Environmental Science: Processes & Impacts最新文献

Organic peroxides (POs) are an important component of secondary organic aerosol (SOA) and contribute to the generation of reactive oxygen species associated with adverse health effects. However, their molecular-level evolution upon atmospheric aging, particularly in SOA from typical terpenes like limonene, remains poorly characterized. In this study, limonene SOA was generated in an oxidation flow reactor under controlled OH exposure (equivalent photochemical age, PCA = 0.6–13.2 days). The SOA yield exhibited a nonlinear peak at PCA = 7.4 days, followed by a decline at 13.2 days, a trend that was accompanied by a shift in RO₂ reaction pathways from dimerization to reactions with excess oxidants. POs were quantified using iodometry-assisted high-resolution mass spectrometry (HRMS), and their yields decreased progressively with aging. It was found that 100% of highly oxygenated organic molecules (HOMs) were POs at low OH exposure (0.6 days), whereas only 27% of HOMs were POs at high OH exposure (13.2 days), indicating rapid conversion to non-peroxide, highly oxidized molecules (e.g., acids or esters). Key monomeric (C₈–C₁₀) and dimeric (C₁₅–C₁₉) species were identified at the molecular level. This work elucidates the fate of POs within aged SOA, highlighting the limitations of using HOMs as proxies for POs, and provides critical information for assessing the health risks of SOA.

We assessed potential exposures to a broad suite of contaminants (inorganic, organic and microbial) in culturally important surface waters from three watersheds in a northern plains Native American community (Apsáalooke [Crow Tribe of Montana]) in south-central Montana, United States, with water insecurity concerns. Inorganic (37), organic (435) and microbial (3) constituents were assessed in 12 surface water sites from the Pryor Creek (n = 2), Bighorn River (n = 2) and Little Bighorn River (n = 8) valleys. Twenty-six organics, 33 inorganics and Escherichia coli were detected. Despite relatively low concentrations in surface waters within the Crow Reservation, mixture toxicity indicated prevalent chronic ecological effects and human-health secondary contact (recreation) effects at multiple sites. Further, to address Tribal concerns over the prevalence and corresponding risks of per- and polyfluoroalkyl substances (PFAS), we sampled water, sediment, biofilms and fish at a limited number of locations in the Little Bighorn River. Results indicated that PFAS were prevalent in fish tissues, including whole blood and filets, and to a lesser extent in biofilms, despite few detections in water and sediment samples. This is the first attempt to document environmental PFAS contamination within the reservation and the potential human-health concerns for the general population from consumption of recreational/subsistence fish. Overall, this effort provided preliminary information on the contaminant mixtures present and their potential health implications, which can support the protection of community health and culturally meaningful resources across the Crow Reservation.

Many industrial chemicals are recognized as carcinogenic to humans. In this study, we developed predictive models for binary carcinogenicity data in rats that are closely associated with human carcinogenicity. This study involves a range of feature-based and chemical language modeling approaches. After the training-test split and selection of essential structural and physicochemical descriptors, we developed a simple linear discriminant analysis model. Thereafter, we computed similarity- and error-based descriptors, pooled them with structural and physicochemical descriptors, and developed classification read-across structure-activity relationship (c-RASAR) models using a range of machine learning algorithms, including an artificial neural network (ANN). Additionally, the pooled feature matrix was used to compute two ARKA (arithmetic residuals in K-groups analysis) descriptors, and a simple logistic regression model was trained on the two-descriptor feature matrix. Moreover, we adopted the long short-term memory (LSTM) architecture to develop a model based on SMILES strings. The results suggested that the logistic regression RASAR-ARKA model was the best-performing, and it was subsequently used to predict external data efficiently, along with the ANN c-RASAR model. Moreover, the ARKA framework allowed us to identify activity cliffs and explain the reason for mispredictions. In addition to providing an efficient prediction framework, the structure-function analysis suggests that the presence of nitrogen atoms, including in hydrazine derivatives and nitrosamines, and greater branching are responsible for carcinogenicity, while increased molecular size reduces the carcinogenic potency.

A total of 44 PM_2.5 samples were collected intermittently over three winter months (December 2021–February 2022) in the urban center of Chongqing, a city in southwestern China, and analyzed for per- and polyfluoroalkyl substances (PFAS, 20 species). The concentrations and compositions of the PFAS were analyzed by HPLC-MS/MS to determine their sources and potential human health risk. The PFAS concentrations ranged from 70.3 pg m⁻³ to 404.9 pg m⁻³, with an average of 197.1 ± 73.7 pg m⁻³. Monthly variations were as follows: January (281.9 pg m⁻³) > February (160.6 pg m⁻³) > December (148.7 pg m⁻³). The PFAS were dominated by perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA), and 2-perfluorohexyl ethanoic acid (6:2 FTCA). Positive Matrix Factorization (PMF) identified aqueous film-forming foam (AFFF) (43.2%) and precursor degradation (38.3%) as the main sources, followed by lifestyle-related pollution (18.5%). Median Estimated Daily Intake (EDI) for children (age-stratified: 0–6, 6–12, 12–15, 15–18 years) and adults for PFOA (7.69 pg per kg per day) and perfluorooctane sulfonate (PFOS) (0.52 pg per kg per day) was substantially below the U.S. EPA reference dosage (20 000 pg per kg per day). The Hazard Quotient (HQ) was far lower than 1, indicating negligible inhalation-related risk. The results of these two models both implied acceptable PFAS exposure levels. However, prolonged cumulative exposure via PM_2.5-bound PFAS inhalation warrants greater attention due to their lifelong health implications.

