The integration of molecular colorimetric sensors with smartphone-assisted image analysis and machine learning has emerged as a next-generation sensing paradigm for environmental diagnostics. Herein, we report an artificial intelligence (AI)-integrated chemosensing platform based on a norbornene-appended rhodamine derivative (RhB-NBE) for the sequential monitoring of Fe[3+] and arsenic species [As(V)/As(III))] in aqueous media. The probe was synthesized through a Schiff base condensation reaction and fully characterized using NMR, X-ray, and other spectroscopic techniques. RhB-NBE exhibited highly selective and instantaneous recognition of Fe[3+] over competing metal ions, including Fe[2+], through a spirolactam ring-opening mechanism that generated a discrete colorimetric response. The resulting RhB-NBE + Fe[3+] ensemble served as a secondary sensing platform for arsenite and arsenate via a cation-displacement process, producing a visible color transition from pink to colorless with a low detection limit of 2 nM (below the World Health Organization critical limit). Practical applicability was demonstrated using portable paper-based sensing strips, and successful quantification of arsenic species in environmental water samples with excellent recovery values. Despite the rapid advancement of AI-assisted chemical sensing, integration of machine learning with colorimetric arsenic detection remains largely unexplored due to challenges in sensor reproducibility, image standardization, and reliable concentration classification. Herein, we combine a selective colorimetric chemosensor with AI-based image analytics for rapid field monitoring. Smartphone images were analyzed using GNB, SVM, and CNN models trained on 1000 RGB datasets; SVM achieved 97.0% accuracy for equipment-free arsenic screening.

The increasing resistance of the yellow fever mosquito, Aedes aegypti, to conventional larvicides underscores the critical need for novel vector control strategies. This work investigates the intrinsic larvicidal activity of free-thiol derivatives (3-mercaptopropionic acid (MPA) and cysteamine (CA)) and evaluates how their specific functional groups (carboxylic acid and amine) govern molecular interactions within the larval digestive system. The free MPA and CA compounds exhibited remarkable larvicidal efficacy against fourth-instar (L4) larvae, presenting LC50 values of 18.34 ± 0.68 mg L[-1] and 8.26 ± 0.58 mg L[-1], respectively. Ingestion assays revealed that spatial nanoprobe distribution is strictly regulated by the larval intestinal pH gradient and ligand pKa. While negatively charged CdTe-MPA maintained broad colloidal stability across the midgut, CdTe-CA underwent charge neutralization in the alkaline central midgut, triggering localized colloidal deposition at neutral-to-acidic boundaries. Both probes showed strong affinity for chitinous structures, compromising gut homeostasis. This study provides mechanistic proof of concept that surface-charge tailoring can exploit vector physiology for targeted pest control.

Shale gas activities can release trace elements and naturally occurring radionuclides into aquatic environments, yet the long-term impact of low-intensity contamination events remains poorly constrained. This study investigates a localized geochemical anomaly observed in river sediments collected in 2021 near a documented shale-gas-related spill and waste disposal area in the Kennebecasis River watershed. Sediment cores and associated porewaters were collected to assess the distribution, potential sources, and mobility of uranium (U), barium (Ba), and radium-226 ([226]Ra). Results reveal localized enrichment of U and Ba near the disposal site. Elemental and radionuclide activity ratios ([238]U/[226]Ra, Th/U, Ba/Ca, and [226]Ra/Ca), together with contaminant spatial distributions, are consistent with an anthropogenic source potentially associated with shale-gas-related waste disposal. Early diagenetic processes appear to promote contaminant release into porewaters, whereas transfer to the overlying water column remains limited. Distribution coefficients (Kd) and diffusive flux estimates suggest greater mobility of uranium relative to radium. Present-day diffusive flux estimates indicate limited contaminant removal by molecular diffusion. Assuming that current concentration gradients remained broadly stable through time, diffusion would account for only a few percent of the current contaminant inventory, generally less than 8%, over a 15-year period. This estimate should be regarded as a conceptual scenario rather than a reconstruction of actual attenuation history. These results highlight the value of sediment geochemistry and radionuclide tracers for identifying localized environmental anomalies potentially associated with shale-gas-related activities. Future work should include sediment dating and direct characterization of buried waste materials and associated leachates to strengthen source attribution and constrain links with the documented 2006 event.

