Polycyclic aromatic compounds (PACs) are common constituents of crude oil and its refined products, and they can be released into the ambient environment during oil exploitation activities, potentially adversely affecting environmental and human health. Herein, forehead (n=76) and hand wipes (n=76) and urine samples (n=102) from oilfield workers as well as indoor dust samples (n=19) (not individually paired with skin wipe and urine samples) in the oil exploitation area were collected, and 45 PACs and 15 PAC metabolites (mPACs) in these matrices were comparably determined. The median concentrations of ∑PACs in forehead and hand wipes and ∑mPACs in urine were 1.2-4.3 times higher in frontline workers than those in office administrators. Significant differences in PAC profiles were observed between different matrices, with relatively hydrophilic PACs being least in indoor dust, intermediate in hand wipes, and most abundant in forehead wipes. Furthermore, five PACs in forehead and hand wipes and their corresponding mPACs in urine exhibited significant positive correlations. Exposure assessment indicated that dermal uptake of low molecular weight (LMW) PACs contributed dominantly to internal exposure (20.2%-67.4%) compared to dust ingestion (< 2%). The quantile g-computation model revealed that hydroxynaphthalene (∑OH-Nap), 1-OH-pyrene, and 2-OH-dibenzofuran were the major contributors to the mPAC mixture's effect on lipid peroxidation, and dermal exposure may represent a potential pathway by which LMW PACs, particularly Nap, were associated with lipid peroxidation based on multiple linear regression. This study enhances understanding of less well-studied PAC exposure and supports oil exploitation contamination control.
To support targeted mitigation of road-transport carbon dioxide (CO2) emissions, this study constructs a machine-learning-based high-resolution CO2 emissions inventory for South Korea at the hourly road-link level. The results show that roads with similar monthly total emissions can exhibit substantially different hourly emission patterns, which were systematically classified into three major types-Daytime-Steady, Commuting-Peak, and Mixed/Weekend-High-according to road class and regional characteristics. To examine regional predictive associations, shapley additive explanations (SHAP) analysis was conducted using emissions and land-cover data. In metropolitan areas, road-cover contribution was dominant, reflecting road saturation associated with high population density, whereas building-cover contribution was highest in non-capital regions, highlighting the importance of managing activity-centered emission hotspots rather than focusing solely on road infrastructure alone. Overall, the results suggest that road CO2 emissions are associated with interactions between temporal demand and spatial context, providing a basis for targeted mitigation, atmospheric and climate modeling, and carbon monitoring and verification.
The interaction between CO2 enrichment and nitrogen uptake under anthropogenic nitrogen inputs in the tropical coastal seas remains poorly understood. In this experimental study, we investigate the effects of elevated CO2 and impacts of various nitrogen sources such as river runoff, submarine groundwater discharge, industrial effluents, and atmospheric deposition, adding on NH4+ and NO3-uptake in tropical coastal waters. Using microcosm experiments along the west coast of India, a representative model system for tropical coastal ecosystems experiencing rapid anthropogenic development, we show that CO2 enrichment enhances nitrogen uptake, under intense anthropogenic nutrient enrichment. Our observations revealed a distinct uptake pattern of initial preference for NH4+ actively suppressed NO3- assimilation, subsequently leading to the co-dominance of NO3- and NH4+ uptake rates. The correlation between regenerated and new production acts as an efficient coastal biological pump in the coastal waters. These findings suggest that rising anthropogenic CO2, alongside nutrient inputs, may intensify nitrogen cycling in tropical coastal oceans, with implications for primary production and ecosystem dynamics under changing environmental conditions.
