Search Results (175)

Both organic matter and iron oxide (FeO) dynamics pose key roles in soil cadmium (Cd) bioavailability. However, the microbially driven transformation of soil organic matter and FeO and their linkages to Cd fractions remain unclear under reductive soil disinfestation (RSD) with different organic sources, which limits our mechanistic understanding of Cd immobilization by RSD. To address this gap, we conducted a 45 day microcosm experiment using a paddy soil contaminated with 22.8 mg/kg Cd. Six treatments were established: untreated control (CK), waterlogged (WF), and RSD-amended soils with 0.7% or 2.1% wheat straw (LWD, HWD) or soybean meal (LSD, HSD). We systematically assessed soil Cd fractionation, organic carbon and FeO concentrations, and bacterial community structure, aiming to clarify differences in Cd immobilization efficiency and the underlying mechanisms between wheat straw and soybean meal. For strongly extractable Cd, wheat straw RSD reduced the soil Cd concentrations from 6.02 mg/kg to 4.32 mg/kg (28.2%), whereas soybean meal RSD achieved a maximum reduction to 2.26 mg/kg (62.5%). Additionally, the soil mobility factor of Cd decreased from 44.6% (CK) to 39.2% (HWD) and 32.5% (HSD), while the distribution index increased from 58.5% (CK) to 62.2% (HWD) and 66.8% (HSD). Notably, the HWD treatment increased soil total organic carbon, humus, and humic acid concentrations by 34.8%, 24.6%, and 28.3%, respectively. Regarding amorphous FeO, their concentrations increased by 19.1% and 33.3% relative to CK. RSD treatments significantly altered soil C/N ratios (5.91–12.5). The higher C/N ratios associated with wheat straw stimulated r-strategist bacteria (e.g., Firmicutes, Bacteroidetes), which promoted carbohydrate degradation and fermentation, thereby enhancing the accumulation of humic substances. In contrast, the lower C/N ratios of soybean meal increased dissolved organic carbon and activated iron-reducing bacteria (FeRB; e.g., Anaeromyxobacter, Clostridium), driving iron reduction and amorphous iron oxide formation. PLS-PM analysis confirmed that wheat straw RSD immobilized Cd primarily through humification, whereas soybean meal RSD relied on FeRB-mediated FeO amorphization. These findings suggest that Cd immobilization in soil under RSD may be regulated by microbially mediated organic matter transformation and iron oxide dynamics, which was affected by organic materials of different C/N ratios. Full article

Soil co-contamination with cadmium (Cd) and zinc (Zn) poses serious threats to environmental safety and public health. This study investigates the enhancement effect and underlying mechanism of the biodegradable chelator Ethylenediamine-N,N′-disuccinic acid (EDDS) on phytoremediation of Cd-Zn contaminated soil using Sedum lineare. The results demonstrate that EDDS application (3.65 g·L⁻¹) effectively alleviated metal-induced phytotoxicity by enhancing chlorophyll synthesis, activating antioxidant enzymes (catalase and dismutase), regulating S-nitrosoglutathione reductase activity, and promoting leaf protein synthesis, thereby improving photosynthetic performance and cellular integrity. The combined treatment significantly increased the bioavailability of Cd and Zn in soil, promoted their transformation into exchangeable fraction, and resulted in removal rates of 30.8% and 28.9%, respectively. EDDS also modified the interaction patterns between heavy metals and essential nutrients, particularly the competitive relationships through selective chelation between Cd/Zn and Fe/Mn during plant uptake. Soil health was substantially improved, as evidenced by reduced electrical conductivity, enhanced cation exchange capacity, and enriched beneficial microbial communities including Sphingomonadaceae. Based on the observed ion antagonism during metal uptake and translocation, this study proposes a novel “Nutrient Regulation Assisted Remediation” strategy to optimize heavy metal accumulation and improve remediation efficiency through rhizosphere nutrient management. These findings confirm the EDDS–S. lineare system as an efficient and sustainable solution for remediation of Cd–Zn co-contaminated soils. Full article

