环境科学与生态学最新文献

The article provides results of the study on retrospective evaluation of ¹⁴C pollution from Ignalina Nuclear Power Plant (INPP). Transfer factor approach was applied coupled with the radiocarbon measurements in Scots pine tree rings of extended network of 9 sampling sites around the INPP within the distance of 1.8 - 6.6 km from the INPP ventilation stacks. The measured ¹⁴C activity in tree rings suggested the annual airborne release estimate from the INPP to be in the range 0.43 - 11 TBq depending on the lifetime period of INPP which is in good agreement with other studies. The estimated average annual emission factor ranged from about 1 TBq/GWa in early operational years up to about 3 TBq/GWa after 10 years of operation. The most probable reason for this increase is the accumulation and aging of the graphite stack of INPP RBMK reactors. The last operational decade (1999 - 2009) is characterised by large fluctuations of releases which may be caused by the maintenance and waste management activities at INPP. The trend of last decade of our observations (2009 - 2019) is a continuous decrease of emissions up to 0.5 TBq per year after final shutdown of the reactors in 2009. The study shows high potential of accumulated ¹⁴C activity release due to dismantling and decontamination activities during the decommissioning phase of the NPP. The extended sampling site network effectively functioned as an aerial averaging system, reducing the influence of local peculiarities on sampling and modelling. As a result, the overall radiocarbon emissions reconstruction model uncertainty was estimated at approximately of 24%.

Hexavalent chromium (Cr(VI)) immobilization on iron oxides is commonly considered to rely on Fe(II)-mediated mineral transformation. Fulvic acid (FA) is ubiquitous in natural environments and interferes with interfacial reactions, yet its regulatory linkage between mineral evolution and Cr immobilization remains poorly understood. This study explored Fe(II)-mediated transformation of Cr(VI)-loaded lepidocrocite (LepCr) under anoxic conditions using batch experiments, spectroscopic characterization, and sequential extraction. Results confirmed that Cr(VI) was completely reduced to Cr(III) with no secondary release in all Fe(II)-amended systems. FA displayed a concentration-dependent effect on mineral conversion, which was partially decoupled from Cr immobilization. Lw FA (12 mg/L) facilitated lepidocrocite-to-goethite conversion via molecular bridging, whereas high FA (86 mg/L) significantly inhibited mineral recrystallization. Notably, as FA concentrations increased from 12 to 86 mg/L, the dominant Cr immobilization pathway shifted from mineral-transformation-associated processes to interfacial FA-Cr(III) complexation. Despite suppressed mineral transformation, high FA greatly elevated the proportion of non-extractable Cr from 25% to 54%, strengthening Cr immobilization. These results demonstrated that efficient Cr immobilization could be attained with reduced dependence on mineral transformation, where FA-Cr(III) complexation and Cr(III)-Fe(III) interfacial passivation dominated. Synchronous redistribution of FA at the solid-liquid interface further reinforced Cr sequestration. This work clarified the decoupled mechanism between mineral transformation and Cr immobilization, providing a mechanistic basis for optimizing Cr immobilization strategies in organic-rich contaminated environments.

Climate warming is expected to reshape sediment-associated metal behavior, yet whether warming responses of sediment metal(loid) lability are systematically regulated by baseline thermal conditions remains unresolved. Here, we combined diffusive gradients in thin films (DGT) measurements with controlled sediment incubations across 0-40 °C to quantify temperature-dependent lability responses of multiple metal(loid)s in coastal sediments. Distinct element-specific response regimes emerged. Redox-sensitive elements (Mn, V, and As) exhibited nonlinear increases in DGT-labile concentrations with warming, cobalt showed transitional non-monotonic behavior, whereas most particle-associated metal(loid)s displayed monotonic declines. These contrasting responses indicate that warming does not uniformly enhance sediment metal(loid) lability but reorganizes reactive metal behavior in patterns consistent with element-specific differences in solid-phase resupply and retention. Despite divergent element-specific trends, identical warming perturbations consistently induced larger relative lability changes at lower baseline temperatures. Model-based sensitivity analysis further showed that proportional warming responses were amplified under cold baseline conditions, identifying baseline temperature as a first-order regulator of sediment metal(loid) responsiveness to warming. This baseline-temperature control implies that climate warming may redistribute sediment contaminant sensitivity across thermal regimes, with cold coastal sediments exhibiting disproportionate geochemical responses. Our results provide a process-based framework linking warming, element-specific resupply kinetics, and sediment metal(loid) lability, and highlight baseline temperature as a critical but previously underrecognized control on contaminant dynamics at the sediment-water interface.

