Diffusive Gradients in Thin Films Technique Equipped with a Mixed Binding Gel for Simultaneous Measurements of Dissolved Reactive Phosphorus and Dissolved Iron

• Published in: Environmental science & technology 2013-09, Vol.47 (18), p.10477-10484
• Main Authors: Xu, Di, Chen, Yifei, Ding, Shiming, Sun, Qin, Wang, Yan, Zhang, Chaosheng
• Format: Article
• Language: English
• Subjects: Analysis methods; Applied sciences; Aquatic ecology; Exact sciences and technology; Gels; Geologic Sediments - chemistry; Iron; Iron - analysis; Iron - chemistry; Phosphorus; Phosphorus - analysis; Phosphorus - chemistry; Pollution; Resins, Synthetic - chemistry; Sediments; Soil and sediments pollution; Thin films; Zirconium - chemistry
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es401822x

Developing a technique to track the release of phosphorus (P) and iron (Fe) simultaneously in sediments would be very useful in deepening our understanding of the internal loading process of P coupled with Fe cycling in aquatic systems. In this study, a new technique was established to measure simultaneously the dissolved reactive P (DRP) and dissolved Fe primarily released from sediment solids based on the diffusive gradients in thin films (DGT) theory. A mixed binding gel (ZrO-Chelex gel) used for assembling DGT was developed for simultaneous uptake of DRP and dissolved Fe(II) using amorphous zirconium hydroxide (Zr-oxide) and Chelex-100 resin as binding agents. Simultaneous measurements of DRP and dissolved Fe(II) with the ZrO-Chelex DGT were validated in solution and were independent of solution pH and ionic strength in normal environments. The capacities of the ZrO-Chelex DGT for measurements of DRP and dissolved Fe(II) were 90 μg P cm–2 and 75 μg Fe cm–2, with the latter being greater than that (45 μg Fe cm–2) observed with the Chelex-100 resin DGT commonly used in DGT measurements of metals. Microcosm experiments further confirmed the feasibility of the ZrO-Chelex DGT for simultaneous measurement of P and Fe in sediments, with a higher concentration of Fe being measured due to this method’s higher capacity compared with the Chelex-100 resin DGT.