Environmental Science & Technology Letters Environ.最新文献

Many “smart” and “fitness” watch bands are advertised to contain fluoroelastomers, a type of synthetic rubber designed to be resilient against skin oils and sweat. Fluoroelastomers, which are considered a polymeric form of per- and polyfluoroalkyl substances (PFAS), have historically involved the use of shorter-chain PFAS as surfactants in the polymerization process. In this study, 22 watch bands were analyzed across numerous brands and price points for the presence of PFAS. Products were first screened for total fluorine using particle-induced gamma-ray emission spectroscopy on the surface of these bands, and 15 of the 22 watch bands contained total F concentrations >1% fluorine, suggesting the widespread use of fluoroelastomers in this product category. Watch bands then underwent solvent extraction and targeted LC-MS/MS analysis for 20 PFAS. Perfluorohexanoic acid (PFHxA) was the most frequently detected compound with concentrations from <LoD to 16662 ng/g. A subset of six watch bands also underwent direct total oxidative precursor (dTOP) assay to determine the presence of PFAS precursors. The very high concentrations of PFHxA readily extractable from the surfaces of fluoroelastomer watch bands, together with the current limited knowledge on the dermal absorption of PFHxA, demonstrate the need for more comprehensive exposure studies of PFHxA.

Hazardous air pollutant (HAP) emission regulations in the US often rely on modeled estimates of ambient exposures. Model accuracy compared to real-world measurements of HAPs is crucial for understanding and mitigating exposure and associated health harms. While previous work shows ambient measurements are higher than regulatory model estimates, the implications for health risk assessments are rarely discussed. We provide a comprehensive comparison of the modeled and measured concentrations at 489 US monitoring sites for 79 HAPs. We quantify how model-measurement discrepancies affect the estimation of the exposure and risk of adverse health effects. Measurements were higher than modeled concentrations in 74% of comparisons over all monitors, chemicals, and years assessed, with measurements a median 2 (IQR 1–9) times higher than model estimates. Measurements exceeded noncancer adverse health effect thresholds, while the model did not (model false negatives) for nine pollutants. Adjusting for model bias in two industrial centers, we found the number of people with multipollutant exposure above the US EPA’s acceptable excess lifetime cancer risk increased by a factor of 30 times in Houston, Texas, and 13 times in Baton Rouge, Louisiana. Our results imply that assessments relying exclusively on models like those we evaluated likely underestimate the spatial extent and magnitude of health hazards and risk.

Addressing methane emissions across the liquefied natural gas (LNG) supply chain is key to reducing climate impacts of LNG. Actions to address methane emissions have emphasized the importance of the use of measurement-informed emissions inventories given the systematic underestimation in official greenhouse gas (GHG) emission inventories. Despite significant progress in field measurements of GHG emissions across the natural gas supply chain, no detailed measurements at US liquefaction terminals are publicly available. In this work, we conduct multiscale, periodic measurements of methane and carbon dioxide emissions at two US LNG terminals over a 16-month campaign. We find that methane emission intensity varied from 0.007% to 0.045%, normalized to methane in LNG production. Carbon dioxide emissions accounted for over 95% of total GHG emissions using 100-year global warming potential (GWP) for methane. Thus, contrary to observations across other natural gas supply chain segments, we find that reported GHG emissions intensity closely matches measurement informed GHG emissions intensity of 0.24–0.27 kg CO₂e/kg CH₄. In the context of developing LNG supply chain emissions intensity, we conclude that the use of the Greenhouse Gas Reporting Program emissions intensity provides reasonably accurate estimates of total GHG emissions at LNG terminals.

Addressing methane emissions across the liquefied natural gas (LNG) supply chain is key to reducing climate impacts of LNG. Actions to address methane emissions have emphasized the importance of the use of measurement-informed emissions inventories given the systematic underestimation in official greenhouse gas (GHG) emission inventories. Despite significant progress in field measurements of GHG emissions across the natural gas supply chain, no detailed measurements at US liquefaction terminals are publicly available. In this work, we conduct multiscale, periodic measurements of methane and carbon dioxide emissions at two US LNG terminals over a 16-month campaign. We find that methane emission intensity varied from 0.007% to 0.045%, normalized to methane in LNG production. Carbon dioxide emissions accounted for over 95% of total GHG emissions using 100-year global warming potential (GWP) for methane. Thus, contrary to observations across other natural gas supply chain segments, we find that reported GHG emissions intensity closely matches measurement informed GHG emissions intensity of 0.24-0.27 kg CO₂e/kg CH₄. In the context of developing LNG supply chain emissions intensity, we conclude that the use of the Greenhouse Gas Reporting Program emissions intensity provides reasonably accurate estimates of total GHG emissions at LNG terminals.

Rapid retreat of glaciers accompanied by the release of mercury (Hg) in the Tibetan Plateau (TP), known as the “Asian water tower”, threatens the water security of billions of people living downstream in China and Southwest Asia. It is thus crucial to identify the sources and transformations of Hg in TP ecosystems. Here we measured Hg isotopes in water samples collected from two adjacent TP rivers, the Upper Mekong River (UMR) and the Upper Salween River (USR), to better constrain Hg geochemistry and its export under climate changes. We found similar δ²⁰²Hg and Δ²⁰⁰Hg variations in the two rivers, which reflect a similarly mixed contribution of atmospheric precipitation and catchment input to both rivers. However, in general, USR shows notably higher Δ¹⁹⁹Hg than UMR. As the catchment of USR has a larger glacier-covered area than UMR, we propose that the higher Δ¹⁹⁹Hg of USR water samples reflects a higher glacier Hg input, which is typically characterized by extremely positive Δ¹⁹⁹Hg. Our study indicates that increasing glacier melting, vegetation greening and precipitation induced by climate changes may enhance Hg export from TP, potentially endangering the fragile Tibetan ecosystem and human health.

