Organochlorine pesticides (OCPs) remain a critical environmental concern due to their persistence and bioaccumulative potential. This study investigated OCP residues across three matrices-water, sediment, and macroinvertebrates-within the Awetu, Kito, and Boye aquatic systems in southwestern Ethiopia. Analysis using Gas Chromatography with Electron Capture Detector (GC-ECD) identified nine OCPs, with p, p'-DDT and its metabolite p, p'-DDE as the dominant contaminants. Concentrations varied across the three matrices (water: ng/L; sediment and macroinvertebrates: ng/g), and values are not directly comparable due to differences in units, matrix properties, and analytical methodologies. The screening-level Ecological Risk Assessment (ERA) indicated potential high ecological risk to aquatic biota. Risk Quotients (RQ) for macroinvertebrates showed extreme risk from heptachlor epoxide (RQ = 738.8) and high risk from dieldrin (RQ = 1.53), demonstrating that these legacy pollutants bioaccumulate to levels that may cause secondary poisoning to higher trophic levels. Statistical analysis confirmed significant variation in pesticide distribution across the three matrices (p < 0.001), with a contamination hierarchy of sediment > macroinvertebrates > water. This pattern is primarily driven by the high lipophilicity and environmental persistence of OCPs, which favor adsorption to organic-rich sediments and subsequent bioaccumulation in aquatic biota. In contrast, the low concentrations in the water column reflect the poor aqueous solubility of these hydrophobic compounds. These findings highlight the persistence of legacy OCPs in Ethiopian aquatic ecosystems despite existing bans, with the Boye-Awetu-Kito system acting as a long-term reservoir. The extreme ecological risk observed underscores the urgent need for targeted remediation of the Boye wetland and stronger regulatory enforcement to mitigate trophic transfer and protect the regional aquatic ecosystem.
Aquatic product spoilage primarily results from specific spoilage organisms (SSOs) such as Pseudomonas, Aeromonas, and Shewanella, with biofilm formation playing a pivotal role in accelerating deterioration. The bacterial second messenger bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) orchestrates this process by regulating biofilm assembly. Intracellular c-di-GMP levels, modulated by diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), dictate bacterial behavior: higher concentrations suppress motility, promote adhesion, and trigger extracellular polymeric substance (EPS) secretion, reinforcing biofilm integrity. This protective matrix enhances SSO resistance to refrigeration, antimicrobial agents, and environmental stressors. Within biofilms, SSOs display heightened metabolic activity, producing proteases and lipases that degrade proteins and lipids, yielding spoilage metabolites such as trimethylamine, hydrogen sulfide, and organic acids-compounds responsible for off-odors, texture deterioration, and quality loss. Interventions targeting c-di-GMP signaling, such as DGC/PDE inhibitors, quorum-sensing disruption, and combined physical-chemical treatments, may effectively suppress biofilm formation and prolong shelf life. Further studies should elucidate c-di-GMP's interactions with other regulatory networks and its influence on multispecies biofilm dynamics in aquatic products. This review examines biofilm formation and its role in aquatic product spoilage, along with c-di-GMP's regulatory function in spoilage-associated biofilms and its broader spoilage implications, offering a theoretical foundation for further research on c-di-GMP-mediated interactions in multispecies biofilm systems.
