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PubMed2026

The spatial and temporal distribution of Staphylococcus aureus along a tropical Hawaiian watershed.

Staphylococcus aureus is a leading cause of community-acquired skin and soft-tissue infections worldwide. One major route of exposure is recreating in marine waters, but knowledge is limited regarding the drivers of S. aureus in surface waters that discharge into marine environments. This study explores spatial and temporal distributions of S. aureus, including antimicrobial-resistant and virulence genes, using both culture-dependent and molecular techniques across a tropical Hawaiian watershed with a gradient of human influence. Negative binomial generalized linear mixed models revealed that the interaction between spatial and temporal factors was the strongest predictor of S. aureus and associated genes. Cultured S. aureus was highest at mid-watershed sites in summer, which included a popular swimming hole, suggesting human shedding as a significant source. Molecular detection of S. aureus (femA gene) yielded concentrations two orders of magnitude higher than cultured concentrations and peaked at estuarine sites with the greatest nutrients and water residence times. In the winter at upstream sites with no public access, staphylococci antibiotic-resistant (mecA) and S. aureus virulence gene (etb) were elevated, indicating highly pathogenic S. aureus strains in surface waters may originate from zoonotic sources. Our findings indicate that human and zoonotic sources contribute antibiotic-resistant and virulent S. aureus to watersheds, with streams facilitating environmental transmission to marine waters. This watershed-scale assessment enables the prediction of spatial and temporal conditions associated with elevated S. aureus concentrations, thereby reducing exposure and infections.

Staphylococcus aureus↗

PubMed2025

Tracking microplastic contamination across seasons in a freshwater reservoir: Evidence from surface water, sediments, and fishes.

Microplastics (MPs) are prevalent contaminants in aquatic environments, posing substantial ecological and health risks. These particles migrate within the different layers of aquatic bodies with time and affect the respective biota. Thus, to get an in-depth understanding of the particles, this current study investigated the seasonal distribution, morphological and chemical characteristics, along with potential ecological and human health impacts in the samples including surface water, sediment, and fish from a drinking water supplying reservoir in eastern India. Across three different seasons, pre-monsoon, monsoon, and post-monsoon samples were collected using optimized methods. Results revealed distinct seasonal trends: MP abundance in surface water peaked during the monsoon (mean: 1.15 MPs/L), while sediment showed the highest concentrations in the pre-monsoon (mean: 596 MPs/kg), indicating temporal accumulation dynamics influenced by runoff, hydrodynamics, and sedimentation. Fish gut analysis confirmed ingestion of MPs across five species, with concentrations ranging from 26 to 100 MPs/kg, depending on feeding habits. The most dominant MP type were fragments, followed by fibers, films, and beads. Polymer analysis via µFTIR identified polyethylene, polypropylene, and polyvinyl chloride as prevalent, with hazard assessments (i.e., Polymer Hazard Index (PHI)) indicating medium to very high ecological risks. Heavy metal association was more dominant in the MPs isolated from sediments than the waterborne MPs. Pollution Load Index (PLI) values were > 1 in most seasons, confirming contamination. Health risk analysis suggested potential exposure through both drinking water and fish consumption. This study emphasizes the need for seasonal monitoring, improved waste management, and mitigation strategies to address MP pollution in freshwater ecosystems.

Microplastics↗

PubMed2026

Biomass burning contributions to Mexico City's atmospheric CO2 estimated using a multi-isotope approach.

Fossil fuel combustion dominates anthropogenic emissions worldwide; however, special attention should be addressed to biomass burning, since it is an increasingly important contributor under warmer, drier fire-weather conditions exacerbated by climate change. These emissions could impact the atmospheric composition of heavily urbanized environments. To assess the influence of biomass burning, along with fossil fuels combustion and soil and plant respiration on Mexico City's atmospheric composition, we conducted a year-long (December 2023-December 2024) isotopic monitoring of atmospheric CO2, combining radiocarbon (Δ14C), CO2 stable isotopes (δ13C, δ18O), and CO/CO2 ratios. Once defined the isotopic signatures and the characteristic CO/CO2 that describe the sources, we performed Monte Carlo simulations under two tracer modalities (Δ14C + CO/CO2 and Δ14C + CO2 stable isotopes) for source apportionment. Results show that during the dry season, particularly in March-April, atmospheric Δ14C values approached and overlapped background levels despite Mexico City's fossil-fuel dominance, indicating enhanced non-fossil inputs. Moreover, backward HYSPLIT trajectories supported that these elevated Δ14C values coincided with regional wildfire activity. Monte Carlo results attributed up to ∼34 %-60 % of local CO2 to biomass burning in April, followed by March with contributions of ∼31 %-49 %. Since these biomass burning figures contrast with the official emissions inventory of Mexico City metropolitan area, which assigns <1 % of total CO2 emissions to biomass burning, this study could exhibit the emissions inventory underestimation of this source, and thus, the need to reassess and incorporate top-down isotopic constraints in fire-affected urban regions.

