The possibilities of voltammetry in the study reactivity of dissolved organic carbon (DOC) in natural waters

This paper describes the application of a methodology, which primarily involves low-cost voltammetry, to rapidly track the reactivity (i.e. surfactant activity, SA) of dissolved organic carbon (DOC) in aquatic systems. The approach is based on the quantitative measurement of total surface activity (expressed as Triton-X-100 equivalent) of adsorbing organic compounds (AOCs) of amphiphilic and/or hydrophobic nature at the mercury electrode/electrolyte interface in natural water samples using phase-sensitive (out-of-phase) alternating current voltammetry (PSACV). The SA results were normalized to the DOC content. A graphical representation of DOC-normalized SA for different water systems allows a rough characterization and comparison of the DOC type at different scales (spatial, seasonal, temporal short- and long-term) and in extreme natural events such as different hydrological, meteorological, biological, and physical processes. The main idea is to demonstrate the capabilities of PSACV in the study of DOC in water systems. The presented methodology could be used in future research and monitoring studies, as PSACV is the only practical method available for the determination of surface active DOC in natural waters.