Pond fertilization is a crucial factor in enhancing the productivity of inland aquatic resources. Organic fertilizers, such as vermicompost and biocompost derived from water hyacinth, promote the growth of algae and insects, which serve as essential food sources for fish. This study investigated the effects of water hyacinth vermicompost as a fertilization strategy in aquaculture, specifically examining its impact on fish growth compared to traditional fertilizers, such as triple superphosphate (TSP) and a combined fertilizer of TSP and urea. Water hyacinth, an invasive aquatic plant, was processed through vermicomposting to produce a nutrient-rich organic fertilizer. Over three months, from mid-November 2021 to mid-February 2022, various pond fertilization techniques and physicochemical parameters were examined in concrete ponds at the Batu Fish and Other Aquatic Life Research Center. Twelve concrete partitioned fish ponds, each measuring 6 m², were constructed and stocked with 18 Oreochromis niloticus fingerlings each, weighing approximately 7 g, randomly sourced from Batu Fish and Other Aquatic Life Research Center. This pond was equally divided into four treatments with three replicates (4T x 3R). The growth performance of Oreochromis niloticus was measured every 15 days for 90 days in water-filled ponds treated with mixed fertilizer (a 1:1 ratio of triple superphosphate and urea), triple superphosphate (TSP) alone, vermicompost (VC) as a direct application fertilizer, and control ponds. ANOVA was employed to analyze the data, which included growth parameters such as weight gain and feed conversion ratio, and the overall fish health was inspected and monitored throughout the study. Results indicated that ponds treated with water hyacinth vermicompost achieved significantly higher fish growth rates compared to those receiving TSP, TSP combined with urea, and the control group at p < 0.05. Specifically, the VC-treated pond recorded a final fish weight of 69.00±0.78964 g, followed by mixed fertilizer (66.1917±0.57309 g), TSP (63.144±0.51088 g), and the control ponds (51.00±0.82446 g). In the VC-treated pond, there was a high abundance of zooplankton, and high plankton production was observed in all treatments except in the control ponds. Water quality assessments showed that the use of vermicompost significantly improved the overall health of the pond. For example, dissolved oxygen (DO) levels increased, while ammonium (NH₄⁺) levels decreased, as ammonia could be absorbed by the available phytoplankton. The study recorded dissolved oxygen (DO) levels ranging from 8.06 ± 1.09 mg/l in the control group to 8.7583 ± 0.7 mg/l in the VC group. Consequently, the application of vermicompost released nutrients that fostered plankton production, which supported fish growth. Overall, Water hyacinth vermicompost is a viable, eco-friendly alternative to inorganic fertilizer for enhancing the productivity of semi-intensive Nile tilapia ponds.
Inorganic pollutants released into aquatic habitats by human activity, such as metals and radionuclides, present a serious threat to biodiversity and ecosystem health. Various biomonitoring efforts were established to track their release and environmental concentrations, including sampling of bioindicator species, which can accumulate these pollutants and facilitate their detection. Dragonflies (order Odonata) are considered valuable bioindicator organisms due to their relative longevity and predatory lifestyle, and have been used to assess environmental concentrations of a wide variety of pollutants. However, there is a lack of systematic effort to determine which elements are likely to be accumulated in dragonfly tissue from surrounding water, and how the concentrations of accumulated materials correlate to their environmental concentrations. In this review, studies that used dragonflies as bioindicators for metals and radionuclides in aquatic environments were analyzed, and bioaccumulation factors for each element were calculated. The highest bioaccumulation factors were obtained for U and Cs, elements with the highest numbers of bioaccumulation studies were Hg and Cu, and Se was the most consistently accumulated element in analyzed studies. The results have shown that dragonflies are suitable bioindicator organisms for a variety of different radioactive and non-radioactive elements, and calculated bioaccumulation factors provide a link between their presence in dragonfly tissue and the environmental concentrations in their habitats.
Microfibers (MFs) are a prevalent form of microplastics in aquatic environments and are frequently ingested by aquatic organisms. In nature, individual fibers do not always remain straight but can bend, coil, or become partially self-entangled, potentially altering their biological interactions. However, how such morphological variability influences MF ingestion by benthic gastropods remains poorly understood. Here, we exposed the freshwater snail Sinotaia quadrata to 50 items/L, within the range reported for freshwater systems, of polyethylene terephthalate and polyamide MFs, including elongated single fibers and coiled forms derived from the same individual fibers of corresponding lengths but exhibiting smaller external dimensions. Regardless of food availability and across all tested size classes, snails ingested significantly more elongated single fibers than coiled MFs. Ingestion of both forms peaked within 6 h; however, elongated fibers exhibited longer retention times in the digestive tract, whereas coiled forms were largely egested within 24 h. Microscopic observations indicated that radula-mediated feeding interactions more effectively captured elongated, flexible fibers, whereas coiled MFs were more likely to undergo transient contact without sustained retention and be dislodged during repeated radula-mediated movements. Scanning electron microscopy and micro-Raman analyses further revealed localized surface irregularities on ingested fibers. Together, these results provide experimental evidence that feeding interactions may enhance the bioavailability of elongated MFs and may facilitate their physical alteration. Our findings underscore the importance of fiber morphology and feeding mode in shaping MF exposure pathways and fate in benthic freshwater ecosystems.
