[Analysis of phytoplankton absorption coefficients and their effect factors in Taihu Lake]

To estimate the spatial variation characteristics of Taihu Lake phytoplankton and its influencing factors, samples were taken at 52 sampling sites during Apr. 2009. Then the total concentration of Chla and absorption coefficient of phytoplankton were measured the very day the samples were delivered to the lab. In the present research, results on pigment package effect by former researchers were taken to calculate its influence on specific absorption coefficients, the power of package effect of different areas in Taihu Lake were estimated, and the package effort revision was done to absorption coefficient of phytoplankton. Ratio of blue and red band of absorption coefficients (a(ph) (440)/a(ph) (675)) and standardization specific absorption spectrum were used to measure the influence on specific absorption coefficients by accessory pigment in different areas of Taihu Laik and different bands. Results showed that (1) specific absorption coefficients of phytoplankton in Taihu Lake vary more in short wave bands than that at 675 nm, specific absorption coefficients in Meiliang Bay are lower than in other areas. (2) Spatial variation of specific absorption coefficients in Taihu Lake is seriously influenced by package effect, and this influence occurred more seriously in Meiliang Bay than in other areas and more seriously in alongshore water body than in offshore water body. (3) Influence on specific absorption coefficients by accessory pigment is relatively weak, and mostly concentrates in short wave band, while auxiliary pigment influence is less at 675 nm, and in Meiliang Bay accessory pigment influence is less than in other areas, and its influences are less in alongshore water body than in offshore water body.