Understanding phosphate (PO4[3-]) transport during anaerobic treatment is essential for improving nutrient removal from municipal landfill leachate. This study tested the hypothesis that the Generalized Fulazzaky (GF) equations can quantitatively distinguish external, internal, and global mass-transfer processes and identify the dominant rate-controlling resistance governing PO4[3-] removal in anaerobic systems. A laboratory-scale up-flow anaerobic sludge blanket (UASB) reactor equipped with a gas-liquid-solid separator was operated under mesophilic conditions (38 °C) for 197 d to treat municipal landfill leachate. During the initial operating stage, PO4[3-] removal was limited because the anaerobic sludge (ANS) was still acclimating and granule development was incomplete. As the biomass matured and the influent PO4[3-] concentration increased from 5.02 to 10.93 mg L[-1], the removal efficiency improved from 25.25% to 57.79%. Linear GF analysis showed an excellent fit (R[2] = 0.9929), enabling determination of the β and B parameters for kinetic simulation. The global mass-transfer factor closely followed the internal mass-transfer factor, whereas the external mass-transfer factor remained consistently lower, indicating that external mass-transfer resistance governed overall PO4[3-] removal under the investigated conditions. Analysis of the C/N/P ratio further demonstrated the coupling between nutrient availability, ANS development, and phosphate transport. These findings provide new mechanistic insight into PO4[3-] biosorption in anaerobic systems and demonstrate that the GF framework is a useful mechanistic tool for interpreting nutrient mass-transfer behavior in laboratory-scale UASB reactors, providing a basis for future pilot-scale validation.

Over the past three decades, the Tapajós River Basin, Brazilian Amazon, has become a major setting for investigating chronic environmental mercury (Hg) exposure, predominantly associated with dietary methylmercury (MeHg) intake through fish consumption. This critical review synthesizes Hg research conducted between 1990 and 2026, tracing scientific progress from contamination sources to human exposure, health effects, biological susceptibility, and emerging environmental health challenges. Early studies identified artisanal and small-scale gold mining, the remobilization of legacy Hg through biogeochemical processes, and fish consumption as central components linking environmental Hg sources to human exposure. Subsequent investigations expanded this evidence by examining health effects, biological susceptibility, nutritional interactions, and multiple environmental stressors. Although Hg concentrations in piscivorous fish have remained persistently elevated, biomonitoring studies suggest a gradual decline in Hg exposure in some communities, potentially reflecting changes in dietary patterns, socioeconomic conditions, sampling characteristics, and study locations. Despite major advances in characterizing contamination and exposure, less progress has been achieved in understanding long-term health consequences. Most epidemiological studies remain descriptive or cross-sectional, limiting causal inference and characterization of exposure-response relationships. Neurological, sensory, visual, and motor alterations remain the most consistently reported outcomes, yet uncertainties persist regarding causality, individual susceptibility, and mechanisms underlying variability among exposed populations. The contrasting findings of the Faroe Islands and Seychelles longitudinal cohorts illustrate these challenges. Recent studies increasingly recognize that Hg toxicity is shaped by complex exposomes involving selenium (Se), co-exposure to lead (Pb) and other contaminants, nutritional transition, infectious diseases, climate change, and social determinants of health. Future progress will require adequately powered longitudinal cohorts, population-specific reference values, biomarkers of exposure, effect and susceptibility, and integration of multi-omics, exposome, and One Health approaches to strengthen causal inference and improve environmental health policies for Amazonian populations.