Polycyclic aromatic hydrocarbons (PAHs) are compounds with well-established negative health effects. In this study, the levels of the 16 Environmental Protection Agency (EPA) - PAHs were determined in air and deposited dust in different indoor environments, including schools, homes and sports halls in six metropolitan areas across Europe (Athens, Barcelona, Colchester, Copenhagen, Helsinki and Lisbon). However, naphthalene, acenaphthylene, anthracene, and dibenz[ah]anthracene were excluded from the final dataset due to analytical limitations. Results showed considerable spatial variability, suggesting that the highest median PAH concentrations (>50,000 pg/m3) in both schools and homes are linked to emissions from intensive local residential wood burning and poor ventilation, while the lowest PAH concentrations were observed in south-western Europe (<10,000 pg/m3). The levels of high-molecular weight (HMW) PAHs were generally higher in schools compared to homes likely due to greater occupancy and accumulation of outdoor-derived particles. Low molecular weight (LMW) PAHs, on the other hand, were more prominent in homes and associated with household practices (e.g., cleaning and ventilation frequency). In addition to active air sampling, indoor air concentrations were also estimated based on concentrations in the deposited dust samples. However, this methodology underestimated HMW-PAHs. The estimated Excess Cancer Risk for a 5-year primary education exposure period (ECR5) across all monitored sites ranged from 10-8 to 10-5, remaining below the unacceptable risk value of 10-4, which was used as a contextual reference within the USEPA cancer risk assessment framework. Nevertheless, these findings highlight the need for continuous proactive strategies to reduce PAH exposure and improve indoor air quality, particularly in environments occupied by children.
Recycled aggregate concrete (RAC) is vulnerable to freeze-thaw damage because adhered old mortar and multiple interfacial regions facilitate pore coarsening and crack propagation. This study investigated whether graphene oxide (GO) could mitigate such damage while compensating for its additional production burdens. The compressive strengths of reference (Ref) and GO-modified RAC were first compared for fractal gradations of D = 2.3-2.8, after which D = 2.5 was selected for 0-30 freeze-thaw cycles. Macroscopic testing, quantitative BSE imaging, exploratory CNN analysis of local image patches, cyclic molecular simulations involving tensile loading and unloading, and a cradle-to-gate assessment normalized by residual compressive strength were integrated. Both mixtures attained their highest strength at D = 2.5 within the investigated range. After 30 cycles, the residual compressive strengths of Ref and GO-modified RAC were 12.217 and 17.500 MPa, respectively. GO therefore provided 43.3% higher residual strength and reduced strength loss from 52.3% to 44.5%. BSE observations and idealized molecular simulations were consistent with less coarsening of pores and defects, weaker deformation localization, and slower cyclic stiffness degradation. Under the baseline GO price of 40 USD/kg, the 30-cycle cost, GHG, and PED per unit residual strength were 8.92%, 28.63%, and 24.91% lower than those of Ref, respectively. Normalized GHG remained 28.42%-28.63% lower across the tested GO GHG scenarios, whereas normalized cost became 27.98% and 64.88% higher when the GO price increased to 120 and 200 USD/kg. GO improved residual load-bearing performance, although its economic viability depended strongly on price.
Selective adsorption of fluoride (F-) is an efficient and feasible technology for the remediation of F- contamination in wastewater. However, there are scientific difficulties unsolved regarding low adsorption capacity and selectivity, restricting its extensive engineering applications, especially in industrial wastewater. In this work, selective F- removal from wastewater was achieved through functional groups interaction and ligand with a core-shell structure material (aAlOx@C). This material offered higher adsorption capacity (26.77 mg/g) and superior performance for F- removal (95.73%) under initial concentration of 9.5 mg/L. Both groups interaction and ligand (C-F and Al-F bond) were contributed to the higher adsorption capacity and selectivity for F-. Density functional theory showed that the decrease of overlapping energy bands between Al 3p and F 2p and the increase of ΔE (1.72 eV) between C-F and Al-F facilitated the conversion of C-F into Al-F bond. The constructed unsaturated Al not only promoted the group exchange between -OH and F-, but also served as a host for selective F- removal via Al-F bond. Impressively, such material established excellent adsorption capacity (16.24∼24.19 mg/g) for different industrial wastewater treatment with discharge standard (3 mg/L) in continuous-flow mode.
