Mehrab Narges, Chorom Mostafa, Norouzi Masir Mojtaba, Biswas Jayanta Kumar, Fernandes de Souza Marcella, Meers Erik
Department of Soil Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
J Environ Health Sci Eng. 2023 Jun 7;21(2):319-332. doi: 10.1007/s40201-023-00857-y. eCollection 2023 Dec.
The aim of this study was to evaluate the effectiveness of nitrilotriacetic acid (NTA) on cadmium (Cd) fractions and microbial biomass in a calcareous soil spiked with Cd under cultivated ( L.) and uncultivated regime subject to soil leaching condition. Expanding investigations related to soil-plant interactions on metal-contaminated soils with insights on microbial activity and associated soil toxicity perspective provides novel perspectives on using metal-chelating agents for soil remediation.
The experimental factors were three levels of Cd contamination (0, 25, and 50 mg kg soil) and three levels of NTA (0, 15, and 30 mmol L) in loamy soil under maize-cultured and non-cultured conditions. During the experiment, the adding NTA and leaching processes were performed three times.
The results showed that the amount of leached Cd decreased in cultivated soil compared to uncultivated soil due to partial uptake of soluble Cd by plant roots and changes in Cd fractions in soil, so that Cd leached in CdNTA was 9.2 and 6.1 mg L, respectively, in uncultivated and cultivated soils. Also, Cd leached in CdNTA was 5.7 and 3.1 mg L respectively, in uncultivated and cultivated soils. The best treatment in terms of chemical and microbial characteristics of the soil with the high percentage of Cd removed from the soil was CdNTA in cultivated soil. In CdNTA compared to CdNTA in cultivated soil, pH (0.25 unit), microbial biomass carbon (MBC, 65.0 mg kg), and soil respiration (27.5 mg C-CO kg 24 h) decreased, while metabolic quotient (qCO, 0.05) and dissolved organic carbon (DOC, 20.0 mg L) increased. Moreover, the changes of Cd fractions in CdNTA in cultivated soil compared to uncultivated soil were as follows; the exchangeable Cd (F, 0.27 mg kg) and Fe/Mn-oxide-bounded Cd (F, 0.15 mg kg) fractions increased, in contrast, carbonate-Cd (F, 2.67 mg kg) and, organically bounded Cd (F, 0.06 mg kg) fractions decreased. NTA had no significant effect on the residual fraction (F).
The use of NTA, especially in calcareous soils, where most of the Cd is bound to calcium carbonate, was able to successfully convert insoluble fractions of Cd into soluble forms and increase the removal efficiency of Cd in the phytoremediation method. NTA is a non-toxic chelating agent to improve the accumulation of Cd in maize.
本研究旨在评估次氮基三乙酸（NTA）对在培养（玉米）和未培养状态下添加镉的石灰性土壤中镉组分及微生物生物量的影响，该土壤处于土壤淋溶条件。对金属污染土壤上土壤 - 植物相互作用展开更多研究，深入了解微生物活性及相关土壤毒性，为利用金属螯合剂进行土壤修复提供了新视角。
实验因素为壤土中镉污染的三个水平（0、25和50 mg/kg土壤）以及NTA的三个水平（0、15和30 mmol/L），实验设置玉米培养和未培养条件。实验期间，NTA添加和淋溶过程进行了三次。
结果表明，由于植物根系对可溶性镉的部分吸收以及土壤中镉组分的变化，与未培养土壤相比，培养土壤中淋溶出的镉量减少，因此在未培养和培养土壤中，CdNTA中淋溶出的镉分别为9.2和6.1 mg/L。同样，在未培养和培养土壤中，CdNTA中淋溶出的镉分别为5.7和3.1 mg/L。从土壤中去除镉百分比来看，在土壤化学和微生物特性方面最佳的处理是培养土壤中的CdNTA。与培养土壤中的CdNTA相比，CdNTA中pH值（降低0.25个单位）、微生物生物量碳（MBC，65.0 mg/kg）和土壤呼吸（27.5 mg C-CO₂/kg·24 h）降低，而代谢商（qCO₂，0.05）和溶解有机碳（DOC，20.0 mg/L）增加。此外，与未培养土壤相比，培养土壤中CdNTA中镉组分的变化如下：可交换态镉（F₁，0.27 mg/kg）和铁/锰氧化物结合态镉（F₃，0.15 mg/kg）组分增加，相反，碳酸盐结合态镉（F₂，2.67 mg/kg）和有机结合态镉（F₄，0.06 mg/kg）组分减少。NTA对残留态组分（F₅）无显著影响。
使用NTA，特别是在石灰性土壤中，其中大部分镉与碳酸钙结合，能够成功地将不溶性镉组分转化为可溶性形式，并提高植物修复方法中镉的去除效率。NTA是一种无毒螯合剂，可提高玉米中镉的积累。