Mexico↗

PubMed2026

Comprehensive source-risk assessment of organophosphate esters in surface water of the Dianchi Lake Basin, Yunnan, China.

Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have been increasingly detected in aquatic environments. However, investigations of their distribution in high-altitude plateau lakes remain scarce. Identifying and quantifying the sources and associated risks of OPEs are crucial for subsequent water environment management. In this study, an integrated source-risk analysis approach was employed by combining the Positive Matrix Factorization (PMF) model, the Geodetector (GD) model, and risk quotient (RQ). Analysis of 14 OPEs in surface waters of the Dianchi Lake Basin (DLB) revealed 12 detectable compounds, with total OPEs concentrations (ΣOPEs) ranging from not detected (ND)-64.6 ng/L during the wet season and ND-35.8 ng/L during the dry season. Elevated ΣOPEs were primarily observed at inflow sites in the northern part of the lake and in urban rivers. Source apportionment indicated four major contributing sources: agricultural films containing flame-retardant and plasticizer additives, traffic-related particulate emissions, releases from household and personal care products, and industrial production and applications of flame retardants in plastics, electronics, and related products (the predominant source). The ecological impact caused by OPEs ranges from no risk to low risk, with tris(2-chloroethyl) phosphate emitted from industrial source being the primary driver of potential environmental risk. These findings highlight the necessity of prioritizing industrial sources in future management strategies. Overall, this study provides a methodological framework for source apportionment and risk assessment of OPEs and offers scientific evidence to support environmental management of OPEs in the DLB.

Environmental Monitoring↗

PubMed2026

Variability and ozone formation potential of ambient non-methane hydrocarbons in a tropical semi-arid atmosphere of northwest India.

We present first-time measurements of twenty-six ambient non-methane hydrocarbons (NMHCs; C2-C8), including isoprene (C5H8), at a semi-arid site in northwest India (Ajmer; 26.45°N, 74.64°E), during January 2022-December 2023. Ambient samples were analyzed using a thermal desorption gas chromatography system equipped with dual flame ionization detectors. Daily total NMHC levels ranged from 6 ppbV to >100 ppbV. Most NMHCs, except isoprene, toluene, ethylbenzene, m-xylene and o-xylene, exhibited the highest levels in winter and the lowest in the monsoon. In contrast, others were highest in the pre-monsoon and toluene was highest during monsoon. These variations reflect the combined influence of emissions, chemistry and meteorology. Toluene and o-xylene were the dominant NMHCs (25 %-67 %). Correlation analyses indicated major contributions from liquefied petroleum gas (LPG) and vehicular emissions, with additional influence from urban and oil and natural gas activities. Compared with other Indian sites, NMHCs levels at Ajmer were 2-5 times lower than Ahmedabad and Udaipur and 10 times lower than Delhi. The total ozone formation potential was highest in the monsoon (about 175 ppbV) and lowest in the post-monsoon (about 55 ppbV), with dominance of o-xylene (24 %-33 %) and toluene (8 %-37 %). Propylene-equivalent concentrations were highest in the pre-monsoon (30.23 ppb C) and lowest in the post-monsoon (7.28 ppb C). Similarly, OH reactivity was highest in the pre-monsoon (19.58 s⁻¹) and lowest in the post-monsoon (4.71 s⁻¹), dominated by benzene and toluene. These findings emphasize the importance of NMHC chemistry in a climatically sensitive region and highlight the need for their continuous monitoring.

India↗

PubMed2026

Long-term petroleum pollution alters soil microbial communities via electron transfer capacity: Evidence from a 35-year chronosequence.