The advancement of ozonation for wastewater treatment requires a thorough understanding of transformation processes affecting emerging contaminants such as pharmaceuticals and personal care products (PPCPs). This study investigates the degradation products of umifenovir (Arbidol) during aqueous ozonation. Using HPLC-ESI-HRMS, 23 primary (intermediate) transformation products were identified, their structures proposed, and degradation pathways established. The highest product diversity occurred at neutral pH due to reactions involving both molecular ozone and hydroxyl radicals. Initial transformation pathways include sulfide group oxidation with thiophenol moiety elimination, and indole ring oxidation followed by debromination. Under excess ozonation, GC-HRMS and mixed-mode (WAX/WCX) HPLC-HRMS revealed over 42 low-molecular-weight deep degradation products. Most arise from parent molecule transformation (e.g., trimethylamine or thiophenol) and subsequent oxidation. In addition to expected products, side radical reactions such as chlorination and dealkylation were observed. The bromine atom in umifenovir enabled HPLC-ICP-MS quantification of bromine-containing transformation products without individual standards. Umifenovir is rapidly removed from the reaction medium; however, persistent intermediate and deep transformation products remain even under excess ozonation. These findings highlight the need for advanced analytical methods for transformation product identification and for evaluating ozonation efficiency based on product formation rather than parent compound removal alone.

Heavy metal (HM) toxicity has become one of the major environmental concerns in recent years. In this study, we investigate the adsorption-based approach for the detection and removal of heavy metal ions (HMIs) from wastewater applications. Density functional theory (DFT) calculations are used to systematically investigate pristine γ-graphyne (γ-GY) and transition-metal-decorated γ-graphyne (TM/γ-GY) as efficient adsorbents for Hg, As, and Pb removal under implicit solvation conditions. Pristine γ-GY exhibits adsorption of Hg, As, and Pb with adsorption energies of -1.17 eV, -2.21 eV, and -3.46 eV, respectively. Transition metal doping enhances adsorption performance via strengthened TM-C interactions, increased electron transfer, enhanced stability, and electronic structure tuning. Re/γ-GY and Os/γ-GY show exceptionally strong adsorption for As and Pb (-4.81 and -4.30 eV, respectively), while Mn/γ-GY offers balanced adsorption for all HMIs. TM doping reduces the γ-GY band gap from 0.37 eV to below 0.15 eV in several systems, enhancing both electrical conductivity and adsorption sensitivity. Sensitivity analysis shows that Re/γ-GY achieves ∼100% sensitivity toward As, while Mn/γ-GY and Os/γ-GY selectively respond to Hg with >90% sensitivity. Adsorption capacity calculations show that pristine γ-GY exhibits a Hg uptake of 1043 mg g[-1], while TM doping enhances As and Pb capacities to 237 mg g[-1] and 984 mg g[-1] on Mn/γ-GY, respectively. Through a descriptor-guided framework incorporating adsorption selectivity, sensitivity, and adsorption capacity, Mn/γ-GY attains the highest overall performance score (0.72), making it the most promising adsorbent for multi-contaminant heavy metal removal.

