Guidelines for thermodynamic sorption modelling in the context of radioactive waste disposal

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dc.contributor.authorPayne, TEen_AU
dc.contributor.authorBrendler, Ven_AU
dc.contributor.authorOchs, Men_AU
dc.contributor.authorBaeyens, Ben_AU
dc.contributor.authorBrown, PLen_AU
dc.contributor.authorDavis, JAen_AU
dc.contributor.authorEkberg, Cen_AU
dc.contributor.authorKulik, DAen_AU
dc.contributor.authorLützenkirchen, Jen_AU
dc.contributor.authorMissana, Ten_AU
dc.contributor.authorTachi, Yen_AU
dc.contributor.authorVan Loon, LRen_AU
dc.contributor.authorAltmann, Sen_AU
dc.date.accessioned2013-04-23T06:21:39Zen_AU
dc.date.available2013-04-23T06:21:39Zen_AU
dc.date.issued2013-01-01en_AU
dc.date.statistics2013-04-23en_AU
dc.description.abstractThermodynamic sorption models (TSMs) offer the potential to improve the incorporation of sorption in environmental modelling of contaminant migration. One specific application is safety cases for radioactive waste repositories, in which radionuclide sorption on mineral surfaces is usually described using distribution coefficients (K-d values). TSMs can be utilised to provide a scientific basis for the range of K-d values included in the repository safety case, and for assessing the response of K-d to changes in chemical conditions. The development of a TSM involves a series of decisions on model features such as numbers and types of surface sites, sorption reactions and electrostatic correction factors. There has been a lack of consensus on the best ways to develop such models, and on the methods of determination of associated parameter values. The present paper therefore presents recommendations on a number of aspects of model development, which are applicable both to radioactive waste disposal and broader environmental applications. The TSM should be calibrated using a comprehensive sorption data set for the contaminant of interest, showing the impact of major geochemical parameters including pH, ionic strength, contaminant concentration, the effect of ligands, and major competing ions. Complex natural materials should be thoroughly characterised in terms of mineralogy, surface area, cation exchange capacity, and presence of impurities. During the application of numerical optimisation programs to simulate sorption data, it is often preferable that the TSM should be fitted to the experimentally determined K-d parameter, rather than to the frequently used percentage sorbed. Two different modelling approaches, the component additivity and generalised composite, can be used for modelling sorption data for complex materials such as soils. Both approaches may be coupled to the same critically reviewed aqueous thermodynamic data sets, and may incorporate the same, or similar, surface reactions and surface species. The quality of the final sorption model can be assessed against the following characteristics: an appropriate level of complexity, documented and traceable decisions, internal consistency, limitations on the number of adjustable parameter values, an adequate fit to a comprehensive calibration data set, and capability of simulating independent data sets. Key recommendations for the process of TSM development include: definition of modelling objectives, identification of major decision points, a clear decision-making rationale with reference to experimental or theoretical evidence, utilisation of a suitable consultative and iterative model development process, testing to the maximum practicable extent, and thorough documentation of key decisions. These recommendations are consistent with international benchmarks for environmental modelling. Copyright © 2013, Elsevieren_AU
dc.identifier.citationPayne, T.E., Brendler, V., Ochs, M., Baeyens, B., Brown, P.L., Davis, J.A., Ekberg, C., Kulik, D.A., Lutzenkirchen, J., Missana, T., Tachi, Y., Van Loon, L.R., & Altmann, S. (2013). Guidelines for thermodynamic sorption modelling in the context of radioactive waste disposal. Environmental Modelling & Software, 42, 143-156. doi:10.1016/j.envsoft.2013.01.002en_AU
dc.identifier.govdoc4865en_AU
dc.identifier.issn1364-8152en_AU
dc.identifier.journaltitleEnvironmental Modelling & Softwareen_AU
dc.identifier.pagination143-156en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/4574en_AU
dc.identifier.urihttps://doi.org/10.1016/j.envsoft.2013.01.002en_AU
dc.identifier.volume42en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectThermodynamicsen_AU
dc.subjectSorptionen_AU
dc.subjectMigrationen_AU
dc.subjectCalibrationen_AU
dc.subjectRadioisotopesen_AU
dc.subjectUraniumen_AU
dc.titleGuidelines for thermodynamic sorption modelling in the context of radioactive waste disposalen_AU
dc.typeJournal Articleen_AU
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