Assessing the complexation of trace metals in natural waters is critical to understanding their toxicity and behavior. While both inorganic and organic complexes are important, organic complexation dominates aqueous speciation of many metals, such as copper (Cu). Unfortunately, rapid and reliable evaluation of trace metal complexation with dissolved organic matter (DOM) is extremely challenging. Fast Scan Cyclic Voltammetry (FSCV) has recently been shown to have a high sensitivity (ppb levels) for Cu with near real-time temporal resolution of 100 ms. This sensitive and rapid detection of trace metals allows analytical chemist to gain additional insight into Cu-DOM complexation and provides an opportunity to assess biogeochemical cycling in new ways. In this presentation we explore the use of FSCV to detect and quantify Cu binding and release with DOM reference standards in real-time, and quantify the release of Cu due to competitive binding by aluminum. Comparing immediate versus 5 day complexation experiments demonstrates kinetic limitations in Cu-DOM complex formation for all DOM standards. When Cu-DOM complexes were subjected to competitive binding by aluminum (Al), significant differences between types of DOM (humic acid, fulvic acid, etc.) were observed. This presentation quantifies these interactions and discusses the implications of FSCV measurements of metal complexation in environmental systems.

Evaluating complexation of copper with dissolved organic matter and competitive aluminum binding using fast scan cyclic voltammetry

248th National Meeting (2014)

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