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20 March 2026
Volume 46 Issue 3
    
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    Ozone Pollution Control
  • The impact of land-sea air masses interaction processes on ozone pollution in Shenzhen
    CHEN Jing, LIU Yu-chen, FU Xiao
    China Environmental Science. 2026, 46(3): 1185-1193.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To better understand the impact of land-sea air masses interaction processes on ozone (O3) pollution in Shenzhen, two typical land-sea interaction processes (long-range air masses transport and sea-land breeze (SLB) circulation) were analyzed based on ten years of observational ozone concentrations, meteorological dataset, meteorological reanalysis data and the HYSPLIT backward trajectory model. Long-range air masses were identified and further categorized into oceanic, coastal, and inland types according to trajectory pathways. The corresponding mean O3 concentrations were (45.5±26.1), (71.3±33.7) and (68.4±30.6)μg/m3, respectively. Among them, coastal air masses exhibited the highest O3 pollution levels, with a frequency of 39%, and showed particularly strong transport potential in autumn, making it a major source of O3 pollution in Shenzhen. In addition, the SLB circulation further influenced O3 concentration in Shenzhen. The annual frequency of SLB days in Shenzhen over the past 10 years was 18.8%, with the highest occurrence in spring and summer. O3 concentrations on SLB days were significantly higher than that on non-SLB days, with an average annual difference of 9.6%, primarily due to low wind speeds, inversions, and recirculation conditions. The difference was most pronounced in autumn (12.28μg/m3) which could be attributed to favorable conditions, including clear and dry weather, lower background wind speeds, and a higher likelihood of SLB development. Overall, O3 pollution in Shenzhen was strongly influenced by land-sea air masses interactions, particularly in autumn, which should be prioritized for mitigation.
  • Characteristics analysis of autumn ozone pollution weather patterns in the Pearl River Delta based on the SOM method
    LI Yun-wei, WU Yan-xing, ZHANG Jing-wen, LIU Run
    China Environmental Science. 2026, 46(3): 1194-1201.
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    Given the ozone (O3) pollution events in the Pearl River Delta (PRD) region frequently occur in autumn and the increasing application of objective weather classification methods in urban agglomeration pollution studies, this study employed the Self-Organizing Map (SOM) method to classify the sea level pressure fields in the PRD and to investigate the impacts of different weather patterns on severe autumn O3 pollution. The results indicated that 15weather patterns identified from sea level pressure fields could be categorized into four groups based on O3 pollution levels: heavy pollution, moderate pollution, light pollution, and clean. Among them, heavy and moderate pollution weather patterns exhibited distinct seasonal distributions, with the weak cold high-pressure combined with typhoon and subtropical high pattern (T12) (The average O3 concentration was 118.2 μg/m3, with an exceedance rate of 22.4%) was associated with the most severe O3 pollution. Autumn O3 exceedance days under heavy pollution patterns were generally accompanied by high solar radiation (554.1kJ/m2 above the mean), high temperature (3.1℃ above the mean), and low relative humidity (9.2% below the mean), which were highly favorable for O3 formation. Using the circulation field of heavy pollution weather patterns with autumn O3 exceedance day as a reference, the study found that the number of days favorable for O3 exceedance during 2015~2024 was significantly correlated with autumn O3 concentration. Furthermore, the number of favorable days under similar circulation conditions showed a significant increasing trend during 1995~2060 (with an average growth rate of 0.14d/a).
  • Synoptic mechanisms analysis and prediction model development for ozone pollution triggered by approaching tropical cyclones in the Guangdong-Hong Kong-Macao Greater Bay Area
    WANG Jun-bin, LI Ting-yuan, CHEN Jing-yang, GONG Yu, SHEN Jin
    China Environmental Science. 2026, 46(3): 1202-1215.
