Odorous volatile compounds released from waste and wastewater treatment, soil remediation, industrial manufacturing, and livestock operations have become a growing environmental and public health concern. However, identifying key odor compounds within complex emissions remains a fundamental challenge, as odor impact is governed not solely by chemical concentration, but by the odor detection thresholds (ODTs) and odor qualities. Although machine-learning approaches have shown promise in predicting odor characteristics of compounds, existing models primarily rely on molecular physicochemical properties while overlooking the biological interactions between odorants and the human olfactory system. Here, a computational framework integrating molecular descriptors, structural fingerprints, and simulated molecule-olfactory receptor (OR) binding affinities was developed to predict ODTs and odor qualities of volatile compounds. Our framework outperforms conventional physicochemical-based models, with particularly strong discriminative capability for garlic, alliaceous, and sulfurous odors-compound classes commonly associated with odor pollution. The molecular polarity, structural complexity, and OR binding affinity are further identified as prior factors for odor perception. Key ORs governing ODT and odor quality predictions are separately pinpointed. By bridging odorant-OR interaction and molecular information, this framework offers a practical tool for screening unknown environmental odorants, supporting targeted odor pollution management, regulatory threshold setting, and development of environmental monitoring strategies.
Although previous zebrafish studies have reported developmental, immune, intestinal, and reproductive effects of 2,4-di-tert-butylphenol (2,4-DTBP), evidence linking adult neurobehavioral outcomes with brain neurotransmitter-related changes and histopathological responses remains limited. Herein, we employed a zebrafish model subjected to a 21-day exposure across an environmentally informed and sublethal concentration range (0.01-1 μM), integrating a multi-tiered assessment that combined behavioral assays, biochemistry, molecular biology, histopathology, and computational toxicology. Our results showed reduced upper-zone exploration in the Novel Tank Test (p < 0.05) and endpoint-specific variation in social approach-related measures in the social preference test. These behavioral changes were accompanied by vascular-adjacent and parenchymal histopathological alterations in the brain. At the molecular level, 2,4-DTBP exposure altered cholinergic and serotonergic endpoints, including ACh accumulation, 5-HT depletion, and selective transcriptional changes involving slc5a7a and tph2. Notably, bdnf expression was markedly upregulated (p < 0.001), consistent with a stress-related or injury-associated transcriptional response. Molecular docking predicted a pose of 2,4-DTBP within the acetylcholinesterase (AChE) aromatic gorge, with a favorable Vina score (≈ -7.57 kcal/mol) and predicted π-π/hydrophobic interactions with aromatic residues. Collectively, these findings support the use of a putative AOP-informed framework to organize neurotransmitter-related alterations, vascular-associated and parenchymal histopathological changes, and anxiety-like behavioral responses in adult zebrafish exposed to 2,4-DTBP.
Existing studies rarely assess and capture both the mortality and morbidity risks from the joint exposures of meteorological factors and air pollution, while also accounting for between-communities variations. We developed a Weather and Air Health Risk Index (WAHRI) to quantify and communicate short-term combined and community-specific mortality and morbidity risks in relation to multiple weather and air stressors. Daily counts of deaths, hospital admissions, and emergency department (ED) visits were collected from 2014 to 2019 across 66 Statistical Area Level 3 (SA3) communities in Victoria, Australia. Health outcomes were SA3-specific daily counts of all-cause, cardiovascular disease (CVD)-related, and respiratory disease-related mortality, hospital admissions, and ED visits. SA3-specific daily average weather and air pollution variables included temperature, relative humidity, air pressure, ultraviolet B radiation, wind speed, rainfall, fine particulate matter and daily maximum 8-hour ozone. Outcome-specific random forest models were trained to estimate health risks associated with combined environmental exposures, and SHAP values were used to construct interpretable WAHRI indices. We found that higher WAHRI was consistently associated with increased risks across all-cause, CVD and respiratory disease-related mortality, hospital admissions and ED visits. Among the included environmental factors, temperature and ultraviolet B radiation were the leading contributors across most outcomes. Although the geographical distributions of WAHRI varied across outcomes, high-risk days were more frequent in socioeconomically disadvantaged, lower-GDP, and communities with older populations. WAHRI provides an interpretable, outcome-specific framework for assessing combined weather-air pollution health risks and will support short-term environmental health surveillance and alerts, public risk communication, and health-service preparedness.
