UV and Fluorescence Spectroscopy Used to Characterize and Quantify Dissolved and Colloidal Organic Material in Northwest Streams as an Indicator of the Bioavialability of Toxic Metal Cations (Cuii, Znii)
Wildlife & Ecosystems
Research Idea Scope
Using a modification of the methods used by J.C. Rochaa et al. J. Braz. Chem. Soc. Water Samples from 5-10 NW Salmon Streams will be taken and the fulvic acid and colloidal organic compounds (DOC) partitioned according to size and charge using liquid-resin chromatography and correlated to their UV absorbance and fluorescence spectrum. Once partitioned, fractions will be analyzed (Atomic Absorption Spectroscopy) for their heavy metal content to determine which fraction sequesters the highest concentration of heavy metals. In addition series of “titration’s” with ionic copper solutions with serial dilutions of the natural DOC fractions and sampled over time, will be used to determine the various fractions ability to absorb and render ionic copper biologically unavailable. Confirmation of the lack of bio availability will be made initially using a Microtox technique, and ultimately by bioassay using juvenile salmonids. We will also explore the use of confocal microscopy to assess the effects of ionic and DOC bound copper on neural calcium discharges in ciliated olfactory and lateral line receptor cells.
Urgency and Payoff
Currently NOAA fisheries is concerned about operationally defined Copper concentration in 2-10 ppb affecting olfactory ability in Juvinile T&E Salmon. This has resulted from studies conducted in the Lab which did not use natural water. Natural waters typically contain high levels of colloidal and dissolved organic matter which efficiently absorbs and renders biologically unavailable many metal cations in particular Copper. By developing a fairly simple (UV spectroscopy) method to quantify and characterize a natural waters ability to absorb copper and render it biologically un- available we will be able to better assess when and if costly WQ mitigation measures are appropriate and required.
William Van Peeters, SF Resource Center FHWA DOT , Telephone: 415 744 0116