Improvement of the phytoremediation efficiency of Neyraudia reynaudiana for lead-zinc mine-contaminated soil under the interactive effect of earthworms and EDTA

Abstract

Slow plant growth, low biomass, and low bioavailability of heavy metals in soil are important factors that limit remediation efficiencies. This study adopted a pot cultivation method to evaluate the phytoremediation efficiency of Neyraudia reynaudiana, planted in contaminated soil from a lead-zinc mining area. The soil was inoculated with earthworms (Eisenia fetida), and mixed with the chelating agent ethylenediaminetetraacetic acid (EDTA) one month after planting. The addition of earthworms significantly increased the aboveground biomass of N. reynaudiana and activated heavy metals in the soil, thus facilitating heavy metal uptake by N. reynaudiana. The addition of EDTA significantly increased the incorporation and transport of heavy metals, reduced the uptake of heavy metals by the plant cell wall, and increased the proportions of cellular soluble constituents. Especially with regard to lead, inoculation with earthworms and EDTA application significantly promoted the accumulation efficiency of N. reynaudiana, increasing it 7.1-16.9-fold compared to the control treatment without earthworms and EDTA, and 1.5-2.3-fold compared to a treatment that only used EDTA.

Improved Growth and Nutrition of Sorghum (Sorghum bicolor) Plants in a Low-Fertility Calcareous Soil Treated with Plant Growth–Promoting Rhizobacteria and Fe-EDTA

“…Regarding Cu concentration and content in plants, Fe-EDTA was significantly more effective than Fe-EDDHA. EDTA was shown to have a high binding constant for Cu, allowing its dissolution (Li et al 2018). Ghasemi-Fasaei et al (2005) reported that soil application of Fe-EDTA increased the content and concentration of Cu in chickpea significantly, whereas Abo-Rady et al (1987) found soil application of Fe-EDDHA had no significant effect on Cu concentration in the leaves of two different date varieties.…”

Chelate induced redistribution of Pb and Zn fractions in contaminated soils and implications on phytoremediation

“…2a). Li et al (2018) showed that after EDTA application, , the exchangeable Pb fraction increased significantly (17-90%) whereas the residual Pb fraction decreased (10-23%) suggesting that the complexation of EDTA and Pb is facilitated by Pb conversion from the residual fractions to exchangeable fractions, which then increased plant availability. In fact, the overall changes (sum of changes) in the Pb fractions (Exch, Carb, Oxide and Org) was around ±12.1% indicating mobilization/immobilization for a proportion of the residual Pb fraction but with no clear trend.…”

Heavy metal phytoremediation: Potential and advancement

“…Naturally occurring species such as aromatic plants and energy crops can grow in such contaminated sites that accumulate heavy metals very well. In order to enhance the metal uptake by plants, strategies such as the addition of chelating agents such as ethylenediaminetetraacetic acid (EDTA), ethylenediamine-N, N'-disuccinic acid (EDDS), humic substances have been successful (Luo et al, 2018).…”