The traditional environmental enforcement framework is fraught with conflicts stemming from the dichotomy between fragmented enforcement and integrated governance, the tension between local protectionism and stringent environmental regulation, and the disparity between imbalanced information structures and the need for precise governance. These conflicts have led to weakened environmental regulation and a concomitant decline in environmental quality. In response, the Chinese central government has initiated a centralized environmental enforcement system reform（EESR）. The theoretical underpinnings of this reform are rooted in the integration of functions to mitigate the fragmentation, the reconfiguration of power to prevent local interference, and the leveraging of technology to facilitate comprehensive and transparent oversight. Based on this, we have constructed annual panel data for 192 prefecture-level cities spanning the period from 2013 to 2022. Utilizing a Difference-in-Differences（DID）approach, we found that EESR has significantly led to stricter environmental enforcement, with a post-EESR increase of 49.8% in environmental administrative penalties levied by cities. However, economic factors would modulate the efficacy of the EESR. Cities closer to the western regions exhibit a less pronounced positive impact of the reform on environmental enforcement. Further analysis indicated that the EESR has had a significant positive effect on air quality, with substantial reductions in concentrations of PM_2.5, PM₁₀, and SO₂ following its implementation. This study offers guidance for the further development and improvement of the EESR in later stages, as well as insights into understanding the positive effects of a centralized environmental control system.

In this study, the adsorption and distribution processes of 6:2 fluorotelomer sulfonic acid（6:2 FTSA）and perfluorohexane sulfonate（PFHxS）in polyamide（PA）microplastics and soil interaction systems were investigated, and the effects of various factors on their adsorption were explored. The results indicated that the adsorption equilibrium time for 6:2 FTSA and PFHxS in the microplastic-soil interaction system（approximately 120 hours）was significantly slower than in individual microplastic and soil systems（approximately 24 hours）. Furthermore, the adsorption equilibrium capacity of 6:2 FTSA（0.044mg/g）and PFHxS（0.173mg/g）in the microplastic-soil interaction system was considerably lower than in PA microplastics alone（6:2FTSA:2.698mg/g;PFHxS: 3.518mg/g）, but slightly higher than in soil alone（6:2FTSA:0.026mg/g;PFHxS: 0.048mg/g）. With the increase of the content of microplastics in soil, the proportion of 6:2FTSA and PFHxS on microplastics gradually increased, especially for PFHxS. From the perspective of microplastics, the interaction with soil altered the surface properties of microplastics. As soil minerals occupied some adsorption sites of microplastics, the adsorption capacity of microplastics for 6:2FTSA and PFHxS was significantly reduced. Conversely, from the soil perspective, the presence of microplastics enhanced the soil's adsorption capacity for 6:2FTSA and PFHxS, with this effect becoming more pronounced as the proportion of microplastics increased, due to the strong adsorption affinity of microplastics for PFAS. In the co-cultivation system of microplastics and soil, although the surface properties of microplastics were modified over time, the overall adsorption of 6:2FTSA and PFHxS by the PA microplastics-soil system was not been significantly altered. These findings suggest that microplastics exert a long-lasting and relatively stable influence on PFAS in soil.

The migration behavior of microplastics in aquatic environments is governed by complex interactions among hydraulic, physical, and material-specific factors. This study integrates hydraulic experiments and force analysis to identify the critical hydraulic parameter thresholds influencing state transitions of different microplastic types in freshwater systems. A Lagrangian particle tracking method is then employed to develop a migration model grounded in well-defined physical principles. This model simulates microplastic trajectories, predicting their ultimate movement states and environmental fate. The model is validated using field data from the urban section of the Jialu River in Zhengzhou, China. Results indicate that 66.79% of microplastics in this section have particle sizes smaller than 0.5mm, with fragmented（31.1%）and fibrous（29.2%）shapes being predominant. Polypropylene（PP）migrates as floating debris with the highest velocity, while polystyrene（PS）and polyamide（PA）particles smaller than 0.5mm migrate as suspended load. In contrast, polyethylene terephthalate（PET）and PA particles larger than 0.5mm migrate as bedload or remain stationary on the riverbed. Under flow rates of 14m³/s and 20m³/s, retention rates of microplastics over 36hours were 43.79%and 47.85%, respectively, with PA and PET constituting the major retained microplastic types. These findings provide valuable insights into the hydrodynamic behavior and environmental fate of microplastics, offering guidance for pollution management in freshwater systems.

