Remediation of former wood treatment sites is challengingdue tothe presence of contaminants with distinct physicochemical properties,such as arsenic (As) and polycyclic aromatic hydrocarbons (PAHs).This study evaluated a low-voltage electricity-induced soil remediationmethod designed to immobilize As while simultaneously degrading PAH in situ. A field pilot experiment was conducted at a highlycontaminated site using iron (Fe) electrodes supplying pulsed directcurrent to promote PAH oxidation and Fe release from electrodes forAs immobilization. Groundwater in five wells was monitored for concentrationsof contaminants, their degradation byproducts, and microbial and fungalcommunity structures. Over two years, dissolved PAH16 concentrationsdecreased by 62–94% across wells, with no accumulation of oxygenatedor nitrogen-containing PAH. Dissolved As concentrations declined byup to 88% at low PAH levels, but reductions were weaker (55–57%)and more variable at very high PAH concentrations (hundreds to thousandsμg L–1). Microbial communities, both prokaryoticand fungal, were characterized by taxa often found in contaminatedaquifers and soils, with enrichment of PAH-degrading and As-tolerant Pseudomonas, Rugosibacter, and Duganella, but showed no adverse effect of the treatment.Overall, the method promoted concurrent PAH degradation and As immobilizationwith minimal secondary impacts, demonstrating potential for remediationof mixed-pollutant soils.

Stormwater systemsincreasingly rely on polymer-basedmaterialssuch as polyvinyl chloride (PVC), polyethylene (PE), high-densitypolyethylene (HDPE), and polypropylene (PP) due to their durability,low cost, and corrosion resistance. However, these materials are susceptibleto photochemical, abiotic chemical (e.g., oxidation/chlorination fromdisinfectants and oxidants), biological (microbial/enzymatic), andmechanical degradation, resulting in the release of micro- and nanoplastics(MNPs) throughout their service life. This perspective criticallyexamines the mechanisms underlying MNP formation in stormwater infrastructure– including ultraviolet (UV)/photoaging, chemical oxidation,hydraulic abrasion, and bed-load interactions – and evaluateslaboratory methods used to study these processes. Standardized toolssuch as the Taber abrasion, Darmstadt rigs, circulating-loop systems,UV weathering, and chemical aging protocols are evaluated for theirability to simulate real-world conditions and quantify plastic particlerelease. Existing methods primarily quantify material durability butrarely capture or characterize released MNPs, leading to gaps in emissionfactor development and poor translation of laboratory results to stormwaterenvironments. Analytical techniques such as μ-FTIR, Raman spectroscopy,SEM/EDX, and Py-GC/MS are reviewed for their complementary roles inparticle identification and quantification. Key methodological gapsare identified, including inconsistent sampling protocols, limiteddetection of nanoplastics (NPs), unrealistic hydraulic simulations,and sparse comparisons between recycled and virgin pipe materials.To address these issues, this perspective proposes a hydraulicallyrealistic circulating-loop platform capable of integrating stormwater-likehydraulics with UV and chemical aging, as well as analytical techniquesto quantify MNP emissions from pipe materials under environmentallyrelevant conditions. This integrated framework supports the developmentof predictive models that link material degradation to MNP release,thereby advancing sustainable infrastructure design and plastic pollutionmitigation in water systems.

Biofilm-associated contamination represents a persistentand costlychallenge across environmental systems, causing reduced efficacy ofdisinfectants. Recently, nanobubbles (NBs) have shown promise forbiofilm decontamination; yet, their underpinning mode of action remainsa topic of debate. In this study, the interaction of air-generatedNBs with Escherichia coli and Staphylococcus aureus biofilms was investigated.NBs were generated using a venturi nozzle and characterized usingNanoparticle Tracking Analysis, revealing a NB density of 5.66 ×108 particles/mL and a mean diameter of 84 nm. Applicationof NB solution to microbial biofilms resulted in a 2.16 log reductionfor E. coli and 1.52 log reductionfor S. aureus, along with visible morphologicalchanges such as cell collapse, wrinkling, and matrix disruption. ESRspin trapping confirmed hydroxyl radical formation, but intracellularROS and lipid peroxidation levels were minimal and, in some cases,not significantly different from Milli-Q water controls. After 28days, NBs remained present and continued to demonstrate antimicrobialactivity, biofilm disruption, and some ROS activity. These findingsindicate that although hydroxyl radicals are generated, oxidativestress is not the dominant antimicrobial mechanism under the examinedconditions, suggesting physical biofilm disruption is the primarymode of action.

