Search Results (2,722)

The newly identified greisen-hosted Nb-Ta mineralization in the Qidashan iron deposit, Liaoning Province, China, offers a unique opportunity to explore how hydrothermal processes contribute to the enrichment of critical metals. In this study, an integrated analytical approach of petrographic observation and scanning electron microscopy–energy-dispersive spectrometer (SEM-EDS), electron probe microanalyzer (EPMA), and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) U-Pb dating of columbite-group minerals (CGMs) were employed to systematically decipher the paragenetic sequence, micro-structure, elemental composition and mineralization age of CGMs, aiming at the genesis of greisen-hosted Nb-Ta mineralization. The mineralization is characterized by the abundant occurrence of CGMs. Three generations of CGMs and two mineralization stages are distinguished: stage I contains CGM Is and CGM IIs, with Nb₂O₅ ranging from 25.7 to 69.56 wt.% and Ta₂O₅ from 5.8 to 52.5 wt.%; stage II contains CGM IIIs, with Nb₂O₅ between 59.5 and 71.5 wt.% and Ta₂O₅ between 3.5 and 16.2 wt.%. CGM Is consist of euhedral, homogeneous crystals of more than 100 μm, exhibit low Ta/(Nb + Ta) ratios (0.05–0.06) and high Mn/(Fe + Mn) ratios (0.19–0.26), and belong to columbite-Fe. CGM IIs generally overgrow on CGM Is with hydrothermal overprinting textures, and show significant compositional gaps compared to CGM Is, exhibiting higher Ta/(Nb + Ta) ratios (0.13–0.55) and restricted Mn/(Fe + Mn) ratios (0.15–0.18), with some belonging to columbite-Fe and others to tantalite-Fe, which reveals a transition from magma to “hydrosilicate fluid”. CGM IIIs are mainly anhedral and homogeneous, with a grain size of less than 50 μm. However, some CGM IIIs overgrow on CGM IIs and/or CGM Is with patchy textures indicative of subsequent hydrothermal overprinting of hydrosilicate fluid, forming a coarse-grain size over 100 μm. CGM IIIs are characterized by lower Ta/(Nb + Ta) ratios (0.03–0.14) and variable Mn/(Fe + Mn) ratios (0.08–0.26), and they belong to columbite-Fe. LA-ICP-MS U-Pb dating yields weighted mean ²⁰⁶Pb/²³⁸U ages of 2646 ± 15 Ma for stage I and 2500 ± 28 Ma for stage II, indicating two-stage Nb-Ta mineralization. The early mineralization may correlate with the partial melting of volcanic–sedimentary rocks due to the geothermal anomalies associated with ~2.7 Ga submarine volcanism, and the late mineralization formed by the magmatic hydrothermal activities related to emplacement of the Qidashan granite in 2.5 Ga. We therefore propose that the two-stage greisen-hosted Nb-Ta mineralization probably widely occurred in these sedimentary–metamorphic iron deposits in the Anshan–Benxi area and even in the northern edge of the North China Craton, and it may provide new insights for evaluating the Nb-Ta resource potential in similar Algoma-type iron deposits globally. Full article

Human activities inevitably affect natural ecosystems, the impact of which most often refers to negative factors resulting in the accumulation of toxic elements in environmental components. This study quantified the presence of 12 toxic elements (Cd, Co, Cr, Cu, Hg, Fe, Mn, Ni, Pb, Zn, As, and Se) in water, soil, and six melliferous plant species across the Republic of Croatia. Sampling sites were classified into four groups according to the dominant anthropogenic impact: agricultural areas, urban and traffic-affected zones, industrial vicinities, and forested hill regions. The results demonstrate the transfer of toxic elements from abiotic matrices into plants, indicating their potential as bioaccumulators. Soil contamination with toxic metals was identified as a relevant ecological risk factor, while contamination of melliferous plants highlights potential implications for human health through the production of honeybee-derived products. Element concentrations in water and soil were determined using three atomic absorption spectrometry techniques (FAAS, GFAAS, and CVAAS), whereas concentrations in floral samples of melliferous plants were measured using inductively coupled plasma mass spectrometry (ICP MS). The obtained results were interpreted in relation to natural background levels and the current national legislation. Anthropogenic impacts were further evaluated using environmental quality indices and bioaccumulation factors, revealing site-specific contamination patterns of both natural and anthropogenic origin. Full article

