Influence of commercial amendments on Cu and Zn mobility, phytoavailability, and microbial activities on two contaminated soils

Abstract

Adding cost-effective amendments and their composites is generally considered a feasible technique to remediate heavy metals-contaminated soils. Hence, the effects of four cost-effective amendments (i.e., bentonite (B), talc (T), activated carbon (AC), cornstarch (CS)) and their composites (BAC, BCS, TAC, and TCS) were simultaneously investigated, at an application rate of 2 wt%, on the immobilization and phytoavailability of Cu and Zn as well as soil microbial communities for two contaminated soils (i.e., natural soil - NS and artificial soil - AS). For this, a pot experiment with lettuce was conducted for 45 days with and without amending. Physicochemical and biological properties of soil (e.g., pH, CEC, TCLP-extracted Cu and Zn in soil, soil respiration, and microbial activities) and plants (e.g., bioconcentration factor, plant growth, and biomass) were monitored before and after amending. Experimental results showed that composites amendments significantly (p < 0.05) reduced extractable Cu and Zn in both soil NS and AS, e.g., BAC, and BCS. Plant growth parameters were induced after amending soils, especially in BAC. Furthermore, amending soils with TCS, BCS, and TAC showed a development in the microbial community for both contaminated soils. Results demonstrated that adding a composite of cost-effective amendments effectively immobilized heavy metals and induced plant growth parameters and microbial diversity.