Environmental Science & Technology Letters Environ.最新文献

Cyanophycin is a nitrogen- and carbon-rich reserve biopolymer conserved across diverse microbial taxa and ecological habitats, yet its in situ distribution and ecological role remain poorly understood due to limitations in existing detection methods. Here, we present a high-resolution, label-free, and extraction-free method for detecting and semiquantifying intracellular cyanophycin using single-cell Raman spectroscopy (SCRS) integrated with explainable machine learning. Genetically engineered cyanophycin-producing and nonproducing strains of Acinetobacter baylyi and Escherichia coli are used to provide robust positive and negative controls. Our explainable machine learning approach uncovered that Raman peaks at 898.0, 982.0, 1230.0, and 1674.0 cm^–1 should be used to identify intracellular cyanophycin. A linear dose–response relationship (R² = 0.9924) confirmed the semiquantitative capability of SCRS for intracellular cyanophycin detection. In a proof-of-concept study using full-scale enhanced biological phosphorus removal system biomass spiked with engineered cyanophycin-producing A. baylyi ADP1-ISx, SCRS successfully detected cyanophycin-positive cells within complex microbial matrices. These findings establish SCRS as a powerful tool for noninvasive monitoring of nitrogen polymer storage in environmental microbiomes at the single-cell level, offering new opportunities for understanding and managing microbial nitrogen cycling in engineered ecosystems.

Textiles used in firefighting turnout gear were previously treated or manufactured with per- and polyfluoroalkyl substances (PFAS) to provide water and oil repellency, help pass flammability requirements, and provide increased breathability for heat relief. Due to concerns about potential exposure and health risks, manufacturers developed non-PFAS-treated textiles; however, new chemistries remain undisclosed, particularly in moisture barriers that replaced expanded polytetrafluoroethylene (ePTFE). To probe new chemistries that may be used in these textiles, this study tested 12 used turnouts manufactured between 2013 and 2024, including three advertised as non-PFAS-treated. All three layers of each garment were separately tested for 52 PFAS and 19 brominated flame retardants (BFRs) using mass spectrometry and for total fluorine and bromine using combustion ion chromatography (CIC). BFRs were found in significantly higher concentrations (p < 0.01) compared to PFAS, and in all three layers of the garments tested. Notably, non-ePTFE moisture barriers contained decabromodiphenyl ethane (DBDPE), a BFR, at concentrations ranging from 7,290 to 10,600 ng/cm², indicating intentional addition rather than contamination during use. CIC and nontargeted GC-HRMS analyses of the moisture barriers also confirmed that nine garments from one manufacturer had intentional applications of polymeric BFRs while three garments from another manufacturer did not. These results highlight a need to study BFR exposures among firefighters.

In January 2025, a series of severe wildfires in Los Angeles County burned over 50000 acres, destroyed over 16000 structures, and caused 30 fatalities. These fires, driven by intense Santa Ana winds, rank among the most destructive and deadliest fires in California’s history. Beyond the destruction and loss of lives, these fires also contributed to unhealthy levels of pollutants, such as fine particulate matter (PM_2.5), which cause increased respiratory and cardiopulmonary morbidity, yet this smoke-specific mortality burden is not routinely documented in official reports of wildfire damage and losses. By employing high-resolution air-quality forecast data, we quantify the excess mortality from smoke exposure during a wildfire episode in Los Angeles County in 2025. We found unhealthy air quality in the most populous census tracts immediately after the fire outbreak that persisted for several days. We estimated a total of 14 unaccounted excess deaths from acute wildfire smoke exposure, which is equivalent to 47% of direct fire fatalities. Our study shows that excess mortality from smoke exposure, even for a few days, causes increased mortality, which requires consideration for a comprehensive assessment of wildfires.

Aqueous film-forming foams (AFFFs) are a major source of per- and polyfluoroalkyl substances (PFAS) contamination in groundwater and soil. Although PFAS sorption is known to depend on the properties of solid matrices, the roles of organic matter and iron (hydr)oxides remain poorly understood, especially for polyfluorinated compounds. To investigate the interplay between particulate organic matter and iron (hydr)oxides in PFAS-contaminated subsurface environments, we studied the partitioning of neutral, cationic, and anionic PFAS in AFFF to well-characterized solids using the mixed-mode solid-phase extraction (SPE) technique combined with the total oxidizable precursor (TOP) assay. Our results indicated that organic matter consistently enhanced PFAS sorption. In contrast, the effect of goethite, a representative iron-containing mineral, on PFAS sorption varied with the PFAS charge. Using three different AFFFs, we found that anionic PFAS exhibited strong sorption regardless of the organic matter content, while cationic and zwitterionic PFAS sorbed poorly. These trends were more pronounced for iron-coated sand, which showed a higher affinity for anionic PFAS. Treatment with ascorbate, a mild reductant, released PFAS associated with iron (hydr)oxides. These findings highlight the importance of iron (hydr)oxides in the retention of anionic PFAS and could be leveraged to manage PFAS mobility through subsurface iron amendments or in situ iron (hydr)oxide formation/dissolution.

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.