Voltammetric Investigations of Natural Organic Matter

Redox activity is one of the most important, and yet poorly understood, properties of natural organic matter (NOM). It is well known that NOM can act as a reducing agent (reductant), and this is central to the role that NOM plays in the biogeochemical cycling of carbon. More recently, there has been growing interest in the role that NOM plays as an electron shuttle (mediator) in biogeochemical cycles. For example, several recent studies have shown that the addition of NOM to cultures of iron reducing bacteria can increase the rate of dissimilatory iron reduction [1]. These effects have been attributed to polyphenolic (especially hydroquinonoid) moieties that comprise a portion of NOM [2]. There are, however, other moieties that may contribute to the overall redox activity of NOM (e.g., complexed metals [3]), and this complexity has been one of the main impediments to the development of chemically exact descriptions of redox processes involving NOM.