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    Based on tropical cyclone (TC) data, reanalysis data, and ozone monitoring data from 2014 to 2024, the synoptic mechanism by which approaching tropical cyclones (ATCs) trigger ozone pollution in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) was analyzed. A prediction model was developed using Spearman's rank correlation coefficient and the random forest regression method. The results indicated that: ATCs inducing ozone pollution in the GBA were primarily distributed within a range of 270~1758km, and a clear disparity in intensity was observed on the eastern and western sides of the line connecting Taiwan Island and Luzon Island. The ATCs east of the line all reach typhoon intensity or above, while those west range from tropical depression to severe typhoon intensity. Ozone pollution was induced by ATCs through the generation of subsiding airflows in upper levels, which reduces cloud cover over the GBA, increases downward shortwave radiation, elevates surface temperatures, and reduces relative humidity, precipitation and wind speed. Through SOM clustering analysis, four ozone pollution distribution patterns triggered by ATCs in the GBA were identified: the southwestern pollution pattern, the widespread pollution pattern, the western pollution pattern, and the northeastern pollution pattern. These patterns are associated with the transport and convergence effects of different surface wind fields. Ozone concentrations in the 11cities of the GBA were found to correlate well with tropical cyclone characteristics (radius of 7-level wind circle and proximity rate), as well as significant correlations with surface meteorological factors (such as land-sea wind direction difference and land-sea meridional wind speed difference) and upper-air meteorological factors (such as 200 hPa vertical velocity, 700 hPa meridional wind, 700 hPa specific humidity, and 925 hPa zonal wind). The forecasting model constructed based on 18factors, including tropical cyclone characteristics and surface and upper-air meteorological elements, demonstrates high generalizability and accuracy. The average correlation coefficient between the model's forecast values and the actual monitoring values reached 0.811, the average root mean square error was 30.2μg/m3, and the average TS score for ozone level prediction was 0.668.
  • Policy-driven spatiotemporal difference and dominant factors evolution of O3 and PM2.5 compound pollution in Chinese cities
    ZHANG Xiang-xue, XU Cheng-dong, CHENG Chang-xiu, KONG Shao-jie, YU Jie
    China Environmental Science. 2026, 46(3): 1216-1228.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To evaluate the impact of air pollution prevention and control policies on the spatiotemporal evolution of Ozone (O3) and fine particulate matter (PM2.5), this study analyzed the spatiotemporal stratified heterogeneity of O3 and PM2.5 pollution across 331 Chinese cities from 2014 to 2024 using a Bayesian spatiotemporal hierarchical model. The GeoDetector model was further employed to quantify the determinant power and interactive effects of meteorological, socioeconomic, and other pollutant factors on summer O3 and winter PM2.5 pollution during the implementation of three key policies: the Air Pollution Prevention and Control Action Plan (2014~2017), the Blue Sky Defense Action Plan (2018~2020), and a circular on further Promoting the Nationwide Battle to Prevent and Control Pollution (2021~2024). The results indicate that O3 concentration exhibited a trend of initial rapid growth followed by a slower rate, with hotspots mainly distributed in North China and the Yangtze River Delta (YRD). Conversely, PM2.5 concentration continuously decreased, and high-value areas shrank and concentrated in North China, the YRD, and the Chengdu-Chongqing region. A positive correlation between O3 and PM2.5 was frequently observed in the southern and northeastern humid regions, whereas a negative correlation prevailed in the northwestern semi-arid areas. Although the dominant factors for O3 and PM2.5 evolved across policy stages, the determinant power of the interactions among different factors were consistently stronger than that of individual factors. Specifically, from 2014 to 2017, O3 was mainly affected by maximum temperature (Geo_q=0.24), industrial output (Geo_q= 0.22), and PM10 (Geo_q = 0.60); PM2.5 was primarily affected by maximum temperature (Geo_q = 0.41), population density (Geo_q = 0.40), and PM10 (Geo_q = 0.88). From 2018 to 2020, the dominant factors for O3 shifted to precipitation, population density, and PM10, while those for PM2.5 shifted to average temperature, population density, and PM10. From 2021 to 2024, the dominant factors for both shifted toward average temperature, population density, and PM10, albeit with significant differences in their determinant power. This research reveals the dynamic evolution of the spatiotemporal patterns of O3 and PM2.5 pollution driven by policies implementation, emphasizing the dominant role of multi-factor interactions in the composite pollution formation process. The findings provide a crucial scientific basis for formulating regionalized and phased synergistic control strategies for O3 and PM2.5.
