Model Predictions of Metal Speciation in Freshwaters Compared to Measurements by In Situ Techniques

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• 作者：Emily R. Unsworth ; Kent W. Warnken ; Hao Zhang ; William Davison ; Frank Black ; Jacques Buffle ; Jun Cao ; Rob Cleven ; Josep Galceran ; Peggy Gunkel ; Erwin Kalis ; David Kistler ; Herman P. van Leeuwen ; Miche
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：March 15, 2006
• 年：2006
• 卷：40
• 期：6
• 页码：1942 - 1949
• 全文大小：272K
• 年卷期：v.40,no.6(March 15, 2006)
• ISSN：1520-5851

文摘

Measurements of trace metal species in situ in a softwaterriver, a hardwater lake, and a hardwater stream werecompared to the equilibrium distribution of species calculatedusing two models, WHAM 6, incorporating humic ionbinding model VI and visual MINTEQ incorporating NICA-Donnan. Diffusive gradients in thin films (DGT) andvoltammetry at a gel integrated microelectrode (GIME)were used to estimate dynamic species that are both labileand mobile. The Donnan membrane technique (DMT)and hollow fiber permeation liquid membrane (HFPLM)were used to measure free ion activities. Predictions ofdominant metal species using the two models agreedreasonably well, even when colloidal oxide componentswere considered. Concentrations derived using GIME weregenerally lower than those from DGT, consistent withcalculations of the lability criteria that take into accountthe smaller time window available for the flux to GIME. Modelpredictions of free ion activities generally did not agreewith measurements, highlighting the need for further workand difficulties in obtaining appropriate input data.