While biotransformation of chlorinated paraffins (CPs) has been demonstrated in various compartments, their hydroxylated and oxidized metabolites have only recently been identified using non-target screening approaches. The lack of authentic standards for these tentative metabolites impedes definitive structural characterization and toxicity assessment. To address this gap, reference standards for hydroxylated and carbonylated CP metabolites were synthesized, analyzed using liquid chromatography (LC) with high-resolution mass spectrometry (HRMS), and evaluated for their capacity to compete with thyroid hormone for binding to transthyretin (TTR). Matching LC-HRMS data demonstrated that the newly synthesized 3,4,7,8,10,11-hexachloro-1-undecanol and 1,2,5,8,9-pentachloro-4-undecanol (C11H17Cl6-OH and C11H18Cl5-OH) were in vitro metabolites of 1,2,4,5,8,9-hexachloroundecane (C11H18Cl6) following incubation with rat liver S9 fractions. CP single congeners exhibited limited aqueous solubility and weak TTR binding capacity. Hydroxylation increased aqueous solubility, enabling hydroxylated CPs to bind TTR at higher concentrations. In contrast, carbonylated CPs were less potent competitors than hydroxylated CPs for fluorescent thyroxine (FITC-T4) binding to TTR. This study confirms the biotransformation of CPs into hydroxylated metabolites, which may cause thyroid hormone system disruption. It is important to further investigate whether the binding of hydroxylated CPs to TTR facilitates their transport across the placenta or the blood-cerebrospinal fluid barrier, thereby posing risks to fetal development.
BACKGROUND:Residential wood combustion is a major source of ambient particulate matter in Northern Europe and is associated with adverse respiratory health outcomes. However, the acute effects of short-term wood smoke exposure on small airways remain incompletely characterized. OBJECTIVE:To investigate the acute effects of controlled wood smoke exposure on airway function in healthy adults, with specific emphasis on small airway mechanics, spirometry, and respiratory symptoms. METHODS:In a randomized, double-blind crossover-designed study, 14 healthy non-smoking adults (11 men, 3 women; mean age 26 years) underwent 2-hour chamber exposures, under two occasions, to wood smoke (PM1: 453 ± 13 μg/m3) and to filtered air separated by a three-weeks washout period. Lung function was assessed before and after each session using Forced Oscillation Technique (FOT, tremoFlo®) and spirometry. Symptoms were recorded on a modified Borg scale at 30-minute intervals. RESULTS:Exposure to wood smoke significantly elicited nasal irritation (p = 0.003) and showed trends toward increased cough and unpleasant odor perception. No exposure-specific changes were detected in spirometric parameters or oscillometric resistance parameters (R5, R5-R19, R5-R20). Reactance (X5) and resonant frequency (Fres) showed significant time-dependent changes irrespective to exposure condition (p < 0.001 and p = 0.022, respectively). CONCLUSIONS:Short-term controlled wood smoke exposure induced sensory upper airway irritation without detectable changes in small airway mechanics in healthy adults. Peripheral airway mechanical changes may require higher exposure concentration, longer durations, or susceptible populations. Furthermore, reliance on spirometry may underestimate early health effects, as irritative symptoms precede measurable mechanical dysfunction. TRIAL REGISTRATION:ClinicalTrials.gov NCT03302117.
Fluorite CeO2 is promising for heterogeneous ozonation due to its tunable electronic structures, but its rigid lattice limits defect formation and electron mobility. Herein, we propose a lattice-engineering strategy by substituting La into the framework to form La2Ce2O7 as new catalysts. This substitution induces lattice distortion and generates abundant oxygen vacancies (OVs, 43.4% Oβ on La2Ce2O7vs. 28.4% on CeO2), forming adjacent Lewis acid sites (Ce3+) and OVs as dual active centers. Under optimal conditions, the La2Ce2O7 system reached 91.5% of oxytetracycline (OTC) degradation within 25 min, which is 1.8 and 5.0 times higher than that with CeO2 and sole ozonation, respectively. Total organic carbon removal reaches 85% after 240 min, evidencing deep mineralization. Mechanistic investigations reveal the synergistic interplay: Lewis acid sites initiate O3 adsorption and activation (supported by XPS and radical analysis), while adjacent OVs likely serve as electron transfer sites to accelerate the Ce4+/Ce3+ redox cycle (Ce3+ fraction 42.97% pre- vs. 41.24% post-reaction), thereby enhancing the generation of both surface-bound and free •OH. Moreover, a counterintuitive hydrodynamic effect was uncovered: SO42- suppresses bubble coalescence, reducing average bubble diameter from 1.52 mm to 0.80 mm, increasing specific interfacial area by ∼90% and nearly doubling KLa, thereby overcoming radical scavenging and boosting OTC degradation in saline water. The La2Ce2O7 catalyst maintains >90% OTC removal over 48 h continuous-flow operation, and the treated effluent shows dramatically reduced ecotoxicity (LC50 from 1.12 to >100 mg·L-1). This work establishes a dual-center lattice engineering paradigm, showing that salinity turns a traditional inhibitor into a performance enhancer for treating refractory pharmaceutical wastewater.