    • Air Pollution Control
  • Spatial distribution of near-surface atmospheric CH4 and CO2 concentrations and their carbon isotopic compositions in the coastal region of eastern China
    BIAN Tian-yu, DUAN Xiao-yong, TONG Gang, LI Xue, YIN Ping, CAO Ke, CHEN Bin, ZHANG Da-hai
    China Environmental Science. 2026, 46(3): 1229-1237.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The concentration and carbon isotope compositions (δ13C-CH4, δ13C-CO2) of methane (CH4) and carbon dioxide (CO2) along the coastal of eastern China were studied using vehicle mounted mobile measurement methods. The results indicated that the CH4 concentration was observed to range from (1.84~2.94) ×10-6, with an average concentration of 2.09×10-6. The highest value was recorded in Jiangmen, Guangdong (2.32×10-6), while the lowest value was recorded in Zhangzhou, Fujian (1.94×10-6). The CO2 concentration was found to range from (420.51~857.33) ×10-6, with an average concentration of 525.70×10-6. The highest value was measured in Shenzhen, Guangdong (599.08×10-6), and the lowest value was measured in Nantong, Jiangsu (477.42×10-6). Both CH4 and CO2 levels in the study area were found to exceed the atmospheric background values. The δ13C-CH4 values ranged from -62.62‰ to -29.70‰, with an average of -43.65‰. The highest value was observed in Qingdao, Shandong (-40.24‰), and the lowest value was observed in Zhangzhou, Fujian (-48.25‰). The δ13C-CO2 values ranged from -28.64‰ to -9.19‰, with an average of -17.53‰. The highest value was recorded in Nantong, Jiangsu (-14.45‰), and the lowest value was recorded in Shenzhen, Guangdong (-19.13‰). In the study area, CH4 concentration was found to be positively correlated with its carbon isotope signature, while CO2 concentration was negatively correlated with its carbon isotope signature. Per capita GDP, the number of civilian vehicles, livestock inventory, and rice cultivation area were all positively correlated with CH4 concentration and its carbon isotope signature. In contrast, the forest coverage rate was negatively correlated with CH4 concentration and its carbon isotope signature. δ13C (CO2) was utilized to trace the sources and sinks of atmospheric CO2 along the coastal regions of Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, and Guangdong. Their respective δ13C (CO2) source signatures (δ13Cs) were determined to be: -37.90‰, -37.67‰, -41.24‰, -34.12‰, -33.99‰, and -32.39‰. These values indicated that the combustion of petroleum and natural gas was identified as the primary contributing source to CO2 emissions in the study area.
  • Spatiotemporal characteristics of black carbon over the Tibetan Plateau and validation of MERRA-2 and TAP datasets
    LAI Jing, XIE Min-sheng, WANG Ya-qiang, KANG Shi-chang, CHEN Peng-fei, WAN Xin, CONG Zhi-yuan
    China Environmental Science. 2026, 46(3): 1238-1246.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To evaluate the applicability of the MERRA-2 and TAP datasets over the Plateau, ground-based observations from the Qomolangma, Nam Co, and Waliguan stations were utilized to validate the accuracy of atmospheric black carbon (BC) in both datasets. Results showed that Nam Co had the lowest annual mean BC concentration (0.04μg/m3), while Qomolangma (0.26μg/m3) and Waliguan (0.28μg/m3) recorded higher levels. All stations exhibited a clear seasonal cycle, with higher concentrations in winter and spring and lower values in summer. MERRA-2 effectively reproduced the seasonal and temporal variations of BC, whereas TAP displayed a systematic overestimation across the Plateau, with annual deviations reaching up to four times in some years, indicating lower accuracy. During the March 2021 transboundary BC transport event from South Asia, MERRA-2 showed good capability in capturing the process, providing direct scientific evidence for cross-border pollutant transmission to the Plateau.
