Reaction-Based Model Describing Competitive Sorption and Transport of Cd, Zn, and Ni in an Acidic Soil
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- 作者：Andreas Voegelin ; Vijay M. Vulava ; and Ruben Kretzschmar
- 刊名：Environmental Science & Technology
- 出版年：2001
- 出版时间：April 15, 2001
- 年：2001
- 卷：35
- 期：8
- 页码：1651 - 1657
- 全文大小：116K
- 年卷期：v.35,no.8(April 15, 2001)
- ISSN：1520-5851
文摘
Predicting the mobility of heavy metals in soils requiresmodels that accurately describe metal adsorption in thepresence of competing cations. They should also be easilyadjustable to specific soil materials and applicable inreactive transport codes. In this study, Cd adsorption toan acidic soil material was investigated over a wideconcentration range (10-8 to 10-2 M CdCl2) in the presenceof different background electrolytes (10-4 to 10-2 MCaCl2 or MgCl2 or 0.05 to 0.5 M NaCl). The adsorptionexperiments were conducted at pH values between 4.6and 6.5. A reaction-based sorption model was developedusing a combination of nonspecific cation exchange reactionsand competitive sorption reactions to sites with highaffinity for heavy metals. This combined cation exchange/specific sorption (CESS) model accurately described theentire Cd sorption data set. Coupled to a solute transportcode, the model accurately predicted Cd breakthroughcurves obtained in column transport experiments. The modelwas further extended to describe competitive sorptionand transport of Cd, Zn, and Ni. At pH 4.6, both Zn and Niexhibited similar sorption and transport behavior asobserved for Cd. In all transport experiments conductedunder acidic conditions, heavy metal adsorption was shownto be reversible and kinetic effects were negligiblewithin time periods ranging from hours up to four weeks.