Environmental Science: Processes & Impacts最新文献

Freshwater harmful algal blooms (HABs) pose significant health risks to communities through drinking water sources and contact recreation. Cyanobacteria that drive HABs produce a complex array of secondary metabolites, notably cyanotoxins. The spatiotemporal variability of cyanometabolite mixtures during HAB events remains poorly understood, particularly in agroecosystems, where heavy nutrient loading can alter normal lake dynamics. Therefore, we applied high-resolution mass spectrometry-based suspect screening to characterize cyanometabolite mixture dynamics during active HAB events in two Eastern Iowa lakes as test sites, using time controlled sampling at one lake and locationally controlled sampling at the other. Using the CyanoMetDB to enable complex mixture comparisons alongside ELISA-based microcystin (MC) quantification, we tentatively identified 38 unique cyanometabolites, revealing substantial chemical diversity beyond traditional monitoring targets. Spatial analysis at one of the lakes exhibited dramatic variability across a 104-meter beach, where MC concentrations ranged from 0.65 µg L^-1 (below advisory limits) to 36.86 µg L^-1 (4.6-fold greater than the USEPA health advisory threshold), with metabolite mixtures exhibiting low similarity (cos(θ) = 0.38) for those same sites. Temporal monitoring at the other test lake demonstrated rapid temporal changes, with MC concentrations dropping from 19.98 to 8.64 µg L^-1 within one hour; however, the cyanometabolite mixtures over the same time were similar (cos(θ) = 0.97). Collectively, these findings demonstrate that HAB chemical composition and toxicity fluctuate substantially over short distances and time scales. This first HAB metabolite suspect screening in agroecosystem lakes thus provides a useful initial framework for characterizing overlooked cyanometabolite diversity and tracking chemical dynamics, advancing efforts to better understand, monitor, and mitigate HAB-related exposure.

Unconventional oil and gas development (UOGD) in the Marcellus Shale of southwestern Pennsylvania has raised persistent concerns regarding groundwater quality. Previous work identified potential regional associations between UOGD activity and elevated salinity in heavily drilled counties based on samples collected between 2008 and 2018. Here, we collected 97 water samples from private wells, springs, and streams in 2024 to evaluate whether such associations persist and to assess whether impacts, if present, are regional or highly localized. Sampling targeted previously identified chloride hotspots, decommissioned wastewater impoundments, and recent spills, with comparisons to control locations. Major ions, trace metals, dissolved gases, isotopes, and organic compounds were analyzed and compared with drinking water standards, historical datasets, and proximity to UOGD features while accounting for geologic, hydrogeologic, and topographic controls. Most samples met drinking-water standards, and statistical comparisons revealed no robust regional differences between treatment and control samples after Benjamini-Hochberg correction. Fixed-effects models showed no evidence of widespread groundwater degradation attributable to UOGD. Among spill sites sampled, only one groundwater sample exhibited elevated salinity and brine-associated constituents. Geochemical, isotopic, and topographic evidence suggests this anomaly reflects localized influence from produced water or natural Appalachian Basin brine migrating along deeper flow paths rather than surface transport. Our results indicate that contamination patterns are best explained by highly localized rather than region-wide problems, consistent with rare and localized detectable impacts within the targeted sampling framework used here and highlighting challenges in defining appropriate controls given hydrogeologic heterogeneity. This work emphasizes combining regional screening with targeted, hydrogeology-informed monitoring to assess UOGD-related groundwater contamination.

Metal adsorption in porous environments occurs under flowing conditions, where transport, diffusion, and reaction act on comparable timescales and thermodynamic equilibrium is rarely achieved. To address this non-equilibrium regime at the pore scale, we use a microfluidic-polarographic approach that provides controlled access to short residence times under laminar flow. This study investigates Pb(II) adsorption onto carboxylated polystyrene latex nanoparticles (PSL-COOH) under dynamic flow conditions. Batch experiments show a biphasic behaviour, with rapid electrostatic adsorption followed by slower site-specific binding. Under laminar flow conditions, Pb(II) adsorption reaches ∼97-98% over a wide range of flow rates, corresponding to residence times between 0.9 and 35 s. Reactive transport modelling shows that, although outer-sphere adsorption is intrinsically fast, Pb(II) adsorption within the microfluidic channel remains diffusion-limited under laminar co-flow. Accounting for downstream droplet formation demonstrates that efficient mixing provides a short additional interaction time sufficient to complete Pb(II) adsorption and explain the nearly flow-independent adsorption observed experimentally. These results show that microfluidic-polarographic systems enable controlled investigation of short residence-time adsorption regimes and provide a framework to characterise adsorption under transport-limited, non-equilibrium flow conditions relevant to porous environmental systems.