Tire wear particles (TWPs) are a major source of microplastics in the environment, including aquatic ecosystems. Their leachates are of growing concern due to their acute toxicity on aquatic organisms. This study investigated the effects of tire leachates on mortality, clearance rate, metal accumulation, and the structure and diversity of the gut microbiota in the blue mussels (Mytilus edulis). Mussels were exposed for one and five weeks to different leachate concentrations (prepared from 5 g of new tire particles (TP) per liter) and a reconstituted metal solution reflecting the concentrations of the major metal constituents of the leachate stock solution. High-concentration exposure resulted in 61% cumulative mortality, compared to other treatments. Clear patterns of zinc, lead, and barium accumulation were observed, reaching 136.6 ± 17.3 mg Zn/kg in mussel tissues exposed to the highest concentration. High-concentration exposure also induced dysbiosis, characterized by an enrichment of anaerobic taxa (Fusobacteriales, Bacteroidales, and Clostridiales). Notably, Amplicon Sequence Variants (ASVs) affiliated with the order Francisellales, which includes lethal pathogens for mussels, were also detected at a higher proportion in the leachate treatments. After depuration, the clearance rate of mussels previously exposed to the highest leachate concentration decreased by 99%, and by 59% in mussels exposed to the metal solution. These results suggest that metals present in tire leachate contribute significantly to the impairment of mussel filtering activity.
Essential oils are naturally volatile substances produced by plants, presenting potential antibiotics and immunoprophylactics, being used as alternative additives in aquaculture. However, how to use different essential oils to promote the disease resistance abilities of aquatic teleosts, and what are the potential regulating mechanisms, are still scarce. In this study, we found that the combined essential oils -a mixture of cinnamaldehyde, thymol, carvacrol, and monolaurin, in a suitable ratio (10%:5%:10%:75%), were added in the basal diet at a 0.1% concentration, could effectively promote disease resistance of zebrafish (Danio rerio), grass carp (Ctenopharyngodon idella), and Chinese soft-shell turtles (Trionyx sinensis). Mechanistically, the combined essential oils promoted the transcriptional expression of anti-inflammatory factors, such as phagosome and antigen processing and presentation genes across species. Meanwhile, the combined essential oils promoted the AKT and ERK pathways to enhance the anti-inflammatory capacities of the teleosts and Chinese soft-shell turtles. These jointly contribute to the improved disease resistance to pathogen infections across species. These data reveal the potential of combined essential oils in promoting the disease resistance of aquatic species, and shed some light on developing green technologies in disease treatment in aquaculture.
Aeromonas veronii is widely distributed in aquatic environments, as well as in a variety of aquatic products, poultry, and other meat products. As a typical zoonotic pathogen, it not only directly infects hosts and threatens their health, but also disseminates through the food chain. The prevention and control of A. veronii, particularly food contamination caused by this pathogen, remains a critical concern, necessitating the development of novel control strategies. Therefore, this study explores the antibacterial efficacy and underlying mechanisms of geranic acid against A. veronii, alongside its practical application in inhibiting bacterial proliferation in marinated beef and perch. Geranic acid exhibited antibacterial activity against various bacterial species, after treatment with geranic acid, the levels of reactive oxygen species (ROS), malondialdehyde (MDA) content, superoxide dismutase (SOD) activity and catalase (CAT) activity of A. veronii were significantly increased, indicating that geranic acid can induce oxidative stress and increase cell membrane permeability, thereby resulting in cell damage and even death. Geranic acid also reduced extracellular protease activity, inhibited early biofilm formation, and interfered with quorum sensing, thus weakening the swarming motility and consequently decreasing the virulence of A. veronii. The application of a relatively high concentration of geranic acid in meat products significantly reduced the total bacterial counts and Aeromonas counts, and improved meat quality to a certain extent. These findings suggest that geranic acid, as an antibacterial agent, has important application potential in controlling microbial contamination of meat products.