  • Source profiles of PM2.5 and their oxidative potential from six typical industrial zones in the Guanzhong Plain
    LIU Li-yan, YANG Meng-yun, XU Hong-mei, ZHANG Ning-ning, WANG Qi-yuan, SHEN Zhen-xing
    China Environmental Science. 2026, 46(3): 1247-1255.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    PM2.5 samples were collected from six types of industrial parks in the Guanzhong region of Shaanxi Province, including cement/concrete, brick/construction materials, forging/metallurgy, thermal power, chemical production, and glass/ceramics. The carbon fractions, water-soluble ions, elements, as well as oxidative potential (OP) of PM2.5samples were analyzed to investigate the emission characteristics of different industrial sources and the relationships between PM2.5 chemical components and OP. The results showed significant differences in PM2.5 concentrations among the industrial parks, with brick/construction materials presenting the highest level (95.2μg/m3). The OC/EC (organic carbon/elemental carbon) ratio in brick/construction materials (5.5) was higher than those in other industries. Cement and concrete industry exhibited the highest Ca2+ concentrations. Elemental analysis showed elevated proportions of V in metal forging. Correlation analysis demonstrated significant positive relationships between OP and inorganic ions (SO42-、NO3-、NH4+) as well as metallic elements (Ca, Al, Cd, Cu). This study provides a scientific basis for identifying the source markers across common industries and for assessing their impacts on atmospheric oxidation capacity and human health.
  • Calculation of maximum allowable increased PM2.5 emissions based on environmental benefit balance of emission increases and reductions in industrial parks and surrounding areas
    LU Cheng-wei, LU Hui, YANG Xin-yue, SONG Dan-lin, ZHU Yi-ping, BAO Wen-yi, SHE Rui, ZHANG Zi-jian, HUANG Lan-yi, ZHAO Bin
    China Environmental Science. 2026, 46(3): 1256-1263.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To investigate the correlation between emissions and environmental quality in industrial parks, thereby achieving refined management and control constrained by the environmental quality baseline, this paper proposes a comprehensive method for determining the maximum allowable emission increments in industrial parks based on the dynamic equilibrium of PM2.5 concentration impacts. The approach balances emission reductions in surrounding buffer zones against increased emissions within the parks, creating development space through emission mitigation in peripheral areas. Case studies were conducted in industrial parks of Tianfu, Shuangliu, and Longquan district, Chengdu. Evaluations demonstrate that buffer zone emission reductions lowered PM2.5 concentrations in park stations by 2.6, 1.7, and 2.1μg/m3, respectively. Based on current and target concentrations at park stations, the maximum allowable concentration increases were calculated as 1.9, 1.5, and 2.3μg/m3. Derived from simulated PM2.5 concentrations and sequential emission increments, the composite response functions quantified the maximum allowable emission increases at 21.5, 73.7, and 200.1t, respectively. Emission reduction and increasing balance verifications showed that implementing these maximum increments resulted in concentration changes of -0.18, -0.44, and -2.50μg/m3 at control stations, confirming no deterioration of air quality. This methodology provides a novel approach for refined park management, enabling industrial development through peripheral emission reductions without compromising environmental quality, thereby creating sustainable growth space for industrial parks.
  • Spatiotemporal variations of crop straw burning and its impact on air quality in the North China Plain from 2013 to 2023
    WANG Xin-hui, SHEN Xiu-e, JIANG Lei, ZHANG Jian, LI Ling-jun, SONG Xiao-ke
    China Environmental Science. 2026, 46(3): 1264-1277.
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    This study investigated the spatiotemporal characteristics of open-field crop straw burning (hereinafter referred to as crop straw burning) in the North China Plain, based on thermal anomaly data from VIIRS/NPP and agricultural statistics from 2013 to 2023. Furthermore, an emission inventory for major atmospheric pollutants from 2013 to 2022 was developed, and the impact on PM2.5 concentrations during summer harvest season was assessed. The results showed that: significant spatial clustering was observed in the distribution of crop straw burning fire points, with two primary high-density zones identified in the southern Henan-northern Anhui region and the Bohai Rim region. The number of fire points decreased significantly during the study period, with the southern experiencing greater reductions than the northern. Intra-annual variations were highly synchronous with agricultural activities, showing distinct peaks during the summer and autumn harvest periods. The pollutant emissions declined by over 50% from 2013 to 2022, with a rapid decrease from 2013 to 2016 followed by a stabilization. The seasonal peak of emissions shifted from summer-autumn to winter-spring over time, while the spatial distribution of high-emission areas became increasingly fragmented. In terms of crop-specific contributions, emissions from corn straw burning consistently exceeded those from wheat straw burning. During the June harvest period, a significant positive correlation (r = 0.70~0.91) was found between province-level PM2.5 emissions from straw burning and ground-level PM2.5 concentrations across Henan, Shandong, Jiangsu, and Anhui provinces on an interannual scale. Daily-scale analysis indicated that a strong contribution from straw burning to PM2.5 levels in the southern Henan-northern Anhui region from 2013 to 2016 (r = 0.68), with its influence weakening after 2017. The impact in the Bohai Rim region was generally weaker throughout the study period. However, case studies demonstrated that concentrated burning events could still trigger significant short-term PM2.5 pollution episodes. Therefore, synchronous large-scale burning across multiple regions should be avoided to prevent regional pollution episodes.
