Extending the functionality of the slurry ferrihydrite-DGT method: Performance evaluation for the measurement of vanadate, arsenate, antimonate and molybdate in water. (October 2017)

• Record Type: Journal Article
• Authors: Zhang, Shu; Williams, Paul N.; Zhou, Chun-Yang; Ma, Lena Q.; Luo, Jun
• Is Part Of: Chemosphere. Volume 184(2017)
• Page Start: 812
• Page End: 819
• Publication Date: 2017-10
• Subjects: Diffusive gradients in thin-films -- Metal -- Oxyanions -- Monitoring -- Slurry ferrihydrite; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.06.062
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The monitoring of oxyanions in waters, presents significant challenges due to their relatively low concentrations, and a characteristically changeable/unstable/reactive geochemistry with high spatial and temporal turnover. This results in a very heterogeneous pattern of mobility and bioavailability, which is difficult to capture reliably and in a cost effective manner. The diffusive gradients in thin-films (DGT) technique is a popular analytical tool for testing water quality, primarily because it provides a time-integrated measurement. However, to date, the most widely used DGT configuration for oxyanion sampling, the slurry ferrihydrite binding layer (SF-DGT) has only been fully characterized for phosphate. Confirmatory testing of the functional range of ionic strengths, pH, deployment times and ionic competition effects, that the SF-DGT's operates within has not been carried out, but is addressed in this study for V V, As V, Sb V, and Mo VI . In this study SF-DGT Sb V measurements functioned over the largest range of conditions (ionic strength, 0.1–500 mM; pH 3.86–9.90), while ionic strengths above 100 and 500 mM were found to be problematic for As V and Mo VI, respectively. Low pH (below 4) caused inferences with V V, conversely As V and Mo VI determination faltered/deviated from predicted responses in pH conditions of ∼9. SF-DGT measurements adequately predicted up to weeklong averaged in situ metal oxyanion concentrations in a freshwater river. This study concludes that the SF-DGT configuration is highly suitable for pollution monitoring applications in freshwater systems for key oxyanion species. Graphical abstract: Highlights: SF-DGT was characterized for measuring V V, As V, Sb V and Mo VI in lab. DGT measured concentrations of these elements were comparable to those in river. SF-DGT provides an easy way to investigate biogeochemistry of elements.