matter From Algaes In Different Incubations In Bohai Bay

Bohai Bay is semi-enclosed seas, relatively poor water exchange capacity, and spring and summer is sunlight, nutrients in water is quite rich, it is very suitable for phytoplankton growth and reproduction. Metabolism and biological degradation of phytoplankton populations is an important source of chromophoric dissolved organic matter (CDOM) in seawater, which can significantly affect the colored dissolved organic matter (CDOM) changes in the ocean.CDOM of Chaetoceros、 Dunaliella and Mix Algae culture in the Bohai Bay seawater were researched in this paper and characteristics of the culture CDOM changed during three growth phases namely exponential phase, stationary and senescent phase were analyzed, quantitative analysis of different CDOM optical properties of the three algaes released, further understanding of the marine algae releasing CDOM and the main factors and assessed sunshine affected characteristics of CDOM in Chaetoceros culture during different growth phases.The results showed that:①CDOM changed faster than chlorophyll-a in Chaetoceros Dunaliella and Mix Algae culture, but CDOM in the entire culture period were cumulative, the final CDOM absorption coefficient changed from initial value 6.509m-1、7.671m-1 and 4.798 m-1 to 12.615m-1、10.137m-1 and 6.081m-1;②From exponential to stationary phase, the Chaetoceros and Dunaliella culture CDOM absorption coefficient acdom(350) and chlorophyll-a had shown a positive correlation, the correlation coefficients were 0.894 and 0.988, but the Mix Algae acdom(350) showed rapidly increasing trend towards the end of the stationary phase, and it did not show a positive correlation;③uring the phytoplankton thriving, the absorption coefficient of CDOM acdom (350) and absorption spectral slope S showed a good negative correlation relationship, the correlation coefficient of three algaes were 0.938、0.761 and 0.563;④There was a significant positive correlation between DOC concentration and the absorption coefficient of CDOM acdom (350) from the exponential phase to the senescent phase, the correlation coefficient was 0.866、0.616 and 0.736, CDOM can be used as a good tracer substance for DOC;⑤During photochemical degradation process, degradation of CDOM in the Chaetoceros culture in senescent phase were relative best, the degradation half-life were 7.91 days, and some CDOM were resisted photodegradation in the stationary phase. Experiments of three algaes culture revealed that the phytoplankton in the marine environment was a potential source of CDOM, and assessed that autochthonous CDOM had a strong CDOM photochemical degradation activity.