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

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