The particle number concentration and size distribution of combustion emissions from seven types of honeycomb briquettes and eleven types of lump coal were investigated using a Scanning Mobility Particle Sizer (SMPS) in a laboratory-simulated combustion setup with a dilution channel sampling system. Emission factors for the number concentration of various particle size segments were calculated, yielding essential data for the construction of a number concentration inventory and the enhancement of effect simulations. The results indicated the following: A significant quantity of submicron particles was emitted during the combustion processes of both coal types. The number concentrations exhibited a decreasing trend with increasing particle size, notably in the nucleation and Aitken modes. However, this decreasing trend was less pronounced in the lower particle size section of the accumulation mode (100nm ≤ Dp ≤ 200nm), while the number concentration of larger particles (200nm ≤ Dp) gradually increased with increasing particle size. The total number concentration emission factors from the combustion of honeycomb briquettes and lump coal were determined to be 9.9×10¹⁴±5.3×10¹⁴ particles/kg and 1.4×10¹⁵±7.9×10¹⁴ particles/kg, respectively. For lump coal, the emission factors across the three modes of combustion emissions were calculated as 1.0×10¹⁵±5.9×10¹⁴ particles/kg, 2.8×10¹⁴±2.5×10¹⁴ particles/kg, and 6.4×10¹³±3.5×10¹³ particles/kg. Notably, the three-modal mean concentration emission factors for lump coal were 1.3, 1.9, and 1.5times higher than those for honeycomb briquettes. Furthermore, the ICRP computational model was employed to estimate the total respiratory deposition flux (RDF) ranges of 7.6×10¹² to 4.7×10¹³ particles/min for honeycomb briquettes and 5.7×10¹² to 3.3×10¹³ particles/min for lump coal. It was found that over 90% of the RDF was attributed to the nuclear mode particles when compared to Aitken mode particles in the combustion emissions of submicron particles within the respiratory tract. Additionally, the particle RDF size distribution exhibited a decreasing trend across all three regions of the respiratory tract. Overall, this study provided a comprehensive analysis of particle number concentrations, size distributions, emission factors, and inhalation exposures associated with particulate matter from civil coal combustion emissions across different particle size sections. The findings contribute valuable data and essential support for the development of numerical concentration inventories, improvements in effect simulations, and assessments of health risks.

As a kind of complex polar organic compounds commonly existing in the atmosphere, dissolved organic carbon (DOC) in precipitation has extensive and far-reaching influences on regional ambient air quality, global climate change and carbon cycle process, and has become one of the hot spots in current global change research. This article systematically summarized the research progress on atmospheric precipitation DOC in recent decades both domestically and internationally from three aspects: the abundance and bioavailability of DOC in atmospheric precipitation, the spatial and temporal distribution characteristics and influencing factors of DOC concentration and wet deposition flux in precipitation, and the ecological and environmental effects of DOC wet deposition. In the end of the article, the future development direction was discussed. The results indicated that the chemical composition of precipitation DOC is exceptionally complex, mainly composed of low molecular weight organic acids, amino acids and urea, etc. with high bioavailability. There were significant spatiotemporal differences in precipitation DOC concentration and wet deposition flux among different areas, which were mainly controlled by emission sources, emission intensity, and complex weather conditions. The DOC in the atmosphere could affect the properties of aerosols and precipitation (acid rain), and DOC settling on the surface of snow and ice could accelerate the melting of glaciers. At the same time, the input of DOC brought by wet deposition can enrich the organic carbon levels on the surface of seawater. Active DOC can promote the improvement of secondary productivity in marine ecosystem, while refractory DOC could contribute to the refractory dissolved organic carbon pool in the ocean, which is conducive to carbon sequestration and enhances ocean carbon sinks, helping to achieve the goals of "Ocean Negative Carbon Emissions" and "Carbon Neutrality". Future research should continue to focus on developing and using advanced instruments and equipment to accurately identify and quantitative the chemical composition of precipitation DOC, to have a deeper understanding of the bioavailability/inertness characteristics of precipitation DOC. At the same time, new numerical simulation techniques should be developed and utilized to conduct in-depth research on the spatiotemporal heterogeneity of atmospheric DOC wet deposition fluxes with different properties of on the global scale, and quantify the indirect wet deposition flux of atmospheric DOC. On this basis, elucidating the significance and value of atmospheric DOC wet deposition as one of the new pathways for improving global ocean carbon sequestration, so as to gain a deeper understanding on the position and role of atmospheric deposition in global carbon cycling and ocean “missing carbon sink” research.

