The recycling of waste photovoltaic panels is of great significance for environmental protection and the realization of resource recycling. Under the national dual carbon policy, the carbon footprint assessment, evaluation of waste photovoltaic panel recycling and treatment technology have become key issues for the sustainable development of the photovoltaic industry. This paper establishes a carbon footprint evaluation system for the recycling of waste photovoltaic panels. Using the Life Cycle Assessment (LCA), the environmental impact assessment and carbon footprint analysis are conducted for three typical recycling technologies for waste photovoltaic panels (i.e., the alkaline-acid electrolysis method (PI), the improved reverse electroplating-alkaline-acid method (PII), and the improved salt etching method (PIII)). Through LCA normalization analysis, the environmental impacts of the three processes are typical alkali-acid electrowinning method > improved reverse electroplating-alkali-acid method > improved salt etching method. Sensitivity analysis indicates that PI and PII use relatively small amounts of hydrofluoric acid and acetic acid, resulting in the highest sensitivity. Material flow and carbon flow analysis clearly demonstrated the sources and sinks of material consumption and carbon emissions. The results showed that the chemical waste generation and carbon emissions of PIII were significantly reduced. Further carbon reduction potential analysis explored the improvement space for each process in terms of emissions reduction, concluding that all three processes have high carbon reduction potential under a low-carbon energy scenario, with the improved salt etching method achieving a comprehensive carbon reduction potential of up to 82%. Carbon footprint analysis indicate that the improved salt etching method achieves the best performance (0.83kg CO₂eq). This study precisely quantifies the carbon footprint of waste photovoltaic panel recycling technologies and identifies directions for green and low-carbon development, providing reference for government and enterprise decision-making and optimization of waste photovoltaic panel recycling technologies.

This study focused on 26 cities within the Yangtze River Delta urban agglomeration and employed a comprehensive analytical approach, utilizing the Super-SBM model, Malmquist index, Gini coefficient, standard deviation ellipse model, and Tobit model based on statistical data from 2010 to 2023. The study systematically analyzed regional disparities, dynamic evolutionary characteristics, and the factors influencing water environment governance efficiency. Key findings included that the overall water governance efficiency in the Yangtze River Delta urban agglomeration exhibited a fluctuating upward trend, with a notable dip in 2022 attributed to a decline in scale efficiency (SE), with an average value of 1.121. Spatially, water governance efficiency followed a "high-west, low-east" pattern: western cities experienced significant efficiency gains through ecological compensation and green industrial transfer, while eastern cities relied on technological innovation to drive improvements. The largest intergroup disparity in water environment governance efficiency occurred between the Anhui Province and Zhejiang Province, with an average value of 0.067. Within the Jiangsu-Shanghai region, the internal equilibrium was the highest, with an average value of 0.055. The hyper-variation density contributed the most to the overall difference, with an average annual value of 38.053. Over the study period, the center of gravity of the standard deviation ellipse for water environment governance efficiency shifted southwestward, suggesting a trend toward a more aggregated spatial distribution. Population size, urbanization level, and industrial structure showed significant negative correlations with water environment governance efficiency in the Yangtze River Delta urban agglomeration. In contrast, innovation levels, environmental management, openness to external markets, and industrial scale positively drove water environment governance efficiency.

Addressing the shortcomings in theoretical research and practice regarding the realization of ecological product value including unclear definitions of certain concepts, ambiguous value realization mechanisms, imperfect value accounting methods, lagging marketization and industrialization, and unsound implementation mechanisms, we systematically reviewed and summarized the conceptual connotation, basic attributes, realization mechanisms, evaluation systems, path models, and policies and systems of ecological products in my country using a literature review approach. From the aspects of formulating ecological product evaluation standards, improving the accounting methods for the gross ecosystem product, deepening the application of the accounting results for the gross ecosystem product, and strengthening the confirmation of ecological resource rights and the development of ecological industries, the following countermeasures and suggestions were proposed: Formulate scientific, unified, and operable national standards for the definition, classification, and evaluation of ecological products, taking into account the natural origin, environmental attributes of the place of origin, final use of the product, full identification of benefits, and avoidance of duplication in accounting. The existing methods and frameworks should be optimized for calculating the value of ecological products from the perspectives of scientific methodology, digitalization of the accounting process, comparability of accounting results, and applicability of policies and systems. The results of the gross ecosystem product should be applied in a diversified and institutionalized manner in areas such as ecological civilization construction and high-quality economic development, so as to achieve a fundamental shift from "calculating" to "using". Based on the fundamental characteristics and multiple value attributes of ecological products, we should strengthen the confirmation of ecological asset rights, the evaluation of ecological product value and supply-demand matching, vigorously develop ecological industries, and comprehensively utilize both government regulation and market mechanisms to realize the value of ecological products.