Organic light-emitting diode (OLED) screens are widely used display products today, yet chemical emissions during normal use and end-of-life handling remain poorly characterized. Here, we conducted two complementary experiments: (i) an adsorption-based collection setup coupled with gas chromatography-high-resolution mass spectrometry (GC-HRMS) to characterize emissions during normal screen operation, and (ii) online pyrolysis-GC-HRMS to examine chemicals generated during thermal treatment at end of life. Temperature-programmed pyrolysis (100-600 °C) was used to probe temperature-dependent release, while layer-resolved high-temperature pyrolysis (600 °C) was used to characterize final products and their layer origins: the display functional laminate (DFL) and the module carrier layer (MCL). Thousands of volatile and semi-volatile organic compounds (VOCs/SVOCs) were detected in both scenarios, with VOCs predominating by number. Pyrolysis profiles were strongly temperature- and layer-dependent, with more compounds originating from the MCL than from the DFL. Suspect screening supported by authentic-standard confirmation identified polycyclic aromatic hydrocarbons, benzene derivatives, and phthalate esters in both scenarios, while siloxane-related and selected nitrogen-containing compounds were observed during pyrolysis, potentially reflecting fragments of OLED-related materials. Targeted quantification indicated that phthalate esters, mainly associated with the MCL, dominated the confirmed emissions. These results provide the first molecular-level picture of chemical emissions from OLED screens during use and thermal treatment.

Bisphenol analogues (BPs) have raised increasing concerns regarding their occurrence and risks in drinking water systems. This study systematically investigated the occurrence, spatial distribution, ecological risks, and human exposure of 14 BPs in surface water, tap water, and commercially available bottled water in Sichuan Province, China. Thirteen to fourteen BPs were detected across the samples, with sum BP concentrations (ΣBPs) ranging from 2.29 to 98.3 ng L^-1 in surface water, 10.5 to 670 ng L^-1 in tap water, and 2.73 to 38.2 ng L^-1 in bottled water. Relatively higher accumulation of ΣBPs was found in surface water from the Northeast Sichuan Economic Zone and the Chengdu Plain Economic Zone (median: 13.0 and 11.1 ng L^-1, respectively), compared to the Panxi Economic Zone (median: 4.27 ng L^-1). Ecological risk assessment indicated that BPA, BPBP, and BPG may pose low to moderate risks to ecosystems, while the estrogenic risk estimated using the estrogen equivalent was negligible. Furthermore, the estimated daily intake (EDI) of BPA from tap water exceeded the tolerable daily intake recommended by the European Food Safety Authority, indicating a potential health risk from dietary exposure.

Biodegradation makes major contributions to the removal of micropollutants from contaminated environments, but the factors that influence the removal rate in specific environments remain unclear. This study examined environmental biochemical oxygen demand (BOD) as a potential indicator of site-specific attenuation rate constants for 47 micropollutants. A modified BOD protocol for water-sediment systems was developed and applied in parallel with a modified OECD 309 biodegradation test on samples collected from 10 sites along an urban wastewater-impacted river. The biodegradation test provided attenuation rate constants for 34 compounds that met quality criteria for at least three sites. After normalizing by sediment dry weight, 23 compounds showed a significant positive correlation (p < 0.05) between BOD and attenuation rate constant, with an average linear regression R² of 0.71. Normalization by BOD significantly (p < 0.05) decreased the observed variability in attenuation rates. If biodegradation mainly occurs through co-metabolism, BOD may act as an integrative indicator of microbial metabolic activity relevant to micropollutant transformation. Our results suggest that a water-sediment BOD test may provide a practical indicator of relative biodegradation rate across sites for a subset of compounds.

Photochemical degradation is a significant pathway controlling the fate of surface oil following marine oil spills; however, the mechanisms governing transformation in oil films remain poorly understood due to the complexity of crude oil mixtures. To address this, we optimized a hydrophobic model system with a representative polycyclic aromatic hydrocarbon (PAH) and sensitizer, specifically benzo[a]pyrene (BaP) and tetracene (TCN), and then validated it with a broader set of hydrocarbons, including both saturated compounds and PAHs. Scavenger experiments confirmed that TCN generates singlet oxygen (¹O₂) as the dominant oxidant, while TCN transformation products, particularly quinones, sustained photoreactivity over time. Application of the system to mixtures of hydrocarbons and crude oil showed that only larger PAHs (≥3 rings) underwent significant, sensitizer-enhanced loss. In contrast, monoaromatics, naphthalenes, and saturated compounds remained stable under the studied conditions. Replacing TCN with crude oil as a sensitizer mirrored the degradation pattern observed in the TCN-based system, validating the role of indirect photooxidation in petroleum. These results indicate that indirect, sensitizer-driven pathways selectively control the transformation of PAHs in oil films and that evolving sensitizer pools prolong photoreactivity. Overall, the model system provides a tractable framework for dissecting hydrocarbon-class-specific oil photooxidation mechanisms in a homogeneous hydrophobic phase.