Petroleum pollution poses a serious threat to soil ecosystems, especially in areas surrounding oil wells, where contamination should not be overlooked. Through a 35-year longitudinal study of soils surrounding oil wells, we demonstrate that petroleum hydrocarbons accumulate predominantly in the top 10 cm of soil, reducing the electron acceptor capacity (EAC) by 61.59 % (from 12.68 to 4.87 μmole-/gC) and decreasing the electron transfer capacity (ETC) by 43 %. Structural equation modeling identified ETC as the critical mediator of microbial community shifts, with EAC playing a pivotal role in sustaining redox processes. Notably, hydrocarbon accumulation triggered a microbial succession: The abundance of Actinomycetota (including genera Rhodococcus, Arthrobacter, and Rubrobacter) showed the most significant fluctuations within 2 years, while Pseudomonadota (genera Methylobacter, Thiobacillus, and Pseudomonas), which were dominant in uncontaminated soils, decreased markedly during this period. This transition coincided with peak microbial dysbiosis (microbial dysbiosis index in 2022 reached 31.41 times that of controls). Within two to four years following mild petroleum stress, the bacterial community established a new structural configuration, revealing a crucial window for ecological recovery. The coupling between ETC reduction and microbial succession highlights the pivotal role of electron flux in soil recovery. Our findings establish a mechanistic framework for ETC-targeted restoration strategies to enhance bioremediation in petroleum-contaminated soils.

Soil Microbiology↗

PubMed2025

Influence of soil types with different soil-forming process on the qualitative and quantitative detection of microplastics by near-infrared spectroscopy.

Microplastics (MPs) have become a pressing global environmental threat, with soils-acting as sinks for MPs from multiple sources-gaining increasing attention. Near-infrared (NIR) spectroscopy offers a promising tool for MPs detection due to its rapid, non-destructive, and field-applicable features. Although previous studies have focused on the effects of individual soil components on the NIR detection performance of MPs, there is still a lack of systematic research on how the complex background-formed by the coupling of multiple physicochemical properties in natural soils-affects detection performance. This study focuses on soil types with different soil-forming processes, selected five representative agricultural soils to systematically evaluate how the combinations of physicochemical properties they represented affect the performance of NIR-based qualitative and quantitative analysis of MPs in soils. The results demonstrated that soil type significantly affected both the spectral response and detection performance of MPs. Brown Pedocals and Brown Earth exhibited clearer characteristic absorption and stronger linear responses, achieving higher identification accuracy under low (<1.5 %) or zero MPs concentrations and the best quantitative performance (R2 ≥ 0.988, prediction set root mean square error (RMSEP) ≤ 0.110 %). In contrast, Phaeozem and Red Soil were more prone to misclassification at low concentrations, while Fluvo-aquic Soil showed the poorest quantitative performance. This study is the first to reveal, at a holistic level, the critical constraints posed by natural soil complexity on the NIR detection of MPs, offering targeted empirical evidence to support the application of NIR technology in real-world soil environments.

Soil↗

PubMed2025

Effects of aerosol aging on composition and light-absorbance of nitrogen-containing organic compounds: Evidences from ultra-high-resolution mass spectrometry analysis.

Nitrogen-containing organic compounds (NOCs) are key components of particulate matter (PM), but their compositional evolution and light-absorbing properties during atmospheric aging remain poorly understood. In this study, ultra-high-performance liquid chromatography coupled with Orbitrap mass spectrometry was used to semi-quantitatively analyze 59 PM1 samples collected in Shanghai. NOCs accounted for 31 % and 64 % of the detected species in negative (ESI-) and positive (ESI+) ionization modes, respectively. Atmospheric aging significantly reduced the molecular diversity of polar organics, with both the number and mass concentration percentages of CHON- compounds showing significant negative correlations with aging degree. Van Krevelen analysis demonstrated a decrease in the number of carboxylic-rich alicyclic molecules and their CHON- contributions during the aging process (from 37.7 % in fresh samples to 21.2 % in aged samples). CHN+ compounds, a major NOCs group in ESI+ mode, also decreased with aging. Correlation analyses involving the Bep/(Bep+Bap) ratio, relative humidity, and mass absorption efficiency at 365 nm revealed a decline in light absorption capacity with aging, suggesting aqueous-phase oxidation as a dominant aging mechanism. CHON- and CHN+ compounds were identified as the principal light-absorbing constituents in PM1. This work provides new insights into the aging-induced transformations of NOCs in urban PM1, and their changing role in light absorption, highlighting the need for further investigation of the aging mechanisms of NOCs.