Activating peroxymonocarbonate (HCO4-), generated in-situ by the reaction between H2O2 and HCO3-, is a promising remediation technology for pollutants treatment. However, the utilization of HCO3- with concentration higher than surface water and the generation of weakly oxidizing reactive oxygen species face the bottleneck challenges of high treatment cost and refractory pollutants inefficient degradation. The present work has been confirmed an attractive result that the •OH formation was significantly promoted with broad-spectrum responsive Cu2(OH)PO4 catalyst in sunlight-driven heterogeneous photo-Fenton system with the environmental relevant concentration (2 mM) of HCO3- (SH-PF+HC system), thereby effectively degrading refractory imidacloprid. The conversion of H2O2 to HCO4- in the presence of HCO3- inhibited the occurrence of H2O2 unsatisfactory decomposition to O2/H2O/•O2-. The HCO4- was more prone to electron transfer with Cu2(OH)PO4 and reduced reaction energy barrier for generating •OH based on the results of electrochemical measurements and theoretical calculation, causing a 2-fold increase in the utilization efficiency (74.6%) of H2O2 for yielding •OH. The effective mineralization and detoxification of imidacloprid were realized in SH-PF+HC system, which existed robust anti-interference against coexisting substances and universality for various pollutants degradation. The HCO3- in natural waters can be effectively utilized to accelerate imidacloprid degradation using Cu2(OH)PO4 catalyst in SH-PF system. The study has provided an effective strategy to promote •OH formation by using low-dose HCO3- in sunlit natural waters for the practical treatment of refractory pollutants.
Antarctic coastal systems are changing under the combined influence of climate warming and increasing human activity, but the interaction between contaminants of emerging concern (CECs) and legacy contaminants (LCs) remains poorly resolved. Here, we investigated their occurrence, sources, partitioning, and ecological risks in suspended particulate matter (SPM) (n = 15) and sediments (n = 15) from Admiralty Bay, Northern Antarctic Peninsula, using gas chromatography coupled to a quadrupole time-of-flight high-resolution mass spectrometer for CECs, and to a triple-quadrupole mass spectrometer for LCs. In SPM, contaminants showed a heterogeneous distribution across Admiralty Bay and generally higher concentrations. In contrast, sediment contamination was more associated with preferential deposition areas and showed a greater diversity of detected compounds. Source apportionment suggested a combination of local sources, including wastewater discharge, fuel use, and station activities, together with long-range atmospheric transport and secondary remobilization. Risk assessment highlighted a functional difference between contaminant groups. CECs, such as octocrylene and triclosan, drove immediate ecological risk (RQ > 1) due to high exposure in SPM, while LCs, including PCBs and alkylated PAHs, remained dominant in toxicological priority. These findings show that Antarctica is no longer only a passive sink, but an active system where recent inputs and historical reservoirs interact, emphasizing the need for integrated monitoring and management strategies based on exposure and hazard.
Low-carbon secondary effluent presents significant challenges for effective nitrogen removal due to limited available organic carbon. In this study, a laboratory-scale microbial system integrating a polysaccharide-based external carbon source (MP) with the nitrate-assimilating bacterium Enterobacter hormaechei EN-1 was developed to enhance aerobic nitrogen removal. The tested co-culture model increased total nitrogen removal efficiency from 63.46% to 85.86%. In batch tailwater microcosms, MP supplementation combined with EN-1 inoculation improved nitrate transformation and nitrogen removal. In the 7-day semi-continuous shake-flask microcosms, treatment-associated changes in microbial community composition and the abundance of the denitrification-related genes nirS and nosZ were observed. Biomass-associated nitrogen measurements indicated that growth-related assimilation was an important measured route of nitrate removal by EN-1. Time-course HPLC analysis showed dynamic changes in soluble monosaccharides and organic acids during EN-1 cultivation. Cell-free medium conditioned by EN-1 during cultivation with the dialyzed high-molecular-weight MP fraction enhanced nitrate transformation by DE6 relative to the matched abiotic control. An HPLC-informed organic-acid mixture also altered nirS and nosZ transcription in DE6 under the tested conditions. These results support a potential soluble-product-mediated facilitation, but do not establish direct metabolite-specific carbon transfer from EN-1 to DE6. Overall, EN-1 associated transformation of the tested MP preparation was linked to improved short-term nitrogen transformation in laboratory tailwater microcosms and to denitrification-associated community and functional-marker responses. These findings provide a laboratory-scale proof of concept and a basis for future validation in long-term continuous-flow systems.