INTRODUCTION:Green space exposure during pregnancy and the early postnatal period is associated with lower autism spectrum disorder (ASD) risk. However, averaged exposure studies may miss time-specific sensitive windows spanning prenatal to early postnatal periods. Whether PM2.5 mediates or modifies this relationship remains unclear. This study aimed to identify critical windows of green space exposure and examine PM2.5's role. METHODS:A 1:3 matched case-control study was conducted, including 207 children with ASD and 621 healthy controls individually matched by age and sex. Participants were recruited from a tertiary maternal and child health hospital in central China. Monthly residential normalized difference vegetation index (NDVI), a satellite-derived metric of vegetation greenness, and fine particulate matter (PM2.5) levels from 10 months before to 3 months after birth were estimated for each participant based on maternal residential addresses. A distributed lag nonlinear model (DLNM) was used to quantify the association between monthly NDVI exposure and ASD risk and to detect critical windows for the protective effects of green space. Product terms were incorporated into conditional logistic regression models to test multiplicative interactions between NDVI and PM2.5. The bootstrap method was used to evaluate mediating effects, and Bonferroni correction was applied to account for multiple testing. RESULTS:Children with ASD had consistently lower monthly NDVI values than controls across all 14 months (from 10 months before birth to 3 months after birth; all FDR-adjusted P values < 0.01). A critical window was identified from 6 months to 1 month before birth (lags -6 to -1), during which higher NDVI was associated with lower odds of ASD. For this window, each interquartile range (IQR) increase in window-averaged NDVI was associated with a 46.6% reduction in the odds of ASD (OR = 0.534, 95% CI: 0.415-0.688). No significant multiplicative interaction between NDVI and PM2.5 was observed for any month (all P > 0.05 after correction), and mediation analyses revealed no evidence of mediation by PM2.5. CONCLUSIONS:Green space exposure during mid-to-late pregnancy (corresponding to 6 to 1 month before birth for term births) is associated with substantially lower odds of ASD, independent of PM2.5. These findings suggest that prenatal care providers should consider advising pregnant women to increase green space contact during mid-to-late pregnancy. The identification of this temporally specific window also supports urban planning efforts to prioritize green space preservation in residential areas with high concentrations of pregnant women.
Cu is an environmental trace metal, but excess Cu is known to disrupt chemosensory functions. However, the chronic effects on the olfacto-retinal centrifugal (ORC) pathway and feeding-related behavior of Cu in fish remain largely uncharacterized. Zebrafish (Danio rerio, six-month-old) were exposed to environmentally relevant concentrations of Cu (i.e., 1.6, 5.6, 16, and 35 μg L-1; Cont, Cu-L, Cu-M, and Cu-H) over a 30-day period. Behavioral, neurochemical, and transcriptional biomarkers were measured to evaluate toxic effects of Cu. The results demonstrated that Cu significantly accumulated in olfactory tissues, eyes, and brains. Cu induced divergent olfactory and visual impairments in female and male fish. It markedly impaired olfactory signal transduction and processing (e.g., gnal; ∼56% decrease), while visual function was more severely impaired in females (e.g., a 48% decrease in velocity during visually guided behavior). Correlation analysis further showed that Cu induced coordinated changes between olfactory tissue and eyes. Meanwhile, such olfactory and visual impairments, together with altered neurotransmitter levels and disruptive appetite regulation (e.g., ∼1.2-fold increases in the orexigenic neuropeptide Y (NPY) and the anorexigenic pro-opiomelanocortin (POMC)), may collectively contribute to the 6.0-17% decline in feeding-related behavior. Our findings suggest that Cu-induced feeding suppression may involve disrupted ORC pathway and sex-dependent appetite regulation, providing critical insights into the ecological risks of Cu contamination.