PM_2.5 control in the Guanzhong region has achieved significant progress, but the situation regarding ozone pollution remains severe. To continue advancing the fine management of VOCs (volatile organic compounds) in the Guanzhong region, with Xi'an and Xianyang as representatives, six industries—packaging printing, electronic product manufacturing, industrial coatings, paint and ink manufacturing, furniture manufacturing, and rubber products — were selected for sample collection. This study examines the VOC emission profiles, ozone formation potential (OFP), and secondary aerosol formation potential (SOAFP) of typical industries in the Guanzhong region. The results show that in the packaging printing and industrial coating industries, the primary VOCs emitted are oxygenated volatile organic compounds (OVOCs) (53%~73%) and alkanes (17%~34%); in the electronic product manufacturing industry, they are OVOCs (68%) and alkenes (29%); in the paint and ink manufacturing industry, the main VOCs are OVOCs (61%) and aromatic hydrocarbons (22%); in the furniture manufacturing industry, the primary VOCs are aromatic hydrocarbons (78%) and OVOCs (19%); and in the rubber products industry, alkanes (78%) dominate. Key characteristic species emitted by typical industries in the Guanzhong region include ethanol, acetone, isopropanol, formaldehyde, ethyl acetate, and m-/p-xylene. Based on the Maximum Incremental Reactivity (MIR) method and the Aerosol Formation Coefficient (FAC) method, it was found that OVOCs, aromatic hydrocarbons, and alkenes are the main contributors to OFP, while aromatic hydrocarbons are the primary source of SOAFP. The major emission sources are the paint and ink manufacturing, industrial coatings, and furniture manufacturing industries, which should be prioritized for control.

To investigate the seasonal variation and source of oxidative potential (OP) in atmospheric fine particulate matter (PM_2.5) in Xi’an, the mass normalized OP (OP^DTTm) was measured using the dithiothreitol (DTT) method, and the influence of chemical components of PM_2.5 on OP^DTTm was analyzed, and the contributions of different sources to OP^DTTm was quantified using a positive matrix factorization coupled with an artificial neural network multilayer perceptron (PMF-ANN-MLP) model. The findings revealed that OP^DTTm in Xi’an was highest during summer ((13.2 ± 5.4) pmol(min·µg)) and lowest in winter ((5.6 ± 2.7) pmol(min·µg)). Correlation analysis indicated that nitro-containing aromatic compounds and carboxylic acids have a significant impact on OP^DTTm, and the difference in molecular abundance was the main reason for the seasonal variation of OP^DTTm. Source apportionment showed that dust (26.7%), traffic (35.1%), secondary formation (23.2%), and biomass burning (24.5%) and coal combustion (25.8%) were the predominant contributors to OP^DTTm during spring, summer, autumn, and winter, respectively. These results provide a scientific foundation for developing effective air pollution control measures aimed at safeguarding public health.