Klebsiella pneumoniae is a major opportunistic pathogen and a recognized contributor to the global burden of antimicrobial resistance (AMR). Although traditionally associated with healthcare settings, it is increasingly detected in environmental compartments influenced by anthropogenic activities. Aquatic ecosystems may act as reservoirs and dissemination hubs for multidrug-resistant (MDR) lineages and resistance genes. However, genomic data on environmental K. pneumoniae in Morocco remain scarce. This pilot study aimed to characterize a targeted subset of MDR K. pneumoniae isolates recovered from Moroccan rivers using whole-genome sequencing (WGS), with a focus on resistance determinants, virulence-associated loci, plasmid content, and phylogenetic relationships. The main findings revealed marked genetic heterogeneity among the environmental K. pneumoniae isolates. Of the 44 isolates recovered from six Moroccan rivers, 11 MDR isolates were selected for WGS and belonged to nine distinct sequence types, including the high-risk clones ST147 and ST307. Resistance to extended-spectrum β-lactams was mainly associated with ESBL genes, particularly blaCTX-M-15, whereas carbapenem resistance was linked to blaOXA-48 and blaNDM-14 in a subset of isolates. The genomes also carried multiple determinants associated with resistance to other major antimicrobial classes. In addition, the isolates showed diverse plasmid backgrounds, heterogeneous virulence-associated loci, and substantial capsular diversity. Phylogenetic and pangenome analyses further indicated high intraspecific variability and extensive genome plasticity across the collection. This pilot study provides the first whole-genome-based characterization of river-derived MDR K. pneumoniae in Morocco. It demonstrates that aquatic ecosystems harbor genetically diverse lineages carrying clinically relevant resistance and virulence determinants. These findings underscore the imperative of integrating environmental surveillance into national AMR monitoring strategies within a One Health framework.
Rapid advances in materials chemistry and data-driven approaches have accelerated the development of aquatic chemical sensors, yet accurate, real long-term nutrient monitoring remains a significant challenge. Reliable real-time detection of nitrate (NO3-), nitrite (NO2-), and ammonium (NH4+) ions is essential for understanding aquatic biogeochemistry, mitigating eutrophication, ensuring precision fertigation, and ensuring sustainable water resource and crop management. Conventional electrochemical sensors can achieve low detection limits, but issues of accuracy, reproducibility, and stability under variable conditions hinder their broader application. In this preliminary study, electrochemical impedance spectroscopy (EIS) was employed in a three-electrode system to capture impedance responses over a wide frequency range, where the electrode-electrolyte interface was modelled using an equivalent circuit comprising resistive, capacitive and impedance elements. Impedance features including the real part, imaginary part, amplitude, and phase were analyzed as functions of concentration and frequency for the three target ions. To address the inherent nonlinearities of EIS data, advanced machine learning models were applied, with extreme gradient boosting (XGBoost) used for feature extraction, principal component analysis (PCA) for dimensionality reduction and a stacked ensemble (SVR-MLP-ridge regression) yielding the highest overall predictive accuracy (R2 = 0.99, RMSE < 0.921 ppm, MAE < 0.808 ppm, EV = 0.99) across all analytes. The developed hybrid tree-PCA-ML framework enables interpretable frequency-based analysis consistent with the physicochemical interpretations from the equivalent electrical circuit models. This combined EIS-ML approach not only enhances predictive accuracy for nutrient concentrations but also identifies critical frequency regions governing the sensing mechanisms, offering a pathway toward high-precision, real-time water quality monitoring.
The growth of the aquaculture sector poses challenges in maintaining product quality, particularly regarding contamination, which risks aquatic organisms and human health. Advanced oxidation processes using UV-C radiation can remove persistent compounds and pathogens from aqueous matrices through the generation of reactive species. However, their chemical non-selectivity may produce toxic disinfection by-products (DBPs), which require cautious ecotoxicological assessment. This study aimed to evaluate the ecotoxicological effects of UV-C/oxidant processes on aquaculture effluents by employing survival assays with Daphnia magna (D. magna) and growth inhibition assays with Pseudokirchneriella subcapitata (P. subcapitata). UV-C treatment of synthetic and real aquaculture effluents was intensified by hydrogen peroxide (H2O2), peracetic acid (PAA), sodium hypochlorite (NaClO), potassium peroxymonosulfate (PMS), and sodium persulfate (PS). UV-C treatment combined with PAA, PMS, or PS showed promising reductions in toxicity and high D. magna survival rates, whereas treatments with H2O2 and NaClO resulted in significant adverse effects on its survival. This is likely due to residual oxidants and DBPs, as dark controls showed lower toxicity, and UV-C alone had a negligible effect. For P. subcapitata bioassays, UV-C/PMS and UV-C/PS were identified as the most suitable treatments. Our findings support the use of UV-C-based AOPs for aquaculture effluent treatment, with prudent selection and addition levels, while highlighting dilution via recirculation in recirculating aquaculture systems (RAS) as an intrinsic advantage for mitigating relevant ecotoxicological risks.