Urban particulate matter (PM) pollution poses a serious threat to residents' health, and urban park green spaces (UPGSs) can play an important role in reducing the PM. Previous studies have highlighted how differences in plant traits, community structure, and green space configuration influence PM reduction. However, the extent to which meteorological factors, park built-up environment indicators, and other variables differentially drive PM reduction by UPGSs remains unclear. This study investigated 37 parks in Hohhot to assess the reduction rates (DR) of six PM size fractions using summer daytime data. A multistage modelling framework was employed to compare the linear, generalised additive, and random forest (RF) models. RF was selected as the better-performing model through leave-one-park-out cross-validation (point-level R2: 0.19-0.58; park-level R2: 0.18-0.72). SHapley Additive exPlanations identified key driving factors, while the derivatives of partial dependence plots and individual conditional expectation plots quantified their marginal effects, revealing nonlinear relationships. The results showed that: (1) PM concentrations and DR varied markedly across parks, exhibiting considerable spatial heterogeneity; (2) nine primary drivers were identified, and their comprehensive threshold ranges during summer daytime were determined: meteorological factors (air temperature: 22.08-33.26 °C, relative humidity: 29.71-67.17%, dew point temperature and wet bulb temperature: 11.47-24.38 °C, and wind speed: 0.14-1.12 m/s), park built-up environment indicators (distance from the city centre: 2.7-16.79 km), park spatial form indicators (perimeter-area ratio: 0.15-0.33, contiguity index: 0.24-0.48), and landscape indices (aggregation index: 78.46-86.85%). Beyond these ranges, the marginal mitigation effects plateaued. Therefore, strategically regulating key driving factors within their optimal ranges can effectively maximise DR, thereby providing actionable guidance for enhancing the ecological health services of UPGSs.
Ambient air pollution is recognized as a major global health concern, but evidence on its association with childhood myopia remains limited, particularly under multi-pollutant exposure conditions. A school-based study was conducted in Tianjin, China, including 212,566 students in grades 4-6. The 3-yr mean concentrations of particulate matter with aerodynamic diameter 2.5 μm (PM2.5), its major components (sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), organic matter (OM), and black carbon (BC)), and ozone (O3) were estimated using machine-learning exposure models and linked to school locations. Restricted cubic splines and quartile-based modified Poisson models were used to assess single-pollutant exposure-response relationships, and quantile-based g-computation was applied to estimate joint pollutant associations. In single-pollutant models, the highest quartile of SO42- was associated with higher myopia prevalence compared with the lowest quartile (PR = 1.10; 95% CI, 1.07-1.13). O3 showed weaker and non-monotonic positive patterns (Q4 vs Q1: PR = 1.03; 95% CI, 1.00-1.05). In mixture analyses, a one-quartile increase in joint exposure was associated with higher myopia prevalence (PR = 1.017; 95% CI, 1.007-1.027). Sensitivity analyses generally supported the direction of the main findings. These findings suggest that long-term exposure to specific ambient air pollutants may be associated with myopia in school-aged children.
