Reactive transport modeling for supporting climate resilience at groundwater contamination sites

[摘要] Climate resilience is an emerging issue at contaminated sites and hazardouswaste sites, since projected climate shifts (e.g., increased/decreasedprecipitation) and extreme events (e.g., flooding, drought) could affectongoing remediation or closure strategies. In this study, we develop areactive transport model (Amanzi) for radionuclides (uranium, tritium, andothers) and evaluate how different scenarios under climate change willinfluence the contaminant plume conditions and groundwater wellconcentrations. We demonstrate our approach using a two-dimensional (2D) reactive transport model for the Savannah River Site F-Area, including mineral reaction and sorption processes. Different recharge scenarios are consideredby 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 basecase to isolate the sorption effects with changing recharge rates. Themodeling results indicate that the competing effects of dilution andremobilization significantly influence pH, thus changing the sorption ofuranium. At the maximum concentration on the breakthrough curve, higheraqueous uranium concentration implies that sorption is reduced with lower pHdue to remobilization. To better evaluate the climate change impacts in thefuture, we develop the workflow to include the downscaled CMIP5 (CoupledModel Intercomparison Project) climate projection data in the reactivetransport model and evaluate how residual contamination evolves through 2100 under four climate Representative Concentration Pathway (RCP)scenarios. The integration of climate modeling data and hydrogeochemistry models enables us to quantify the climate change impacts, assess whichimpacts need to be planned for, and therefore assist climate resiliencyefforts and help guide site management.

[学科分类] 妇产科学