Abstract: Spectral absorption of chromophoric dissolved organic matters(CDOM) in 250 samples collected from 50 sampling stations in Lake Taihu from 2006 to 2007 were simulated using four different models in this present study.Four models included three exponential models using linear and nonlinear fitting,and a hyperbolic model.It was found that the other three models(Model 2,3 and 4) performed better than the conventional single exponential model(Model 1).Statistics show that the power function model fitted the best,being 0.999 0 in average determination coefficient,higher than the other three;but was lower in average relative error and root mean square error(RMSE) than the other three(ANOVA,P<0.001).Calculation,using the power function model(Model 4),demonstrated within the spectra range 280-500 nm,the CDOM mean spectral slope(S) value was(6.66±0.40) nm^-1 with a variation coefficient being 6.08%.The frequency distribution of S value basically followed a normal distribution.Spatially,the S value was significantly higher in Meiliang Bay than in the open water area of Lake Taihu(ANOVA,P<0.001).Temporally,S value followed the order of spring>winter>summer>autumn.The CDOM S value demonstrated a significant negative correlation with absorption coefficient,but a positive one with wavelength.

Key words: chromophoric dissolved organic matter(CDOM), absorption coefficient, spectral slope, Lake Taihu