Effects of Simultaneous Application of Double Chelating Agents to Pb-Contaminated Soil on the Phytoremediation Efficiency of Indocalamus decorus Q. H. Dai and the Soil Environment

Abstract

Recent studies have shown that the combined application of ethylenediaminetetraacetic acid (EDTA) and degradable chelating agents can enhance EDTA’s affinity for heavy metals and reduce its toxicity, but the effect of this combination on the phytoremediation remains largely unknown. This study evaluated and compared the effects of EDTA, nitrilotriacetic acid (NTA), and glutamic acid-N,N-diacetic acid (GLDA) alone (E, N, G treatment), and in combination (EN and EG treatment), on the growth of dwarf bamboo (Indocalamus decorus Q. H. Dai), their phytoremediation efficiency, and the soil environment in Pb-contaminated soil. The results showed that treatment E significantly reduced the biomass, while treatments N and EN were more conducive to the distribution of aerial plant biomass. Except for treatment E, the total Pb accumulation in all treatments increased significantly, with the highest increase in treatment EN. For double chelating agents, the acid-soluble Pb concentrations in rhizosphere and non-rhizosphere soils of treatments EN and EG were lower than those of treatment E, and the soil water-soluble Pb content after 20 days of treatment EN was significantly lower than that of treatment EG. Furthermore, chelating agents generally increased soil-enzyme activity in rhizosphere soil, indicating that chelating agents may promote plant heavy-metal uptake by changing the rhizosphere environment. In conclusion, treatment EN had the highest phytoremediation efficiency and significantly lower environmental risk than treatments E and EG, highlighting its massive potential for application in phytoremediation of Pb-contaminated soil when combined with I. decorus.