Analysis of suspended solids in water using remotely sensed high resolution derivative spectra

Discrimination of the chlorophyll signal from those of suspended sediments and the water itself has proven to be a difficult problem in optical remote sensing of algal biomass. Our study uses numerical differentiation of high resolution spectral data collected at close range over experimental tanks to address this problem. Results indicate that pure water effects can be reduced by a first-order derivative curve and suspended sediment effects can be removed by a second-order transformation. Chlorophyll content is correlated with the difference between the second derivates at 660 and 695 nanometres. This relationship holds even in the presence of background turbidity. Thus, it is an effective means of compensating for interference from suspended solids. Our findings are discussed as they relate to the use of remote sensing for lake and reservoir management. -Authors