Sequential Application of Column Leaching and Plant Uptake Tests to Assess the Effect of Various Commercial Amendments on Cu Immobilization in Ultra-High Cu-Contaminated Soil

The presence of copper (Cu)-contaminated soil has increased recently due to agricultural and industrial activities. Immobilization techniques using soil amendments have attracted significant research because of their cost-effectiveness, eco-friendliness, and community acceptance. This study used various commercial amendments, including magnetite (M), talc (T), activated carbon (AC), and cornstarch (CS), to immobilize Cu in soil contaminated by acidic waste materials with Cu in Korea (9546 ± 5 mg/kg). To evaluate the immobilizing effect of these amendments, this study applied a sequential process of column leaching and plant uptake tests to observe the ability of Cu to remain in soil with and without amendments through the Cu removal rate. The amendments were characterized by SEM, XRD, and specific surface area and applied to the soil at a rate of 2% (w/w). The first stage of evaluation, i.e., the column leaching test, was conducted by continuously pumping distilled water (DW) for 28 days, and the second stage of evaluation, i.e., the plant uptake test, was started immediately after by planting 10-day-old lettuce seedlings for 28 days. The experimental results showed that all of the amendments had a significant effect on Cu immobilization Cu in soil (p < 0.05), and the T treatment showed the highest efficiency in Cu immobilization, with only 47.0% Cu loss compared to 73.5% in the control soil when assessed by sequential column leaching and plant uptake tests. In conclusion, this study provides an effective assessment method to evaluate the effect of amendments on Cu immobilization in soil, as well as providing feasible options to immobilize Cu using commercial amendments.