Environmental Science & Technology Letters Environ.最新文献

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants found in groundwater sources and a wide variety of consumer products. In recent years, electrochemical approaches for the degradation of these harmful contaminants have garnered a significant amount of attention due to their efficiency and chemical-free modular nature. However, these electrochemical processes occur in open, highly non-equilibrium systems, and a detailed understanding of PFAS degradation mechanisms in these promising technologies is still in its infancy. To shed mechanistic insight into these complex processes, we present the first constant-electrode potential (CEP) quantum calculations of PFAS degradation on electrified surfaces. These advanced CEP calculations provide new mechanistic details about the intricate electronic processes that occur during PFAS degradation in the presence of an electrochemical bias, which cannot be gleaned from conventional density functional theory calculations. We complement our CEP calculations with large-scale ab initio molecular dynamics simulations in the presence of an electrochemical bias to provide time scales for PFAS degradation on electrified surfaces. Taken together, our CEP-based quantum calculations provide critical reaction mechanisms for PFAS degradation in open electrochemical systems, which can be used to prescreen candidate material surfaces and optimal electrochemical conditions for remediating PFAS and other environmental contaminants.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants found in groundwater sources and a wide variety of consumer products. In recent years, electrochemical approaches for the degradation of these harmful contaminants have garnered a significant amount of attention due to their efficiency and chemical-free modular nature. However, these electrochemical processes occur in open, highly non-equilibrium systems, and a detailed understanding of PFAS degradation mechanisms in these promising technologies is still in its infancy. To shed mechanistic insight into these complex processes, we present the first constant-electrode potential (CEP) quantum calculations of PFAS degradation on electrified surfaces. These advanced CEP calculations provide new mechanistic details about the intricate electronic processes that occur during PFAS degradation in the presence of an electrochemical bias, which cannot be gleaned from conventional density functional theory calculations. We complement our CEP calculations with large-scale ab initio molecular dynamics simulations in the presence of an electrochemical bias to provide time scales for PFAS degradation on electrified surfaces. Taken together, our CEP-based quantum calculations provide critical reaction mechanisms for PFAS degradation in open electrochemical systems, which can be used to prescreen candidate material surfaces and optimal electrochemical conditions for remediating PFAS and other environmental contaminants.

Scented wax melts are being popularized as a safer, nontoxic alternative to traditional candles and incense for indoor aromatherapy. We performed field measurements in a residential test house to investigate atmospheric nanoparticle formation from scented wax melt use. We employed a high-resolution particle size magnifier-scanning mobility particle sizer (PSMPS) and a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) for real-time monitoring of indoor atmospheric nanoparticle size distributions and terpene mixing ratios, respectively. Our findings reveal that terpenes released from scented wax melts react with indoor atmospheric ozone (O₃) to initiate new particle formation (NPF) events, resulting in significant indoor atmospheric nanoparticle concentrations (>10⁶ cm^-3) comparable to those emitted by combustion-based scented candles, gas stoves, diesel engines, and natural gas engines. We show that scented wax melt-initiated NPF events can result in significant respiratory exposures, with nanoparticle respiratory tract deposited dose rates similar to those determined for combustion-based sources. Our results challenge the perception of scented wax melts as a safer alternative to combustion-based aromatherapy, highlighting the need for further research on the toxicological properties of the newly formed nanoparticles to better understand their environmental health implications.

Scented wax melts are being popularized as a safer, nontoxic alternative to traditional candles and incense for indoor aromatherapy. We performed field measurements in a residential test house to investigate atmospheric nanoparticle formation from scented wax melt use. We employed a high-resolution particle size magnifier-scanning mobility particle sizer (PSMPS) and a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) for real-time monitoring of indoor atmospheric nanoparticle size distributions and terpene mixing ratios, respectively. Our findings reveal that terpenes released from scented wax melts react with indoor atmospheric ozone (O₃) to initiate new particle formation (NPF) events, resulting in significant indoor atmospheric nanoparticle concentrations (>10⁶ cm^–3) comparable to those emitted by combustion-based scented candles, gas stoves, diesel engines, and natural gas engines. We show that scented wax melt-initiated NPF events can result in significant respiratory exposures, with nanoparticle respiratory tract deposited dose rates similar to those determined for combustion-based sources. Our results challenge the perception of scented wax melts as a safer alternative to combustion-based aromatherapy, highlighting the need for further research on the toxicological properties of the newly formed nanoparticles to better understand their environmental health implications.

The recent global resurgence of measles in 2023–2024, despite vaccine preventability, underscores a critical public health issue, largely due to reduced vaccination coverage during the SARS-CoV-2 pandemic. In response, Ottawa Public Health intensified vaccination efforts in 2023 and 2024. Additionally, a research initiative began in April 2024 to monitor Ottawa wastewater for measles virus (MeV) using established wastewater and environmental surveillance (WES) protocols. Unexpected positive MeV detections through RT-qPCR in Ottawa wastewater─despite no active regional cases─prompted genotypic and retrospective analyses of archived RNA samples dating back to 2020. The genotypic analysis identified positive detection to belong to genotype A, the progenitor strain of the viral vaccines, marking the first report of MeV vaccine RNA in a large catchment area. Linear regression analysis revealed detections aligned with intensified vaccination efforts by Ottawa Public Health. These findings emphasize the importance of integrating genotypic analysis into WES practices to mitigate possible confounding factors, such as vaccine shedding into wastewater. Additionally, this research highlights potential public health applications using MeV WES as a complementary tool. Implementing the findings of this study for MeV WES, and for other re-emerging viruses, could improve public health response and resource allocation.