Due to the unclear evolution characteristics of single high-temperature event days (OHT days), single stagnation event days (OAS days), and their compound event days (HT-AS days) and their impact mechanisms on O₃ pollution, based on hourly O₃ concentration and meteorological reanalysis data in the warm season (May to September) of the Beijing-Tianjin-Hebei (BTH) region from 2015 to 2024, the interannual variation characteristics of the three types of meteorological event days were systematically analyzed, and the response degree of O₃ pollution to these three types of event days was evaluated. Results show that the daily maximum 8-hour average O₃ concentration (MDA8O₃) during HT-AS event days, OHT event days, OAS event days, and other event days reached (195.3±32.5), (185.1±37.1), (151.9±33.8) and (136.6±34.1)μg/m³, respectively. On an interannual scale, the frequency of HT-AS compound event days was significantly positively correlated with both the number of O₃ exceedance days (MDA8O₃≥160 μg/m³) and the regional average O₃ concentration, with correlation coefficients of 0.65 and 0.66, respectively. This indicates that such compound event days are the primary meteorological drivers of interannual O₃ pollution variability in this region. Compared with OHT and OAS event days, HT-AS event days are characterized by more unfavorable meteorological conditions, including intense solar radiation, high temperatures, low cloud cover, and weak winds, constituting the key meteorological background for O₃ pollution formation in BTH. During these days, O₃ concentration is significantly modulated by solar radiation, temperature and cloud cover contributing 37.5%, 21.0% and 20.2% to O₃ variability, respectively.

In this study, the direct and combined effects of meteorology and meteorology-driven biogenic volatile organic compound (BVOC) emissions on surface ozone (O₃) during the 2017 heatwaves in the Yangtze River Delta were quantified using a coupled WRF-MEGAN-CMAQ system. Regional BVOC emissions were estimated at 2.07 million tonnes annually, dominated by isoprene (54.0%) and monoterpenes (19.0%), with higher emissions in the south and 64.0% occurring in summer. During heatwave periods, total BVOC emissions increased by 248%, dominated by isoprene surge. Heatwave-induced increases in BVOCs elevated the regional maximum daily 8-hour average O₃ concentrations by 3.6% (+6.1μg/m³), with strongest contributions in urban areas of northern Zhejiang, southern Jiangsu, and the Anhui Yangtze River corridor, where photochemical conditions could favor O₃ formation. Meteorological conditions associated with heatwaves (the "direct effect") were identified as the dominant driver of O₃ enhancement, contributing up to 22.0% (+38.1μg/m³), with impacts decreasing from coastal to inland regions. Shanghai exhibited the highest O₃ sensitivity to heatwaves (+81.0μg/m³), while Jiangsu showed the strongest O₃ response to BVOCs emission increments (+6.8μg/m³). These results demonstrate that heatwaves exacerbate O₃ pollution through dual pathways: direct meteorological effects and indirect BVOCs-mediated enhancement. To address O₃ pollution risks under future climate warming, differentiated mitigation strategies targeting heatwave-sensitive regions and high-BVOC emission areas are required.

To investigate the particle size distribution and formation pathways of atmospheric secondary organic aerosols (SOA), size-resolved aerosol sampling was conducted in Chengdu. The results revealed a bimodal distribution dominated by fine particles, with mass concentration peaks observed at 0.56~1.0μm and 3.2~5.6μm. Organic matter was the most abundant component in both fine and coarse modes. SO₄^2-, NH₄⁺, and K⁺ were mainly present in the fine mode, while NO₃^-, Ca²⁺, and Mg²⁺ were enriched in the coarse mode, indicating a strong influence of soil dust on coarse particles. Source apportionment showed that SOA accounted for 67% of the total organic matter. Correlation analysis revealed that fine-mode SOA was significantly associated with SO₄^2- and NH₄⁺, while coarse-mode SOA was positively correlated with Ca²⁺, Mg²⁺, and water-soluble Fe, suggesting that the formation of coarse mode SOA was related to the heterogeneous reaction of soil dust containing transition metal element Fe. The differing correlations of pH and aerosol liquid water content with SOA across particle sizes highlight their complex and combined roles in SOA formation.

This study established a five-component aerosol model (including Black Carbon (BC), Brown Carbon (BrC), Ammonium Sulfate (AS), Dust (DU), and Water (AW)) utilizing AERONET data, to perform inversion calculations on the aerosol components variability in the Himalayas and surrounding regions. The results indicated that, on a multi-year average, the proportion of the mass concentration of each component at various monitoring sites was similar, with AS, DU, AW, BrC, and AW accounting for 53.49%, 29.33%, 10.63%, 5.27%, and 1.28%, respectively. The aerosol mass concentration in the southern slope of the Himalayas (annual average of 390mg/m²) was significantly higher than that in the northern slope (annual average of 49mg/m²), primarily due to the substantial obstruction of South Asian pollutant aerosols by the high-altitude mountains during transboundary transport crossed the Himalayas (with only about 13% transported over the Himalayas). Generally, the aerosol mass concentration in the Himalayan region was highest in spring (multi-year average), while it saw significant reductions in summer, autumn, and winter. This variation was mainly attributed to the cumulative effect of atmospheric pollutant emissions prior to the South Asian Monsoon (SAM) and the substantial transport of dust aerosols from South Asian deserts, which were greatly diminished during the summer monsoon period due to heavy precipitation. Interannually, the average aerosol mass concentration from 2015 to 2024 (with southern slope average of 370.83mg/m²) was slightly lower than that during the earlier period from 2006 to 2015 (with southern slope average of 453.26mg/m²), reflecting an improvement in recent pollution levels in South Asia. However, the overall atmospheric pollution remained extremely serious. Given that the absorbing aerosols like black carbon and brown carbon can significantly accelerate the melting of glacial snow, the persistent high emissions of polluted aerosols in the South Asian region may continue affecting the accelerated glacial changes in the Himalayas in the future.