The Guanfang tungsten deposit in the Bozhushan ore district, southeastern Yunnan, is genetically linked to Late Yanshanian granitic intrusions. To elucidate the petrogenesis and mineralization potential of the causative granite, this study presents a detailed mineral chemical analysis of biotite from the Guanfang pluton using electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The biotite crystals exhibit relatively high euhedrality, show no obvious alteration features, and are chemically characterized by reduced Na and Ca contents. These features, along with petrographic observations, confirm its origin as primary magmatic biotite. Crystallization conditions, calculated from biotite chemistry, indicate temperatures of 700–720 °C and pressures of 1.22–1.73 kbar, corresponding to a mesozonal emplacement depth of 4.6–6.5 km. Oxygen fugacity estimates, plotting near the Ni-NiO buffer, reveal an oxidized magmatic environment. Geochemical discrimination diagrams suggest the Guanfang granite exhibits transitional features between S-type and I-type affinities and is classified as a syn-melting (high-temperature) type. The biotite contains relatively low F (0.71–0.97 wt%), but elevated Cl (0.13–0.20 wt%) and Sn (43–56 µg/g) contents. This specific geochemical signature—combined with the medium- to high-temperature crystallization setting—is highly favorable for W-Sn mineralization. Furthermore, the high-Ti, syn-melting character of the granite implies additional potential for Cu-Pb-Zn-Au-Ag polymetallic mineralization. This study employs biotite chemistry to assess the petrogenesis and metallogenic potential of the Guanfang granite. The subsequent discovery of industrial ore bodies corresponding to some of the elements identified as having metallogenic potential confirms the feasibility of this approach. Accordingly, this method provides a new tool for future exploration in the Bozhushan district. Full article

Inorganic lead (Pb) poses a significant public health concern due to its toxicity and widespread industrial use. Dermal contact, an under-researched pathway of Pb exposure relative to inhalation and ingestion, is typically not factored into regulatory exposure limits because of the paucity of validated studies. This study investigated the influence of sweat on the bioaccessibility of inorganic lead for dermal absorption. Dissolution testing was conducted to determine the dissolution kinetics of inorganic Pb (lead nitrate) in synthetic sweat relative to deionized water (DIW). Particle sizes of samples ranged from 0.70 µm to 118 µm. Non-linear dissolution kinetics were observed in both DIW (control) and sweat. The iPb ion concentration in DIW after 3 h (test period) accounted for 100% of the initial mass of iPb, compared to 67% of the initial mass of iPb in sweat. Higher variability was observed in sweat (SD: 1.47 to 8.2) compared to DIW (SD: 0.80 to 3.88). Precipitation was observed in sweat but not in DIW. Wilcoxon rank-sum test indicated a statistically significant difference in dissolution between sweat and deionized water (Z = −4.50, p < 0.0001). Findings suggest that sweat composition limits the extent of dissolution of soluble inorganic Pb, thereby influencing its dermal bioaccessibility. Full article

