Using Hyperspectral Remote Sensing to Map Methylmercury Concentrations in the San Francisco Bay-Delta

Start/End: January, 2014 to December, 2015

 Sediment-bound mercury in the foothills of the Sierras – the legacy of the Gold Rush – is an ongoing source of the toxic heavy metal in the San Francisco Bay-Delta. This project seeks to demonstrate the ability to estimate surface concentrations of mercury’s toxic bioavailable form (methylmercury) based on the optical properties of methylmercury-containing organic material, as measured by NASA’s Portable Remote Imaging Spectrometer (PRISM) sensor, developed by NASA’s Jet Propulsion Laboratory. The fundamental premise of the research is that methylmercury, when bound to organic material in the water column, will have a uniquely defining spectral fingerprint. For this project, the PRISM sensor will be mounted on an airplane and flown over the Bay-Delta multiple times to obtain data on water color (reflectance) at 1- to 2-meter resolutions. The precise number of flights will depend on funding; however, the goal is to survey the region seasonally, before and after large rainfall events, and over a tidal cycle. The fellow will develop an algorithm for estimating methylmercury concentrations and will test and validate it with direct field measurements. If the algorithm proves reliable, the fellow will use the reflectance data to monitor the effects of wetland restoration, periodic flooding of rice fields and precipitation on methylmercury concentrations. The remote sensing data will also be used to quantify the photochemical degradation of methylmercury.

Research mentor: Michelle Gierach, NASA’s Jet Propulsion Laboratory

Community mentors: Brian Bergamaschi and Michael Sauer, U.S. Geological Survey