Estuarine distributions of dissolved titanium

Abstract

Adsorptive cathodic stripping square wave voltammetry was used to determine dissolved Ti at nanomolar to sub-nanomolar levels in estuarine samples over a range of salinities and dissolved organic matter concentrations. Dissolved Ti concentrations range from 0.2 to 13.7 nM and from 0.2 to 67 nM in the Delaware Bay and Winyah Bay (USA) estuarine systems, respectively. Early and late spring surveys in Delaware Bay show that dissolved Ti is largely removed during estuarine mixing. Dissolved Ti concentrations decrease with decreasing filter size fraction, suggesting that Ti is associated with particles or colloids. Mechanisms of Ti removal in estuaries may be similar to those of other particle-reactive elements, such as Fe. Some coherence between the dissolved Si and Ti distributions during a spring diatom bloom suggests that biological scavenging may also be important. In the organic-rich Winyah Bay system, Ti concentrations are patchy, indicating that both addition and removal occur during the mixing of multiple source waters. As biological productivity is low, a variety of physical and chemical processes probably control Ti behavior. Such processes include interactions between particles, dissolved organic matter, and fluxes from adjacent reservoirs.