Heavy metals in agricultural systems pose a significant challenge to food security, especially in regions with long-term intensive land use. While the Pannonian Plain represents Croatia’s primary breadbasket, accounting for a significant portion of the nation’s cereal production, data on the soil-to-grain transfer of heavy metals and the associated human exposure risk are limited. The objective of this study was (i) to determine the concentrations of arsenic (As), cadmium (Cd), and lead (Pb) in agricultural soils and corresponding grains (wheat, barley, and maize) across four principal counties within the Pannonian region of Croatia; (ii) to evaluate the soil-to-grain transfer factors that varied regionally and among cereal types; and (iii) to assess the potential non-carcinogenic health risks for both adults and children highlighting differences in exposure due to body weight and consumption patterns. Soil and cereal grain samples were collected in 2019 and 2020, and metal concentrations were determined by ICP-MS after microwave acid digestion. The transfer of metals from soil to grain was estimated using the transfer factor (TF), while exposure assessment was conducted by calculating the estimated daily intake (EDI), hazard quotient (HQ), and hazard index (HI). Due to the nonlinear distribution of the data and the lack of strictly matched soil and grain samples, median metal concentrations pooled across all studied regions were used for exposure assessment. For As, a conservative approach was applied, assuming that 50% of the total As is in inorganic form. Additionally, a probabilistic risk assessment using Monte Carlo simulations was conducted to account for variability in body weight and cereal intake, providing a more comprehensive evaluation of potential exposure. The results showed differences in metal accumulation among cereal species, with wheat and barley tending to accumulate more Cd than maize, while As and Pb concentrations in grains were low for all crops studied. Although soil metal concentrations in Međimurje County were generally low, elevated TF values for As and Pb were observed, indicating enhanced soil-to-plant transfer under specific local soil conditions. In contrast, high soil metal concentrations in Slavonski Brod–Posavina County were associated with low TF values, suggesting limited bioavailability and restricted transfer to cereal grains. Both deterministic and probabilistic assessments indicated that the HQ and HI for adults and children were below 1, suggesting low non-carcinogenic risk from cereal consumption. These findings highlight pronounced regional and crop-specific differences in soil-to-plant metal transfer and confirm that low soil contamination does not necessarily imply low transfer potential, emphasizing the importance of integrated soil–plant–grain monitoring for food safety assessment. Full article

Groundwater in Al-Madinah Al-Munawwarah faces considerable challenges from high salinity, elevated TDS, and nitrate contamination, primarily due to urbanization and industrial activities, making ongoing monitoring and management essential for its sustainable use in both drinking water and agriculture. The assessment of groundwater quality was conducted on 44 wells tapping two major aquifers (basaltic and alluvial) in the region, utilizing various geochemical techniques, including ICP-MS, FAAS, and XRF, to evaluate hydrochemical characteristics and identify the primary controlling factors. Key physicochemical parameters, including total dissolved solids (TDSs), electrical conductivity (EC), pH, total hardness (TH), and major ion concentrations, were evaluated. The results indicate that several parameters exceed permissible limits established by Gulf and international standards, reflecting highly saline conditions that could adversely affect drinking water safety and agricultural practices. Elevated nitrate levels and other contaminants indicate a combination of geological processes, including mineral leaching, and anthropogenic activities, such as agricultural runoff. Correlations among various ions reveal complex interactions driven by both natural and human factors. High nitrate and potassium concentrations, particularly in the alluvial aquifer, combined with weak correlations with geogenic ions, indicate anthropogenic inputs. Heavy metals in groundwater were classified into two groups: those within permissible limits (Ag, Ba, Be, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sb, and U) and those exceeding recommended limits (Zn, Al, As, Se, and Tl). Elevated metal concentrations are primarily attributed to water–rock interactions and the fertilizer use in surrounding agricultural areas. These findings highlight the urgent need for continuous monitoring and proactive groundwater to ensure sustainable and safe use of water resources. Full article

