The efficacy and environmental effects of using metal-organic frameworks (MOFs) for the remediation of arsenic (As)-contaminated soil, a significant global problem, remain unclear. This study evaluated MIL-88A(Fe) and MIL101(Fe) coupled with ramie (Boehmeria nivea L.) for As-contaminated soil remediation. A soil incubation experiment revealed that 10,000 mg kg-1 MIL-88A(Fe) and MIL-101(Fe) reduced As bioavailability by 77.1 % and 65.0 %, respectively, and increased residual As fractions by 8 % and 7 % through Fe-As co-precipitation and adsorption. Divergent environmental effects emerged, which were probably due to differences in the framework structures and organic ligands: MIL-88A(Fe) improved soil urease activity and bacterial diversity, whereas MIL101(Fe) induced acidification (decreasing soil pH by 25 %) and salinity stress (elevating soil electrical conductivity (EC) by 946 %). A pot experiment showed that 1000 mg kg-1 MOFs enhanced ramie biomass via As immobilization, whereas 5000 mg kg-1 MIL-101(Fe) suppressed growth because exposure to the MOF caused root damage. The MOFs enriched Pseudomonas (As-oxidizing) and suppressed Dokdonella (pathogenic), enhancing plant resilience. Notably, 100 mg kg-1 MIL-101(Fe) increased As translocation to stems (14.8 %) and leaves (27.6 %). Hydroponic analyses showed that 50-200 mg L-1 MIL-101(Fe) mitigated As-induced chlorophyll degradation (elevating Soil and plant analyzer development (SPAD) by 12.8 %-28.3 %), whereas 500 and 1000 mg L-1 induced oxidative stress (reducing SPAD by 4.2 %-10.7 %). This study provides valuable insights into using Fe-based MOFs in soil remediation and highlights their beneficial and harmful effects.

Long-term exposure to Cd through contaminated food can lead to multiple adverse health effects on humans. Although previous studies have covered global food Cd concentrations and dietary Cd exposures across different populations, there are increasing concerns regarding the adequacy of current food Cd safety standards to protect populations from adverse health effects. Moreover, incorporation of Cd relative bioavailability (Cd-RBA) in foods improves the accuracy of health risk assessment. However, factors influencing food Cd-RBA have not been systematically discussed, thereby hindering its application in risk assessment. This review aims to provide an overview of Cd contents in foods, discuss concerns regarding international food Cd concentration standards, explore factors influencing food Cd bioavailability, and highlight the opportunities and challenges in refining differences between dietary Cd intakes and body burdens. Our findings suggest that current safety standards may be insufficient to protect human health, as they primarily focus on kidney damage as the protective endpoint and fail to account for global and regional variations in food consumption patterns and temporal changes in dietary habits over time. Factors such as crop cultivars and food compositions greatly influence food Cd-RBA. To improve the accuracy of Cd health risk assessment, future studies should incorporate food Cd-RBA, sociodemographic characteristics, nutritional status, and incidental Cd exposure. This review highlights new insights into food Cd safety standards and Cd bioavailability, identifies critical knowledge gaps, and offers recommendations for refining health risk assessments. This information is essential to inform future bioavailability investigations, health risk assessment, and safety standard development.

