Abstract: The spectral and chemical analytical data of Taihu Lake water quality in Nov. 8〖KG-*2〗-〖KG-*7〗22, 2007 were used to analyze the spectral characteristics of dif fuse attenuation coefficient (Kd) of the water body in autumn and related affecting factors. On the basis of this analysis, the Kd at band 490 nm, Kd(490), was used as a variable to build the relationship between Kd and remote sensing reflectance. The results indicated that within the scope of visible band, the Kd of the water body at most locations of Taihu Lake pre sented an exponent decreasing trend with the increase of wave length. Due to the higher concentration of phytoplankton in some locations, a peak value of K d was presented at band 675 nm. Non-organic suspended particles, because of t heir higher content in suspended sediment, had larger effects on Kd than o rganic suspended ones. There was a good correlation between Kd and remote sensing reflectance. Taking Rrs(550), Rrs(675) and R rs(731) as independent variables and doing regression analysis with Kd(4 90), a good linear relationship was found between Kd(490) and Rrs (731), and multi-variate linear regression analysis using variables R rs(550), Rrs(675) and Rrs(731) could get better effect ( R2>096) than the regression analysis using variable Rrs(731).

Key words: root exudates, ecological effect, affecting factor.