Improving the Phytoextraction Efficiency of Artemisia ordosica Krasch. in Cadmium Contaminated Soil by Use of Tetrasodium N,N-bis(carboxymethyl) Glutamic Acid and Modified Coal Gasification Slag

The novelty and environmental benefits of phytoextraction have attracted considerable attention. However, the main limitation of phytoextraction is low efficiency because of slow growth rate and low plant biomass. In order to enhance the phytoextraction efficiency of Artemisia ordosica Krasch. in cadmium (Cd) contaminated soil, a low-cost and high-efficiency coal-gasification-slag-supported extract-of-municipal-sludge (EMS) composite (CES) was prepared. The effects of CES and N,N-bis(carboxymethyl) glutamic acid (GLDA) on Cd uptake by Artemisia ordosica Krasch. were investigated through pot experiments. In the process, amendment characteristics, soil nutrients and pH, the fraction distribution of water-stable aggregates, and the effect of root exudates were studied. The result indicated that the combined use of CES and GLDA could stimulate obviously plant growth and the formation of macroaggregates. After 90 days, Cd content in soil decreased by 30% through phytoextraction with the assistance of CES and GLDA. The FTIR analyses suggested that the active groups (such as -OH, -COOH, and -NH2) from CES could combine with Cd, and the combining effect could be enhanced by GLDA. Furthermore, root exudates were helpful to the formation of the chelate-uptake-release cycle, and Cd was continuously moved from soil to plant under the cycle. Therefore, the combined use of CES and GLDA improves both Cd bioavailability in soil and Cd uptake by the Artemisia ordosica Krasch., thus providing an effective governance strategy to promote Cd removal from contaminated soils through phytoextraction.

Automated summary

The use of a coal-gasification-slag-supported extract-of-municipal-sludge composite (CES) and N,N-bis(carboxymethyl) glutamic acid (GLDA) can significantly enhance the phytoextraction efficiency of Artemisia ordosica Krasch. in cadmium-contaminated soil. It regulates soil nutrients and pH levels, promotes plant growth and macroaggregate formation, and improves the uptake of Cd by the plant.