The antagonistic geochemical behaviors of cadmium (Cd) and arsenic (As) in co-contaminated soils complicate their simultaneous remediation. This study aimed to develop a synergistic immobilization strategy by converting Spirulina residue into a magnetic biochar-layered double hydroxide composite (FSRBL). The composite was applied to both acidic red and calcareous black soils, and its effects on Cd and As, immobilization efficiency, and ecotoxicity were evaluated. The results showed that FSRBL effectively transforms Cd and As from mobile fractions to stable residual forms. At a 2.5% application rate, FSRBL achieved remarkable immobilization efficiencies of 39.2% for Cd and 57.5% for As, representing effectiveness 3.55 and 5.97 times higher than that of unmodified biochar, respectively. A dose–response relationship between the application amount of FSRBL and the immobilization efficiency of As and Cd was observed and further quantified using a logistic model. The results indicate that while increased FSRBL application enhances immobilization efficiency, the marginal benefit of each additional unit diminishes as the application rate increases, demonstrating a significant diminishing marginal effect. According to the ecotoxicity assessment experiment, the soil leachate from FSRBL-amended soil remarkably decreased the ecological toxicity to rice (Oryza sativa L.). Mechanistic investigations employing SEM/TEM-EDS, XRD, and XPS revealed that the synergistic immobilization could be ascribed to the multi-component cooperation within FSRBL, which resolved the conflicting pH/Eh requirements for the immobilization of Cd and As: (1) the LDH phase efficiently immobilized As oxyanions through anion exchange and isomorphic substitution; (2) the magnetic Fe phase concurrently immobilized Cd²⁺ and As oxyanions via redox transformation and coprecipitation, resulting in the formation of precipitates such as Fe/Ca/Cd–As(V). This work demonstrates a feasible approach to upcycle biomass waste into a value-added material for sustainable remediation of Cd–As co-contaminated soil. Full article

The metallurgical industry generates substantial amounts of heavy metal-containing solid waste, posing significant environmental and health risks. This study systematically evaluates the environmental behavior and ecological risks of heavy metals in four typical metallurgical wastes: jarosite slag (SW1), electric arc furnace ash (SW2), chromium-containing sludge (SW3), and acid-base sludge (SW4). We demonstrate that particle size fundamentally governs heavy metal mobility, with fine-structured SW1 and SW2 (D₅₀ = 4.76 µm and 1.34 µm) exhibiting enhanced metal mobility and bioavailability. In contrast, coarser SW3 and SW4 particles (D₅₀ = 268.83 µm and 133.94 µm) retain heavy metals in more stable forms. Among all metals analyzed, cadmium (Cd) presents the most severe ecological threat, with acid-extractable fractions reaching 52% in SW2 and 45% in SW3—indicating high release potential under changing pH conditions. Risk assessment confirms high to very high ecological risks for Cd in both SW2 and SW3. Moreover, under acidic leaching conditions, SW1 and SW2 show significantly higher cumulative toxicity than SW3 and SW4. These findings highlight the critical role of waste-specific properties in controlling heavy metal fate and provide a scientific basis for targeted risk management and sustainable remediation strategies. Full article

Soil passivation conditioners effectively reduce cadmium (Cd) bioavailability and limit its accumulation in rice, though their efficacy and stability vary considerably among different types. A three-year paddy field study in southern China evaluated a calcium–silicon–magnesium composite (CSM) applied at 1500 and 3000 kg/ha (CSM1 and CSM2), with a no-CSM control (CK), on Cd behavior, soil properties, and functional groups. Results demonstrated a clear dose–response relationship, with CSM reducing brown rice Cd by 35−74% across sites (2021−2023). High-dose treatments achieved grain safety standards (0.183 mg/kg, p < 0.05). Soil pH increased annually by 0.2−0.37 units, while DTPA-extractable Cd decreased by 2.6−27% over three years. CSM application significantly transformed Cd speciation, reducing exchangeable Cd by 3% while increasing the iron–manganese oxide-bound fraction by 5%. Soil base saturation increased from 42.6% to 73.2% (HS) and 71% to 97.3% (XY). FTIR analysis revealed enhanced silicate polymerization, increased hydroxyl group abundance, and Si-O-Mg/Fe vibrations indicating a significant increase in Cd complexation in treated soil. The CSM passivator immobilizes Cd by elevating soil pH to promote its transformation into stable Fe-Mn-bound forms, enhancing hydroxyl and siloxane complexation with Cd, and synergizing with silicon–calcium ionic antagonism, collectively reducing Cd bioavailability while improving soil fertility through base saturation regulation. Full article

