Int. J. Environ. Res. Public Health 2010, 7 Figure 8. Scatter plots of Chl-a versus reflectance at 733.1 nm. 2447 Figure 9. Scatter plots of Chl-a versus first-derivative of reflectance at 446.9 nm. Figure 10. Scatter plots of Chl-a versus reflectance ratio R861.1/R865.7.