Electrochemical and analytical techniques to assay in situ environmental lead concentrations and to predict bioavailability
Description
Metals are released and accumulated in both living and environmental systems, and given the complex matrices unique to the two systems, there exist ion extraction and detection methods. This dissertation aims to combine analytical methods of both biological and environmental sciences to provide a means to assess the biological impact of environmental pollution Instrumentation commonly used for trace metal detection is too large or power consuming for practical field use. One trace level analytical method, cyclic voltammetry (CV), was adapted for field deployment. After using a 50% v/v nitric acid ion extraction method and optimizing CV instrumentation (e.g. mercury free high surface area graphite electrode cleaning and eliminating nitrogen purge) lead levels were determined in situ at three polluted urban locations in New Orleans, Louisiana. The results were compared to an established ion extraction method (ASTM D 3974) and analytical analyses (differential pulse polarography and dispersive X-ray diffraction). Despite higher ion and organic detection limits (two orders and four orders of magnitude, respectively) compared to other detection methods and spurious results at one test site, the field deployable analytical methods and instrumentation will provide environmental researchers with tools for the rapid analysis of environmental samples and identification of localized polluted areas with ion concentrations greater than 10 ppm The research measured lead extraction with simulated digestive acid exposure to polluted kaolin clay and Bayou Trepagnier sediment in vitro. The lead accumulation potential in catfish and crayfish based upon these experiments and published findings by other researchers, was estimated in catfish and crayfish to be 29.6 and 133 ppm, respectively Further development of the techniques and hardware in this work may provide researchers with tools that can identify environmental lead levels and predict lead ion bioaccumulation