Micropollutants in aquatic environments pose a significant threat to human health, which requires new designs of photoreactor and photocatalyst for better degrading micro pollutants. Here, we have designed a flow surface concave photoreactor through 3D printing, which can improve light collection ability by reflecting light multiple times on the surface. It is combined with a single atom modified Cr-Bi3O4Br/PVDF photocatalytic membrane for photo driven removal of antibiotics at environmentally relevant concentrations (100 ng L-1 to 10 mg L-1). The use of photocatalytic membrane flow system can effectively promote the contact between micro pollutants and active hydroxyl radicals ·OH generated in nanopores, thereby significantly improving degradation efficiency. Notably, in a 100 ng L-1 tetracycline (TC) solution, the removal rate can reach 99.9%, demonstrating the importance of designing flow-through concave photoreactor and photocatalytic membrane. Under natural sunlight conditions, the removal rate of TC reached an impressive 99% and total 5000 mL after 5 cycles with flow velocity 1.68 mL/min. This work not only provides an effective strategy for the removal of micro pollutants driven by sunlight, but also provides important references for the design of water treatment equipment through the synergistic effect of 3D printed concave photoreactors and composite materials.
Exogenous halide ions in aquatic environments can generate highly toxic halogenated disinfection byproducts during the advanced oxidation process, posing new environmental risks. However, the release of halide ions from widely utilized halide-containing catalysts and subsequent formation of these highly toxic byproducts have largely been overlooked. Herein, in this study, metallic Bi deposited onto BiOI to promote peroxydisulfate (PDS) activation for the degradation of bisphenol A (BPA). The results showed that the degradation rate constant of BPA on Bi/BiOI (0.323 min-1) was 8.97 times higher than that on pristine BiOI (0.036 min-1). Mechanism studies revealed that the active sites (Bi/Bi(III)) of Bi/BiOI undergo strong covalent hybridization with the p-orbitals of oxygen in PDS. This interaction disrupted the local structure of Bi/BiOI, thereby liberating iodide ions (∼0.11 mM). Quenching experiments and electron paramagnetic resonance (EPR) analysis demonstrated that the released iodide ions were locally oxidized by surface-adsorbed sulfate (Bi-*SO4·-) into reactive iodine species. Consequently, these reactive iodine species attacked BPA to form highly toxic iodinated byproducts and dimers, as identified via high-performance liquid chromatography-high-resolution mass spectrometry (HPLCHRMS). This study provides new insights into the activation mechanism of PDS by Bi/BiOI and highlights potential environmental risks of deploying BiOX-based catalysts to activate oxidants for pollutants degradation.
The current study aimed to quantify the antimicrobials amoxicillin (AMX), cefazolin (CFZ), chloramphenicol (CHL), metronidazole (MTZ), and sulfamethoxazole (SX) in effluents and surface water of an important Cerrado river, calculate their half-lives, and analyze their ecotoxicity following single and combined exposures. Four sampling surveys were carried out to identify the antimicrobials employing HPLC-MS/MS. Surface water was collected from the river's spring to the mouth, and effluent samples were taken at a sewage treatment plant (STP). The pySiRC tool was used to predict the half-life of antimicrobials in aqueous media under •OH-attack. Ecotoxicity was assessed using a zebrafish embryo-larval toxicity assay at environmentally relevant concentrations of the detected antimicrobials. Just MTZ (0.1 to 45.5 ng L-1) and SX (0.1 to 502.7 ng L-1) were detected in this study. The persistence of MTZ and SX in the aqueous environment was estimated at 14 to 139 days and 9 to 88 days, respectively. The single exposure to MTZ induced cardiotoxicity and changes in the swim bladder and tail curvature. MTZ and SX induced sensory and physiological morphometric changes compared to the control. MTZ, alone or combined with SX, affected the larvae's behavior. Our findings contribute to the understanding of the presence, persistence, and ecotoxicity of antimicrobials in aquatic environments.