Silver nanoparticles (Ag0-NPs) are among the most widely used nanomaterials, yet current risk assessments predominantly focus on particle size while overlooking the role of dynamic speciation. Here, using the estuarine fish Scatophagus argus, we demonstrated that primary particle size (20, 60, and 100 nm) and the bidirectional Ag0-NPs/dissolved Ag+ interconversion critically governed in vivo toxicity. Our results revealed that Ag exposure induced the most pronounced pro-inflammatory immunotoxicity, characterized by selective enrichment of gut Gram-negative bacteria, lipopolysaccharide (LPS) translocation across a compromised intestinal barrier, and subsequent activation of the TLR/MyD88/NF-κB (Toll-like receptor/myeloid differentiation primary response 88/nuclear factor kappa-B) signaling pathway, an effect most pronounced with 20-nm Ag0-NPs and Ag+ exposure. Counterintuitively, 20-nm Ag0-NPs at an environmentally relevant concentration (10 μg/L) caused significantly higher mortality than equimolar Ag+ exposure (15.75 μg/L AgNO3). This disparity arose because administered Ag+ (∼10%) was rapidly sulfidated into low-bioavailability Ag2S-NPs, constituting an endogenous detoxification mechanism, whereas 20-nm Ag0-NPs sustained elevated intracellular and luminal Ag+ levels through continuous dissolution. Prolonged Ag0-NPs exposure exacerbated gut microbiota dysbiosis and systemic inflammation. Crucially, fecal microbiota transplantation from exposed donors into germ-free medaka recapitulated elevated serum LPS and enhanced inflammatory response, confirming a causal link between nanoparticle exposure, gut microbiota perturbation, and host immune dysfunction. These findings reveal that the synergistic interplay between particle size and in vivo silver transformation dictates nanotoxicity, underscoring that secondary particle formation and transformation-dependent toxicity are underestimated in conventional risk paradigms.
Volatile organic compounds (VOCs) are prevalent environmental pollutants posing significant risks to human health. However, their impact on thyroid function and the latent mechanism remain largely uncharted. This study utilized data of 1201 participants aged ≥20 years from National Health and Nutrition Examination Survey 2011-2012. Weighted generalized linear model (for single-analyte analysis) and quantile g-computation (QgComp) and Bayesian kernel machine regression (BKMR) (for mixture analysis) were employed to capture the individual and mixed effects of 16 VOCs metabolites (derived from 13 VOCs) on 10 thyroid function indicators. Network toxicology was employed to probe the underlying mechanism. In single-analyte effect analysis, we found several VOCs metabolites were positively associated with thyroglobulin (hTg), negatively associated with free thyroxine (FT4), thyroid-stimulating hormone (TSH), thyrotrophic thyroxine resistance index (TT4RI), TSH index, and thyroid peroxidase antibodies (TPO-Ab), while nae associated with total triiodothyronine (TT3), free triiodothyronine (FT3), total thyroxine (TT4), or thyroglobulin antibodies (anti-hTg). Both mixture models (BKMR and QgComp) discovered that the mixture of 16 VOCs metabolites was positively related to TT3 (β = 0.0161; 95% CI: 0.0056∼0.0265) and FT3 (0.0077; 0.0020∼0.0134) while negatively related to FT4 (-0.0158; -0.0248∼-0.0067), TSH (-0.0395; -0.0726∼-0.0065), TT4RI (-0.0552; -0.0883∼-0.0221), TSH index (-0.0336; -0.0556∼-0.0117), and TPO-Ab (-0.1001; -0.2066∼-0.0056). Hypothesis-generating network toxicology showed a significant enrichment in interleukin-17 (IL-17) signaling pathway linking VOCs exposure and thyroid dysfunction. Conclusively, exposure of general adults to single VOC and particularly multiple VOCs mixture was associated with thyroid function alteration, and the possible (hypothesis-generating) mechanism may involve IL-17 signaling pathway.