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.

Microplastics are ubiquitous pollutants in freshwater ecosystems, yet their impacts on freshwater-sediment ecosystems remain poorly understood. Here, we investigated how pristine and mechanically weathered polystyrene (PS) microplastics influence organisms, sediment properties, and overall ecosystem multifunctionality (EMF) within an integrated freshwater-sediment microcosm containing the rooted macrophyte Vallisneria spiralis, the benthic snail Lymnaea stagnalis, and sediments. Results showed that mechanical weathering transformed the originally smooth spherical PS microplastics into particles with rougher and more irregular surfaces. Weathered PS microplastics induced stronger biological stress in both plants and snails, reflected in higher integrated biomarker response (IBR) scores. Weathered PS microplastics reduced chlorophyll a and carotenoid content and also altered plant nutrient content, indicating impaired photosynthesis and altered carbon metabolism. In snails, weathered PS microplastics triggered oxidative stress and significantly increased caspase-3 activity, suggesting elevated apoptotic responses and ionic regulation demands. Despite organism-level impairment, both pristine and weathered PS microplastics enhanced sediment EMF. This enhancement was primarily driven by increased dissolved organic carbon, elevated β-glucosidase activity, and intensified microbial respiration, reflecting stimulated carbon cycling. These results reveal an ecological trade-off between organism health and ecosystem performance. Short-term functional stability was maintained through accelerated microbial metabolism, potentially masking underlying biological deterioration. Our findings demonstrate that microplastic weathering amplifies biological stress while simultaneously promoting ecosystem-level functional buffering, highlighting that apparent stability may entail long-term ecological risk. Integrating environmentally representative mechanically weathered microplastics with multi-species ecosystem assessments provides a more comprehensive framework for evaluating the ecological risks of microplastic contamination.

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 PM_2.5 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 PM_2.5 accumulation, strong stability, and the shallowest boundary layer. Class_2 exhibited enhanced wind speed shear above 500 m and an elevated PM_2.5 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 PM_2.5 concentrations. UAV observations within 0-500 m confirmed distinct PM_2.5 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 PM_2.5 depends on shear height and composition and on the evolving thermal structure of the boundary layer.

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.

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.

Mud volcanism acts as a natural conduit for transporting deep geological materials, saline fluids, and naturally occurring radionuclides to the surface, potentially generating complex environmental hazards. Despite extensive research on the geochemistry of mud volcanoes, the role of particle-size-dependent processes in controlling radionuclide mobility and exposure risk remains insufficiently understood. This study presents an integrated physicochemical and radiological investigation of slurry samples collected from the Wandan mud volcano in southern Taiwan. Particle-size analysis demonstrates that the slurry is dominated by fine-grained materials that are highly susceptible to aeolian and hydrological transport, thereby serving as primary vectors for contaminant dispersion. Further, the slurry is highly alkaline (pH 9.81 ± 0.28) with elevated electrical conductivity (4.10 ± 0.35 mS cm^-1), indicating a chemically hostile environment capable of inducing soil salinization and agricultural stress. Radiological measurements reveal a pronounced inverse correlation between particle size and radionuclide activity, with the finest fraction (<0.061 mm) showing substantially higher activities of natural radionuclides of ⁴⁰K, ²³²Th, and ²²⁶Ra compared with coarser sediments. This enrichment is attributed to surface-controlled adsorption mechanisms, whereby fine silt-clay particles with high specific surface areas, efficiently scavenge radionuclide cations during slurry ascent. Although bulk hazard indices remain below international safety thresholds, particle-specific lifetime cancer risk exceeds the global average, revealing a critical exposure pathway that conventional bulk assessments may overlook. Collectively, these findings demonstrate that fine particles function not only as the most mobile fraction, but also as dominant carriers of radiological risk. This study highlights the necessity of incorporating particle-size-resolved analyses into environmental risk frameworks to improve hazard prediction and land management strategies in mud-volcanic regions.