Metal(loid) contamination is an important environmental concern in lakes of the middle-lower Yangtze River Basin, yet long-term changes in contaminant sources and ecological risk remain poorly resolved. We used a 210Pb-dated sediment core from Wushan Lake to reconstruct century-scale contamination dynamics by integrating enrichment factor (EF), geoaccumulation index (Igeo), potential ecological risk index (RI), positive matrix factorization (PMF), and time-series analyses. Sediments deposited before the mid-1980s showed generally limited anthropogenic enrichment, followed by increased accumulation of Cd, As, Mn, and Cu. RI increased toward recent sediments and was dominated by Cd, but is interpreted as a screening-level indicator rather than evidence of realized ecological effects. PMF supported a predominantly lithogenic component and two anthropogenic-related mixed components. Under the primary model, agriculture-related influence was greater during the late 20th century, whereas industrial-urban-related influence became more prominent after the early 2000s; this temporal succession is treated as model-supported rather than uniquely resolved. Cr and Ni were mainly associated with the lithogenic component, highlighting the importance of site-specific geochemical baselines. After accounting for temporal trends and autocorrelation, most socioeconomic associations weakened, with only As remaining significantly related to the dominant socioeconomic gradient. Recent declines in Cu, Mn, and Pb accumulation coincided with strengthened pollution control but cannot be uniquely attributed to management interventions. Overall, integrating dated sediment archives, local baselines, receptor modeling, and time-series analysis provides a useful framework for reconstructing long-term contamination dynamics while accounting for uncertainty in source attribution and management-related interpretation.
Under hot-weather construction conditions, the rapid setting problem of geopolymer mortar as a sustainable material severely restricts its practical application. This study systematically investigated the retarding behavior of representative inorganic salts (ZnCl2, Na2SO4, BaCl2) in fly ash and slag-based geopolymer mortar at 30-50°C using multi-scale characterization. The results revealed three distinct retardation pathways: ion competition depletion (ZnCl2), precipitation equilibrium regulation (Na2SO4), and interfacial barrier-phase separation (BaCl2). Among the three, BaCl2 exhibited the strongest retarding effect, extending the final setting time from 12.09 min to 139.57 min at 6% content. Notably, all three salts can be sourced from industrial by-product streams or recovered from wastewaters, rather than from primary production, which underscores their circular-economy potential. Life cycle assessment shows that geopolymer mortars containing retarders achieve 24-26% lower embodied carbon and 8-13% lower material costs than OPC mortar. These findings establish a resource-efficient design framework for inorganic retarders, with the key implication that future research and practice should prioritize direct procurement from industrial wastes to maximize both workability control and environmental benefits.
Coastal eutrophication driven by anthropogenic nitrogen (N) is a major pressure on estuarine ecosystems. Here, we analyzed stable N isotopes (δ15N) and tissue N content (%N) in the brown algae Fucus spp., collected in 171 sampling stations along the NW Spanish coastline (ca. 1500 km) between 1990 and 2023, to investigate long-term and spatial N enrichment patterns. We further related these indicators to seawater nutrients, land cover, and anthropogenic pressure proxies. Macroalgal δ15N ranged from 2.98 to 16.8‰ (median = 7.6‰) and was often above regional baseline thresholds for unimpacted systems (≤6‰), indicating widespread anthropogenic influence. Strong spatial gradients occurred, with higher δ15N in inner estuarine areas (Fucus ceranoides) and lower values at exposed sites (F. vesiculosus - F. spiralis). δ15N declined significantly since 1990, consistent with wastewater treatment improvements. However, the following stabilization in recent years, indicate continuing N pressures. Seawater nitrate and phosphate, agriculture land cover and, to a lesser extent, artificial surfaces were significantly associated with macroalgal N indicators, although effects were moderate, highlighting multiple interacting environmental drivers. Highest δ15N values in inner areas were consistent with sewage effluent and manure fertilization, whereas lower values at exposed areas likely reflected upwelling. Overall, macroalgal δ15N was a robust indicator of N enrichment across coastal gradients. However, source attribution remains limited by overlapping isotopic signatures and the limited spatial resolution of available datasets. These results support macroalgae as cost-effective biomonitors for long-term monitoring and underscore the need for integrated approaches to improve N source discrimination and management.