Dechlorane Plus (DP) is a widely used flame retardant in various electronic devices. E-waste (EW) dismantling workers could be widely exposed to DP, but related studies are still limited. Therefore, we conducted an extensive study on the levels of DP and its dechlorinated derivatives (anti-Cl₁₁-DP and Cl₁₀-DP) in various environmental and human samples from a typical e-waste dismantling site located in China. Paired hair, hand wipe, indoor air, and indoor dust samples were collected from EW workers, non-EW workers and nearby residents. Hair was divided into an external fraction (hair-Ex) from surface washing and an internal fraction (hair-In) from digested washed hair. Our findings indicated that the DP concentrations in air and dust samples varied between 7.44 and 6200 pg m⁻³ and 0.355 and 7000 ng g⁻¹, respectively. The DP concentrations in hair-internal, hair-external, and hand wipe samples varied between 0.896 and 39.9 ng g⁻¹, 0.954 and 66.1 ng g⁻¹, and 1.25 and 1080 ng g⁻¹, respectively. The fractional abundance of anti-DP (f_anti) in hair-internal samples was significantly lower than in other samples (P < 0.05). Concentrations of anti-Cl₁₁-DP in both internal and external hair samples collected from EW recycling workers demonstrated statistically significant reductions relative to adult non-occupationally exposed individuals. This disparity may arise from the restricted metabolic clearance capacity of anti-Cl₁₁-DP in human physiological systems. The median proportion of anti-Cl₁₁-DP relative to ∑DPs was significantly elevated in hair-internal samples compared to both indoor dust samples (P < 0.05) and hair-external samples (P < 0.05), indicating a substantial enrichment of anti-Cl₁₁-DP in humans.

Arsenic exposure is a major global health challenge. In addition to well-documented toxic effects in exposed people and animals, there is evidence that exposure to arsenic may lead to transgenerational effects. Transgenerational effects of low levels of exposure are challenging to study in species with long generation times. The model organism Caenorhabditis elegans offers the ability to quickly carry out transgenerational experiments with very large sample sizes of isogenic animals, reducing variation, and numerous biological replicates, to increase statistical rigor. An important challenge historically associated with this species for such work is uncertainty about internal dosimetry and toxicokinetics. Here, we report a 4-generation experiment in which C. elegans were exposed during larval development to sodium arsenite concentrations in the parental generation at concentrations resulting in no or mild growth inhibition up to significant growth inhibition. These exposures resulted in internal concentrations between 0.4 and 6.7 nM and rapid excretion (t_1/2 = 3 hours), despite the lack of arsenic methylation in this species. These exposures had strong and significant effects on the exposed generation later in life, but no transgenerational effects were detected. We discuss possible reasons for this “negative” result. We also report strong similarity of the nematode transcriptomic, metabolomic, and fat accumulation responses in the exposed generation to responses reported in other organisms, including persistent alterations in cysteine and fatty acid metabolism, phase II and III metabolic processes, and increased adiposity. Finally, we discuss ways to take advantage of this species difference in arsenic metabolism for the use of C. elegans in toxicology testing.

Fires in the wildland–urban interface (WUI) introduce pyrogenic organic contaminants to surface waters, but their impacts on microbial dynamics have not been evaluated. We studied the interactions between microbial communities and pyrogenic carbon during post-fire storms in a WUI fire-impacted creek in Orange County, CA. The first storms following the fire (low intensity) brought about the highest discharges of polycyclic aromatic hydrocarbons (PAHs), e.g. benzo[a]pyrene, benz[a]anthracene. Dissolved organic carbon (DOC) loads reached up to 11.2 g-C s⁻¹ during the more severe storms. PAHs correlated with each other but not with DOC or fluctuations in turbidity, suggesting these two variables might not be good predictors of PAH flushes, especially in low-intensity storms. Microbial genera with known PAH-degrading members were differentially abundant during post-fire storms (Pseudomonadota, Bacteroidota, Cyanobacteriota, Actinobacteriota, Bacillota). In addition, predicted metabolic pathways related to the PAH biodegradation intermediates, catechol and protocatechuate, increased significantly at sites downstream of the fire. Overall, our findings suggest pyrogenic carbon from the fire resulted in a detectable shift in microbial community function and composition to favor PAHs degradation just a few months after the fire. This response suggests that PAH-degrading microorganisms are readily found after WUI fires.

