Salinity-Driven Controls on Arsenic Mobility in Naturally Coated Sands: Multi-mineral Sorption, Kinetic Limitations, and Metal-Facilitated Transport: Dataset

This repository contains the laboratory dataset and input files for the one-dimensional (1D) reactive tranport described in Stolze and Rolle (submitted to the journal Geochimica et Cosmochimica Acta) "Salinity-Driven Controls on Arsenic Mobility in Naturally Coated Sands: Multi-mineral Sorption, Kinetic Limitations, and Metal-Facilitated Transport". The laboratory experiments consisted in a series of column experiments in which arsenic solutions (1 mg As / Lw) were injected into two types of quartz sands (SG and SD) under oxic conditions, fully-saturated conditions, at a flow velocity of 1 m/day. Experiments were repeated for different hydrochemical conditions (baseline, acidic, saline, and acidic + saline) to test the impact of acidity and salinity on the mobility of arsenic. Additionally, a stop-flow experiment was performed under baseline condition in which the flow was interruped after 35h in SG and 36h in SD. This data package provide the concentrations of aqueous species measured at the outlet of the columns (As, Al, Na, Cl, Br, pH). Column experiments are denoted "1" to "4" while the stop-flow experiments are denoted "5". The model was used to quantitatively interpret the interactions of arsenate with the solid matrix during its transport through the columns. The model simulates the advective-dispersive transport of the solutes, their chemical and electrostatic interactions of these species with the quartz sand surfaces (represented by explicitely accounting for quartz and metal oxide coatings) by coupling a surface complexation model with the transport model, the kinetically-limited sorption of arsenic, the release of alumnium from the quartz surface under high salinity conditions and the associated al-facilitated transport of arsenic. The simulations were performed using the reactive transport code PHREEQC and executed on the Lichtenberg II supercimputer for parallelizing the simulations during calibration and sensitivity analyses. The thermodynamic database, include the peciation of arsenic, carbonate, and alumnium species, and is adapted from WATEQ4F in which diffusion coefficients have been amended.