10.1021/es501782g.s001 Wenming Dong Wenming Dong Jiamin Wan Jiamin Wan Additive Surface Complexation Modeling of Uranium(VI) Adsorption onto Quartz-Sand Dominated Sediments American Chemical Society 2014 reference quartz unit surface area Savannah River Site component additivity mineral pairs sediment goethite SCM SedimentsMany aquifers Additive Surface Complexation Modeling CA SRS USA surface area abundances South Carolina humic acid adsorption method kaolinite modeling results surface complexation modeling 2014-06-17 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Additive_Surface_Complexation_Modeling_of_Uranium_VI_Adsorption_onto_Quartz_Sand_Dominated_Sediments/2282128 Many aquifers contaminated by U­(VI)-containing acidic plumes are composed predominantly of quartz-sand sediments. The F-Area of the Savannah River Site (SRS) in South Carolina (USA) is an example. To predict U­(VI) mobility and natural attenuation, we conducted U­(VI) adsorption experiments using the F-Area plume sediments and reference quartz, goethite, and kaolinite. The sediments are composed of ∼96% quartz-sand and 3–4% fine fractions of kaolinite and goethite. We developed a new humic acid adsorption method for determining the relative surface area abundances of goethite and kaolinite in the fine fractions. This method is expected to be applicable to many other binary mineral pairs, and allows successful application of the component additivity (CA) approach based surface complexation modeling (SCM) at the SRS F-Area and other similar aquifers. Our experimental results indicate that quartz has stronger U­(VI) adsorption ability per unit surface area than goethite and kaolinite at pH ≤ 4.0. Our modeling results indicate that the binary (goethite/kaolinite) CA-SCM under-predicts U­(VI) adsorption to the quartz-sand dominated sediments at pH ≤ 4.0. The new ternary (quartz/goethite/kaolinite) CA-SCM provides excellent predictions. The contributions of quartz-sand, kaolinite, and goethite to U­(VI) adsorption and the potential influences of dissolved Al, Si, and Fe are also discussed.