The recurrent influx of pelagic Sargassum spp. along Caribbean coastlines poses a significant environmental challenge while offering potential as a resource-recovery agricultural input. However, agricultural reuse of Sargassum biomass raises concerns regarding salinity and trace-metal distribution within the soil–plant–food continuum. This study evaluated the short-term elemental response to a Sargassum-Based Liquid Biofertilizer (SBLB) produced via controlled anaerobic fermentation, using tomato (Solanum lycopersicum L.) grown under greenhouse conditions. Raw biomass, fermented biofertilizer, irrigation water, soils, vegetative tissues, and fruits were chemically characterized. Elemental concentrations were quantified by ICP–OES and ICP-MS and treatment effects were analyzed using one-way and two-way ANOVA (p < 0.05). Anaerobic fermentation resulted in lower measured concentrations of sodium, arsenic, and selected trace elements in the liquid fraction relative to raw biomass. SBLB application increased soil macronutrient availability (N, P, K, Ca, Mg), while soil trace-metal concentrations remained within international reference ranges during the experimental period. Metals of concern (As, Cd, Pb, Ni, Cr) showed no detectable short-term enrichment in soils, vegetative tissues, or fruits relative to controls. In tomato fruits, arsenic, cadmium, and lead were below the limit of quantification across all treatments. Within the experimental timeframe, SBLB application was not associated with detectable trace-element accumulation in the soil–plant system. Long-term field studies and detailed soil physicochemical characterization are required to evaluate cumulative effects under repeated applications. Full article

Thallium (Tl) contamination of soils in lead-zinc mining areas poses potential ecological risks, and the impact of microplastics on Tl accumulation by hyperaccumulator plants remains unclear. This study examined soils collected from the Daliangzi lead-zinc mining area to investigate the characteristics of Tl contamination. These soil samples were used in plant cultivation experiments. The thallium contents in both the soil and plant samples were determined using acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS). The contamination level, plant enrichment capacity, and ecological risk were then comprehensively evaluated through the Geo-accumulation index (I_geo), Bioconcentration factor (BCF), and potential ecological risk index. The results indicated that the I_geo of Tl in the soil was 2.413, corresponding to a moderately to heavily polluted level, which necessitates focused attention. Polyethylene exhibited markedly opposing effects on Pteris vittata and Solanum nigrum: it significantly promoted Tl accumulation in the former, while distinctly inhibiting it in the latter. Microplastics could modify the pH value of soil, as well as the contents of nitrogen (N) and phosphorus (P). Risk assessment indices indicated that Tl pollution in this region reaches a very high contamination level with moderate potential ecological risk. Polyethylene and polypropylene demonstrated a species-specific promoting effect on Tl adsorption by the two hyperaccumulator plants, with polyethylene significantly enhancing the Tl accumulation capacity of P. vittata and polypropylene distinctly promoting Tl adsorption in S. nigrum. Full article

Chronic exposure to heavy metals poses significant health risks. This study analyzed the concentrations of toxic (Cr, Pb, Cd, Ni) and essential (Cu, Zn, Se, Mn) elements in autopsy samples (the frontal pole area of the brain, the 6th intercostal space of the liver, and lungs (average of left and right lung samples) from 45 residents of South-Eastern Poland using ICP-MS. The aim was to determine the average body burden and organ-specific accumulation in a moderately industrialized region. HDBSCAN clustering revealed highly homogeneous elemental profiles, suggesting a unifying influence of local environmental factors. The liver acted as a metabolic hub, showing preferential sequestration (p < 0.0001) of essential elements (Zn, Se, Mn, Cu) regulated by homeostatic mechanisms. Toxic metals exhibited ‘metabolic trap’ patterns, particularly Cd and Pb in the liver and Cr in the lungs, due to their long biological half-lives. Strong positive correlations (Se–Zn, Se–Cu) indicated integrated antioxidant responses, while toxic pairs (Cr–Ni, Pb–Cd) suggested shared exposure pathways and molecular mimicry via transporters such as DMT1. Results confirmed long-term bioaccumulation, with toxic elements in the brain remaining below 0.25 µg/g. In the lungs, the accumulation hierarchy (Pb > Mn > Cd > Cr) reflected inhalation exposure. These findings emphasize the role of organ-specific sequestration in assessing long-term environmental exposure. Full article