Polyphenol-derived metal coordination polymers (MCPs) are promising for constructing hydrophilic and underwater antifouling membrane interfaces. However, conventional pH-regulated fabrication of MCPs is often accompanied by metal-ion hydrolysis, which consumes available metal ions and interferes with effective MCP formation. Herein, a triethanolamine (TEOA)-mediated chelation-competition strategy was developed to guide the in situ assembly of MCPs on separation membranes. TEOA modulated Fe3+ coordination and reactivity, while pre-adsorbed tannic acid (TA) subsequently displaced TEOA through competitive coordination to form Fe-TA MCPs. DFT calculations showed that the conversion from Fe-TEOA to Fe-polyphenol coordination was thermodynamically favorable (ΔG = -335.68 kJ/mol), supporting the proposed chelation-competition mechanism. The resulting FTC-PVDF exhibited superhydrophilicity, underwater superoleophobicity, and low oil adhesion. To leverage the low oil-droplet sliding angle, an inclined gravity-assisted cross-flow mode was further designed to facilitate oil-droplet migration and detachment. FTC-PVDF achieved a high permeance of 5300.5 L m-2∙h-1∙bar-1 and separation efficiencies above 99.5% for surfactant-stabilized emulsions. This work provides a chelation-competition interface-engineering route for regulating polyphenol-derived MCP formation and constructing high-permeance antifouling membranes for emulsion separation.
The intensification of wildfire seasons, driven by global warming, has established wildfires as a primary contributor to aerosol particulate matter (APM) levels. However, the formation mechanisms and molecular composition of nitrogen-containing organic compounds in wildfire-derived APM remain poorly understood. This study characterizes, at the molecular level, wildfire-derived PM2.5 from a wildfire in a temperate coniferous forest in South Korea. Gas chromatography-mass spectrometry analysis revealed that nitrated polycyclic aromatic compound concentrations were approximately 3.4 times higher during the wildfire period (0.122 ng/m3) than the post-wildfire period (0.036 ng/m3), with 2-nitrofluorene and 3-nitrofluoranthene predominating in each period, respectively. Fourier transform ion cyclotron resonance mass spectrometry analysis revealed a relative shift toward CHON compounds across the sampling periods, and rule-based secondary organic aerosol predictions using 12 volatile organic compound precursors matched against observed data, with limonene-derived products showing the highest number of molecular-formula matched compounds. Quantitative structure activity relationship (QSAR)-based lethal concentration (LC50) predictions showed that β-pinene-, α-pinene-, and isoprene-derived compounds exhibited predicted values of 1.0, 1.6, and 8.3 mg/L, respectively. Because these predictions were based on structures assigned at the molecular-formula level, they provide a preliminary hazard ranking of the associated precursor classes rather than confirmed toxicity. Taken together, the observed compositional shifts point to secondary atmospheric processing of nitrogen-containing organic compounds as a factor meriting further consideration in wildfire assessments.