Influenza A viruses present important public health risks, with recent outbreaks of highly pathogenic avian influenza (HPAI) H5N1 in dairy cattle raising concerns about potential transmission through raw milk consumption. This study investigated the persistence of influenza A virus H1N1 PR8 (IAV PR8) in raw cow milk at 4 °C. We found a first-order decay rate constant of −2.05 day^–1 equivalent to a T₉₉ of 2.3 days. Viral RNA remained detectable for at least 57 days with no degradation. Pasteurization (63 °C for 30 min) reduced infectious virus to undetectable levels and reduced viral RNA concentrations, but reduction was less than 1 log₁₀. These findings highlight the potential risk of zoonotic virus transmission through raw milk consumption and underscore the importance of milk pasteurization. The prolonged persistence of viral RNA in both raw and pasteurized milk has implications for food safety assessments and environmental monitoring, particularly in the context of the environmental surveillance of influenza viruses.

Detecting and quantifying tire wear particles (TWPs) in the environment pose a unique environmental challenge due to their chemical complexity. There are emerging concerns around TWPs due to their potential high numbers of particles released, outnumbering microplastics, as well as the leaching of toxic additives such as 6-PPD which has been linked to the death of salmon even when present at very low levels (<0.1 μg/L). Analytical techniques such as pyrolysis gas chromatography mass spectrometry (Py-GC/MS) and thermal extraction-desorption gas chromatography mass spectrometry (TED-GC/MS) have been used but also demonstrate limitations including low sample mass, low sample throughput, and complex characterization and quantification procedures. This work aims to overcome these challenges by developing a new approach which utilizes a coupling between thermogravimetric analysis (TGA) and gas chromatography-mass spectrometry (GC/MS). This work is the first to harness conventional TGA-GC/MS for the analysis of tire rubber, with the detection of additives such as 6-PPD, while also pioneering a novel mode of operation, PyroTGA-GC/MS, using fast heating to enable robust quantitative analysis of TWPs in road dust. The limits of detection and quantification of 0.08/0.16 μg and 0.20/0.40 μg for SBR and PI, respectively, are lower than those achieved using Py-GC/MS and TED-GC/MS for SBR and align with those achieved for PI. This study reveals a clear link between the ratio of PI to SBR and the proportion of heavy goods vehicles. This work solves key issues in tire particle analysis related to sample size and throughput. By overcoming these limitations, we introduce a technique that provides an economically viable solution for large-scale commercial analysis of tire rubber and particles.

Detecting and quantifying tire wear particles (TWPs) in the environment pose a unique environmental challenge due to their chemical complexity. There are emerging concerns around TWPs due to their potential high numbers of particles released, outnumbering microplastics, as well as the leaching of toxic additives such as 6-PPD which has been linked to the death of salmon even when present at very low levels (<0.1 μg/L). Analytical techniques such as pyrolysis gas chromatography mass spectrometry (Py-GC/MS) and thermal extraction-desorption gas chromatography mass spectrometry (TED-GC/MS) have been used but also demonstrate limitations including low sample mass, low sample throughput, and complex characterization and quantification procedures. This work aims to overcome these challenges by developing a new approach which utilizes a coupling between thermogravimetric analysis (TGA) and gas chromatography–mass spectrometry (GC/MS). This work is the first to harness conventional TGA-GC/MS for the analysis of tire rubber, with the detection of additives such as 6-PPD, while also pioneering a novel mode of operation, PyroTGA-GC/MS, using fast heating to enable robust quantitative analysis of TWPs in road dust. The limits of detection and quantification of 0.08/0.16 μg and 0.20/0.40 μg for SBR and PI, respectively, are lower than those achieved using Py-GC/MS and TED-GC/MS for SBR and align with those achieved for PI. This study reveals a clear link between the ratio of PI to SBR and the proportion of heavy goods vehicles. This work solves key issues in tire particle analysis related to sample size and throughput. By overcoming these limitations, we introduce a technique that provides an economically viable solution for large-scale commercial analysis of tire rubber and particles.

Sustained browning of northern waters has prompted inquiries into the drivers of increasing concentrations of organic matter. While reduced sulfur deposition is a key cause, an increasing role of hydrologic mechanisms as a result of cleaner air and progressing climate change has been repeatedly suggested. How these controls act remains however unclear. Here we examine over 30 years of organic carbon concentration and discharge data from four reference streams located across Norway to pinpoint consistent hydrologic changes that may promote water browning. Stable slopes with changing intercepts of the concentration-discharge relations indicate that the influence of air pollution on soil solution chemistry is plausible, supporting available chemical explanations from a hydrologic perspective. Decreasing ratios of concentration to discharge variability, observed in autumn over the years, point to less spatial heterogeneity of the sources of organic carbon. A clear rise in the frequency of runoff events, which increases the opportunities for dissolved organic carbon to transit from soil to streams, also indicates higher hydrologic connectivity and more even mobilization of carbon sources. More connected sources and more frequent runoff events, which jointly enhance the likelihood of organic carbon reaching rivers, may thus contribute to the observed browning of northern waters.