Atrazine (ATZ), the second most widely used pesticide globally, poses potential risks to non-target aquatic organisms. However, its toxicological impacts on the economically valuable Chlamys nobilis remain unknown. This study investigates the toxicological effects of ATZ on the economically important C. nobilis. We assessed tissue integrity, physiological functions, and transcriptional profiles following ATZ exposure. Mortality in C. nobilis was observed to be time- and dose-dependent. Gill tissue damage was first noted at 5 μg/L ATZ, with severity increasing at higher concentrations. Superoxide dismutase (SOD) and catalase (CAT) activities were significantly elevated at 5 μg/L and 50 μg/L compared to controls but declined at 500 μg/L (P < 0.05). Glutathione S-transferase (GST) activity increased in all exposed groups except at 500 μg/L, peaking at 5 μg/L (P < 0.05). Malondialdehyde (MDA) levels rose significantly at 0.5 μg/L and further increased with higher ATZ concentrations (P < 0.05). RNA-seq analysis revealed 167 and 282 differentially expressed genes (DEGs) at 0.5 μg/L and 50 μg/L, respectively, enriched in pathways related to the endocrine, sensory, and digestive systems. Our findings highlight the toxic effects of ATZ on C. nobilis and contribute to the environmental risk assessment of this pesticide.
Phenolic pollutants, originating from petrochemical production, dyeing and domestic wastewater, are among the most persistent and toxic organic contaminants in aquatic systems. Their structural diversity and similar physicochemical properties often lead to overlapping signals in traditional detection methods, hindering accurate identification and quantification in real-world samples. Conventional spectroscopic, electrochemical, and colorimetric techniques offer fast response and high sensitivity but often struggle to distinguish structurally similar phenolics in complex mixtures. Therefore, developing sensing strategies that generate rich feature information and enable multidimensional recognition have become increasingly essential. Herein, we developed a fingerprinting sensing strategy based on an ultralow-loading Fe-Mo double-atomic site catalyst (DAC) coupled with H2O2 and TMB. Compared with isolated Fe or Mo single-atomic sites, the Fe-Mo DAC exhibited markedly enhanced peroxidase-like activity, which is attributed to Mo-induced modulation of the electronic structure and oxidation state of Fe centers. This catalytic synergy enables broad detection ranges, high sensitivity, and ultralow limits of detection (LOD, 0.76 μM) for five representative phenolic compounds and their binary mixtures. Experimental and theoretical investigations reveal that the variation in LOD is governed by the phenols' intrinsic oxidation energy barriers and reducing abilities. By integrating multiple linear and nonlinear spectral descriptors into a four-dimensional feature matrix, followed by PCA and LDA, the system achieved accurate high-dimensional discrimination of phenolic species. This work offers a rapid, sensitive, and robust method for identifying phenolic pollutants, enabling mixture discrimination, source tracing, and environmental monitoring. The approach also provides a generalizable framework for expanding nanozyme-based sensing toward complex chemical mixtures.
Zn(II) contamination in aquatic systems poses significant risks to environmental safety and public health. In this study, BaCO3/BaAl2O4/C nanocomposites, denoted BA600 and BA800, were synthesized by a facile Pechini sol-gel route at 600 and 800 °C and evaluated for Zn(II) removal from aqueous solutions. Besides, XRD data evidenced the presence of crystalline BaCO3 and BaAl2O4 phases, and the average crystal size increased from 54 nm for BA600 to 66 nm for BA800. Morphological analyses showed that BA600 had a denser aggregated structure, whereas BA800 exhibited coarser and more uniform particles. Under the optimum conditions of pH 6, adsorbent dose 0.1 g, and 298 K, equilibrium was reached within 60 min for BA600 and 80 min for BA800. The maximum adsorption capacities were 124.38 mg/g for BA600 and 90.58 mg/g for BA800. Zn(II) adsorption followed the pseudo-second-order kinetic model and the Langmuir isotherm and was found to be spontaneous, exothermic, and predominantly chemical in nature. After five adsorption/desorption cycles, the removal efficiencies decreased from 79.62 to 69.76% for BA600 and from 56.31 to 44.57% for BA800, corresponding to retention of 87.62% and 79.15% of their initial performance, respectively. In real wastewater, the adsorption capacities reached 110.40 mg/g for BA600 and 77.60 mg/g for BA800. These findings demonstrate that BA600, in particular, is an efficient adsorbent for Zn(II) removal from aqueous media.