The influence of solar radiation, climate, soil, and vegetation on the vapor pressure deficit (VPD), as well as the characteristics of its spatiotemporal heterogeneity under the effects of its interaction with the terrestrial-atmospheric system, were explored using spatiotemporal trend analysis, geodetector, and geographical and temporal weighted regression (GTWR) models. The results showed that the multi-year average VPD value for the Jizi Bay of the Yellow River from 1982 to 2021 was 0.785kPa, with the highest annual VPD value found in the northwestern part of the area, followed by the central and western parts. Interannual and seasonal VPD showed a significant increase in all regions (P<0.05), with the highest increase in summer VPD [0.072kPa/10a] and a high increase in mean annual VPD in the east [0.045kPa/10a]. On the interannual scale, moisture conditions (precipitation and soil moisture) had the strongest influence on VPD, followed by temperature; in the southeast, NDVI had a strong influence on VPD. Additionally, the interaction of precipitation and temperature had the strongest influence on VPD, followed by the interaction of deep soil moisture with precipitation, temperature, and vegetation indices. On the spatiotemporal scale, from the 1980s to the 2010s, the limiting effects of precipitation and vegetation indices on VPD were gradually enhanced over time from the northwest to the southeast of the region. Furthermore, the promoting effects of temperature on VPD gradually increased with time from the south to the north, while the limiting effects of deep soil moisture on VPD gradually weakened with time from the southeast to the northwest. The results of this study provide a scientific basis for revealing the process of land–atmosphere interaction in this region and promoting the ecological protection and high-quality development of the Yellow River Basin.

A case study was conducted at Tianjin Airport by the research team, in which the predicted emissions using default parameters (recommended values) were compared with the results based on inputs that had been adjusted to real-world airport operations. A high spatial resolution (45m×45m) emission inventory was established in the airfield area to identify emission hotspots, and the results indicated that the daily emissions generated by all mobile sources at the airport based on recommended values were 2,320.01kg (NO_x), 12,919.90kg (CO), 199.36kg (SO₂), 76.83kg (PM) and 635.92kg (HC). After adjustment of inputs based on real-world airport operations, the emissions results were 1,982.65kg (NO_x), 722.25kg (CO), 157.27kg (SO₂), 70.48kg (PM) and 86.38kg (HC). The time between 08:00 to 09:00 (the departure peak at the airport) was identified as the period when the maximum total emissions across time of day occurred. Results of the spatial analysis showed that the emission hotspots were predominantly distributed as follows: for NO_x, near the end of the departure runway; for CO, the merging area of taxiways (which connect arriving and departing flights); for SO₂ and PM, the aprons with a larger number of arriving and departing flights; and for HC, both the merging area of connecting taxiways and the aprons with a larger number of flights. The top 20% of emissions were primarily from: for NO_x the take-off stage of aircraft; for CO, taxiing stage of aircraft; for SO₂ and HC, the ground support equipment in the parking position during the service stage and taxiing stage of aircraft; and for PM, ground support equipment at parking lots and service lanes.

To investigate the spatio-temporal variations, influential factors and environmental health effects of negative air ions (NAIs) in Hainan tropical rainforests, a mobile comprehensive measurement platform was utilized to carry out field observation during typical tourist season (January), four types of typical forest stands (evergreen broad-leaved, deciduous broad-leaved, coniferous and bamboo forests) at eleven different altitudes in the Wuzhishan area of the Hainan Tropical Rainforest National Park were measured. The concentrations, spatiotemporal variations of NAIs, and their relationships with forest types, meteorological factors, air quality, and volatile organic compounds (VOCs) were analyzed. A comprehensive evaluation method for the ecological health function of tropical rainforest based on the Forest Health Index (FHI) was established. The results showed that the NAI concentration in the Wuzhishan area was relatively high (3541±882) moles/cm³, reaching Level VI of the World Health Organization's air freshness classification standard. The NAI concentration was increased with altitude initially and then decreased. Coniferous forest was found to have the highest NAI concentration, followed by broad-leaved forest, with bamboo forest having the lowest. A total of 66VOCs were detected, with sesquiterpenes and oxygenated organic compounds accounting for over 80%. NAIs were shown significant positive correlations with relative humidity, fine particulate matter, and monoterpenes, and significant negative correlations with sesquiterpenes and aromatic hydrocarbons. The FHI in the afternoon was generally found to be higher than that in the morning, with most sampling sites reaching Level II or above.