Spectral reflectance and water quality of Adirondack mountain region lakes

The reflectance properties of lakes in the Adirondack mountain region are described. Five distinct types of reflectance spectra are identified and related to differcnccs in water quality. No relationship was found between reflectance and acidification status. A reflectance model based on literature absorbance and scattering cross-sections of water, plant pigments, dissolved organic carbon (DOC), and suspended inorganic matter is used to generate reflectance spectra of each reflectance type. Use of a variable Q factor during the conversion of remotely sensed reflectance to irradiance reflectance improves the correspondence between mea-sured and modeled irradiance reflectance spectra. Comparison of measured reflectance with model reflectance also demonstrates the importance of small concentration changes as well as the inter-active influence of plant pigments, DOC, and suspended material on lake color. Correlograms depict the wavelength-dependent relationships between reflectance and water qual-ity. Plant pigments, DOC, and suspended material are negatively correlated with reflectance from 400 to 600 nm and positively correlated from 600 to 750 nm; parameters associated with lake acidification, pH, alkalinity, and aluminum concentrations are poorly correlated with reflectance