Influence of calcite on uranium(VI) reactive transport in the groundwater-river mixing zone.
Calcite is an important, relatively soluble mineral phase that can affect uranium reactive transport in subsurface sediments. This study was conducted to investigate the distribution of calcite and its influence on uranium adsorption and reactive transport in the groundwater-river mixing zone of the Hanford 300A site, Washington State. Simulations using a two-dimensional (2D) reactive transport model under field-relevant hydrological and hydrogeochemical conditions revealed the development of a calcite reaction front through the mixing zone as a result of dynamic groundwater-river interactions. The calcite concentration distribution, in turn, affected the concentrations of aqueous carbonate and calcium, and pH through dissolution, as river waters intruded and receded from the site at different velocities in response to stage changes. The composition variations in groundwater subsequently influenced uranium mobility and discharge rates into the river in a complex fashion. The results implied that calcite distribution and concentration are important variables that need to be quantified for accurate reactive transport predictions of uranium, especially in dynamic groundwater-river mixing zones.
School of Environmental Studies, China University of Geosciences, Wuhan, China.
Rui
R
Ma
Chongxuan
C
Liu
Janek
J
Greskowiak
Henning
H
Prommer
John
J
Zachara
Chunmiao
C
Zheng
D000327:Adsorption; D002118:Calcium / Q000032:analysis; D002119:Calcium Carbonate / Q000737:chemistry*; D002254:Carbonates / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry; D060587:Groundwater / Q000737:chemistry*; D007700:Kinetics; D045483:Rivers / Q000737:chemistry*; D014501:Uranium / Q000032:analysis / Q000737:chemistry*; D014861:Washington; D014872:Water Movements; D014875:Water Pollutants, Radioactive / Q000032:analysis / Q000737:chemistry*
D002254:Carbonates; D014875:Water Pollutants, Radioactive; D014501:Uranium; D002119:Calcium Carbonate; D002118:Calcium
Calcite; Groundwater–river mixing zone; Hanford 300A site; Reactive transport modeling; Uranium mobility