Diffusive gradients in thin films technique equipped with a mixed binding gel for simultaneous measurements of dissolved reactive phosphorus and dissolved iron.
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.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Di
D
Xu
Yifei
Y
Chen
Shiming
S
Ding
Qin
Q
Sun
Yan
Y
Wang
Chaosheng
C
Zhang
D005782:Gels; D019015:Geologic Sediments / Q000737:chemistry; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
D005782:Gels; D012117:Resins, Synthetic; C024997:Chelex 100; D010758:Phosphorus; D015040:Zirconium; D007501:Iron; C028541:zirconium oxide