Microplastic (MP) uptake and retention in freshwater invertebrates are shaped by both particle characteristics and feeding conditions, yet the specific influence of diet composition remains poorly understood. This study examined the concentration- and time-dependent ingestion, as well as depuration, of 45-53, 63-75, and 90-106 μm polyethylene MPs in adult Daphnia magna acclimated to three diets, with exposure assays conducted under either fed or unfed conditions. Concentration-dependent accumulation experiments were conducted at 4, 8, 40, 80, 400, and 800 mg/L for 48h. Time-dependent accumulation was assessed at 60 mg/mL for 60h. Depuration was measured for 6h following a 48h exposure to 60 mg/L. The experimental diets consisted of live Chlorella vulgaris, a dried spirulina and yeast mixture, or a combination of both. Concentration-dependent uptake followed Michaelis-Menten kinetics, with the smallest MPs retained in the highest numbers and food deprivation resulting in greater particle retention across all diets. Time-dependent uptake showed a sigmoidal trend shaped by MP size, diet type, and food availability. Depuration exhibited a reverse sigmoidal pattern, and D. magna acclimated to the live algae diet generally displayed more rapid MP clearance, indicating that prior dietary history influenced elimination. Together, these results indicate that MP ingestion and depuration in adult D. magna depend on both MP size and feeding conditions, and that diet composition plays a critical role in short-term MP fate. In conclusion, the present study suggests that feeding history and diet composition influence MP ingestion and depuration under controlled conditions and should be considered when designing and interpreting laboratory exposure studies.
Microplastics can move among terrestrial, aquatic, and atmospheric systems. However, the role of aquatic insects in transporting microplastics, and their potential contribution to cross-ecosystem transfer, remains poorly understood. In this study, we examined the accumulation of three microplastic types (polyethylene (PE) fragments, tire wear particles (TWPs), and polyacrylonitrile (PAN) fibres) in the merolimnic mayfly Cloeon dipterum. Larvae were exposed to two microplastics concentrations (500 and 5000 particles/L), and microplastics associated with larvae and newly emerged adults were quantified and characterized. All three microplastic types were detected in larval digestates, indicating their association with the organisms in the aquatic environment; however, ingestion and surface adhesion could not be distinguished. PE fragments were the most abundant (16-49 particles per larva), followed by TWPs (3-9 particles per larva), and PAN fibres (≤2 particles per larva). Microplastics were also found in both the washing water of emerged adults (representing surface-adhered particles) and their digestates (representing ingested particles), demonstrating that particles remained adhered to and inside the organisms after metamorphosis. Particle size analysis revealed preferential retention of smaller PE fragments and TWPs during both ingestion and adhesion, with the median size of recovered particles being 30-57% and 24-42% smaller, respectively, than that of the particles introduced into the system. Exposure to PAN fibres at the higher concentration (5000 particles/L) significantly reduced the time to 50% emergence by one day, whereas none of the treatments affected adult fatty acid profiles. Overall, our findings demonstrated that all three tested microplastic types can be associated with emerged aquatic insects, highlighting a potential pathway for the biologically mediated redistribution of microplastics. Further studies are needed to identify the mechanisms governing microplastic retention and to disentangle the effects of particle characteristics, such as polymer type, size, and shape, on these processes and their ecological significance.
Transformation of per- and polyfluoroalkyl substance (PFAS) precursors during drinking-water disinfection may generate persistent perfluoroalkyl acids (PFAAs), yet the roles of precursor structure and disinfection configuration remain unclear. Here, four representative precursors-N-methyl perfluorooctane sulfonamidoacetic acid (N-MeFOSAA), perfluorooctane sulfonamide (PFOSA), 8:2 fluorotelomer sulfonate (8:2 FTS), and 8:2 fluorotelomer phosphate diester (8:2 diPAP)-were compared across individual, simultaneous, and sequential ultraviolet (UV)/chlor(am)ination processes. Individual treatments showed limited precursor transformation, whereas simultaneous UV/disinfectant treatment increased conversion to 16.7-40.8%, with sulfonamide-based precursors exhibiting higher reactivity than fluorotelomer precursors. Fluorine mass balance revealed structure-dependent fluorine fates: sulfonamide precursors were transformed more extensively toward quantified PFAAs, whereas fluorotelomer precursors retained larger estimated unmeasured fluorine fractions. The same transformation behavior was also observed in actual drinking water. Mechanistic analyses integrating non-target high-resolution mass spectrometry (HRMS), reactive-species probe experiments, and density functional theory (DFT) calculations suggested that precursor structure governed reactive-species susceptibility and transformation pathways, with hydroxyl radicals playing a major role in precursor conversion toward PFAAs and chlorine radicals contributing to the initiation of one-electron oxidation steps that enabled subsequent chain shortening. Simultaneous UV/disinfectant treatments also increased PFAA-associated ecological risks and JEG-3 cytotoxicity, and the two endpoints were strongly positively correlated, suggesting that greater PFAA formation during precursor transformation may be accompanied by increased health-relevant toxicity. These findings highlight the importance of precursor structure in determining PFAS transformation and its potential health implications during drinking water disinfection.