  • Simulation study on PM2.5 concentration in subway system based on network model
    WANG Chun-wang, LI Xiao-feng, TONG Lin-quan, ZhANG Zhong-bin, FAN Jing-guang, JIN Long-zhe
    China Environmental Science. 2026, 46(3): 1278-1287.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A network model based on mass conservation was established to simulate PM2.5 dispersion in subway systems, integrating a source model for train-induced dust in tunnels. The model was applied to a representative line in southern China and validated with field measurements, showing errors within 10%. Results indicate that station PM2.5 concentration increases nonlinearly with train frequency (approximately +86% for a +78% frequency increase) and exhibits a near-constant differential relative to outdoor concentration, suggesting a linear additive effect. Notably, for lines operating at over 24 trains per hour during peak periods, station PM2.5 levels consistently exceeded the indoor air quality standard (50μg/m3), even when outdoor concentrations met the WHO guideline (15μg/m3).
  • Research on AI-based algorithms for atmospheric carbon dioxide data imputation and reconstruction
    GU Tao-feng, YUE Hai-yan, XIONG Zi-li, LIANG Jian-ping, WU Yan-ling, LIU Li-xin
    China Environmental Science. 2026, 46(3): 1288-1297.
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    To address the challenge of partial missing data in atmospheric CO2 concentration observations, this study systematically evaluated the performance of 12 mainstream machine learning algorithms for data imputation, utilizing CO2 measurement data collected at the 30m (L1 layer) and 80m (L2 layer) heights of the Longfengshan Regional Atmospheric Background Station over the period from January 2009 to June 2022. An optimized ensemble machine learning method was proposed, with the distance-weighted K-Nearest Neighbors (KNeighborsDist) algorithm as its core framework. This method reconstructs missing data by leveraging synchronous observational records from the two co-located height layers. Validation analysis of the reconstructed dataset yielded excellent performance (R230.98), which confirms a strong correlation between the reconstructed greenhouse gas data and in-situ measurements, as well as the effectiveness and accuracy of the proposed model in greenhouse gas data reconstruction tasks. The method successfully filled the data gaps in the original dataset of Longfengshan Station, generating a continuous 5minute interval CO2 dataset with a completeness rate of 100%. Additionally, it well preserved the long-term trends and seasonal, monthly, and diurnal variation characteristics of CO2. The proposed AI-based data reconstruction algorithm is applicable to other atmospheric background stations and can provide high-quality data support for regional climate change analysis, carbon emission accounting, and inversion research.
  • Regional scale inversion of CH4 emissions from rice paddies based on atmospheric concentration observations
    YANG Wen-wu, PENG Ting, WU Ying, WANG Yu-xiang, ZHU Jun, ZHAO Mei-ling, ZHANG Yi-fan, SHI Xue-jing, XIAO Wei, HU Cheng
    China Environmental Science. 2026, 46(3): 1298-1309.