Paddy soils undergo wet-dry cycles that greatly influence the behaviour and availability of nutrients, but also of potentially toxic elements (PTEs). This study assessed the quality of paddy soils (actively cultivated and abandoned) and rice (white, brown, and wild) produced in the Baixo Vouga Lagunar (BVL) region, central-north Portugal. Surface soils were analysed for physicochemical parameters and chemical compositions, alongside sequential selective chemical extraction to evaluate metal(loid) availability. Chemical analyses were also performed on interstitial- and irrigation waters, and rice grains. The BVL soils are very strongly to moderately acidic (pH = 4.4-5.8), with organic matter contents reaching up to 34%, and exhibit a wide range of electrical conductivity values. Abandoned rice fields generally show higher values of these parameters and evidence of saline water intrusion. Several sites showed As, Cu, Pb, and U concentrations exceeding Portuguese thresholds for agricultural soils. While Cu levels were similar in both cultivated and abandoned fields, the latter had higher contents of As, Pb, and U. A geogenic origin is envisaged for these metal(loid)s, though anthropogenic contributions cannot be excluded. Sequential selective chemical extraction showed that Pb and U are strongly associated with available fractions, whereas amorphous Fe-oxyhydroxides primarily support As and Cu. Nevertheless, porewaters and irrigation waters showed low concentrations of these PTEs, suggesting minimal mobilisation to water. Furthermore, translocation to rice grains was low, with concentrations well below European Commission limits, indicating that elevated PTEs in soils do not necessarily lead to toxic levels in rice, providing reassurance regarding food safety.

Iron (Fe) deficiency is a critical constraint on global food security, particularly affecting high-value horticultural crops such as strawberries (Fragaria x ananassa). This study examines the roles of melatonin and hydrogen sulfide (H2S) signaling in mitigating Fe deficiency stress by improving Fe bioavailability and enhancing plant resilience. Strawberry plants were cultivated under Fe-sufficient and Fe-deficient conditions and treated with 100 mu M melatonin and 3 mM dl-propargylglycine (PAG), an inhibitor of L-cysteine desulfhydrase (L-DES), which regulates H2S production. Fe deficiency significantly reduced chlorophyll content and photosynthetic efficiency while elevating oxidative stress markers such as hydrogen peroxide (H2O2), malondialdehyde (MDA), and electrolyte leakage (EL). Melatonin application alleviated Fe deficiency effects by enhancing Fe utilization, stimulating L-DES activity, and promoting H2S production. Melatonin also improved antioxidant defenses by boosting the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as maintaining ascorbate-glutathione (AsA-GSH) redox dynamics. The addition of 3 mM PAG inhibited L-DES activity, resulting in reduced H2S levels and diminished melatonin-induced benefits, underscoring the essential role of L-DES-mediated H2S synthesis. Despite the presence of PAG, the co-application of 0.2 mM sodium hydrosulfide (NaHS) and melatonin restored Fe bioavailability, growth, and antioxidant capacity, suggesting a synergistic interaction between melatonin and H2S. This study highlights the potential of melatonin and H2S signaling to improve Fe homeostasis and mitigate oxidative stress in Fe-deficient plants. The findings offer strategies to enhance crop resilience and productivity in nutrient-deficient soils, thereby promoting sustainable agriculture and global food security.

Globally, humans face gut microbiota dysbiosis; however, its impact on the bioavailability of cadmium (Cd) and arsenic (As) from rice consumption-a major source of human exposure to these metals-remains unclear. In this study, we compared Cd and As accumulation in the liver and kidneys of mice with disrupted gut microbiota (administered cefoperazone sodium), restored microbiota (administered probiotics and prebiotics following antibiotic exposure), and normal microbiota, all after consuming cocontaminated rice. Compared to normal mice, microbiota-disrupted mice exhibited 30.9-119% and 30.0-100% (p < 0.05) higher Cd and As levels in tissues after a 3 week exposure period. The increased Cd and As bioavailability was not due to changes in the duodenal expression of Cd-related transporters or As speciation biotransformation in the intestine. Instead, it was primarily attributed to a damaged mucus layer and depleted tight junctions associated with gut dysbiosis, which increased intestinal permeability. These mechanisms were confirmed by observing 34.3-74.3% and 25.0-75.0% (p < 0.05) lower Cd and As levels in the tissues of microbiota-restored mice with rebuilt intestinal barrier functions. This study enhances our understanding of the increased risk of dietary metal(loid) exposure in individuals with gut microbiota dysbiosis due to impaired intestinal barrier functions.