The sustainable remediation of nitrogen polluted aquatic sediments is often constrained by the spatial separation of electron donors and acceptors, which limits intrinsic microbial nitrogen removal. The long-distance electron transport capacity of cable bacteria offers a natural strategy to overcome this limitation but the kinetic mechanisms remains poorly understood. Herein cable bacteria were enriched from ammonia impacted freshwater sediments and their role in enhancing nitrogen removal was systematically investigated. Biogeochemical analysis showed that cable bacteria reduced ammonium by 93% and increased sulfate accumulation 2.07 times relative to controls. Critically, DGT induced fluxes in sediments and soils (DIFS) modeling at depths of 4 mm and 20 mm revealed that cable bacteria maintained uniformly low nitrate and ammonium diffusion fluxes, whereas in the control nitrate fluxes were 4.5-fold higher and ammonium fluxes were 8.9- to 53-fold higher. This kinetic evidence indicates that cable bacteria accelerate nitrogen removal by enhancing the coupling between nitrification and denitrification, thereby mitigating the classical diffusion limitation that restricts these processes in surface sediments. Metagenomic analysis showed that cable bacteria orchestrated a community shift increasing Nitrospira abundance from 0.4% to 20% and enriching genes for respiratory nitrate reduction (narG) and assimilatory sulfate reduction (cysH, sir), establishing a self-sustaining syntrophic network that coordinated nitrogen and sulfur fluxes. These findings establish cable bacteria as a promising bioremediation tool for cleaner nitrogen management in contaminated aquatic systems.
Chlorine oxide radicals (ClO·) possess excellent application potential for the selective oxidation of ammonia and efficient degradation of organic pollutants. However, it remains challenging to attain high efficiencies for ClO· generation. In this study, a novel photoanode was prepared by anchoring Cl-doped Ru-Co oxide nanoparticles on Sn-doped TiO2 nanowire arrays (Sn-TiO2). Sn doping improved the photocatalytic activity and electrical conductivity of TiO2, and Cl doping optimized the chlorine evolution performance of Ru-Co oxide. Benefitting from these modifications, enhanced ammonia oxidation (96.6%), and ethylenediaminetetraacetic acid removal (99.4%) were obtained synchronously, accompanied by a chemical oxygen demand (COD) removal efficiency of 52.1% and a low NO3--N accumulation of 1.3 mg/L. The toxicity variation during the degradation process was evaluated, and chloramine could be effectively eliminated by appropriately extending the reaction time. The photoanode exhibited excellent application potential for actual electroplating tail wastewater treatment. Experimental results showed that 95.7% of NH4+-N and 89.4% of COD could be degraded within 140 min. Theoretical calculations confirmed that Cl doping enhanced Cl- adsorption on Ru/Co sites, facilitating chlorine evolution. Meanwhile, Sn-TiO2 promoted ·OH generation. Additionally, the inter-wire gaps of the nanowire arrays favored sufficient contact between free chlorine and ·OH. Consequently, the reaction between them was promoted and the generation of ClO· was boosted, ultimately improving pollutant degradation. This study develops a high-efficiency photoanode for enhanced ClO· production, which may contribute to the advancement of photoelectrocatalytic chlorination technology for water remediation.
Zooplankton play a crucial role in marine food webs and biogeochemical cycles, and their rapid responses to environmental changes make them effective indicators of ecosystem health. However, limited data on zooplankton diversity within the polymetallic nodule (PMN) contract area of the Central Indian Ocean Basin (CIOB) restrict the reference information available for future monitoring. Mesozooplankton communities were characterised through morphological identification and 18S rRNA metabarcoding. Samples were obtained using a depth-stratified Multilayer Plankton Net (MPN; 0-5000 m) and mesopelagic Bongo net tows (∼250 m) at three locations: the Impact Reference Zone (IRZ), the Preservation Reference Zone (PRZ), and BC20, located outside the proposed mining area. In total, 115 taxa comprising 82 genera were identified using both morphological and molecular analysis. Most taxa were shared across sites, with 13, 10, and 12 taxa unique to IRZ, PRZ, and BC20, respectively. Both methods revealed vertical structuring of zooplankton communities. Taxonomic richness and Shannon-Wiener diversity were highest in the upper water column and declined with increasing depth, whereas community composition varied along the depth gradient. Overall, diversity was greater at IRZ compared to the other two sites. Pearson correlation revealed depth associations, most of the genera decreased with increasing depth. These results indicate that depth is the primary factor influencing zooplankton community organisation in the CIOB. The study also highlights integrating molecular and morphological methods can provide a more comprehensive assessment. This study establishes a pre-disturbance reference for monitoring mesozooplankton diversity in potential regions targeted for deep-sea mineral exploration and future mining.