As a key determinant of atmospheric oxidation capacity, the hydroxyl radicals (·OH) govern the removal of primary pollutants and the formation of secondary pollutants. This study estimated ·OH levels from 2015 to 2023 using a parameterization approach based on surface air pollutant observations and reanalysis meteorological data. The results showed that daytime ·OH concentration (08:00~18:00) exhibited a single-peak seasonal pattern, with the highest levels occurring in summer and the lowest in winter. The annual mean daytime ·OH concentration displayed a significant upward trend (0.05×10⁶cm^-3a^-1). Spatially, the most rapid increases were found in Handan and Tangshan, while Tianjin exhibited relatively smaller increases. Among seasons, the summertime trend was the most pronounced (0.07×10⁶cm^-3a^-1). At present, ·OH concentrations in the BTH region lie on the declining branch of the nonlinear response curve to nitrogen dioxide (NO₂). Under the present NO₂ levels, continued reductions in NO₂ weaken the dominant ·OH sink reactions, constituting the key chemical mechanism driving the net increase in ·OH concentrations.

Most existing studies of VOCs based on single monitoring sites cannot fully characterize VOC transport and aging. Here, we conducted 45-day synchronous online VOC measurements in summer using GC-MS at an urban site in Suzhou (eastern Yangtze River Delta) and a downwind site on Xishan Island, Taihu Lake. Combined with positive matrix factorization (PMF), we investigated the sources and transport-aging processes of VOCs. The average φ(TVOCs) in urban Suzhou was 28.6×10^-9, higher than 17.5×10^-9 downwind. Urban VOCs were dominated by alkanes, whereas OVOCs and halocarbons showed larger fractions at the transport site. PMF revealed four factors (vehicle exhaust, gasoline evaporation, solvent use, and industrial emissions) with source profiles and temporal patterns consistent between sites, but all exhibited pronounced aging downwind, reflected by systematic increases in OVOC contributions. Biogenic emissions were also important downwind, where isoprene levels were 143.8% higher than urban values. Subtropical high-pressure systems with elevated temperatures and weak winds promoted O₃ formation, whereas typhoon circulation mitigated O₃ pollution via enhanced dispersion and wet deposition. Regional pollution episodes were driven by urban traffic emissions, especially during rush hours when primary pollutants peaked. During transport, primary VOCs underwent continuous aging with alkanes converting to OVOCs, further enhancing downwind O₃ pollution. O₃ and PM_2.5 exhibited synchronized peaks, and SOA contributions in PM_2.5 increased markedly. These findings demonstrate that traffic-related NO_x and VOC emissions contribute to local O₃ formation and, through aging during transport, drive regional O₃ pollution, providing critical insights into compound air pollution mechanisms in the Yangtze River Delta.

Studying the impact of heating changes on the occurrence characteristics and sources of polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 is of great significance for urban air pollution control. In this study, 42 PM_2.5 samples were collected at three sites in the urban area of Shijiazhuang during the heating and non-heating seasons. The concentrations of 16 PAHs were determined using gas chromatography-tandem mass spectrometry (GC-MS/MS). Based on these data, the concentration changes, sources, and health risks of PAHs were analyzed. The results showed that the average concentrations of PAHs during the heating and non-heating seasons were 13.97ng/m³ and 10.63ng/m³, respectively, with benzo[a]pyrene (BaP) being the primary pollutant. PAHs exhibited significant negative correlations with temperature, humidity, and O₃, and significant positive correlations with PM_2.5, PM₁₀, SO₂, NO₂, and CO. It was concluded that temperature, PM_2.5, and O₃ were the primary factors influencing PAH concentrations before and after the heating season. Both the characteristic ratio method and positive matrix factorization (PMF) source apportionment indicated that transportation emissions and coal-biomass combustion sources were the primary sources of PAHs during the heating season, while transportation emissions and petroleum-related pollution (including oil evaporation and liquid fuel combustion) were the primary sources during the non-heating season. Transportation emissions were the main contributor to PAHs. The TrajStat model analysis revealed that the primary pollution sources of PAHs originate from the northwest, with the Beijing-Tianjin-Hebei region and Henan Province being the main pollution areas, and PAH dispersion conditions were poor during the heating season. The health risk assessment results indicate that the PAHs in PM_2.5 in Shijiazhuang city do not pose a risk to adults or children, but the lifetime cancer risk value for children is twice that for adults, warranting attention.