Acquisition of Advanced Equipment for Measurement of Metal Speciation in Fresh Waters

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0132428BenoitThis grant provides support for the acquisition of a Brinkmann automated voltammetry system (VA Trace Analyzer, Model 746) and a MARS 5 microwave digestion system (CEM Corp.) to facilitate measurement of rapid changes in chemical speciation that occur in freshwater systems as a result of both natural biogeochemical processes and point and nonpoint source pollution. The Brinkmann voltammetry system automates basic voltammetric functions and combines this ability with an automatic titration system and 80 position autosampler. The MARS 5 Microwave Digestion system is able to digest colloids and particles in multiple samples rapidly and completely, and has the unique ability to increase analyte concentration through evaporation of the digestion matrix. The information on total metal concentrations provided by analysis of digested samples is a necessary component in the process of evaluating chemical speciation. The increased sample processing efficiency and reproducibility of the MARS 5 microwave digestion system will complement the increased sample throughput of the Brinkmann automated voltammetry system in improving the ability of researchers in our laboratory to measure rapid changes in metal speciation within freshwater systems. Current research on metal complexation by NOM (natural organic matter) aims to identify easily measurable characteristics of NOM (e.g., spectroscopic) that can be used to estimate their complexation characteristics (abundance and strength of binding sites). Future work on NOM will evaluate rapid variations in quantity and quality that occur during storm events and with changing water flowpaths through soils. Other projects study metal binding by reduced sulfur compounds in fully-oxygenated surface waters. This newly discovered class of ligands is poorly understood, but may be as important as NOM in many instances. ***