Trace metals and metalloids pose persistent threats to freshwater ecosystems, yet their trophic transfer and sublethal effects across food webs remain poorly understood. We investigated bioaccumulation patterns and biomarker responses in a predator–prey system comprising Prussian carp (Carassius gibelio) and Great Cormorant (Phalacrocorax carbo) nestlings from the Danube floodplain wetland Kopački rit Nature Park (Croatia) during 2023–2024. Concentrations of arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg) and lead (Pb) were determined in Prussian carp liver and in Great Cormorant whole blood. The activities of acetylcholinesterase (AChE), carboxylesterase (CES), glutathione S-transferase (GST) and the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) were measured in brain, muscle and gill tissues of Prussian carp, as well as in plasma and S9 blood fractions of Great Cormorants. In addition, tissue-specific metal concentration ratios (TSMCR) were calculated to assess the relative magnitude of recent dietary exposure in the predator compared to the prey. Biomarker activity showed strong tissue- and fraction-specific variation, with temporal differences. Exposure–response modelling revealed significant associations between As, Cd, and Hg and specific biomarkers, particularly in gill and plasma. Cross-species comparisons indicated elevated TSMCR as a proxy for recent trophic exposure only for Hg in 2023, whereas As and Se exhibited lower TSMCR. These findings demonstrate that metal exposure in floodplain systems induces physiological responses and Hg poses the greatest prey-to-predator exposure risk, highlighting the value of integrating pollutant measurements with mechanistic biomarker endpoints to evaluate ecosystem-level impacts. Full article

This study investigates the relationship between kidney function and exposure to low-level cadmium (Cd) and lead (Pb) in individuals with and without diabetes. Specifically, it tests the hypothesis that the nephrotoxicity of Cd and Pb reduces the tubular degradation of filtered proteins, namely β₂-microglobulin (β₂M). Data were obtained from a Thai cohort of 137 people, of which 65 were diagnosed with diabetes. Blood Cd, blood Pb, and urinary excretion of Cd (E_Cd) were used as exposure indicators, while urinary N-acetylglucosaminidase (E_NAG) and fractional tubular degradation of β₂M (FrTD_β2M) reflected kidney tubular cell injury and the function of tubular cells, respectively. Spearman’s rank correlation revealed that FrTD_β2M varied directly with the estimated glomerular filtration rate (eGFR; r = 0.434), and inversely with fasting plasma glucose (r = −0.215), E_Cd (r = −0.527), E_NAG (r = −0.536), and Cd/Pb exposure (r = −0.249). In a multiple regression model analysis adjusting for potential confounders, the association between FrTD_β2M and eGFR in those with diabetes was particularly strong (β = 0.476) compared to controls (β = 0.360), whereas an inverse association of FrTD_β2M and E_Cd (β = −0.295) was found only in those with diabetes, along with a positive association of E_NAG with E_Cd (R² = 0.071). A mediation analysis has revealed that tubular injury (E_NAG) mediated 26% of the FrTD_β2M decrease associated with Cd/Pb exposure. These findings suggested that tubular protein degradation pathways may be compromised under combined metabolic and environmental stressors, Cd, and Pb. Full article

Rice (Oryza sativa L.) exhibits a heightened ability to bioaccumulate arsenic (As) and cadmium (Cd), which directly affects the quality of agricultural products and poses serious risks to both the ecological environment and human health. Due to considerable differences in the occurrence states and chemical behaviors of As and Cd, simultaneous remediation efforts for water or soil contaminated by these elements often prove challenging. Our previous study indicated that the addition of both As and Cd markedly promoted the immobilization of each other by sulfidized nano-zero-valent iron (S-nZVI). To further explore the influence of S-nZVI on the passivation of As-Cd composite contamination, we examined its effect on the residual proportions of As and Cd in the soil by varying the dosage of S-nZVI, the soil moisture content and pH levels. At 2 g·kg⁻¹ S-nZVI over a 90-day period, residual fraction reached 83% for As and 39% for Cd. When the water content was 100%, residual fractions peaked at 83% for As and 29% for Cd. Additionally, variations in initial pH levels were found to have no significant impact on the remediation efficiency of As and Cd. This suggests that S-nZVI has the ability to sustain the stabilization of As and Cd in soil across diverse environmental conditions. The evident passivation effects on As-Cd composite contaminated soil can effectively reduce the potential ecological risk associated with these contaminants. Full article

