Effect of pumping-induced soil settlement on the migration and transformation of aniline

Abstract

This study selected a contamination site associated with pesticide production to investigate the impact of soil settlement induced by pumping on the migration and transformation of the principal pollutant, aniline. The TMVOC model was enhanced by incorporating the settlement effect and validated through a soil-column experiment, which examined aniline distribution, phase transformation, and remediation efficiency under soil settlement. The results indicate that the optimized TMVOC model can accurately simulate the impact of pumping-induced soil settlement on aniline removal. The longitudinal migration of aniline was reduced, with the area of high concentrations drawing nearer to the surface. Furthermore, soil settlement negatively affected the removal of aniline in the Non-Aqueous Phase Liquid (NAPL) phase, resulting in a 10.59 % decline in the removal rate. In contrast, soil settlement positively influenced aniline removal in the gas and aqueous phases, increasing the removal rate by 12.55 % and 5.04 %, respectively, with the gas phase showing the most significant increase. Soil porosity decreased due to soil settlement, leading to a change in the proportion of each phase, with NAPL increasing after remediation. Additionally, soil settlement exhibited hysteresis, as evidenced by a noticeable decrease in the removal rate in the 10th month of the remediation process, and the final mass removal rate was reduced by 5.93 %.