Benchmark problems for reactive transport modeling of the generation and attenuation of acid rock drainage

Mayer, K. Ulrich; Alt-Epping, Peter; Jacques, Diederik; Arora, Bhavna; Steefel, Carl I. (2015). Benchmark problems for reactive transport modeling of the generation and attenuation of acid rock drainage. Computational geosciences, 19(3), pp. 599-611. Baltzer Science Publishers 10.1007/s10596-015-9476-9

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Acid rock drainage (ARD) is a problem of international relevance with substantial environmental and economic implications. Reactive transport modeling has proven a powerful tool for the process-based assessment of metal release and attenuation at ARD sites. Although a variety of models has been used to investigate ARD, a systematic model intercomparison has not been conducted to date. This contribution presents such a model intercomparison involving three synthetic benchmark problems designed to evaluate model results for the most relevant processes at ARD sites. The first benchmark (ARD-B1) focuses on the oxidation of sulfide minerals in an unsaturated tailing impoundment, affected by the ingress of atmospheric oxygen. ARD-B2 extends the first problem to include pH buffering by primary mineral dissolution and secondary mineral precipitation. The third problem (ARD-B3) in addition considers the kinetic and pH-dependent dissolution of silicate minerals under low pH conditions. The set of benchmarks was solved by four reactive transport codes, namely CrunchFlow, Flotran, HP1, and MIN3P. The results comparison focused on spatial profiles of dissolved concentrations, pH and pE, pore gas composition, and mineral assemblages. In addition, results of transient profiles for selected elements and cumulative mass loadings were considered in the intercomparison. Despite substantial differences in model formulations, very good agreement was obtained between the various codes. Residual deviations between the results are analyzed and discussed in terms of their implications for capturing system evolution and long-term mass loading predictions.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Rock-Water Interaction

UniBE Contributor:

Alt-Epping, Peter

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1420-0597

Publisher:

Baltzer Science Publishers

Language:

English

Submitter:

Peter Alt-Epping

Date Deposited:

19 Aug 2015 09:15

Last Modified:

19 Aug 2015 09:15

Publisher DOI:

10.1007/s10596-015-9476-9

BORIS DOI:

10.7892/boris.70948

URI:

https://boris.unibe.ch/id/eprint/70948

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