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    Jiangsu Province—one of China’s major rice-producing regions—was selected as the research area. A high-precision CH4 observation system was established at a height of 50m in Taizhou City, central Jiangsu, and the period from 20th May to 31st October 2023, covering the local rice-growing season, was used for analysis. Paddy CH4 flux was retrieved at a 10d scale by coupling an atmospheric transport model with an optimized inversion framework. The main findings are as follows: (1) The “bottom-up” approach based EDGAR prior inventory exhibited neither distinct temporal variability nor emission peaks for paddy CH4 fluxes, inconsistent with the observed peak emissions during the tillering-booting stage in July~August in Jiangsu, which should be constrained and calibrated by using atmospheric CH4 observations. (2) Inversions revealed that both Taizhou City and Jiangsu Province experienced peak CH4 emissions in early to mid-August, followed by a gradual decline. The peak fluxes reached (966.6 ± 104.6) mg/(m2·d) and (1182.9 ± 128.0) mg/(m2·d), respectively, which were (3.27 ± 0.35) times higher than the prior estimates. (3) Over the entire study period, the posterior mean paddy CH4 flux for Taizhou and Jiangsu were (307.3 ± 40.5) mg CH4/(m2·d) and (376.7 ± 49.7) mg CH4/(m2·d), respectively, (1.37 ± 0.18) times the prior values. These results indicate that the prior inventory substantially underestimated both the magnitude and temporal variation of paddy CH4 emissions.
  • Study on in-situ modification of coarse fiber with sucrose derived carbon and its filtration performance
    HAN Wu-wang, ZHOU Hao, YAO Qing-dong, CHU Hua-qiang, LV Li, QIAN Fu-ping, XU Jun-chao
    China Environmental Science. 2026, 46(3): 1310-1319.
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    A thin carbon layer (~1.15μm thick) was fabricated on coarse polyethylene terephthalate (PET) fibers via in-situ modification with sucrose-derived carbon (SDC), which only occupied 10-3 of the fiber’s pore size and significantly improved the dielectric properties. The composite filter material achieved a high filtration efficiency of 98.10% for 0.3μm particles while maintaining low resistance, resulting in a comprehensive quality factor (CQF) significantly higher than that of the origin PET fibers. Furthermore, the carbon layer was strongly bonded to the PET fibers, ensuring excellent long-term stability and suitability for repeated use.
  • Response characteristics of Co-ZnO gas-sensing materials to acetone and waste gas detection
    YANG Jia-li, DANG Xiao-qing, WANG He
    China Environmental Science. 2026, 46(3): 1320-1330.
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    Co-doped ZnO gas-sensitive materials were synthesized via a hydrothermal method, and the influence of varying Co doping concentrations on their gas-sensing properties was systematically investigated. Furthermore, focusing on the emission characteristics of acetone within the multi-component VOCs generated during rubber vulcanization, the feasibility of real-time acetone detection using these materials was explored, aiming to enable cost-effective operation of adsorption systems under compliance conditions. The results indicated that the Co-ZnO-2% sensor achieved a high response value of 1146.8 to 260mg/m3 acetone at 240°C, with rapid response and recovery times of 16s and 8s, respectively. Additionally, it exhibited excellent selectivity, reproducibility, and long-term stability toward acetone. In a simulated VOC adsorption purification experiment, the Co-ZnO-2% sensor was applied, and its response values were demonstrated to effectively indicate both the breakthrough and saturation states of the adsorbent. Under multi-component adsorption conditions, with acetone as a representative indicator, a warning threshold and a concentration prediction model, Xacetone=(Y-16.89)/4.47, were established to estimate VOC concentrations. This approach successfully realized online monitoring of the adsorption process and evaluation of the emission status.
    • Water Pollution Control
  • Enhanced phosphorus removal in aerobic granular sludge system seeded with dewatered sludge pre-granules: Performance and mechanism
    YANG Hao-sheng, LI Hui-ping, WANG Xing-bo, CHEN Guang, WANG Li-hua, LV Yan, PANG Wei-hai, XIE Li, YANG Dian-hai
    China Environmental Science. 2026, 46(3): 1331-1343.
