Large-scale modeling of reactive solute transport in fracture zones of granitic bedrocks

摘要: Final disposal of high-level radioactive waste in deep repositories located fractured granite formations is being considered by several countries. The assessment the safety such requires using numerical models groundwater flow, solute transport and chemical processes. These are developed from data knowledge gained situ experiments as Redox Zone Experiment carried out at underground laboratory Aspo Sweden. This experiment aimed evaluating effects construction access tunnel on hydrogeological hydrochemical conditions a fracture zone intersected tunnel. Most species showed dilution trends except for bicarbonate sulphate which unexpectedly increased with time. Molinero Samper [Molinero, J. Samper, Groundwater flow zones: an improved model large-scale field (Sweden). Hydraul. Res., 42, Extra Issue, 157-172] presented two-dimensional water finite element reproduced measured drawdowns curves conservative species. Here we extend their reactive accounts aqueous complexation, acid-base, redox processes, dissolution-precipitation calcite, quartz, hematite pyrite, cation exchange between Na+ Ca2+. provides field-scale estimates capacity potential recharge. It serves also to identify mineral phases controlling solubility iron. In addition, useful test relevance geochemical Model results rule calcite dissolution process causing increase concentration reject following possible sources sulphate: (1) pyrite dissolution, (2) leaching alkaline sulphate-rich waters nearby rock landfill (3) iron monosulphides contained Baltic seafloor sediments. Based these results, microbially mediated processes postulated most likely hypothesis explain dissolved bicarbonates sulphates after construction. © 2005 Elsevier B.V. All rights reserved.