Preprints
https://doi.org/10.5194/hess-2021-338
https://doi.org/10.5194/hess-2021-338

  02 Aug 2021

02 Aug 2021

Review status: this preprint is currently under review for the journal HESS.

Reactive Transport Modeling for Supporting Climate Resilience at Groundwater Contamination Sites

Zexuan Xu1, Rebecca Serata1, Haruko Wainwright1, Miles Denham2, Sergi Molins1, Hansell Gonzalez-Raymat4, Konstantin Lipnikov3, David Moulton3, and Carol Eddy-Dilek4 Zexuan Xu et al.
  • 1Lawrence Berkeley National Laboratory
  • 2Panoramic Environmental Consulting
  • 3Los Alamos National Laboratory
  • 4Savannah River National Laboratory

Abstract. Climate resilience is an emerging issue at contaminated sites and hazardous waste sites, since projected climate shifts (e.g., increased/decreased precipitation) and extreme events (e.g., flooding, drought) could affect ongoing remediation or closure strategies. In this study, we develop a reactive transport model (Amanzi) for radionuclides (uranium, tritium, and others) and evaluate how different scenarios under climate change will influence the contaminant plume conditions and groundwater well concentrations. We demonstrate our approach using a two-dimensional reactive transport model for the Savannah River Site F-Area, including mineral reaction and sorption processes. Different recharge scenarios are considered by perturbing the infiltration rate from the base case, as well as considering cap failure and climate projection scenarios. We also evaluate the uranium and nitrate concentration ratios between scenarios and the base case to isolate the sorption effects with changing recharge rates. The modeling results indicate that the competing effects of dilution and remobilization significantly influence pH, thus changing the sorption of uranium. At the maximum concentration on the breakthrough curve, higher aqueous uranium concentration implies that sorption is reduced with lower pH due to remobilization. To better evaluate the climate change impacts in the future, we develop the workflow to include the downscaled CMIP5 (Coupled Model Intercomparison Project) climate projection data in the reactive transport model, and evaluate how residual contamination evolves through 2100 under four climate Representative Concentration Pathway (RCP) scenarios. The integration of climate modeling data and hydro-geochemistry models enables us to quantify the climate change impacts, assess which impacts need to be planned for, and therefore assist climate resiliency efforts and help guide site management.

Zexuan Xu et al.

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-338', Jinwoo Im, 30 Aug 2021 reply

Zexuan Xu et al.

Zexuan Xu et al.

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Short summary
Climate change could change the groundwater system and threaten water supply. To quantitatively evaluate its impact on water quality, numerical simulations with chemical and reaction processes are required. With the climate projection dataset, we used the newly-developed hydrological and chemical model to investigate the movement of contaminants, and assist the management of contamination sites.