Aerosols↗

PubMed2026

Marine air promotes structural compaction and coating growth of soot aerosols after long-range transport from East Asia.

Soot aerosol, a key global warming contributor, undergoes morphological and chemical transformations during atmospheric transport, particularly in humidified marine environments. This study investigates morphology, mixing state, and aging mechanisms of soot particles collected in the Bohai Sea and Yellow Sea. Transmission electron microscopy analyses reveal that coated soot particles dominate the marine atmosphere, accounting for over 98 % of soot-containing particles, with a mean mixing state index (χ) of 0.83. The fractal dimension (Df) of soot particles is 1.84 ± 0.05 in the Northern Yellow Sea, 1.90 ± 0.08 in the Bohai Sea, and 1.96 ± 0.07 in the Southern Yellow Sea, indicating structural compaction during long-range transport. Correspondingly, the average Dp/Dcore ratios (particle to core size ratio) are 5.3 in the Bohai Sea, 4.2 in the Northern Yellow Sea, and 3.9 in the Southern Yellow Sea. Notably, those ratios are higher in marine environments compared to those observed during continental regional transport from northern to southern China (3.54), suggesting enhanced coating growth in humid marine air. The results highlight the important role of marine atmospheres in accelerating soot aging, which in turn leads to significantly stronger light absorption compared to soot in continental air. Our results highlight the necessity of incorporating compact morphologies, uniform mixing states, and thick coatings into optical models for accurate radiative forcing simulations.

Aerosols↗

PubMed2025

Coupling of spectroscopy and nitrogen-oxygen isotopes unveils the mechanisms of dissolved organic matter and nitrate pollution in lakes within the agro-pastoral transition zone.

Lakes in arid and semi-arid regions are subjected to severe ecological stress, such as organic pollution, eutrophication, and salinization, due to climate change and human activities. This study investigates Chagannur Lake, a typical arid-region lake that is representative and ecologically sensitive in Northern China's agro-pastoral ecotone, to uncover its pollution characteristics and mechanisms. We employed fluorescence spectroscopy and stable isotope analysis to trace dissolved organic matter (DOM) and nitrate sources. The DOM composition was dominated by microbial metabolic byproducts and protein-like substances, suggesting that microbial processes are key to organic matter transformation. Source apportionment revealed that pollutants primarily originated from livestock and poultry manure (37.6 %), agricultural fertilizers (35.6 %), and soil erosion (24.7 %), with agricultural fertilizers contributing most significantly in the Gogstai River (63.3 %). A structural equation model (SEM) coupling spectral and mass spectrometric data revealed that microbial transformation significantly impairs the lake's self-purification capacity, thereby promoting pollutant accumulation (path coefficient = 0.91,*p < 0.05). Moreover, microbial processes link endogenous and exogenous pollution, a mechanism effectively traced by isotopic and fluorescence indices (path coefficient = 0.55, ⁎⁎p < 0.01). These findings enhance the understanding of pollution sources and transformation mechanisms in arid-region lakes and offer foundational theoretical support for policymakers engaged in pollution control strategies.

Lakes↗

PubMed2026

Three-dimensional source apportionment and quantitative characterization of horizontal and vertical transport fluxes of O3 and its precursors in the Beijing-Tianjin-Hebei region, China.