Gestational exposure to cadmium (Cd), a widespread environmental toxicant, disrupted placental angiogenesis to induce fetal growth restriction (FGR). This study aimed to clarify the mechanism by which Cd disrupts placental angiogenesis. Human and mouse studies indicated that Cd exposure reduced VEGF-A to disrupt placental angiogenesis. Further data confirmed that gestational Cd exposure promoted estrogen receptor ESR1-specific degradation via ubiquitin-proteasome system (UPS), thereby decreasing placental VEGF-A. Bortezomib, the only clinically approved protease inhibitor, blocked ESR1 degradation to alleviate Cd-impaired placental angiogenesis. Based on mouse and human transcriptomics, WWP2 was identified as an unreported ubiquitin E3 ligase targeting placental ESR1. Specifically, both WWP2 knockdown and its inhibitor NSC2805 treatment consistently reversed environmental Cd-induced placental angiogenesis disorders and FGR. Furthermore, the m6A modification in Wwp2 mRNA was increased in Cd-exposed placentae. METTL3 and ELAVL1 knockdown verified that m6A modification enhanced the stability of Wwp2 mRNA. SAH, an inhibitor for METTL3, not only decreased WWP2 but also alleviated Cd-impaired placental angiogenesis and fetal growth. Based on a human case-control study, m6A-methylated Wwp2 was positively correlated with placental angiogenesis inhibition and all-cause FGR. In conclusion, gestational Cd exposure enhanced m6A modification in Wwp2 mRNA to drive ESR1 degradation, thereby inhibiting placental angiogenesis and fetal growth.
Microplastics (plastic particles ≤5 mm) are a persistent and widespread pollutant in aquatic ecosystems, where they can accumulate in the larvae of aquatic insects inhabiting benthic habitats. Aquatic insects cross aquatic-terrestrial boundaries through metamorphosis, yet few studies have investigated their role in transporting microplastics to terrestrial ecosystems as emergent adults. This study sampled upstream and downstream of eight municipal wastewater treatment plants in the Grand River watershed, Ontario, Canada, in 2022 and 2023 to assess whether these facilities increase microplastics occurrence in aquatic and riparian food webs. Larval and adult caddisflies (Hydropsychidae), mayflies (Heptageniidae), midges (Chironomidae), and riparian spiders (Tetragnathidae) were collected to examine microplastics accumulation, retention through metamorphosis, and cross-ecosystem transfer into riparian spiders. Larval Heptageniidae, adult Chironomidae, and Tetragnathidae exhibited higher microplastic abundances downstream relative to upstream, with concentrations approximately 2.4-, 3.7-, and 2-fold higher, respectively, although the magnitude of differences varied across sites; no significant differences were observed for the other taxa. Organic (cellulose-based) and polyester fibres were the most common, representing ∼25-68% and ∼16-50% of particles across taxa, respectively. Relationships between total microfibre concentration and trophic position (δ15N) were generally weak and site specific, while TTFs >1 were observed between biofilm and larval taxa at most sites but were generally <1 between adult insects and spiders. Together, these findings demonstrate that emergent aquatic insects retain and transfer microplastics across aquatic-terrestrial boundaries to riparian predators but provide limited evidence for consistent trophic magnification across the food web. This research addresses a critical knowledge gap by advancing our understanding of microplastic uptake and movement through nearshore food webs via emergent aquatic insects.
