Modeling EDTA-facilitated cadmium migration in high- and low-permeability systems using MODFLOW and RT3D

Xueji You; Shuguang Liu; Somayeh G Esfahani; Yanping Duan; Jixiang Li; Chaomeng Dai; Charles J Werth

doi:10.1016/j.jconhyd.2023.104171

Modeling EDTA-facilitated cadmium migration in high- and low-permeability systems using MODFLOW and RT3D

J Contam Hydrol. 2023 May:256:104171. doi: 10.1016/j.jconhyd.2023.104171. Epub 2023 Mar 17.

Authors

Xueji You¹, Shuguang Liu², Somayeh G Esfahani³, Yanping Duan⁴, Jixiang Li⁵, Chaomeng Dai⁶, Charles J Werth⁷

Affiliations

¹ Department of Hydraulic Engineering, College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China; Department of Civil, Architectural, and Environmental Engineering, The University of Texas at Austin, 301 E. Dean Keeton St., Stop C1786, Austin, TX 78712, USA.
² Department of Hydraulic Engineering, College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
³ Department of Civil, Architectural, and Environmental Engineering, The University of Texas at Austin, 301 E. Dean Keeton St., Stop C1786, Austin, TX 78712, USA.
⁴ School of Environmental and Geographical Sciences, Shanghai Normal University, No. 100 Guilin Road, Shanghai 200234, China.
⁵ Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 200120, China.
⁶ Department of Hydraulic Engineering, College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China. Electronic address: daichaomeng@tongji.edu.cn.
⁷ Department of Civil, Architectural, and Environmental Engineering, The University of Texas at Austin, 301 E. Dean Keeton St., Stop C1786, Austin, TX 78712, USA. Electronic address: werth@utexas.edu.

PMID: 36963123
DOI: 10.1016/j.jconhyd.2023.104171

Abstract

Cadmium (Cd) has impacted groundwater resources and can pose a serious threat to human health and the environment. Its fate in groundwater is complex and challenging to predict, as it is affected by adsorption to sediments, complexation with aqueous phase ligands, and variations in hydraulic conductivity. In this study, a 2D reactive transport model based on MODFLOW and RT3D is used to simulate published experimental results of cadmium migration without and with EDTA present in a flow cell containing high- and low-permeability zones (i.e., HPZs and LPZs). The model is then extended to conceptual flow cells with more complex LPZ configurations. Simulation results generally match the experimental data well, and analysis of experimental and simulated Cd effluent concentration profiles shows that EDTA enhances Cd removal from LPZs relative to water alone. Simulation results indicate that faster Cd removal is due to EDTA complexation with adsorbed Cd in LPZs, which enhances its solubilization and subsequent back diffusion. Lastly, simulation results show that with increasing LPZ heterogeneity more Cd is retained in flow cells, and EDTA is more effective in enhancing Cd removal relative to water alone; these results are attributed to more LPZ-HPZ interfaces that enhance Cd mass transfer into LPZs during contamination, and enhance EDTA mass transfer into LPZs to promote cleanup. Overall, the results highlight the promise of using EDTA to remove Cd from heterogeneous sites, but caution is advised due to model simplicity and lack of consideration of changes in solution pH, redox potential, or competing cations.

Keywords: Back diffusion; Cadmium; Complexation; EDTA; High- and low-permeability; MODFLOW-RT3D.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Cadmium* / analysis
Computer Simulation
Edetic Acid
Humans
Permeability
Water*

Substances

Cadmium
Edetic Acid
Water