Persistent surface ozone (O3) pollution in the Beijing-Tianjin-Hebei (BTH) region is driven by coupled precursor emissions and multi-scale transport, yet its altitude-dependent transport and source contributions remain insufficiently quantified. Here we integrated the Weather Research and Forecasting and the Comprehensive Air Quality Model with Extensions with the Ozone Source Apportionment Technology and a quantitative transport-flux framework to characterize three-dimensional source apportionment and horizontal/vertical fluxes of O3, Volatile Organic Compounds‌ (VOCs), and Nitrogen Oxides (NOx) across dynamic meteorological scenarios. Simulations showed that VOCs and NOx were dominated by local emissions near the surface (73.61 %-82.18 %), whereas surface O3 was primarily controlled by regional transport, with local contributions of only 11.01 %-13.75 %. Notably, the transport dominance further strengthened with altitude, exceeding 93 % at 1.8 km. Industrial and transportation emissions together contributed more than 75 % of precursor emissions and account for approximately 80 % of O3 formation, while favorable/unfavorable meteorological years modulated long-range transport efficiency and the vertical distribution of contributions. Horizontal flux analysis highlighted three major pathways (Northwest-Southeast, Southeast-Northwest, and Southwest-Northeast), with Shijiazhuang serving as a critical pollutant "sink" across altitude layers. Vertical fluxes revealed an altitude transition near 600 m: net downward transport dominated below 600 m, whereas enhanced summer convection promoted upward transport above 600 m. These results support altitude-dependent, scenario-specific strategies for coordinated regional O3 mitigation in the BTH region.

Ozone↗

PubMed2026

Nitrogen sources and concentrations shape algal odor compounds: Key drivers of β-cyclocitral and β-ionone in water bodies of the lower Yangtze River.

Taste and odor (T&O) compounds derived from cyanobacterial blooms pose escalating threats to freshwater security worldwide, yet the drivers of specific T&O metabolites remain poorly constrained. Here, we investigated the dual effects of nitrogen (N) sources and concentrations on the production of β-cyclocitral and β-ionone, two algal-derived T&O compounds, through integrated field surveys (54 sites across lakes and rivers) in the eutrophic lower Yangtze River, China, and laboratory cultivation of typical cyanobacteria (Microcystis aeruginosa and Pseudanabaena cinerea). Our field data revealed that the concentrations of β-cyclocitral and β-ionone in lakes and rivers were not significantly different, but increased with the trophic level index. Redundancy analysis and Mantel analysis showed that Microcystis and Pseudanabaena were potentially dominant contributors to β-cyclocitral and β-ionone in the water column. Structural equation modeling and variation partitioning analysis showed that enhanced nitrate (NO3--N) significantly promoted the production of these compounds. Laboratory experiments demonstrated that inorganic N (NaNO₃) maximized total T&O yields by promoting algal biomass, whereas organic N (urea and glutamic acid) elevated the T&O production per unit biomass by 1.5- to 9.5-fold. Notably, Pseudanabaena exhibited a 2.3-fold higher β-ionone yield than Microcystis, with greater sensitivity to N concentrations. Our study highlights the critical role of nitrogen pollution, both source and concentration, in the production of T&O compounds by phytoplankton and provides reference data for managing T&O issues in rivers and shallow lakes.

Norisoprenoids↗

PubMed2025

An integrated multiscale air quality modelling framework for industrial park pollution: Linking local emissions to regional transport.

Capturing the spatiotemporal distribution of pollutants in industrial parks remains challenging for regional air quality models because of their coarse resolution (3 km), resulting in uncertainties in local emission quantification. To address this, we developed the Integrated Multiscale Air Quality Modelling System for Industry (IAQMS-Industry), coupling the regional Nested Air Quality Prediction Modelling System (NAQPMS) with a city-scale chemical transport model. This framework integrates point-source locations and Gaussian plume dispersion to simulate particulate matter with a diameter smaller than 2.5 micrometres (PM2.5) at 100 m resolution. Applied to the Beijing Yi Zhuang and Tangshan industrial parks and evaluated against observations. The coupled model achieved a normalized mean bias (NMB) ranging from 3.1 % to 6.2 %, improving upon NAQPMS (-16.9 % to -7.7 %). Spatial analysis revealed that coarse regional grids underestimated the PM2.5 concentrations at industrial sites by smoothing gradients, whereas IAQMS-Industry successfully resolved spatial patterns. Industrial point emissions accounted for 22.9 %-26.4 % of PM2.5 in the coupled model, which was significantly greater than the regional model estimates of 1.6 %-13.7 %. These findings indicate that regional models overestimate pollutant dispersion processes in industrial parks while underestimating local industrial impacts. By explicitly resolving point-source dynamics and linking them to regional transport, IAQMS-Industry provides a robust tool for designing targeted emission controls in industrial cities and balancing local air quality improvements with minimized regional pollution outflow. This study underscores the necessity of multiscale modelling for accurate source apportionment and informed environmental governance in industrial zones.

