Effects of magnetic hydroxyapatite loaded biochar on Cd removal and passivation in paddy soil and its accumulation in rice: a 2-year field study

Design and construction of magnetic nanomaterials and their remediation mechanisms for heavy metal contaminated soil

Soil heavy metal pollution poses huge threat to ecosystem and human health. In-situ chemical remediation aims to immobilize free heavy metals in soil through adding passivators, thereby greatly reducing the mobility and bioavailability of heavy metals. Magnetic nanomaterials (MaN) have strong adsorption and immobilization capabilities for heavy metals due to their significant surface effects, small size effects and interfacial effects. Compared with traditional remediation materials, MaN can be recovered and reused using external magnetic fields. These advantages give MaN broad application prospects in the field of soil remediation. This work provides a comprehensive review of the application of MaN in heavy metal contaminated soil, including the design and application effect of various types of MaN, the influence of MaN on soil properties, environmental toxicity, and microbial composition, the in-situ remediation mechanism of MaN on heavy metal contaminated soil. On the other hand, there are potential risks associated with the remediation of heavy metal contaminated soil using MaN, including their impact on the soil ecosystem and biosafety concerns, requiring further research. Finally, this review proposes the future prospects for the application of MaN in the remediation of heavy metal polluted soil.

Nano-biochar as a potential amendment for metal(loid) remediation: Implications for soil quality improvement and stress alleviation

Metal(loid) contamination of agricultural soils has become an alarming issue due to its detrimental impacts on soil health and global agricultural production. Therefore, environmentally sustainable and cost-effective solutions are urgently required for soil remediation. Biochar, particularly nano-biochar, exhibits superior and high-performance capabilities in the remediation of metal(loid)-contaminated soil, owing to its unique structure and large surface area. Current researches on nano-biochar mainly focus on safety design and property improvement, with limited information available regarding the impact of nano-biochar on soil ecosystems and crop defense mechanisms in metal(loid)-contaminated soils. In this review, we systematically summarized recent progress in the application of nano-biochar for remediation of metal(loid)-contaminated soil, with a focus on possible factors influencing metal(loid) uptake and translocation in soil-crop systems. Additionally, we conducted the potential/related mechanisms by which nano-biochar can mitigate the toxic impacts of metal(loid) on crop production and security. Furthermore, the application of nano-biochar in field trials and existing challenges were also outlined. Future studies should integrate agricultural sustainability and ecosystem health targets into biochar design/selection. This review highlighted the potential of nano-biochar as a promising soil amendment for enhancing the remediation of metal(loid)-contaminated agricultural soils, thereby promoting the synthesis and development of highly efficient nano-biochar towards achieving environmental sustainability.

A Comprehensive Evaluation System for the Stabilization Effect of Heavy Metal-Contaminated Soil Based on Analytic Hierarchy Process

Stabilization technology is widely used in the remediation of heavy metal-contaminated farmland soil. However, the evaluation method for the remediation effect is not satisfactory. To scientifically evaluate the remediation effect, this study constructed a comprehensive evaluation system by bibliometric analysis and an analytic hierarchy process (AHP). Ultimately, 16 indicators were selected from three aspects of the soil, crops, and amendment. The 16 indicators are divided into three groups, namely indicators I that can be evaluated according to the national standards of China, indicators II that can be evaluated according to the classification management of farmland and Indicators III that are the dynamic change indicators without an evaluation criterion. Comprehensive scores for 16 indicators were calculated using three response models, respectively. According to the difference between the scores before and after the remediation, the remediation effect is divided into five levels, which are excellent, good, qualified, poor, and very poor. This study provides a theoretical basis and insightful information for a farmland pollution remediation and a sustainable utilization.