Pyrene belongs to the highly toxic class of polycyclic aromatic hydrocarbons and has carcinogenic properties; thus, the kinetics of its OH-initiated oxidation is theoretically investigated in a wide range of conditions (T = 200–2000 K and P = 7.6–76,000 Torr). The T & P-dependent kinetic behaviors were studied within the stochastic RRKM-based master equation framework with the potential energy profile constructed at the ROCBS-QB3//M06-2X/aug-cc-pVTZ level. The computed total rate constants k_total are in good agreement with the laboratory values, thus helping resolve the discrepancy between the prior calculations and the measured values. The model reveals detailed mechanistic insights: (i) the OH-addition channels from the Cα and Cγ atoms of pyrene (to form the adducts 5-hydroxy-4,5-dihydropyren-4-yl (I1) and 1-hydroxy-1H-pyren-10a-yl (I2)) predominate under atmospheric conditions, while the direct H-abstraction pathways become dominating at T > 500 K; (ii) the U-shaped T-dependent behaviors of k_total and its slightly positive P-dependence at low T (e.g., T ≤ 500 K and P = 760 Torr) are due to the T-dependent mechanism shift. Additionally, pyrene should not be considered a persistent organic pollutant (POP) due to its short calculated atmospheric lifetime (∼4.1 hours toward OH), which is significantly shorter than those resulting from degradation by other abundant oxidants (i.e., Cl, NO₃, and O₃) present in the atmosphere. Moreover, pyren-4-ol (and pyrene-4,5-dione) and pyren-1-ol (and pyrene-1,2-dione) are suggested as the primary products of I1 and I2, respectively, when further oxidized by O₂/NO. The results reveal that both short and long-term pyrene exposure is highly toxic to aquatic organisms; while its main degradation products, namely, I1 and I2, show lower toxicity, they still pose a significant threat to marine organisms and the ecosystem.

Bioplastics are widely promoted as environmentally safer alternatives to conventional polymers; however, their ecotoxicological implications across trophic levels remain poorly understood. In terrestrial detritivore networks, where trophic interactions involve decomposers and necrophagous insects, the ingestion and transfer of microplastics (MPs) derived from bioplastics may induce systemic dysfunctions in organisms with key ecological functions. Here, we investigated the trophic transfer and physiological impacts of polylactic acid microplastics (PLA-MPs) in a simulated terrestrial food chain, from Chrysomya megacephala to Tribolium castaneum. We hypothesized that PLA-MPs would be retained across metamorphosis and transferred between trophic levels, inducing multisystemic effects in secondary consumers. Our findings confirm the transstadial retention of PLA-MPs in C. megacephala and their effective trophic transfer to T. castaneum. Despite a reduction in MP burden across trophic transitions, exposed beetles exhibited behavioral alterations, including hyperactivity and spatial disorganization, alongside decreased levels of serotonin, dopamine, and acetylcholinesterase activity. These neurofunctional impairments were accompanied by redox imbalance, collapse of digestive enzyme activities (including chymotrypsin, trypsin, and alkaline phosphatase), and reduced biomass, despite elevated levels of total proteins, triglycerides, and carbohydrates. Network analysis revealed a systemic reorganization, characterized by the loss of central physiological hubs and the emergence of stress-related biomarkers. Random forest modeling identified nine key variables spanning neurochemical, oxidative, and digestive axes as robust predictors of internal PLA-MP burden. This study provides the first evidence that PLA-MPs can be effectively transferred through a terrestrial detritivore chain via necrophagy, inducing multisystemic physiological disruptions in secondary consumers. Thus, our findings expand current bioplastic risk assessment paradigms by advocating the integration of systemic biomarkers, trophic dynamics, and underexplored exposure pathways in terrestrial scenarios.

The photoaging of polyethylene microplastics (PE MPs) and their interactions with co-contaminants such as ofloxacin (OFL) play a critical role in shaping the composition and characteristics of dissolved organic matter (DOM) in aquatic environments. This study systematically investigates the characteristics and leaching mechanisms of DOM from pristine PE and PE-adsorbed OFL (PE-OFL) under prolonged ultraviolet irradiation. Molecular weight (MW) fractionation revealed that UV exposure significantly enhanced DOM release from pristine PE, with low-MW fractions (<1k Da) dominating (75.6–98.3% of total DOM). In contrast, PE-OFL initially released high-MW compounds (44.9–51.8% > 1k Da), which transitioned to low-MW dominance. Two-dimensional correlation spectroscopy of FTIR spectra indicated that photolytic degradation of pristine PE primarily involved –CH₂ groups, while C–O groups were dominant in PE-OFL, reflecting OFL-induced alterations in photolytic pathways. Energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy demonstrated that OFL adsorption substantially increased surface oxidation, with a 2.4-fold elevation in O/C ratios and enhanced carboxylation (77.5% CO content vs. 32.8% in PE). These findings elucidate that OFL acts as both a photosensitizer and an electron shuttle, accelerating PE backbone scission via reactive oxygen species generation while temporarily stabilizing high-MW intermediates. Overall, the findings highlights that contaminant-laden MPs exhibit distinct DOM profiles compared to pristine MPs, emphasizing the necessity of considering co-pollutant interactions in environmental risk assessments.