Equilibrium-Based Sampler for Determining Cu2+ Concentrations in Aquatic Ecosystems

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• 作者：David B. Senn ; Sarah B. Griscom ; Christopher G. Lewis ; Jennifer P. Galvin ; Martha W. Chang ; and James P. Shine
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：June 15, 2004
• 年：2004
• 卷：38
• 期：12
• 页码：3381 - 3386
• 全文大小：115K
• 年卷期：v.38,no.12(June 15, 2004)
• ISSN：1520-5851

文摘

The bioavailability of potentially toxic metals in aquaticsystems is frequently related to the dissolved free metalion (M²⁺) concentration. However, typical methods used todetermine M²⁺ are labor intensive or require sophisticatedequipment. We developed an inexpensive, in situ samplingdevice-the "gellyfish"-that simplifies Cu²⁺ determinationsin seawater. The gellyfish is a thin disk of polyacrylamidegel embedded with iminodiacetate (Id) groups bound toimmobile beads. The sampler operates on the principle thatthe immobilized Id groups equilibrate with the Cu²⁺concentration of the surrounding solution. Cu is then back-extracted into a known volume of 10% HNO₃ and measuredby inductively coupled plasma mass spectrometry (ICP-MS). In laboratory tests, we varied Cu²⁺ concentrationsbetween 10^-12 and 10^-8 M and salinity between 5 and 35ppt. Id-bound Cu (CuId_measured) did not respond to changesin total Cu. However, CuId_measured does increase in a predictablemanner with increasing Cu²⁺, and prototype gellyfishprecision (average coefficient of variation = 10%) is sufficientto resolve small differences in Cu²⁺ (±30%). Modeled Cuuptake, based on thermodynamic equilibrium speciation ofId within gellyfish, is a good predictor of CuId_measured(r² = 0.96 and n = 45).