Air Pollution↗

PubMed2026

Antarctic Peninsula soil carbon stock and efflux: A complex interplay of soil properties and heavy metals.

This study establishes a quantitative framework for understanding surface soil carbon dynamics and ecosystem connectivity in Fildes Peninsula and Ardley Island, King George Island, South Shetland Islands, Antarctic Peninsula. The mean soil organic carbon (SOC) stock across all study sites was 1.10 ± 1.93 kg C/m². Restricting net carbon balance analysis to Fildes Peninsula, where soil respiration (Rs) data were available, yielded a site-specific SOC stock of 0.45 ± 0.45 kg C/m². Scaling Rs to a realistic 120-day active season and assuming stable SOC stocks resulted in estimated annual carbon loss of 15 g C/(m2·yr), equivalent to 3.3 % of standing SOC. Comprehensive sensitivity analyses spanning plausible winter respiration (0 %-20 % of summer rates) and annual change in SOC stocks (-1 %-2 %) consistently supported a net carbon sink, with turnover rates constrained to 3.3 %/yr-4.7 %/yr. Principal component analysis showed that ornithogenic processes as the dominant control on SOC, total nitrogen (TN), zinc (Zn), copper (Cu), and cadmium (Cd) provide a clear multivariate signature of marine-derived nutrient, while Pb was decoupled from this gradient and associated instead with fine-particle size controls. These results reveal dual but independent drivers of soil metal enrichment in this region. Despite their limited spatial extent, ornithogenic soils store disproportionately large carbon pools. Overall, this integrated analysis reveals how marine-terrestrial subsidies regulate Antarctic carbon cycling and provides a quantitative and reproducible framework for assessing carbon dynamics under ongoing climate change.

Antarctic Regions↗

PubMed2026

Littoral and wetland vegetation decrease carbon emissions from dry inland waters.

Lakes are recognized as active components of the inland water carbon (C) cycle, as organic matter is processed by microbial respiration, inducing large carbon dioxide (CO2) and methane (CH4) emissions. In the context of long-lasting drought periods, large uncertainties remain about: (1) the influence of wet-dry cycle on CO2 and CH4 fluxes in littoral zones and lacustrine wetlands; and (2) the contribution of emergent vegetation to C fluxes in dry inland waters. At the water-land interface of two shallow lakes, this study focuses on CO2 and CH4 fluxes from vegetated and bare dry inland waters in relation to hydrological fluctuations. Three seasonal campaigns were conducted to measure daytime CO2 and CH4 fluxes in pelagic, littoral and wetland surface waters, as well as in temporarily air-exposed sediments, using floating and static chambers, respectively. Our results reveal that wet-dry cycle in the littoral zone and wetlands strongly influence gaseous C fluxes through contrasting patterns, especially in late summer, when the biological processes are most active (primary production and respiration). In air-exposed littoral zones, organic-poor sandy sediments presented the lowest CO2 and CH4 emissions, whereas in air-exposed lacustrine wetlands, water-saturated sediments accumulated high amounts of plant-derived organic matter, promoting intense microbial activity and the highest C emissions. However, amphiphytes and helophytes vegetation in exposed littoral zones and wetlands reversed the direction of C fluxes, inducing the highest CO2 uptake due to high photosynthesis rates. This study underlines the relevance of considering vegetation in dry inland waters, particularly in lacustrine littoral zones and wetlands, to obtain comprehensive lake C budgets, especially under climate change scenarios.

Wetlands↗

PubMed2026

Pollution characteristics and health risks of PAHs and OPAHs in PM2.5 of an inland basin city in China under the influence of the clean air action plan.