Evaluating regional and seasonal air pollution variability is essential for monitoring tropical environments. This study evaluated regional and seasonal variations in fine particulate matter (PM2.5) and ground-level ozone (O3) across five regions of Malaysia using daily atmospheric and meteorological observations from 2018 to 2023 from the Department of Environment (DOE), complemented by ERA5 reanalysis variables (boundary layer height, solar radiation, and cloud cover). Multiple Linear Regression (MLR) and Extreme Gradient Boosting (XGBoost) were compared, while Shapley Additive Explanations (SHAP) were applied to interpret driver importance and nonlinear relationships. Kruskal-Wallis and Dunn post hoc tests identified regional and seasonal differences in both pollutants. PM2.5 varied spatially with (χ[2] = 3239.530, p < 0.001) and seasonally (χ[2] = 477.837, p < 0.001). O3 varied geographically with (χ[2] = 2173.607, p < 0.001) and seasonally (χ[2] = 69.579, p < 0.001). XGBoost outperformed MLR, achieving R[2] = 0.576 and RMSE = 4.87 μg m[-3] for PM2.5, and R[2] = 0.543 and RMSE = 3.4 ppb for O3, with skill varying by region and season and increasing to R[2] = 0.85 when persistence was included. SHAP analysis showed that PM2.5 variability was associated with combustion-related tracers and meteorological factors, whereas O3 was more strongly associated with humidity and temperature, with humidity exerting greater influence during the Northeast Monsoon. These suggest that air pollution variability across Malaysia is governed by interactions between emission patterns and meteorological conditions, emphasizing the importance of season-specific evaluation, explainable machine learning, and regional assessment for policy development.

The ecological relevance of soil invertebrates in contaminated groundwater systems remains largely unexplored, particularly under chronic exposure to petroleum-derived compounds. Here, we provide the first evidence of stable colonization and functional persistence of the model collembolan Folsomia candida within a hydrocarbon-polluted aquifer in Gaeta (central Italy). Long-term monitoring (2019-2023) revealed persistent groundwater contamination, with ethyl tert-butyl ether (ETBE) > 10,000 μg/L and total petroleum hydrocarbons (TPH) > 1000 μg/L. Despite these extreme conditions, F. candida populations were consistently detected on the water surface of quiescent piezometers and taxonomically confirmed via COI DNA barcoding. To disentangle tolerance and potential adaptive responses, we performed ecotoxicological bioassays using three populations (laboratory control, native contaminated population, and a depurated lineage) across aqueous and soil exposure scenarios with site-specific groundwater. Survival remained high (>70%) across all treatments which indicates a limited acute toxicity of ETBE-dominated mixtures. In contrast, reproduction was significantly stimulated under contaminated conditions, suggesting a shift from toxic to trophic effects mediated by hydrocarbon-associated microbial communities, including Aeromonas and Sulfuricurvum, likely providing both nutritional subsidy and oviposition substrates. However, under soil conditions, this enhanced reproductive output was coupled with reduced body length, revealing a contamination-driven life-history trade-off between reproduction and somatic growth. These results demonstrate that organism-microbe-contaminant interactions can modulate ecotoxicological outcomes beyond direct toxicity paradigms, enabling persistence and even functional exploitation of polluted environments. Our findings redefine the ecological boundaries of Collembola and support their use as bioindicators of hydrocarbon contamination pathways across terrestrial and groundwater interfaces, with implications for risk assessment frameworks in subsurface ecosystems.

Chitosan, a biopolymer derived from chitin, has attracted significant attention for use in water treatment applications because of its abundant surface functional groups and affinity for a wide range of contaminants. However, contaminant removal performance can vary with the chitin source and synthesis method, as documented in the literature. This study reviews synthesis methods and key physicochemical characteristics of chitosan relevant to contaminant removal and experimentally evaluates the removal of phosphate and nitrate by four commercial chitosans derived from crustacean shells and mushrooms. The chitosans were characterized using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and zeta potential analysis. Batch adsorption experiments were conducted under varying pH conditions, and the results were analyzed using Freundlich, Langmuir, and Temkin isotherm models to assess adsorption behavior and infer removal mechanisms. The Langmuir model provided the best fit for phosphate adsorption for most chitosans and pH conditions, whereas the Freundlich model more accurately described nitrate adsorption in most cases; however, model performance varied across chitosans and pH conditions. Langmuir-derived phosphate adsorption capacities at unadjusted pH conditions ranged from 17.6 to 41.6 mg/kg, while nitrate adsorption capacities ranged from 59.8 to 129.8 mg/kg. Mushroom-derived chitosan consistently exhibited lower phosphate and nitrate removal than the three crustacean-shell-derived chitosans, and flake-form chitosan showed reduced phosphate removal. Langmuir adsorption capacities decreased as initial solution pH increased, with the lowest values observed at pH 11. Among the four chitosans evaluated, no consistent relationship was found between contaminant removal and molecular weight, degree of deacetylation, or zeta potential. These findings demonstrate that source and physical characteristics contributed to differences in contaminant removal performance among the chitosans tested, and should be considered when selecting a commercial chitosan product for water treatment applications.