The elemental composition of the vitreous humor may reflect physiological and pathological processes occurring in the eye. The objective of this study was to provide a complex multielemental analysis of human vitreous humor. Vitreous humor samples (n = 57) were collected post-mortem during autopsies. Inductively coupled plasma mass spectrometry (ICP-MS) was employed to quantify micro-, trace-, ultra-trace, and toxic elements. The study showed the occurrence of elements at the ppm (Na, K, P, Ca, Mg), ppb (Al, Rb, Zn, Fe, Sr, Cu), and ppt (Ce, La, Nd, Tb) levels. Hierarchical clustering using Ward’s method and k-means analysis revealed four distinct clusters, including two major clusters representing the baseline macro- and microelement profile characteristic for the studied population. Correlations between elements revealed statistically significant (p < 0.05) positive and negative correlations between elements with (I) chemical similarity Ce-La, Cs-Rb, Rb-K, Ca-P, Zn-Cu, and Cs-K; (II) a possible common environmental origin, Cd-P, and Rb-P; (III) involvement in similar biological processes as K-P; and (iv) a common geochemical origin and similar biological functions, i.e., Se-Zn. The study identified several quantitative trends in the demographic and medical characteristics of the participants. Alcohol users had significantly higher Zn concentrations than non-alcohol users; women had significantly higher Ca concentrations than men; higher BMI correlated positively with Cs and negatively with Be and Cr levels; and Cu, Sb, Cd, Se, and Ca concentrations increased with age. The presence of several toxic and potentially toxic elements was identified in the vitreous body: Al (>10 ppb); Cd, Cr, Pb, Ni, Mn; and Ba (<10 ppb); As, Hg, Sb, Tl, Bi, Be (<1 ppb). The study showed that, within a given geographic region, the accumulation profiles of toxic metals are quite homogeneous, indicating common sources of exposure. Full article

Mercury (Hg) is of significant concern due to its toxicity, which strongly depends on its chemical forms, and organic mercury compounds, particularly methylmercury (MeHg), are considered the most toxic species. Therefore, mercury speciation analysis is essential for accurate exposure and risk assessment. The primary dietary source of mercury exposure for humans is food consumption, particularly seafood. Consequently, numerous studies have focused on developing analytical techniques for the identification, characterization, and quantification of Hg species in seafood. This review evaluates and compares recent developments (2014–2025) in analytical techniques for the identification and quantification of Hg species in seafood, focusing on both traditional chromatographic methods and emerging methodologies based on biosensors. Hyphenated techniques such as HPLC–ICP-MS and GC–ICP-MS have enabled significant advancements in mercury speciation analysis. Although chromatographic methods are highly effective and widely accepted due to their accuracy and sensitivity, they often require costly instrumentation, skilled operators, and lengthy analysis times. Biosensors are increasingly proposed as alternatives; however, their applicability to seafood analysis remains limited despite advantages such as portability, simplicity, and rapid response. They are still under development and face challenges in selectivity, stability, and standardization. This review provides an overview of existing methodologies, comparing their advantages and limitations, aiming to guide improvements toward optimal methods incorporating all advantageous features. Full article