Dissolved organic carbon (DOC) is a major and dynamic carbon pool regulating carbon cycling in freshwater systems. Over the past two decades, research on freshwater DOC has moved beyond simple concentration monitoring to examine its sources, molecular composition, degradation potential, and interactions with climate change. Lake studies increasingly focus on DOC processing, long-term storage, and its role in greenhouse gas production, while river studies emphasize DOC mobilization, transport, and connectivity between terrestrial landscapes, inland waters, and downstream coastal environments. Long-term observations reveal increases in DOC concentrations in lakes and rivers, with mean growth rates of 0.042 and 0.015 mg L^-1 per year, respectively. These trends are driven by multiple factors, including recovery from acid deposition, climate warming, extreme precipitation, and intensified human activities such as land-use change and wastewater discharge. Rising DOC concentrations lead to water browning, degraded water quality, biodiversity loss, and increased greenhouse gas emissions, with consequent socioeconomic impacts, particularly in fisheries and tourism. Addressing these challenges requires integrated strategies combining source control, long-term monitoring, and ecosystem restoration. Future research should prioritize global spatiotemporal dynamics of DOC concentration and composition by integrating field observations, remote sensing, and modeling to better understand and mitigate its ecological and socioeconomic impacts.

Quaternary ammonium compounds (QACs) are widely used and have numerous routes to the environment. This work assessed the levels of QACs in surface waters that receive treated wastewater effluent. Samples were collected over a 27 months period from eight different surface waters including rivers, lakes, and a coastal bay. The total summed concentration of 21 targeted QACs including benzylalkyldimethylammonium compounds (BACs), ethylbenzylalkyldimethylammonium compounds (EtBACs), alkyltrimethylammoinium compounds (ATMACs), and dialkyldimethylammonium compounds (DADMACs), were 100-1000 ng L^-1 in surface waters and 500-2000 ng kg^-1 in associated sediments of four rivers, three lakes, and one coastal bay. Based on the profiles of the individual QACs present, surface water exhibited greater compositional similarity to wastewater effluent than sediment, and effluent-derived QAC signatures influenced downstream waters but were modulated by environmental processes or other inputs of QACs. This finding was supported by mass balance calculations, which revealed that the median fraction of QACs attributed to the local wastewater effluent input of the surface water varied from 0.5 to 76% for the four rivers and 1% and 53% for two of the lakes. These results indicate that the QAC profile in a given surface water will be driven by inputs and environmental processes, and that at a given site, the load of QACs likely arises from a combination of inputs and not wastewater effluents alone.

Indoor air quality and indoor environments have become important topics in relation to human health. Heterogeneous surface reactions are recognized to play an important role in indoor air chemistry. HONO is considered a household pollutant due to its nearly 5-fold increased concentration indoors compared to outdoors. It is well recognized that the heterogeneous hydrolysis of nitrogen dioxide (NO₂) on indoor surfaces results in the production of HONO in the gas phase. Despite this knowledge, there are several factors that need to be further understood, including the chemical and physical characteristics of building material surfaces and their coatings that lead to HONO formation. Wildfires near urban locations are occurring with increasing frequency and intensity, and chemicals present in wildfire smoke can adsorb and react on indoor surfaces through smoke infiltration into indoor environments. This current study aims to investigate the effects of guaiacol, an organic compound found in wildfire smoke, on gas-phase HONO concentrations in indoor environments and to better understand surface reactions of guaiacol and NO₂. Surfaces of different building materials were exposed to guaiacol, including kaolinite, titanium dioxide, and gypsum. The impact of guaiacol on HONO formation was monitored via cavity enhanced absorption spectroscopy. Our results show that the effect of guaiacol on gas-phase HONO yields varies depending on the specific surface material. Guaiacol-exposed kaolinite surface films show more than 3 times increase in HONO concentrations compared to kaolinite alone, whereas guaiacol-exposed titanium dioxide had 1.7 times increase in HONO. Guaiacol-exposed gypsum surface films showed no effect on HONO concentrations relative to bare gypsum surface films. We also characterized new surface products that show that NO₂ can react with adsorbed guaiacol to produce nitro-phenolic compounds, which are known to be toxic. Overall, we have identified some considerations of the role of specific surface materials in indoor chemistry relevant to HONO and how this research may be used in the construction and design of indoor environments to improve indoor air quality.