A Critical Review of the Effectiveness of Biochar Coupled with Arbuscular Mycorrhizal Fungi in Soil Cadmium Immobilization

Abstract

Cadmium-contaminated soil significantly threatens global food security and human health. This scenario gives rise to significant worries regarding widespread environmental pollution. Biochar and arbuscular mycorrhizal fungi (AMF) can effectively immobilize cadmium in the soil in an environmentally friendly way. Existing studies have separately focused on the feasibility of each in remediating polluted soil. However, their association during the remediation of cadmium-polluted soils remains unclear. This review paper aims to elucidate the potential of biochar, in conjunction with AMF, as a strategy to remediate soil contaminated with cadmium. This paper comprehensively analyzes the current understanding of the processes in cadmium immobilization in the soil environment by examining the synergistic interactions between biochar and AMF. Key factors influencing the efficacy of this approach, such as biochar properties, AMF species, and soil conditions, are discussed. The influences of biochar-AMF interactions on plant growth, nutrient uptake, and overall ecosystem health in cadmium-contaminated environments are highlighted. This review indicates that combining biochar and AMF can improve cadmium immobilization. The presence of AMF in the soil can create numerous binding sites on biochar for cadmium ions, effectively immobilizing them in the soil. Insights from this review contribute to a deeper understanding of sustainable and eco-friendly approaches to remediate cadmium-contaminated soils, offering potential applications in agriculture and environmental management.

Keywords: cadmium; contamination; environment; health; remediation; soil.

Figure 1

Environmental pollutants in China were assessed in 2014. The acronyms PAHs, DDT and BHC indicate polycyclic aromatic hydrocarbons, dichlorodiphenyltrichloroethane, and benzene hexachloride, respectively.

Figure 2

Effect of biochar on cadmium migration and transformation. The labels of CEC represent cation exchange capacity.

Figure 3

Effects of AMF on the migration and transformation of cadmium. The label of GRSP represents glomalin-related soil protein.

Figure 4

Mechanisms of biochar combined with AMF on the migration and transformation of cadmium.

Figure 5

The significance of the characteristics associated with each experimental factor. The letter ‘S’ at the beginning represents the soil index, while the letter ‘B’ indicates the biochar index. ‘AN’ stands for available nitrogen, ‘AP’ for available phosphorus, TP for total phosphorus and ‘TN’ for total nitrogen. ‘B type’ denotes the type of biochar, ‘dose’ refers to the addition amount, and ‘species’ represents the various plant species. ‘P species’ signifies the plant type, and ‘OM’ stands for soil organic matter.