Magnetite is extensively developed within various alteration zones of the mining district. Some magnetite is closely associated with copper mineralization, possessing significant research value. The Duobuza Cu (Au) deposit is a typical porphyry-type deposit within the Bangong Co-Nujiang metallogenic belt and was the first porphyry Cu-Au deposit discovered in the Duolong copper–gold ore district. Currently, this deposit contains copper resources exceeding 3 million tons @0.46%, with associated gold resources exceeding 80 tons @0.19 g/t. This study focuses on magnetite from the Duobuza deposit. Through field geological logging and microscopic identification combined with electron microprobe analysis (EMPA) and in situ LA-ICP-MS testing, mineralogical and mineral chemical research on magnetite is conducted. This research aims to elucidate the genesis of magnetite in the Duobuza deposit and its implications for mineral exploration. Five magnetite types with different occurrences can be distinguished in the Duobuza deposit: Mt₁ is magmatic magnetite; Mt₂, Mt₃, Mt₄, and Mt₅ are hydrothermal magnetite, with Mt₅ being closely associated with copper mineralization. Mt₁ is relatively enriched in Ti, V, Al, and Cr but depleted in Mn and Si; Mt₂ is relatively enriched in Ti and Al but depleted in Si and Cr; Mt₃ is relatively enriched in Al but depleted in Mg; Mt₄ is relatively enriched in Ti, Al, V, Zn, and Mn; and Mt₅ is relatively enriched in Mg, Si, Ti, Al, Mn, and Zn but depleted in Cr. Based on the Al + Mn vs. Ti + V discrimination diagram, magnetite formed in a medium- to high-temperature environment, with hydrothermal magnetite Mt₄ forming at the lowest temperature. Vanadium (V) content can be used to estimate the oxygen fugacity (fO₂) during mineralization. Mt₁ exhibits the highest V content, indicating relatively low oxygen fugacity, whereas Mt₄ shows the lowest V content, suggesting relatively high oxygen fugacity. Mt₅ has a higher V content compared to other early-stage hydrothermal magnetites, suggesting that a lower fO₂ formation environment favors the precipitation of metal sulfides in the mining district. Trace element analysis of magnetite from the Duobuza, Bolong, and Naruo mining districts reveals that magnetite from all three deposits is enriched in Si and Al and depleted in Ca and Ni. Magmatic magnetite from the Naruo and Duobuza deposits exhibits similar elemental distribution patterns. Hydrothermal magnetite from the Duobuza deposit shows significantly higher Ti and V contents compared to magnetite from the Bolong and Naruo deposits. Full article

In recent years, an ion-adsorption type REE deposit has been discovered for the first time in the weathering crust of epimetamorphic rocks in Ningdu County, Jiangxi Province, which provides a new idea for the exploration of ion-adsorption-type REE deposits. However, most previous studies on the ore-forming parent rocks of ion-adsorption-type REE deposits have focused on granites and volcanic rocks, while studies on epimetamorphic rocks remain extremely scarce. In this paper, petrographic analysis of epimetamorphic rocks, LA-ICP-MS U–Pb dating and trace element analysis of zircon and apatite were conducted on the metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, so as to constrain the formation age and tectonic dynamic setting of the rock mass, investigate the petrogenesis and material source of the rock mass, and reveal the metallogenic potential of the rock mass. The results of zircon and apatite U–Pb dating show that the protolith of the metamorphic tuff from the Kuli Formation formed at ca. 770 Ma, representing a product of mid-Neoproterozoic magmatic activity. The protolith restoration of metamorphic rocks suggests that the protolith of the metamorphic tuff from the Kuli Formation is magmatic rock. The estimated results of zircon Ti thermometry indicate that the magmatic crystallization temperature ranges from 623 to 723 °C, with an average value of approximately 696 °C, and the calculated zircon oxygen fugacity values vary from −18.7 to −9.4, with an average of −13.8, implying that the rock formed under conditions of relatively low temperature and high oxygen fugacity. The correlation diagrams of trace elements and element ratios in zircon and apatite reveal that the magmatic evolution involved extensive fractional crystallization of minerals such as zircon, monazite, apatite, titanite, rutile, and plagioclase during the formation of the rock mass. The discrimination diagrams of trace elements in zircon and apatite demonstrate that the metamorphic tuff from the Kuli Formation was formed in a continental margin arc or arc-related orogenic belt, and the magmatic source is characterized by crust–mantle mixing. Combined with previous research findings on regional tectonic-magmatic activities, it can be concluded that the metamorphic tuff from the Kuli Formation was formed in a tectonic setting of back-arc extension and intra-arc rifting caused by the rollback of the subducting oceanic slab. The upwelling of the asthenospheric mantle induced the partial melting of arc-derived sediments in the continental crust, which was subsequently mixed with mantle-derived magma, ultimately generating the parent magma of the metamorphic tuff. The metamorphic tuff from the Kuli Formation in Ningdu County, Jiangxi Province, has high REE abundance and relatively easily weathered REE mineral assemblages, which can provide sufficient material sources for ion-adsorption REE mineralization and have a great metallogenic potential for ion-adsorption REE deposits. Full article