Aquatic biodiversity assessment using environmental DNA (eDNA) metabarcoding has been increasingly applied for biomonitoring and environmental assessment in coastal waters modified by humans. Lake Shihwa is a historically impacted and intensively managed semi-enclosed system, where seawater exchange by water gate and continuous freshwater inputs generate strong environmental gradients. In this study, surface water samples were collected from exterior to interior stations to investigate the community dynamics of eukaryotic plankton across distinct environmental regimes. To encompass broad biodiversity, eDNA metabarcoding targeting the cytochrome oxidase I (COI) and 18S rRNA genes was performed. Clustering of samples by salinity revealed significant biodiversity differences, which were further supported by salinity-dependent module differentiation identified using a simulated annealing algorithm. Notably, the optimal salinity ranges of taxa within modules corresponded closely with measured salinity conditions. These results demonstrate that distinct diversity patterns observed among stations are primarily structured by salinity along environmental gradients. Together, our findings support the growing reliability of eDNA approaches in capturing ecologically meaningful biodiversity patterns and underscore their strong potential for broader application in environmental monitoring and assessment.
The transformation products (TPs) of pharmaceuticals and pesticides are ubiquitous in aquatic environments, necessitating the development of advanced treatment technologies for effective removal. This study systematically evaluated the degradation efficiency of six typical TPs of carbamazepine and atrazine by UV222-based advanced oxidation processes (AOPs) combined with different oxidants (periodate, hydrogen peroxide, peroxymonosulfate, persulfate, and chlorine). The results indicated that the oxidants were efficiently activated under 222 nm irradiation to generate diverse radical species, thereby accelerating TPs degradation. The dominant reactive species varied significantly across different treatment systems. Notably, the high photon energy of UV222 facilitated substantial ozone formation (6.5 × 10-9-1.61 × 10-6 M•cm2•mW-1), and potentially promoted electron transfer through the formation of excited states of oxidants and TPs. For CBZ-EP, the degradation pathways under UV222/oxidant treatments involved amide hydrolysis, epoxide hydrolysis/oxidation, decarboxylation, dehydrogenation, and aromatization. Economic analysis further confirmed the feasibility of UV222-based technologies. Moreover, the presence of dissolved organic matter (DOM) inhibited TPs removal in the UV222-AOPs, while concurrently altering the optical properties of DOM. DOM underwent dealkylation, oxygenation, and decarboxylation pathways, resulting in the formation of more saturated and highly oxidized molecules, along with the potential generation of disinfection by-products. This study provides insights into the mechanisms of TPs removal by UV222-AOPs and the molecular-level transformation of coexisting DOM, offering guidance for the optimization of advanced wastewater treatment processes.
The global spread of antimicrobial resistance (AMR) is a serious public health concern, driven by widespread antibiotic use and the global environmental circulation of antibiotic-resistant bacteria and resistance genes (ARGs). Wastewater treatment plants (WWTPs) are important sources of anthropogenic AMR entering large rivers, which serve as vital water resources but facilitate downstream dissemination. The drivers and dynamics of AMR propagation along river systems remain poorly understood. As Switzerland's longest and one of its largest rivers, the Aare, situated in the upper Rhine watershed, plays a central role in the 'water castle of Europe'. This study examines the impact of WWTP discharges, some receiving high loads of hospital effluent, on ARG distribution along the 288 km Aare river-continuum. Using quantitative PCR targeting 14 ARGs conferring resistance to eight antibiotic classes, combined with 16S rRNA gene amplicon sequencing, we conducted a high-resolution spatial survey to assess shifts in the riverine ARG content and microbiome. Concentrations of trace metals and nutrients were analyzed as tracers of anthropogenic inputs. Results revealed a progressive increase in ARG abundance downstream, driven by WWTP effluents enriched in ARGs. Effluents had 70-fold higher mean ARG concentrations than upstream waters, raising downstream levels up to 141-fold. Major tributaries such as the Reuss and Limmat sustained elevated ARG levels, while passage through lakes markedly reduced concentrations. This study provides the first detailed baseline for ARG prevalence along a large swiss river system, from pristine headwaters to pollution-affected lower reaches and insights into aquatic AMR dynamics and guidance for future monitoring.