Quantifying the trophic status of lakes using total light absorption of optically active components

Abstract Eutrophication of lakes has become one of the world's most serious environmental problems, resulting in an urgent need to monitor and provide safeguards to control water quality. Results from analysis of lake trophic status based on calculated throphic state index (TSI) showed that 69.5% of the surveyed 277 lakes were in a state of eutrophication. Significant logarithmic relationships between light absorption of optically active components (a OACs ) and TSI (R 2  = 0.78) existed: TSI = 13.64 × ln(a OACs )+43.24, and the regression relationship between a OACs and TSI had a better degree of fit (R 2 ) than the currently used reflectance-TSI relationship. a OACs appeared to be a good predictor of TSI estimation in lake ecosystems. The relationship coefficient (a OACs -TSI) slightly varied with lake type, and relationships in saline lakes and phy-type lakes were shown to be more robust than the relationship with the total lake data. This study highlights the quantification of the trophic status in lakes using a OACs , which realized the monitoring of trophic status in lakes using inherent optical properties on a large-scale. To our knowledge this is the first investigation to assess the variability of trophic status in lakes across China. The assessment trophic state of lakes based on a OACs provides a new way to monitor the trophic status of lakes, and findings may have applications for monitoring large-scale and long-term trophic patterns in lakes using remote sensing techniques.