The presence of heavy metals in soils poses a serious threat due to these harmful elements being transported into the food chain. The aim of the presented research was to evaluate the effect of the extraction of selected heavy metals from soil with a 1 M aqueous solution of citric acid (CA) on the chemical (including mobile) forms of these elements and their bioavailability. A soil sample taken in an industrial area was extracted. Then the total content of selected heavy metals (Pb, Zn, Cu, Cd, Ni), their chemical forms (determined by sequential extraction according to the BCR procedure) and bioavailable forms (determined by one-step extraction with a 1 M HCl) were determined in both types of soil, before and after extraction. The tested soil contained significant amounts of the tested metals, and the amounts can be compared as follows: Pb ≥ Zn > Cu ≥ Cd > Ni. The greatest threat to the environment is associated with the presence of cadmium and lead in the tested soil, the content of which exceeds the limits set for soils in industrial areas. In addition, the level of presence of heavy metals in bioavailable and mobile chemical forms, was considered significant. No clear correlation was observed between the content of the analyzed metals in mobile and bioavailable forms. The tested soil contained significant concentrations of Pb (2141 mg/kg), Zn (2030 mg/kg), Cu (68 mg/kg), Cd (63 mg/kg), and Ni (23 mg/kg), which were reduced to 857, 589, 42, 28, and 14 mg/kg, respectively, after extraction with 1 M CA. The extraction process with a CA solution reduced the content of all metals, and the efficiency of the process can be compared as follows: Zn > Pb > Cd > Ni ≥ Cu, with efficiencies of 71%, 60%, 55%, 41% and 39%, respectively. The extraction process reduced the metal content of all the bioavailable and chemical fractions. The shares of metals in the mobile fractions decreased in favor of the immobilized fractions and ones more stable in the environment. After the process of leaching metals from the soil, a clear tendency towards equalization of the heavy metal content in the mobile and bioavailable fractions was observed. Full article

A green synthesis method for iron nanoparticles was developed using the leaf extract of the invasive plant Spartina alterniflora (Sa-FeNPs), targeting the remediation of cadmium (Cd) in coastal sediments. The obtained Sa-FeNPs, characterized as amorphous Fe-O-C composites, significantly reduced the amount of bioavailable Cd. Specifically, Sa-FeNPs achieved a 34.63–38.39% decrease in the weak-acid-extractable fraction at a 7% application rate. The primary mechanisms underlying the adsorption and complexation of Cd are the large specific surface area of the Sa-FeNPs, their rich functional groups (-OH, -COOH, C=C, C-O), iron redox reactions, and total organic carbon (TOC) conversion. This study offers an environmentally friendly and low-cost remediation strategy for the utilization of excessive S. alterniflora biomass resources and controlling Cd pollution in coastal wetlands. Full article

The Elche palm grove (Spain) produces large surpluses of fresh date fruits due to low industrial processing and strict market standards. This exploratory study assessed the potential of these fruits as sustainable ingredients through the production of freeze-dried date flour and its green hydroethanolic extracts. Computer vision analysis of nine local cultivars (D1–D9) revealed broad chromatic and phenotypic diversity. Mineral and heavy metal analyses in the flour indicated high nutritional value and overall safety: D8 was richest in Mg (1.23 mg/g), P (0.78 mg/g), Fe (15.32 mg/kg), Zn (9.20 mg/kg), Cu (5.22 mg/kg), and Se (68 µg/kg), while D4 showed the highest K (22.1 mg/g) and D1 the highest Ca (1.94 mg/g). Lead and cadmium were highest in D8 and arsenic in D1, although all values remained within the regulatory limits. Hydroethanolic extracts exhibited remarkable compositional variability: D4 and D5 had the greatest carbohydrates (737.70 ± 55.79 mg/g DM), D8 and D9 the highest proteins (up to 40.31 ± 1.33 mg/g DM), and D2 and D8 the highest carotenoids (up to 36.44 ± 1.55 μg/g DM). D8 also showed the highest phenolics (13.98 ± 2.93 mg GAE/g DM) and antioxidant capacity. Cytotoxicity assays in Caco-2 cells showed no significant effects up to 1000 µg/mL. These preliminary findings suggest that green-extracted date fractions may combine nutritional richness, antioxidant potential, and biological safety, providing a basis for future studies on their application as natural and sustainable food ingredients. Full article

Cadmium (Cd) is a recognized environmental contaminant, present in soil, water, and food, which has been reported to cause male reproductive damage in vivo and vitro. Selenium-enriched rapeseed flowering stalks exhibit protective effects against Cd-induced reproductive damage, yet the bioactive components and underlying mechanisms remain unclear. We optimized the process of obtaining the crude extract (CE) via single-factor experiments. Subsequent bioassay-guided fractionation identified the water extract (WE) as significantly more effective in alleviating Cd-induced cytotoxicity compared to the petroleum ether extract, ethyl acetate extract, and n-butanol extract. High-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC-ICP-MS) analysis revealed that WE contained the highest contents of methylselenocysteine (MeSeCys) and selenocystine (SeCys₂) among four fractions. Both MeSeCys and SeCys₂ exhibited protective effects against Cd-induced cytotoxicity. To further elucidate the underlying mechanisms, network pharmacology, RNA-Seq, qPCR, and Western blotting analysis were employed. The results revealed that WE exhibited good free radical scavenging capabilities, and the protective mechanisms of WE, MeSeCys, and SeCys₂ against Cd-induced cytotoxicity were related to a reduction in oxidative damage, the inhibition of the ERK/p38 MAPK signaling pathway, and the suppression of cell cycle arrest, inflammation, and apoptosis triggered by Cd exposure. Collectively, these findings suggest that selenium-enriched rapeseed flowering stalks may serve as a promising dietary supplement in the prevention of Cd-induced reproductive toxicity. Full article