The recent global resurgence of measles in 2023-2024, despite vaccine preventability, underscores a critical public health issue, largely due to reduced vaccination coverage during the SARS-CoV-2 pandemic. In response, Ottawa Public Health intensified vaccination efforts in 2023 and 2024. Additionally, a research initiative began in April 2024 to monitor Ottawa wastewater for measles virus (MeV) using established wastewater and environmental surveillance (WES) protocols. Unexpected positive MeV detections through RT-qPCR in Ottawa wastewater-despite no active regional cases-prompted genotypic and retrospective analyses of archived RNA samples dating back to 2020. The genotypic analysis identified positive detection to belong to genotype A, the progenitor strain of the viral vaccines, marking the first report of MeV vaccine RNA in a large catchment area. Linear regression analysis revealed detections aligned with intensified vaccination efforts by Ottawa Public Health. These findings emphasize the importance of integrating genotypic analysis into WES practices to mitigate possible confounding factors, such as vaccine shedding into wastewater. Additionally, this research highlights potential public health applications using MeV WES as a complementary tool. Implementing the findings of this study for MeV WES, and for other re-emerging viruses, could improve public health response and resource allocation.

The overperformance of wastewater testing during near-source surveillance, especially in venues where defecation is presumed to be de minimis, such as aircraft and nonresidential schools, suggests the possibility of a non-fecal source. To revisit the possibility of urine as an input, data were compiled from 45 studies on SARS-CoV-2 RNA in the urine of 1924 COVID-19 patients. In general, the reporting quality was extremely low. The estimated pooled prevalence of urinary SARS-CoV-2 RNA shedding is 11.3% (95% CI: 8.4–14.3), which roughly agrees with previous reviews. However, the 2-fold prediction interval and wide range of observed prevalences warrant careful consideration of the variability between studies. Among the eight studies reporting sufficient methodological details to estimate the volume of urine being assayed in a single PCR reaction (i.e., the equivalent sample volume, ESV), the RNA urinary shedding prevalence was normally distributed (r² = 1.00) as a function of the ESV. The explanatory power of the ESV suggests the rarity of SARS-CoV-2 RNA in urine could be a methodological artifact. The findings demonstrate that clinical studies designed for clinically relevant hypotheses could produce data subject to important biases relevant to assessing the feasibility of wastewater surveillance.

Prolific use, mobility, and chemical stability make assessing the fate and transport of per- and polyfluoroalkyl substances (PFAS) particularly complex. New analytical techniques will be required to distinguish between PFAS of different origins and to trace their transport through natural systems. This study assesses the stable carbon (δ¹³C) and sulfur (δ³⁴S) isotopic signatures of PFAS from different sources. Bulk elemental analyzer-isotope ratio mass spectrometry and compound-specific gas chromatograph-isotope ratio mass spectrometry (GC-IRMS) analytical methods were used to measure the δ¹³C and δ³⁴S values of multiple PFAS compounds from various vendors and production lot numbers. PFAS originating from different vendors with different lot numbers and different PFAS species showed distinct δ¹³C isotopic values over a wide range of δ¹³C values (−52.8‰ to −26.9‰). Results indicate that GC-IRMS techniques could be utilized to determine the δ¹³C composition of PFAS present at concentrations typical of environmental samples. Coupling stable isotopic data with co-contaminant or isomer data could help to further differentiate PFAS sources. The development of new environmental forensics tools such as these will be necessary to elucidate the PFAS source and transport in natural systems and may inform remediation and pollution prevention protocols for PFAS.

The corrosion products formed in lead water pipes exert strong control over lead concentrations in tap water. Compositions of pipe scales from different drinking water distribution systems vary in appearance, crystalline phases present, and elemental concentrations. This study is based on 76 harvested pipes from 17 different systems across the United States together with data from previously published research. Factors impacting lead pipe scale composition are identified. The characterization data are compared with chemical equilibrium predictions. The specific crystalline lead carbonate solid present depends on the pH and dissolved inorganic carbon (DIC) concentration. Systems with only hydrocerussite [Pb₃(CO₃)₂(OH)₂] tend to have a higher pH (8.5 ± 0.8) and a lower DIC (1.3 ± 0.6 mM) compared to those of systems with only cerussite (PbCO₃) (pH 7.5 ± 0.2 and DIC of 5.5 ± 1.3). While lead(IV) oxide solids are predicted in all free chlorine systems, they were observed in only 43% of them. Lead phosphate solids are more commonly found in systems using orthophosphate at the highest concentrations. Amorphous materials are present as components of many pipe scales, and these amorphous materials are often rich in aluminum. Equilibrium predictions for lead carbonate, lead(IV) oxide solids, and lead phosphate correspond to the observed presence of these solids with accuracies of 95%, 43%, and 73%, respectively.

Recovering nitrogen (N) and phosphorus (P) from wastewater is crucial for environmental protection and resource sustainability. Chemical precipitation and Mg electrocoagulation, although often studied and applied for N and P recovery as struvite, suffer from inherent drawbacks. The former generates poorly settling sludge and re-releases natural organic matter, while the latter encounters issues such as active anode passivation and complex struvite deposition. We propose and validate a new magnesite-assisted electrochemical system that achieved 100.0% NH₄⁺ and 66.9% PO₄^3– removal in easily recoverable struvite without suffering from anode passivation. The system’s core lies in the in situ utilization of the local low-pH environment established via water electrolysis by the anode-packed magnesite minerals, providing an affordable, passivation-free, and tunable Mg source. Meanwhile, the cathode emerges in a local high-pH atmosphere, serving as the sole site for high-purity and condensed struvite precipitation and collection. On top of technological development, we validate a co-treatment concept for the recovery of struvite from mixed wastewater, demonstrating potential cost savings of 76.9% and a 22.4% reduction in CO₂ emissions. Our work offers a new design for enhanced struvite recovery and outlines a green route for co-managing different waste streams and producing valuable products.