Microplastics (<5 mm) are widespread environmental contaminants, with increasing human exposure through ingestion, inhalation, and dermal contact. Their presence in terrestrial, aquatic, and atmospheric systems, along with detection in human tissues such as blood, lungs, placenta, and the gastrointestinal tract, highlights their bioavailability and potential health risks. Owing to their small size, high surface-area-to-volume ratio, and surface reactivity, microplastics can interact with biological molecules and cells, raising concerns about their role in disease development. This review presents a mechanistic perspective on microplastic-induced carcinogenesis. Microplastics can enter the body via multiple routes and disrupt cellular homeostasis by inducing oxidative stress, chronic inflammation, mitochondrial dysfunction, and genotoxicity. These effects contribute to genomic instability and dysregulation of key signaling pathways, including NF-κB, MAPK, and PI3K/Akt, which are associated with tumor initiation and progression. Additionally, microplastics act as "Trojan horse" carriers, facilitating the transport of co-contaminants such as heavy metals, persistent organic pollutants, and microbial agents, thereby enhancing their bioavailability and toxicity. The combined effects of microplastics and associated toxicants amplify oxidative stress, inflammatory responses, and epigenetic alterations, promoting a pro-tumorigenic environment. Despite growing evidence, significant knowledge gaps remain regarding long-term exposure, the behavior of nanoplastics in biological systems, and their direct link to cancer. This review emphasizes the need for integrated and interdisciplinary research to better understand microplastic-associated carcinogenesis and to support effective risk assessment and regulatory strategies.

Phosphorus (P) transport in riparian wetland systems is strongly influenced by hydrological events and interactions with suspended solids, yet association with its speciation and coupling with contaminant transport remain unclear. Here, we investigated P dynamics using high-frequency time-series sampling during five storm events in a riparian-wetland located on the Savannah River Site, South Carolina. Total P was fractionated into dissolved and particulate forms, with particulate P further separated into four operationally defined species identified by sequential extraction techniques. Total P was dominated by particulate P (>85%), with storm-driven increases primarily associated with elevated suspended solids. Marked shifts in P speciation occurred between early and late stormflow stages. Early-stage samples were enriched in reactive particulate P (e.g., exchangeable- and Fe-bound P), whereas late-stage samples contained higher proportions of occluded P and phosphate. These patterns corresponded to changes in particle composition, with early samples associated with Fe/organic matter (OM)-rich flocs and late samples contributed by less reactive mineral particles and aggregates. Strong correlations between P partitioning coefficients and solid-phase Fe and Mn highlight the likely central role of Fe-rich particles in regulating P transport. Significant correlations between stream P and uranium (U), one of key contaminants on the site, indicate their co-variation transport via shared associations with reactive suspended solids, suggesting that P may serve as an indicator of contaminant-associated particle transport under the studied conditions. Overall, storm-driven formation and mobilization of Fe/OM-rich particulates play an important role in regulating P speciation and transport in riparian-wetland systems.