Per- and polyfluoroalkyl substances (PFAS) are widely detected in urban surface waters globally, yet their accumulation in freshwater biota from diffuse pollution remains poorly characterised. Macroinvertebrates are a key component of freshwater food webs and a major dietary pathway for PFAS transfer to higher trophic levels. We quantified PFAS concentrations and compositional profiles in macroinvertebrates collected from 13 urban and 15 non-urban streams in the greater Melbourne region, Australia, all of which lacked known PFAS point sources. Composite macroinvertebrate samples were live-picked and identified to family-level before analysis of 25 PFAS congeners. Overall, 1083 organisms were collected from 57 families. One or more congeners were detected in 89% of samples. Median total PFAS concentrations in urban macroinvertebrates were between 6- and 28.2-times higher than in non-urban macroinvertebrates, and urban organisms had significantly higher PFOS, PFOA, PFDA and PFDoDA concentrations than non-urban organisms. Long-chain congeners dominated tissue concentrations across both land uses, with urban profiles contributing emerging replacement compounds (fluorotelomer sulfonates), whereas non-urban macroinvertebrates exhibited relatively low total PFAS burdens but unexpectedly high concentrations of short-chain PFAS (PFBA). Comparisons with published data show that diffuse urban sources can generate PFAS concentrations in macroinvertebrates approaching those reported at point-source-impacted sites. These findings demonstrate that urban land use strongly influences both the magnitude and composition of PFAS accumulation in freshwater macroinvertebrates and underscore the need for monitoring frameworks that integrate multiple sampling media and consider both legacy and emerging PFAS when assessing ecological risks in freshwater ecosystems.
The mechanisms by which plants tolerate soil contamination have been studied in details in controlled laboratory conditions, but they still remain largely unexplored in natural conditions where mixtures of contaminants are present in soils and their effects might interact with other environmental variables. This is especially true in high-altitude alpine environments, where abiotic stress is naturally heightened, but which so far have received little attention in environmental pollution studies. As we were interested in the tolerance mechanisms at play on very fine spatiotemporal scales for alpine plants growing under multi-stress conditions, we chose Cardamine resedifolia as our biological model. This plant is indeed frequently found in areas contaminated by Trace Metals and Metalloids and Polycyclic Aromatic Hydrocarbons in high elevation. We studied populations from former copper, silver-lead, and coal mines in alpine environments, along with populations growing on nearby reference soils. We measured genetic variability within populations as well as genetic differentiation between them, and tested for local adaptation to soil contamination using reciprocal transplants. Population pairs showing signs of local adaptation were then examined using genome scans to identify genes potentially under selection. We found high levels of genetic differentiation between populations growing on contaminated and reference soils a few dozen meters apart. In most cases local adaptation was detected, especially in former copper mines. Genome scans identified genes involved in metal stress management as potentially being under selection. This study provides evidence for rapid adaptation to human-induced pollution in alpine plants at remarkably small spatial scales. It offers new insights into the short-term ecological and evolutionary consequences of mining activities in alpine ecosystems, particularly in relation to substrate-driven differentiation.
Hydrophobic organic contaminants (HOCs) pose risk to aquatic organisms at high concentrations and have been implicated in the declining health of the endangered fish species, Delta smelt (Hypomesus transpacificus). Legacy and current-use pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were quantified in a surrogate fish species (Wakasagi; Hypomesus nipponensis), sediments, zooplankton, and suspended solids throughout the Sacramento Deep Water Ship Channel (SDWSC). Forty-four of 63 analytes were detected across the tested media, with legacy pesticides (LPs), PAHs, and PCBs being the most prevalent contaminants measured in Wakasagi. Pyrethroids, a class of current-use insecticides, were rarely detected in Wakasagi tissue. Pattern analysis via cosine similarity showed that contaminant concentrations associated with suspended solids best reflected the concentrations measured within the Wakasagi, suggesting that suspended solids may represent a relevant exposure pathway. While only DDE and DDD concentrations exceeded the threshold effect concentration for sediment (TEC), contaminants associated with suspended solids exceeded most sediment quality guidelines. In addition, PAH concentrations in suspended solids exceeded multiple lesion thresholds for a variety of other fish species. These results suggest potential ecological concern from suspended solid-associated contaminant exposure. Future studies need to be performed to assess the relationship between HOCs associated with suspended solids and their potential harm to pelagic organisms for the purpose of contaminant mitigation in the SDWSC.