Soils in alpine mining areas suffer from severe heavy metal contamination and infertility, yet little is known about the effects of different materials on soil improvement in such regions. In this study, a field experiment was conducted in farmlands contaminated by the Lanping lead–zinc mine in Yunnan, China, to compare the effects of four materials (biochar, organic fertilizer, lime, and sepiolite) on soil properties, heavy metal (lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) fractions and their availability, and the growth of Phaseolus coccineus L. Results showed that biochar and organic fertilizer significantly enhanced soil nutrient content and enzyme activities. Lime, biochar, and sepiolite effectively reduced heavy metal bioavailability by promoting their transition to residual fractions. Notably, biochar outperformed other materials by substantially increasing grain yield (by 82%), improving nutritional quality (sugars, protein, and starch contents raised by 20–88%), and reducing heavy metal accumulation in grains (by 36–50%). A comprehensive evaluation based on subordinate function values confirmed biochar as the most effective amendment. Structural equation modeling further revealed that biochar promoted plant growth and grain quality primarily by enhancing soil available nutrients and immobilizing heavy metals. These findings demonstrate the strong potential of biochar for remediating heavy metal-contaminated farmlands in alpine lead–zinc mining regions. Full article

Anthropogenic activity seriously damages the environment. Cadmium, lead, and thallium are toxic elements that are especially hazardous for nature. In polluted air, they are present in the form of microparticles 2–3 μm in size and belong to the PM_2.5 fraction. Such particles can be transported over long distances, penetrate into water and dissolve, and then enter the food chain. This poses a severe threat to human and animal health due to the bioaccumulation of metals. Therefore, it is important to study the properties of toxic metals of this size. In this work, we developed a radiation–chemical method for obtaining microparticles of cadmium, lead, and thallium corresponding to the PM_2.5 fraction and studied their properties in aqueous solutions. In the absence of oxygen, the metals do not dissolve. Over time, they agglomerate and settle. When exposed to air, the particles quickly dissolve in water, usually within a few minutes. This process involves the disappearance of small particles and a decrease in the size of larger ones. The rate of dissolution increases in the Pb-Cd-Tl series. Cadmium dissolves approximately 4–5 times faster than lead, and thallium more than 10 times faster. Acidification of water accelerates this process. Studying the properties of microparticles of heavy metals is important for assessing their migration in the environment, health risks, and developing methods for preventing pollution. Full article

Bioavailable fractions of particulate-bound trace elements are key determinants of inhalation toxicity, yet air-quality assessments typically rely on total metal concentrations, which may underestimate health risks. This study integrates the exchangeable (F1) and reducible (F2) fractions of trace elements in fine (PM_2.5) and coarse (PM₁₀) particulate matter with multi-criteria decision-making (TOPSIS) and similarity-based classification (Czekanowski’s method). Archival weekly-integrated samples from the summer season were collected at eight industrially influenced sites in southern Poland. Sequential extraction (F1–F2) and ICP-MS were applied to quantify concentrations of cadmium, cobalt, chromium, nickel, and lead in PM_2.5 and PM₁₀. Aggregated hazard values were then derived with TOPSIS, and site similarity was explored using Czekanowski’s reordered distance matrices. Regulatory targets for cadmium and nickel, and the limit for lead in PM₁₀ were not exceeded, but F1/F2 profiles revealed pronounced site-to-site differences in potential mobility that were not evident from total concentrations. Rankings were consistent across size fractions, with site P₁ exhibiting the lowest hazard indices and P₈ the highest, while mid-rank sites formed reproducible similarity clusters. The proposed chemical-fractionation and multivariate framework provides a reproducible screening tool for multi-element exposure, complementing compliance checks and supporting prioritisation of sites for targeted investigation and environmental management. In the sustainability context, bioavailability-based indicators strengthen air-quality assessment by linking monitoring data with health-relevant and cost-effective management strategies, supporting efficient resource allocation and reducing exposure in vulnerable populations. Full article