This study evaluates the feasibility of using microplastics(MPs)as cotracers within multitracer hydrogeological frameworks, alongsideestablished tools such as water-stable isotopes, major and trace elements,and chemicals of emerging concern. Given that plastic production expandedglobally only after the 1950s, MPs can serve as event markers delimitingrecent recharge episodes or, when detected in older groundwater, asindicators of mixing or artificial recharge. MP properties includingparticle size, polymer type, shape, and density carry informationabout particulate transport dynamics and anthropogenic influence thatdissolved tracers cannot provide. The utility of MPs as cotracersis particularly relevant in young groundwater systems directly connectedto surface environments. Key limitations include contamination risks,the influence of artificial recharge on signal interpretation, andthe cost and complexity of MP characterization. Integrating MP withhydrochemical and isotopic data sets, developing context-specificsampling protocols, and prioritizing open data sharing would advancethis emerging methodological approach.

Far-UVC at 222 nm is a promising alternative to conventionalUVat 254 nm, offering potent antimicrobial efficacy and in situ oxidationvia radical generation from water constituents such as nitrate. However,the role of nitrate-derived reactive species in microbial inactivationremains unclear. This study quantitatively evaluates the impact ofnitrate-driven radical production by Far-UVC on microbial disinfectionusing krypton chloride (KrCl*) excimer lamps. MS2 and T1UV bacteriophageandPseudomonas aeruginosa inactivationwere evaluated at environmentally relevant nitrate concentrations(0–8 mg N L–1). For MS2, 222 nm achievedhigher inactivation rates than 254 nm, with 4 mg N L–1 nitrate significantly enhancing reduction, attributed to radicalproduction from nitrate photolysis. Quenching with tert-butyl alcohol (TBA) confirmed hydroxyl radical (•OH) as thedominant species, while reactive nitrogen species (RNS) contributedminimally. T1UV exhibited high intrinsic sensitivity to 222 nm directphotolysis, and P. aeruginosa showednegligible enhancement from radicals, indicating limited oxidativecontribution. Apparent biomolecular rate constants, quantified forMS2 and T1UV, were 1.60–5.14 × 1010 M–1 s–1 for •OH and 8.79 × 104–1.46 × 105 M–1 s–1 for RNS. Coupled with radical kinetic modeling, these findings demonstratethat •OH governs oxidative effects in Far-UVC/nitrate systemsfor microorganisms, with implications for the treatment of nitrate-containingwastewater and water.

Gadolinium (Gd) has emerged as a trace contaminant inaquatic environmentsdue to the widespread use of gadolinium-based contrast agents (GBCAs)in magnetic resonance imaging (MRI) diagnostics. This study evaluateshow preservation conditions, including temperature, acidification,and filtration, affect the stability of Gd chelates in three watermatrices (deionized water, tap water, and river water) using inductivelycoupled plasma mass spectrometry (ICP-MS) for total Gd quantificationand ion chromatography coupled with ICP-MS (IC-ICP-MS) for individualGBCA quantification. Across all experiments, the linear GBCA was the most susceptible to degradation, with acidification and ion-richwaters accelerating their dissociation, while macrocyclic agents remainedmore stable. Freezing provided no preservation benefit and sometimesintroduced artifacts possibly related to freeze-concentration effects.Filtration improved recoveries in river water by reducing interactionswith particulates and microbial activity, and refrigeration sloweddegradation but did not fully prevent it in complex matrices. Thesepatterns show that certain preservation choices can alter apparentspeciation and lead to underestimation of linear chelates and misinterpretationof GBCA sources. The results provide standardized preservation protocolsfor sample handling, including avoiding acidification, minimizingstorage time, and refrigerating samples when immediate analysis isnot possible.