AimTo examine the effect of active aluminum (Al) on copper(II) (Cu(II)) bioavailability in an acidic Cu-contaminated soil and uptake of Cu(II) by Chinese cabbage.MethodsA pot trial was conducted with Ca(OH)2 and peanut straw biochar (PB) to investigate Cu(II) uptake by Chinese cabbage. DGT (CDGT-Cu) and CaCl2 extraction methods (CCaCl2-Cu) were used to determine soil available Cu(II) and BCR sequential-extraction was used to determine Cu(II) species in the soil.ResultsThe amelioration of soil acidity with Ca(OH)2 and PB increased soil pH, promoted Chinese cabbage growth, and decreased Cu(II) uptake by plant shoots/roots. There were highly significant positive linear correlations between CDGT-Cu, CCaCl2-Cu and Cu(II) uptake by plant shoots. CDGT-Cu showed a better predictive effect for Cu(II) uptake by plant roots with a greater correlation coefficient (R2 = 0.9756). Thus, the DGT method was more effective in predicting Cu(II) uptake by plants. With increasing soil pH, Cu-HOAc and Cu-Reducible were converted to Cu-Residual, resulting in a decrease in soil Cu(II) bioavailability. The results of Structural Equation Modeling analyses showed that Al uptake by Chinese cabbage had a promoting effect on Cu(II) uptake by the plant, mainly through affecting plant growth indirectly. Soil exchangeable Al inhibited root growth (root length, root dry weight), reduced root resistance of Chinese cabbage and indirectly increased Cu(II) uptake.ConclusionsReducing Al toxicity decreased root damage and Cu(II) uptake by plant, improving the edible quality of Chinese cabbage. When remediating acidic Cu-contaminated soils, more attentions should be payed to mitigating and regulating Al toxicity.

PurposeDeveloping a practical strategy for both remediating and utilizing Cd-contaminated soils is important, particularly in areas with limited soil resources. Here, Erigeron breviscapus, a plant material used for extracting scutellarin, was selected for a pot experiment to evaluate utilization and remediation potential of heavily Cd-contaminated soil. MethodsWe established five treatments, comprising a no-Cd added control (CK) and 0.01% Cd addition with four amounts of lime (0, 5, 15 and 20 gkg-1 for CdL0, CdL5, CdL15 and CdL20, respectively). Systematic analysis of E. breviscapus physiological and biochemical characteristics, Cd-accumulation capacity, and active ingredients content were performed to thoroughly assess the application effectiveness and ecological restoration potential of lime in managing heavily Cd-contaminated soils. ResultsCompared with CdL0, lime application (CdL5, CdL15 and CdL20) reduced soil available Cd and plant shoot-Cd concentrations by 19.2-29.4% and 29.3-36.3%, respectively, due to decreased bioconcentration factor. Soil-Cd concentrations after harvesting E. breviscapus was decreased by 11.8-31.7% with lime application compared with that before cultivation. In the CdL0 treatment, biomass and scutellarin content of E. breviscapus decreased compared to those of the CK. However, plant biomass and scutellarin content increased with CdL15 and CdL20 compared to CdL0. Structural equation modeling indicated that lime application reduced plant Cd uptake via regulating soil-Cd speciation, thereby alleviating damage caused by Cd to photosynthesis, antioxidant system, and Mg acquisition, ultimately increasing biomass and scutellarin content of E. breviscapus. ConclusionsIn summary, growing E. breviscapus after lime application is a feasible method for remediating and utilizing heavily Cd-contaminated soil.