Vertical wind shear (VWS) is a key feature of the dynamical structure of the atmospheric boundary layer, yet its association with the vertical distribution of pollution remains insufficiently understood in complex terrain. This study examined VWS structures and their relationships with PM2.5 in Taiyuan Basin using surface observations, wind profiler radar, microwave radiometer, aerosol lidar, radiosonde, unmanned aerial vehicle measurements, and Weather Research and Forecasting model simulations. Unsupervised clustering identified three distinct VWS regimes. Class_1 featured strong near-surface shear dominated by directional changes and was associated with pronounced near-surface PM2.5 accumulation, strong stability, and the shallowest boundary layer. Class_2 exhibited enhanced wind speed shear above 500 m and an elevated PM2.5 maximum near this height. Class_3 showed strong wind speed shear through most of the layer below 2000 m, together with stronger winds and lower PM2.5 concentrations. UAV observations within 0-500 m confirmed distinct PM2.5 profiles among the three regimes. A pollution episode on 17 January 2024 further showed that strong VWS did not necessarily enhance vertical exchange when the shear layer remained above a shallow, stable boundary layer. Its influence became more evident as daytime heating deepened the boundary layer toward the shear layer, whereas evening boundary-layer contraction renewed near-surface accumulation. These results demonstrate that the relationship between VWS and PM2.5 depends on shear height and composition and on the evolving thermal structure of the boundary layer.
BACKGROUND:Every spring (March-April), biomass-burning fires in the Indo-China Peninsula (ICP) send smoke downwind into southern China, coinciding with elevated springtime PM2.5 in Yunnan, Guangxi, and Guangdong. The radiative and ecological effects of this transport are established, but its springtime population-exposure burden remains poorly characterised. OBJECTIVE:To quantify springtime PM2.5 population exposure under WHO and Chinese benchmarks, and attribute the ICP fire contribution with a controlled model experiment. METHODS:Daily PM2.5 from 51 cities was combined with WorldPop population data to compute exposure above the WHO 2021 guideline (24-h, 15 μg/m3) and China's GB 3095-2012 Grade II standard (75 μg/m3) for March-April 2015-2019, and paired GEOS-Chem simulations at 2° × 2.5° with and without ICP fire attributed the fire contribution. RESULTS:At observed PM2.5 concentrations, exposure above the WHO 24-h guideline was near-universal (the population-weighted share of exceedance days reached 78 to 96% every year). Exposure above the higher China Grade II standard was rare in all three provinces, with the population-weighted share of exceedance days spanning 1 to 6% in Yunnan, 1 to 6% in Guangxi, and 0 to 5% in Guangdong; in absolute terms this corresponds to an average daily exposed population of about 6 million across the corridor, under 3% of its residents, with Guangdong's larger population offsetting its lower exceedance fraction. A controlled GEOS-Chem experiment with and without ICP fire attributed 25% (9.6 μg/m3) of Yunnan's springtime PM2.5 to ICP burning, 6% (3.3 μg/m3) in Guangxi and 4% (1.6 μg/m3) in Guangdong, a monotonic west-to-east gradient paralleled by ozone (10%, 5%, 2%). Translating this attribution into exposure, ICP fire carried an estimated average daily population of 2.2-2.6 million above the China PM2.5 standard (36-44% of all above-standard exposure), and about 11 million above the WHO ozone guideline. CONCLUSIONS:The model-attributed ICP-fire contribution is largest in Yunnan and attenuates eastward, while national-standard exceedance remains episodic across the corridor; this pattern supports province-specific, transport-aware air-quality assessment.