Since the implementation of China's Clean Air Action, remarkable progress has been made in air pollution control, with continuous air quality improvement in Xi'an, a typical inland basin city in the Fenwei Plain. To clarify winter organic aerosol pollution variations and pinpoint targeted control needs under policy regulation, this study investigated PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and oxygenated derivatives (OPAHs) in winter Xi'an, focusing on pollution levels, chemical compositions, source contributions, meteorological impacts, regional transport and health risks. Historical comparison showed generally lower wintertime PAH concentrations in Xi'an during the period of China's clean-air actions. PMF results indicated mixed source influences on PAHs and OPAHs, with biomass-burning-related mixed combustion showing the largest contribution. During haze episodes, absolute concentrations of both PAHs and OPAHs increased; the increase was statistically significant for OPAHs but not for parent PAHs, while 4-5 ring PAHs and BcdPQ dominated the PAH and OPAH profiles, respectively. Meteorological variability, particularly synoptic pressure patterns, was strongly associated with pollutant concentrations, and regional pollution was dominated by in-basin accumulation combined with short-range transport from northern Shaanxi industrial zones. Haze periods exhibited higher toxic-equivalent concentrations, with OPAHs, particularly BcdPQ, dominating the toxicity-equivalent burden. Screening-level ILCR estimates generally remained below 10⁻4 but increased during haze episodes, especially for adult and elderly groups. In conclusion, China's clean air actions have coincided with lower wintertime PAH pollution, but stronger control of residential biomass and other solid-fuel combustion, traffic emissions, and OPAH formation remains necessary in the Fenwei Plain.

China↗

PubMed2026

Quantifying the combined effects of semi-closed terrain and monsoon on PM2.5 and O3 pollution aggregation in the North China Plain.

The North China Plain (NCP) and its surrounding regions represent one of the key priority areas for air pollution control. As anthropogenic emissions decline significantly, the effect of terrain and meteorology on air pollution pattern has become increasingly prominent, particularly given the NCP's unique semi-closed terrain and East Asian monsoon dynamics. However, quantitative characterization of terrain-dominated blocking effects remains unexplored. Here we quantitatively assess the blocking effects of mountains and terrain-coupled meteorological factors on air pollutant dispersion. We find the NCP on the eastern side of the Taihang Mountains showed high PM2.5 and O3 pollution levels, with winter PM2.5 and summer O3 high-value zones showing opposite north-south aggregation patterns. PM2.5 and O3 concentrations were highest in plains, followed by platforms, hills, and finally mountains. Within the 120-km buffer zones of the typical mountains in the NCP and its surrounding regions, PM2.5 and O3 concentrations increased initially with altitude but then decreased markedly above a threshold altitude. Above the threshold altitude, mountain blocking effects became dominant. The effective blocking altitudes of typical mountains in the NCP and its surrounding regions ranged between 22 and 929 m for winter PM2.5 pollution, and between 19 and 1060 m for summer O3 pollution. The Terrain-Wind Close Index indicates that the terrain-coupled East Asian monsoon showed stronger blocking effects on PM2.5 dispersion in southern NCP during winter and on O3 diffusion in northern NCP during summer, matching observed high-pollution zones. This study offers key insights for regional joint air pollution mitigation strategies, as well as regional pollution assessment.

Particulate Matter↗

PubMed2026

Microplastic contamination in South Asian commercially important seafood: A comprehensive assessment of occurrence, source, and human health risk.

Seafood is a cornerstone of global food security and human nutrition, serving as the primary source of animal protein for more than one-fourth of the global population, with South Asia representing one of the world's fastest-growing seafood-consuming regions. However, escalating microplastic (MP) pollution in marine ecosystems poses an emerging threat to seafood safety and human health, yet a comprehensive regional assessment of MP contamination in South Asian seafood remains lacking. This study presents the first region-wide systematic synthesis of the literature on MP contamination in commercially important seafood across South Asia, integrating occurrence patterns, human exposure assessment, polymer-specific hazard evaluation, and bibliometric analysis to address this critical knowledge gap. The meta-analysis estimated an average microplastic exposure of 145 particles/person/day through seafood consumption in South Asia, with fish contributing the highest intake (121 particles/person/day). The detected polymers were classified into PHI hazard levels I-IV, with polyvinyl chloride (PVC), polyurethane (PU), and polyacrylamide (PAM) representing the highest hazard categories. The mean pollution load index (PLI) was 7.71 (Category I), with crustaceans exhibiting the highest contamination (PLI = 10.07). Polypropylene was the predominant polymer, whereas fragments and blue particles were the most frequently reported microplastic characteristics. These findings provide the first regional baseline for assessing microplastic contamination, polymer-associated hazards, and human exposure through seafood consumption in South Asia, underscoring the need for standardized monitoring and targeted mitigation strategies to safeguard seafood safety and public health.

Animals↗