Effects of nitrogen regulation on heavy metal phytoextraction efficiency (Leucaena leucocephala): Application of a nitrogen fertilizer and a fungal agent

• Published in: Environmental pollution (1987) Vol. 355; p. 124102
• Main Authors: Liu, Chao, Liu, Jiayi, Mei, Xiaoli, Zheng, Jiaxin, Zheng, Kang, Li, Ou, Chio, Chonlong, Khatiwada, Janak, Zhang, Xiaoxia, Wang, Dong, Hu, Haibo, Qin, Wensheng, Zhuang, Jiayao
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.08.2024
• Subjects: Leucaena leucocephala; Metal-tolerant fungus; Phytoremediation; Soil microbial community; Soil nitrogen; Soil microbial community; Metal-tolerant fungus; Leucaena leucocephala; Phytoremediation; Soil nitrogen
• ISSN: 0269-7491; 1873-6424; 1873-6424
• DOI: 10.1016/j.envpol.2024.124102

Lead (Pb) and cadmium (Cd) have been identified as the primary contaminants in soil, posing potential health threats. This study aimed to examine the effects of applying a nitrogen fertilizer and a fungal agent Trichoderma harzianum J2 (nitrogen alone, fungi alone, and combined use) on the phytoremediation of soils co-contaminated with Pb and Cd. The growth of Leucaena leucocephala was monitored in the seedling, differentiation, and maturity stages to fully comprehend the remediation mechanisms. In the maturity stage, the biomass of L. leucocephala significantly increased by 18% and 29% under nitrogen-alone (NCK+) and fungal agent-alone treatments (J2), respectively, compared with the control in contaminated soil (CK+). The remediation factors of Pb and Cd with NCK+ treatment significantly increased by 50% and 125%, respectively, while those with J2 treatment increased by 73% and 145%, respectively. The partial least squares path model suggested that the nitrogen-related soil properties were prominent factors affecting phytoextraction compared with biotic factors (microbial diversity and plant growth). This model explained 2.56 of the variation in Cd concentration under J2 treatment, and 2.97 and 2.82 of the variation in Pb concentration under NCK+ and J2 treatments, respectively. The redundancy analysis showed that the samples under NCK+ and J2 treatments were clustered similarly in all growth stages. Also, Chytridiomycota, Mucoromucota, and Ciliophora were the key bioindicators for coping with heavy metals. Overall, a similar remediation mechanism allowed T. harzianum J2 to replace the nitrogen fertilizer to avoid secondary pollution. In addition, their combined use further increased the remediation efficiency. [Display omitted] •Trichoderma harzianum J2 exhibited plant-promoted and Pb–Cd-enriched traits.•Inoculation increased BF, TF, and RF in Leucaena leucocephala, particularly for Pb.•Inoculation regulated nitrogen cycling and improved microbial community structure.•Soil nitrogen properties were key drivers for the removal of Pb and Cd.•Bio-fertilizer J2 could replace nitrogen fertilizers for Pb–Cd remediation.