Environmental Science & Technology Letters Environ.最新文献

The antiozonant 6PPD is commonly added to rubber tires to protect the rubber from ozone attack. Recent studies have illustrated the acute toxicity of its transformation product 6PPD-quinone (6PPD-Q) toward various salmonid fishes. Most studies measuring environmental levels of 6PPD-Q have focused on release from tire wear particles generated on paved roads, with less emphasis on recycled tires at the end of service life. Recycled tires are often converted into landscaping materials, resulting in 6PPD-containing rubber being exposed to ozone and rain, potentially leaching 6PPD-Q. However, the magnitude and duration of these additional releases are presently not known. To address this, we designed a long-term outdoor leaching study to quantify 6PPD-Q release from rubber tire crumb and rubber tire mulch under environmental conditions using liquid chromatography high-resolution mass spectrometry. Measured concentrations ranged from 1.81 to 34.5 μg/L, with a median concentration of 10.6 μg/L. Environmental factors potentially affecting 6PPD-Q concentrations in the leachate were identified using multiple linear regression models. In this way, we could demonstrate that unintended leaching of 6PPD-Q can occur under environmental conditions and highlight multiple factors that influence those outcomes. Ultimately, this paper contributes much-needed data on the sources of 6PPD-Q beyond paved roads.

Patterns of point-source bacteria pollution remain underinvestigated, despite the long-standing implementation of the National Pollutant Discharge Elimination System (NPDES) and its extensive data. Using NPDES pathogen loads measured at permitted outfalls before entering receiving waters (2010–2022), we analyzed their spatiotemporal distribution. We then applied linear mixed models to examine the relationships among racial composition, economic disadvantages, housing characteristics, and pathogen loads across urban–suburban–rural gradients, revealing differences in community exposure risk. We also tested whether pathogens sourced from domestic sewage and wastewater exhibited different patterns. In urban areas, the poverty rate was positively associated with pathogen loads from domestic sewage but not wastewater, suggesting that centralized wastewater systems may mitigate pollution disparities. In suburban areas, low-income census tracts tend to have higher pathogen disparities from wastewater. In rural areas, larger Hispanic/Latino and Black populations were associated with higher pathogen loads from both sources, while the poverty rate was only associated with wastewater pathogen loads. Results suggest that centralized systems are not equitable in Texas rural areas, while decentralized and domestic systems might have insufficient data. The findings underscore the multifaceted factors associated with point-source pathogen pollution patterns and emphasize the need for context-specific interventions according to pollutant sources and urbanization levels.

Perchlorate (ClO₄^–) contamination in water poses significant public health risks due to its endocrine-disrupting properties and resistance to degradation by conventional chemical treatment methods. The concerns about oxychlorine anions (ClO_x^–) also impact destruction technologies for perfluoroalkyl and polyfluoroalkyl substances (PFAS). The stepwise reduction of ClO₄^– often shows intriguing chemical challenges due to the unique reactivity of ClO_x^– intermediates, which motivates innovation in process design. This study presents a two-stage treatment train combining photochemical treatment with catalytic reduction to achieve complete ClO₄^– removal in complex water matrices. The optimized UV/sulfite + iodide (UV/S+I) system achieved efficient ClO₄^– reduction. Surprisingly, the chlorate (ClO₃^–) intermediate is more sluggish than ClO₄^– under UV/S+I treatment. To overcome this challenge, we integrated the H₂+Mo–Pd/C catalytic process as a post-treatment and achieved rapid ClO₃^– reduction to Cl^–. The high performance of the treatment train is validated in practical matrices of tap water and synthetic ion exchange resin regenerant brine. The photochemical stage also degraded nitrate (NO₃^–) and PFAS, which inhibited ClO₄^– reduction at various levels. The treatment train overcomes individual technology limitations while maintaining robustness against the challenging water matrices, offering a practical solution to perchlorate-related scenarios that require comprehensive treatment of various pollutants.

