Chromium Isotope Fractionation During Reduction of Cr(VI) Under Saturated Flow Conditions

详细信息    查看全文

• 作者：Julia H. Jamieson-Hanes ; Blair D. Gibson ; Matthew B. J. Lindsay ; Yeongkyoo Kim ; Carol J. Ptacek ; David W. Blowes
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：June 19, 2012
• 年：2012
• 卷：46
• 期：12
• 页码：6783-6789
• 全文大小：324K
• 年卷期：v.46,no.12(June 19, 2012)
• ISSN：1520-5851

文摘

Chromium isotopes are potentially useful indicators of Cr(VI) reduction reactions in groundwater flow systems; however, the influence of transport on Cr isotope fractionation has not been fully examined. Laboratory batch and column experiments were conducted to evaluate isotopic fractionation of Cr during Cr(VI) reduction under both static and controlled flow conditions. Organic carbon was used to reduce Cr(VI) in simulated groundwater containing 20 mg L^鈥? Cr(VI) in both batch and column experiments. Isotope measurements were performed on dissolved Cr on samples from the batch experiments, and on effluent and profile samples from the column experiment. Analysis of the residual solid-phase materials by scanning electron microscopy (SEM) and by X-ray absorption near edge structure (XANES) spectroscopy confirmed association of Cr(III) with organic carbon in the column solids. Decreases in dissolved Cr(VI) concentrations were coupled with increases in 未⁵³Cr, indicating that Cr isotope enrichment occurred during reduction of Cr(VI). The 未⁵³Cr data from the column experiment was fit by linear regression yielding a fractionation factor (伪) of 0.9979, whereas the batch experiments exhibited Rayleigh-type isotope fractionation (伪 = 0.9965). The linear characteristic of the column 未⁵³Cr data may reflect the contribution of transport on Cr isotope fractionation.