Loading dissolved organic matter (DOM) onto iron–manganese oxides (FeMnOx) was a promising strategy for enhancing the hexavalent chromium (Cr(VI)) removal from wastewater. To optimize this process and gain deeper mechanistic insight, this study systematically investigated the DOM loading characteristics onto FeMnOx and its subsequent effect on Cr(VI) adsorption. DOM loading onto FeMnOx was significantly affected by the initial concentration of DOM and pH, with optimal loading conditions identified as a DOM concentration of 75 mg/L, pH of 4, ionic strength of 0.005 mol/L, temperature of 50 °C, and contact time of 4 h. During loading, FeMnOx preferentially adsorbed low-molecular-weight/low-aromaticity components such as tryptophan-like (C1) and fulvic acid-like (C2) substances. The adsorption process followed a non-uniform monolayer surface adsorption and involved multiple stages dominated by chemical interactions. DOM coating on FeMnOx significantly enhanced the Cr(VI) removal, and the maximum adsorption capacity under optimal loading conditions increased from 18.46 mg/g to 23.26 mg/g. Characterization by SEM-EDS, BET, ICP-MS, XPS, FTIR, and CV revealed that a moderate DOM loading (55–75 mg/L) enhanced the material’s surface reducibility and mesoporous structure. This improvement was attributed to the reduction of surface Mn(IV) to more-reactive Mn(III) by reductive functional groups in DOM, thereby promoting Cr(VI) adsorption and reduction. In contrast, excessive DOM loading (105 mg/L) formed a dense organic layer that masked active sites and hindered electron transfer, ultimately compromising the long-term reductive capability. These findings elucidate the concentration-dependent regulatory role of DOM in modifying FeMnOx properties, providing a theoretical foundation for the rational design of efficient DOM–metal oxide composites for heavy metal remediation in aquatic environments. Full article

Bioretention systems are increasingly implemented as green infrastructure for urban stormwater management. However, their long-term performance is jeopardized by the continuous accumulation of potentially toxic metals in substrates and vegetation, posing significant risks to ecosystem health and human safety. Despite their growing application, the mechanisms driving metal dynamics and plant responses within these systems remain poorly understood. This study conducts a comprehensive multi-factor investigation into the accumulation, mobility, and biological impacts of four representative potentially toxic metals (Cd, Cu, Zn, and Pb) in bioretention soils and vegetation. Through controlled mesocosm experiments, we quantified metal concentrations in soils and three plant species, analyzed alterations in the physical and chemical properties of soil, and assessed plant physiological stress responses. Metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS), and statistical analyses were conducted using one-way ANOVA (p < 0.05). Cadmium exhibited the highest enrichment, with plant uptake increasing by 330.0% to 563.2%, especially in Iris tectorum Maxim., which demonstrated superior phytoaccumulation potential. Conversely, Ophiopogon japonicus Ker Gawl. showed remarkable tolerance to metal-induced stress, maintaining stable levels of chlorophyll content, photosynthetic rate, peroxidase activity, and soluble sugar concentration. Notably, the incorporation of humic substances significantly enhanced metal immobilization in soil, while simultaneously reducing plant uptake and physiological stress, revealing a promising strategy for toxicity mitigation. By integrating the effects of plant species, substrate composition, and influent concentration, this study provides novel insights into the complex interactions governing pollutant fate in bioretention systems. The findings offer critical guidance for optimizing bioretention design and management to ensure sustained pollutant removal efficiency and ecological resilience in urban stormwater treatment. Full article