Reduced hydrogen sulfide-dissolved organic matter (H2S-DOM) systems have been shown to take part in numerous abiotic electron transfer reactions with chemicals of environmental concern.  When investigating these H2S-DOM systems, the bulk electron donating capacity (EDC) can be an important measure of the system reactivity.  This work uses mediated electrochemical analysis as well as substituted nitrobenzene compounds as reactive probes to quantify the EDC of a set of natural wetland sediment porewaters rich in H2S and DOM.  Through reduction of the nitro group on the nitrobenzene probes, total electron transfer from the H2S-DOM system can be calculated and provides a value that can be compared to the EDC determined by electrochemical analysis.  The data shows that each method characterizes different components of the bulk EDC and thus can be useful in understanding the differences in these electron pools.  On average, EDC values from electrochemical analysis are as much as an order of magnitude lower than EDC values calculated from nitrobenzene reduction when the sample tested has high H2S concentrations.  This difference indicates that only DOM EDC is measured through electrochemical methods while reactions of substituted nitrobenzene probes provide a measure of reduced sulfur species EDC.  Furthermore, the kinetics and thermodynamics describing these two methods can provide information on the total H2S-DOM system EDC when it is probed with environmental contaminants of differing reactivity.

Use of electrochemical methods and substituted nitrobenzene chemical probes to measure H<sub>?2</sub>?S-DOM electron donating capacity

248th National Meeting (2014)

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Use of electrochemical methods and substituted nitrobenzene chemical probes to measure H?2?S-DOM electron donating capacity

Use of electrochemical methods and substituted nitrobenzene chemical probes to measure H_?2?S-DOM electron donating capacity