Can imaging spectroscopy facilitate the detection of wastewater effluent in coastal waters?

Joshua P Harringmeyer1, Karl Kaiser2, David R Thompson3, Michelle M Gierach4, Curtis L. Cash5 and Cedric G Fichot1, (1)Boston University, Dept. of Earth & Environment, Boston, United States, (2)Texas A&M University at Galveston, Department of Marine and Coastal Environmental Science, Galveston, United States, (3)Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (4)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (5)City of Los Angeles, Environmental Monitoring Division, LA Sanitation and Environment, Los Angles, CA, United States
Imaging spectroscopy (hyperspectral imagery) has the potential to enhance our ability to detect anthropogenic effects on coastal ecosystems and water quality. Advanced instruments now measure remote-sensing reflectance at high spectral resolution in ultraviolet (UV) wavelengths, potentially enhancing our ability to detect specific constituents or water-quality indicators in complex coastal waters. However, the optically-complex nature of coastal environments requires additional research and validation to demonstrate these capabilities. Here, a planned nearshore, shallow diversion of wastewater effluent in the coastal waters of Santa Monica Bay (Southern California) enabled direct evaluation of imaging spectroscopy to specifically detect the chromophoric (colored) dissolved organic matter (CDOM) associated with the effluent. Fieldwork was conducted over a period of three months in 2015 before, during, and after the wastewater diversion, during which in-situ radiometry (Satlantic® HyperPRO) and absorption spectra and fluorescence matrices of CDOM were collected. A flyover of the NASA airborne Portable Remote Imaging SpectroMeter (PRISM) was also conducted concurrently to a Landsat-8 OLI acquisition during the diversion. Simultaneous in-situ, airborne, and satellite data were used to compare the performance of various empirical and semi-analytical algorithms for retrieving CDOM and to assess the spectral information provided by blue and UV wavelengths. The CDOM associated with the wastewater effluent also has an intense and characteristic fluorescence matrix. The data were also used to assess whether high-spectral-resolution UV-blue remote-sensing reflectances can be used to “fingerprint” effluent-derived CDOM from remote imaging spectroscopy.

A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology. US Government Support acknowledge. Copyright 2019, All Rights Reserved.