Engineered water systems operate under diverse chemicaland physicalconditions that influence disinfection efficiency. Hot water networks(HWNs) exemplify this issue, as thermal control is costly and ineffectivein cooled sections, and chlorine degrades rapidly at elevated temperatures.Consequently, HWNs remain challenging for controlling pathogens suchas Legionella pneumophila. SustainedHWN protection requires a thermally resilient, persistent disinfectant.This study evaluated the stability and efficacy of silver-stabilizedhydrogen peroxide (SSHP) in ultrapure, synthetic, and chloraminatedmunicipal tap waters incubated at elevated temperatures for up to72 h. Culture-based enumeration showed that SSHP antimicrobial efficacyincreased with temperature, achieving >2.4-log reductions of L. pneumophila within 5 min at 55 °C. SSHP retainedfull biocidal activity after 72 h at 60 °C in synthetic tap water,whereas free chlorine lost antimicrobial activity after 24 h. In municipalwaters, total and free chlorine decayed below recommended thresholdswithin 24–40 h at 60 °C, whereas SSHP retained effectiveresiduals after 72 h. Although these controlled experiments cannotcapture real-system complexity, SSHP persisted under thermal conditionsthat accelerated chlorine decay, supporting its use as a resilientHWN disinfectant. This work demonstrates how system-specific evaluationof disinfectants can inform improved strategies for managing microbialrisks in water systems.

We investigated thefate and transformation of dissolved organicnitrogen (DON) during biological nitrogen removal (BNR) cotreatmentof landfill leachate and municipal sewage. Three sequencing batchreactors (SBRs) were operated with high-, medium-, and no-leachateinputs. Systems were maintained at a solids retention time of 15 daysand hydraulic retention time of 1 day, with methanol addition to supportdenitrification. Analytical methods included Fourier transform ioncyclotron resonance mass spectrometry (FTICR-MS), Fourier transforminfrared spectroscopy (FTIR), carbon-13 nuclear magnetic resonance(13C NMR), 16S rRNA gene sequencing, and algal bioassays.All reactors achieved ∼99% ammonium removal and 87–92%total nitrogen removal, with effluent nitrate < 1.1 mg N/L. DONremained the dominant nitrogen form (73–80% of total nitrogen),with concentrations of 5.5, 6.5, and 2.2 mg N/L. FTICR-MS showed morebioavailable protein-like DON in high-leachate conditions (20%) andmore refractory lignin-like DON in medium-leachate conditions (60%).Algal bioassays indicated limited short-term bioavailability. Resultsdemonstrate that while BNR effectively removes dissolved inorganicnitrogen, it produces DON-rich effluent with composition-dependentecological implications.

Subterranean estuaries play a key role in the land-oceaninterfaceby modulating groundwater-borne and recycled solutes discharged tothe coast. Despite their importance for coastal ecosystems, the sensitivityof these systems to human activities is still unknown. To addressthis gap, dissolved organic matter (DOM) and dissolved inorganic nutrientsof a pristine site were compared with those from two nearby, semiurbansites characterized by contrasting oxygen conditions. The local aquiferssurrounding the semiurban subterranean estuaries contained more nitrogen,silicate, and DOM of higher molecular weight than the aquifers surroundingthe pristine site. Despite the different chemical composition of thearriving fresh groundwater, N/P ratios and the quantity of humic-likeDOM compounds at the pristine site were intermediate between thoseof the two semiurban sites. This pattern reflected the intermediatepermeability and oxygenation of the pristine beach, highlighting therole of the sediment matrix in modulating the exported solutes. Enhancedoxygenation at one semiurban site resulted from a human-derived gravellayer that increased sediment permeability and reduced internal residencetimes. The anthropogenic alteration of the sediment permeability hada greater influence on the nutrients and DOM found in subterraneanestuaries than did the chemical composition of the inland aquifers.

This study compared the performance of ozonation (O3), anodic oxidation (AO), and electro-Fenton (EF) as advancedoxidationprocesses (AOPs) in the degradation and mineralization of two prevalentpharmaceutical pollutants: sulfamethoxazole (SMX) and hydrochlorothiazide(HCTZ). The effects of varying currents (150–500 mA) on AOand different Fe2+ concentrations (0–42 mg L–1) on EF were examined. Both EF and O3 achievedfull removal of SMX and HCTZ, whereas AO resulted in 90% removal.EF demonstrated the highest mineralization efficiency, with 88% totalorganic carbon (TOC) removal, followed by AO at 74% and O3 at 24%. Investigations into the degradation pathways of SMX andHCTZ under each AOP revealed identical degradation mechanisms forEF and AO, with hydroxyl (•OH) radicals playinga crucial role. When tested on real municipal effluent, EF showedsuperior mineralization efficiency and was least affected by the watermatrix. This study underscores the effectiveness of EF in the degradationand mineralization of pharmaceutical pollutants, presenting it asa viable option for large-scale wastewater treatment. This work providesthe first side-by-side benchmark of O3, AO, and the combinedAO + EF process for a SMX/HCTZ mixture while jointly evaluating kinetics,TOC mineralization, transformation products, and real-effluent matrixeffects.