Despite the immense potential in environmental remediation, the translation of magnetic nanomaterials (MNMs) from laboratory innovations to practical, field-scale applications remains hindered by significant technical and environmental challenges. This is particularly evident in soil environments—which are inherently more complex than aquatic systems and have received comparatively less research attention. Beginning with an outline of the fundamental properties that make iron-based MNMs effective as adsorbents and catalysts for heavy metals and organic pollutants, this review systematically examines their core contaminant removal mechanisms. These include adsorption, catalytic degradation (e.g., via Fenton-like reactions), and magnetic recovery. However, the practical implementation of MNMs is constrained by several key limitations, such as particle agglomeration, oxidative instability, and reduced efficacy in multi-pollutant systems. More critically, major uncertainties persist regarding their long-term environmental fate and biocompatibility. In light of these challenges, we propose that future efforts should prioritize the rational design of stable, selective, and intelligent MNMs through advanced surface engineering and interdisciplinary collaboration.

Metal pollution in soils is an issue of global concern, and lead (Pb) pollution is considered to be the most serious type. The arid and semi-arid areas of Northwest China are rich in Pb ore resources. In this study, four native crops [wormwood (Artemisia capillaris), dandelion (Taraxacum mongolicum), alfalfa (Medicago sativa), and plantain (Plantago asiatica L.)] that grow naturally around tailings slag in a mining area in Northwest China were selected to screen their ecological restoration impacts on Pb-contaminated soil. In pot experiments, four different metal lead pollution gradients (0, 2, 3, and 5‰ w/w) were set, and crop growth indexes such as plant height, root length, and biomass, together with the changes of soil Pb content in different tissues and organs before and after planting were analyzed. The results showed the difference in the amount of accumulated Pb in relation to the level of Pb content in the soil. It was found that wormwood and plantain have great potential as remediation plants for soil metal lead pollution in the arid and semi-arid lead bearing mining areas of Northwest China.

Mercury (Hg) and arsenic (As) are toxic and harmful heavy metals, with exceedance rates of 1.6% and 2.7%, respectively, in soils across China. Compared to soils contaminated with Hg or As alone, co-contaminated soils pose complex environmental risks and are difficult to remediate. Biochar is widely used as a soil amendment to adsorb and immobilize pollutants such as heavy metals. However, only a few studies have explored the efficiency of biochars produced from different crop straws to reduce the bioavailability of heavy metals in co-contaminated soils, and the effects on soil biological properties are often overlooked. The aim of this study was to investigate changes to the physicochemical properties, enzyme activities, and heavy metal bioavailability of an industrial soil co-contaminated with Hg and As upon the addition of different biochars from reed, cassava, and rice straws (REB, CAB, and RIB, respectively). The soil was amended with 1% biochar and planted with spinach in pots for 30 days. RIB was more effective than REB and CAB in increasing the soil pH, organic matter content, and cation exchange capacity. RIB and CAB exhibited similar positive effects on the soil dehydrogenase, catalase, invertase, and urease activities, which were higher than those of REB. The exchangeable fraction of both metals decreased upon biochar addition, and the residual fraction showed the opposite trend. All biochar amendments reduced the bioconcentration factors of heavy metals (especially Hg) in plants and decreased the metal bioavailability in soil. RIB is the optimal amendment for the stabilization of soil co-contaminated with Hg and As.

Heavy metal pollution in soils is an issue of global concern, and many scholars have focused on Cadmium (Cd) because of its strong biological migration and toxicity. This study explored arable land soil, changes in external Cd contamination processes and its response to soil moisture conditions, and indoor simulation. After adding an external source of 5 mg/kg d.w., the distribution of soil Cd fractions content, EXC-Cd, CAB-Cd, FMO-Cd, OM-Cd, and RES-Cd, were continuously monitored under different water management regimes, and correlation analysis and regression equations were calculated. The results show that after external Cd entered arable land soils, the binging strength of pollutants and soil gradually increased with incubation time, and the distribution of Cd chemical forms was more stable under different water management regimes. The oversaturated water content promotes the transformation of EXC-Cd to other forms. The transformation of CAB-Cd fractions can be accelerated to other fractions by field capacity, and the active conversion period was 30–60 d. Not all Cd fractions correlated between each other, under the four water management regimes, but it seems that the reducibility of the soil environment was more conducive to external Cd fixation and stability. The response surface design method (RSM) was used to establish quantitative regimes between Cd fractions with incubation time and soil moisture, and the soil moisture content and incubation time had an obvious effect on FMO-Cd content, with R² = 0.9542.

To assess the environmental quality of the topsoil (0-20 cm) in an industrial and mining wasteland lacated in a town in northern Shaanxi Province, Shenmu City, over 60 soil samples were collected and analyzed for the presence of heavy metals, including chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb). The degree of heavy metal contamination in the land was assessed using the Land Accumulative Index (LAI) and the Potential Ecological Hazard Index (PERI) methods. The correlation between the heavy metals was also analyzed. The study revealed that the mean levels of Cr, Ni, Cu, Zn, As, Cd, and Pb in the topsoil (0-20 cm) of industrial and mining waste areas were 42.6, 19.7, 19.7, 47.7, 8.6, 0.10, and 21.3 mg/kg, respectively. These levels were found to be lower than the screening values for soil pollution risk on agricultural land. The topsoil in the study area exhibited no enrichment in Cr, Ni, Cu, Zn, and As, with pollution levels limited to mild for these elements. However, Pb exhibited mild pollution levels. Cd posed the risk of potential ecological hazards ranging from mild to very strong in some sample sites, yet the combined potential ecological risks were deemed small. Additionally, there were highly significant positive correlations (p<0.01) between the levels of Cr and Ni and Cu and Zn, while As exhibited significant homology.