Bacterial dehalogenase enzymes catalyze the cleavage of carbon-halogen bonds and play important roles in the microbial transformation of many halogenated contaminants. This review critically examines major classes of bacterial dehalogenases, including haloalkane dehalogenases, haloacid dehalogenases, fluoroacetate dehalogenases, reductive dehalogenases, and halohydrin dehalogenases, with emphasis on their structural features, catalytic residues, cofactor requirements, substrate specificity, and environmental controls on enzyme activity. Particular attention is given to the relevance and limitations of these enzymes for persistent, fluorinated contaminants, using hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX) as a case study. Although microbial dehalogenation is well established for many chlorinated and brominated pollutants, direct enzymatic defluorination of GenX remains insufficiently demonstrated. Current evidence suggests that PFAS structure, including strong carbon-fluorine bonds, ether linkages, chain length, and terminal functional groups, strongly constrains microbial and enzymatic transformation. Therefore, this review distinguishes established dehalogenase-mediated organohalide degradation from emerging and still-unverified applications to GenX and related short-chain PFAS. Key research needs include identification of GenX-transforming microorganisms and enzymes, biochemical validation of reaction pathways, kinetic characterization, transformation-product toxicity assessment, enzyme engineering, computational modeling, and scalable hybrid treatment systems. By integrating mechanistic enzymology, environmental operating conditions, and sustainability considerations, this review provides a critical framework for evaluating whether dehalogenase-based approaches can contribute to future PFAS remediation strategies.

Environmental and biological factors influence element bioaccumulation in top predators, potentially impacting wildlife health. This study evaluated whole blood (n = 60) and lanugo (n = 61) total mercury concentration ([Hg]), total selenium concentration ([Se]), and whole blood Se:Hg molar ratios of California sea lion (Zalophus californianus) pups from central (Granito, Partido/Rasito) and southern (Los Islotes) Gulf of California rookeries. The influence of location, sex, and dorsal standard length (DSL) were assessed. Significant spatial variation was observed, with higher lanugo [Hg] in central rookeries compared to the southern region (p < 0.05). Overall, 11.5% of pups exceeded the toxicological threshold for lanugo [Hg] (20 mg kg[-1] dry weight), with higher prevalences in Partido/Rasito (15%) and Granito (14.3%) compared to Los Islotes (5%). For all individuals, a strong correlation between lanugo and blood [Hg] (r = 0.78, p < 0.05) was detected, but not for [Se]; therefore, lanugo does not reliably reflect circulating [Se], possibly due to homeostatic regulation. Biological drivers influenced element dynamics in whole blood, but not in lanugo. A growth effect was observed, with [Hg] decreasing as DSL increased (p = 0.01); [Se] and Se:Hg molar ratios increased with DSL (p < 0.001). Males had higher [Hg] (p = 0.01); females showed higher [Se] and Se:Hg molar ratios (p < 0.01). These results highlight rookery-specific exposure and suggest effects of sex and growth on element accumulation. California sea lions serve as sentinels of chemical pollution that may affect marine biodiversity and human communities reliant on shared resources in the Gulf of California.

Porous carbon derived from biomass has been widely explored due to its high surface area and adsorption capability. However, its production is typically dominated by aggressive chemical pore-forming processes that prioritize maximum porosity at the expense of process complexity, chemical consumption, and environmental sustainability. In this context, this study challenges the conventional pore-forming-centric approach by demonstrating that HCl treatment functions primarily as a selective demineralization and pore-unblocking agent, shifting the governing mechanism from pore generation to pore accessibility. Palm oil shell was converted into porous carbon through carbonization (300-500 °C, 2-4 h) followed by HCl treatment. The results show that increasing temperature enhances carbon content, structural stability, and energy properties, while demineralization significantly improves pore accessibility and surface exposure. The resulting material exhibits a moderate surface area (up to 139 m[2]/g), indicating that functional performance can be achieved without intensive chemical process. A process-structure-property framework is proposed to link carbonization conditions, structural evolution, and material performance. The findings highlight the dominant role of lignin-derived carbon frameworks in defining pore architecture, while mineral removal governs accessibility. These results suggest that the development of biomass-derived porous carbon does not necessarily rely on aggressive chemical treatment, and instead can be achieved through accessibility-driven design under low-severity conditions, enabling more scalable, resource-efficient, and sustainable carbon materials within a circular economy context.