Assessment of the Water Quality of Lake Ontario using the Varimax Rotated Spectral Decomposition Method

Abstract:

Identification of the constituents that influence the optical properties of the water in Lake Ontario or other optically complex water bodies is challenging. Previous studies document that the presence of excess N and P are a great concern of both the USA and Canada. Harmful water conditions related to cyanobacterial blooms can contain toxins such as microcystin, posing a threat to drinking water in addition to recreation and economic uses of Lake Ontario. Understanding the optical signal of Lake Ontario is critical but getting better information about harmful constituents is difficult using traditional methods. To address that, the Kent State University Varimax Rotated Principal Component Analysis (KSU VPCA) spectral decomposition method is a very effective means to partition the signatures of optically active water constituents from visible reflectance spectra using lab, field or satellite instruments. KSU VPCA method has been applied to Sentinel-3 Level 2 data to develop a seasonal time series from 2017 to 2019. Applying the method to 2017 satellite images throughout the year provides a clear understanding of spectral signatures of water components, pigment degradation products, and mineral mixtures. Preliminary results from cloud-free daily images collected during the summer season indicate spectral responses that identify Chlorophyll a, Allophycocyanin, and Phycocyanin and with a variety of other accessory pigments and minerals that account for smaller fractions of image variance. Comparison of the component signals with lake surface water temperature map suggests that different water surface masses are associated with different optical signatures, demonstrating environmental control of their distribution that can be further elucidated by comparison with other environmental remote sensing methods and/or field observations. Regarding health issues, recreational purposes, and drinking water problems this research will provide stakeholders with additional information that can be used to make timely decisions to safeguard water quality.