Potential health risks of contaminated media linked to bioavailability and hematotoxicity of uranium-238 (U-238) and thorium-232 (Th-232) remain uncertain. This study investigates the relative bioavailability (RBA), histopathological, and hematological effects of acute oral exposure to U-238 and Th-232 in co-contaminated concrete dust using 174 female Sprague Dawley (SD) rats. In order to create a range of U-238 and Th-232 concentrations, concrete was spiked with uranyl and thorium nitrates (similar to 50, 100, and 200 mg kg(-1)). Spiked concretes were then crushed, ground, sieved (<= 75 mu m), and blended uniformly to create co-contaminated concrete dust. SD rats' diet pellet was amended with co-contaminated concrete dust and orally ingested over a 48-h exposure period. The RBA values of U-238 and Th-232 in blood samples from rats' post-exposure were determined as 22.0% +/- 0.86% to 30.8% +/- 1.01% and 11.8% +/- 0.14% to 13.7% +/- 0.29%, respectively. Compared to Th-232, U-238 blood levels of SD rats fed with co-contaminated concrete dust-amended diets were similar to 100-fold higher due to solubility differences, and U-238-RBA values were approximately 2-fold greater, revealing that their absorption rates in the gastrointestinal tract were affected by compound solubility. Post-acute U-238 and Th-232 ingestion from co-contaminated concrete dust demonstrate noticeable histopathological and hematological alterations, implying that intake of U-238 and Th-232 in co-contaminated concrete dust can lead to erythrocytes damage and elevated hematological attributes. Our study would be beneficial for an adequate understanding of the health implications caused by the acute oral exposures of U-238 and Th-232 in co-contaminated concrete dust, especially in the bioavailability and toxicity assessment.

This study aims to explore the effects of biochar ageing on its surface properties and the bioavailability of heavy metals in soil. The biochar was subjected to chemical oxidation/dry-wet cycles (CDWs), chemical oxidation/freeze-thaw cycles (CFTs), and natural ageing (NT) to analyze changes in the elemental composition, pH, specific surface area, pore volume, and surface functional groups. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were applied to characterize the functional groups and microstructure, and the BCR sequential extraction method was employed to demonstrate the fractionation distribution of Cu, Cd, and Pb. The results showed that the CDWs and CFTs treatments significantly reduced the carbon content of the biochar (with a maximum reduction to 47.70%), increased the oxygen content (up to 49.17%), and notably increased the specific surface area and pore volume. The pH decreased significantly from 9.91 to 4.92 and 4.99 for the CDWs and the CFTs, respectively. The FTIR analysis indicated notable changes in hydroxyl and carboxyl functional groups, and the SEM revealed severe microstructural damage in biochar after the CDWs and CFTs treatments. The heavy metal fractionation analysis indicated that exchangeable Cu, Cd, and Pb significantly increased after the CDWs treatment, reaching 31.40%, 5.25%, and 6.79%, respectively. In conclusion, biochar ageing significantly affects its physicochemical properties and increases the bioavailability of heavy metals, raising concerns about its long-term remediation effectiveness.

Mining activities are among the main sources of heavy metal contamination in the environment. The damage caused to land by mining has become an increasingly important problem in some countries. A pot experiment was conducted to evaluate the effects of two application rates (1% and 5% w/w) of rice straw biochars, as prepared at 420 degree celsius and 640 degree celsius(B1420 and B640), and several inorganic amendments (pumice, leca, zeolite and bentonite) on Cd and Pb bioavailability and speciation in soil and their accumulation in maize (Zea mays L.) as an indicator plant. Furthermore, the amelioration effects of the applied amendments on the potential environmental risk of the heavy metals were assessed. The amendments resulted in a considerable reduction of the Cd and Pb contents in the shoots, which was by 28.83-70.72% and 21.78-64.02%, respectively, as compared to the control. Amendments also decreased the DTPA-extractable Pb and Cd in the soil, particularly at the 5% application rate, as compared to those in the un-amended soil. Furthermore, in comparison to the control, the transfer factors of heavy metals were reduced when the amendments were applied. Amendments also decreased the exchangeable portion of Cd and Pb by 10.43-52.11% and by 6.43-55.43%, respectively; most of these were converted into oxides and more stable forms exhibiting the lower risk assessment code (RAC) and the potential ecological risk index (PERI). These results indicate that zeolite and BI420 have a high potential to decrease the uptake of Cd and Pb in the shoots and roots of maize, respectively. Biochar and zeolite, as cost-effective and safe adsorbents, performed the best in immobilizing Pb and Cd in the studied calcareous soil.