Granular activated carbon (GAC) adsorption is the most widely used method for removing per- and polyfluoroalkyl substances (PFAS). Thermal regeneration of spent GAC is currently preferred over solvent-based methods because regenerating both solvents and GAC while preserving the adsorbent performance remains a significant challenge. Here, we proposed an innovative “extract-and-degrade” strategy in which organic solvents, used as GAC extractants, are directly exposed to UV 254 nm irradiation, allowing effective defluorination under mild conditions while simultaneously allowing solvent recycling. Among 18 tested solvents, the aprotic solvent acetonitrile (ACN) resulted in complete PFOA degradation and >70% defluorination within 24 h under UV irradiation. This performance is attributed to the activation of PFOA molecules induced by ACN’s high polarity, which facilitates electron transfer from the negatively charged −C≡N group of ACN to the positively charged −OH group of PFOA. Studies on perfluorocarboxylic acids (PFCAs) with different chain lengths revealed that longer chains are more prone to electron capture for subsequent degradation steps, consistent with their adiabatic electron affinity (AEA) values. Finally, both GAC and ACN demonstrated excellent stability and reusability in cyclic tests. This work sheds light on previously unexplored photochemistry in nonaqueous media and highlights the potential of organic solvents as recyclable platforms for PFCAs defluorination and adsorbent regeneration in water purification systems.

Chlorophenols are prevalent pollutants in aquatic environments that often require advanced oxidation processes (AOPs) for their effective removal. Polymerization has emerged as a promising pathway within AOPs for transforming and eliminating phenolic contaminants. Understanding the early-stage polymerization dynamics of chlorophenols is critical for optimizing the treatment efficiency and minimizing secondary contamination. In this study, surface-enhanced Raman spectroscopy (SERS) was employed to in situ investigate the polymerization of chlorophenols during the initial 2 min of sulfate radical-based AOPs. Structure-dependent interactions distinguished π-mediated physisorption of protonated chlorophenols from the covalent Au–O chemisorption of phenolates. Upon sulfate radical generation, chlorophenols were rapidly oxidized and coupled, forming polymeric radical species with enhanced surface affinity for gold nanoparticle (AuNP) surfaces. Displacement of preadsorbed citrate and chloride by these products served as a proxy for evaluating polymerization potential. Polymerization and adsorption behavior were governed by the halogenation pattern and protonation state, with higher π-electron density correlating with greater reactivity. These findings provide mechanistic insights into radical-mediated surface transformations and offer a potential strategy for in situ AuNP surface functionalization. This work advances the understanding of polymerization kinetics during AOPs and supports the development of plasmonic nanomaterials for environmental sensing and remediation.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants associated with adverse health outcomes, yet the mechanisms underlying their toxicity remain incompletely understood. This Review synthesizes current insights into PFAS toxicity derived from studies using the invertebrate model organism Drosophila melanogaster. Evidence from this model suggests that PFAS promote tumor invasion through MAPK/UPR signaling and metabolic reprogramming, disrupt metabolic homeostasis via insulin signaling and PPAR-like pathways, and induce neurotoxicity via mitochondrial dysfunction, oxidative stress, and calcium dysregulation. Both legacy PFAS (e.g., PFOA, PFOS) and emerging alternatives (e.g., GenX/HFPO-DA) perturb circadian rhythms, impair sleep–wake cycles, compromise reproduction through germ cell targeting and endocrine disruption, and delay development. Notably, low-dose exposures (≤0.05 μM; ≤0.02 μg/mL)─comparable to environmentally relevant or certain human exposure levels─can elicit subtle yet significant metabolic disturbances, circadian rhythm alterations, reduced fecundity, and transgenerational effects, implicating epigenetic mechanisms. Collectively, these findings highlight Drosophila’s value in delineating evolutionarily conserved toxicity pathways of PFAS. However, critical research gaps remain, including organ-specific limitations, mixture effects, and the need for chronic, environmentally relevant exposure paradigms to enhance translational relevance for human health.

Wastewater-based surveillance (WBS) has emerged as a novel public health tool for monitoring the prevalence of community disease. There is great interest in expanding the list of potential targets to those that are difficult to clinically monitor. Lyme disease is the most common tick-borne illness in the United States, accounting for 82% of all clinically reported cases. It is also notoriously hard to diagnose and can become a chronic condition if not treated early. The objective of this study was to determine the feasibility of WBS to monitor Lyme disease and analyze sample data for trends in comparison with public health data, as reported by the Michigan Department of Health and Human Services. Wastewater samples were collected over the course of one year and molecular tests were implemented to detect Borrelia species, the causative bacteria of Lyme disease. Two Borrelia sp. targets (fliD and 16S rRNA) showed significant correlation (p = 0.0028; p < 0.05 is significant) with clinical disease trends (assessed at the county level), with WBS data lagging behind clinical data by 11 weeks. More data are needed to fully understand the connections between WBS data and clinical data. This represents the first study to monitor the causative agent of Lyme disease via WBS.