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    In this study, dewatered sludge pre-granules were used as seed sludge to cultivate aerobic granular sludge (AGS) with high phosphorus removal capabilities over a 120-day operation. Inoculation with pre-granules allowed the system to bypass the initial granulation phase, establishing stable biological phosphorus removal by day 42. During the stable period, the experimental group achieved an average total phosphorus removal efficiency of (94.4±3.7)%, outperforming the control group (85.9±5.1)%. The pre-granulated AGS exhibited a particle size of 1100~1300μm, a sludge volume index of 50~80mL/g, and average removal efficiencies for chemical oxygen demand and total nitrogen of (94.5±2.9)% and (79.3±6.4)%, respectively. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) revealed a notably higher iron content in the pre-granulated AGS (3.87% vs. 0.24% in the control), with iron uniformly distributed inside the granules. High-throughput sequencing further indicated enrichment of extracellular polymeric substance (EPS) secretion microorganisms, such as Candidatus_Competibacter (10.9% vs. 5.0% in the control). The results demonstrated that, unlike the primarily biological phosphorus removal mode in the control, the pre-granulated AGS developed a synergistic chemical-biological removal mechanism. Initially, EPS complexed with residual ferric iron from the dewatered sludge pre-granules, enhancing chemical phosphorus adsorption and providing a structural skeleton that improved granule stability. Subsequently, this stable structure facilitated microbial retention, yielding a higher mixed liquor volatile suspended solids concentration (4.3g/L vs.3.1g/L). Although the relative abundance of polyphosphate-accumulating organisms (PAOs) was similar between groups (0.48% vs. 0.47%), the absolute abundance of PAOs was elevated in the pre-granulated system. Moreover, the stable granular structure likely supported higher metabolic activity PAOs, as reflected by an increase in the relative abundance of key functional genes, such as polyphosphate kinase (ppk1, 0.42‰ vs. 0.34‰).
  • Research on the start-up and denitrification performance of long term 5℃ low-temperature pure MBBR process
    HAN Wen-jie, ZHAO Zhong-fu, ZHOU Jia-zhong, ZHAO Yan-ruo, YANG Zhong-qi, LIANG Yu-hai
    China Environmental Science. 2026, 46(3): 1344-1355.
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    Aiming at the problems of low sewage temperature, poor nitrogen removal efficiency and weak shock resistance of traditional activated sludge process in the alpine regions of southwest China, a pilot-scale experiment of pure moving bed biofilm reactor (MBBR) was conducted. The startup characteristics, nitrogen removal performance, and shock resistance mechanism under long-term ultra-low temperature conditions were systematically investigated. The results showed that the pure MBBR was successfully started up within 25days at a water temperature of (6.14±1.06)℃. During a long-term operation of 245days with an average water temperature of (5.45±1.29)℃, superior effluent quality was achieved with an actual hydraulic retention time (HRT) only 20% of that of the activated sludge process in the same WWTP. After a 1-month shutdown, the treatment capacity was fully restored within only 14days. In the pure-membrane MBBR system, the first-stage nitrification zone realized the removal of inhibitors such as chemical oxygen demand (COD) and preliminary nitrification, the second stage served as the main nitrification zone, and the third stage ensured stable effluent quality. A single-stage process was adopted in the denitrification zone, where the reflux ratio was flexibly adjusted according to the residual nitrate nitrogen in the anoxic zone to enhance nitrogen removal. Regarding nitrogen removal potential, when facing influent quality shock, increasing dissolved oxygen (DO) in the aerobic zone to strengthen mass transfer and oxygen supply could further improve the system's nitrification load by more than 25%, while driving the nitrogen removal capacity to increase by more than 10%. The excellent low-temperature resistance of the pure MBBR was attributed to two aspects: on one hand, the biofilm enhanced the enrichment of nitrogen-removing functional bacteria, especially low-temperature- tolerant strains such as Flavobacterium and Dechloromonas; On the other hand, the biofilm’s dense structure and complex microbial community supported thermal insulation. For pure MBBR design, enhanced functional bacteria enrichment and high effective biomass should be concurrently considered, thus conferring higher treatment load.
  • Synergistic control of manganese and disinfection byproducts formation by potassium permanganate and polyaluminium chloride in water
    LUO Jun-chen, NI Mao-fei, FU Cheng-cheng, ZHANG Run-yu, LUO Xiao-yong, WANG Zhi-kang
    China Environmental Science. 2026, 46(3): 1356-1366.
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    This study examined a combined potassium permanganate (KMnO4) and polyaluminium chloride (PAC) process for treating karst waters, with experiments simulating the seasonal variations in manganese concentration. Using algal organic matter (AOM) from Chlorella sp. and Pseudoanabaena sp., the mechanisms for Mn(II) removal, AOM transformation, and DBPs control were investigated. The results indicated that KMnO4 oxidized Mn(II) to MnO2, while PAC promoted the co-precipitation of MnO2 with AOM through adsorption and bridging. TEM analysis confirmed that MnO2 was encapsulated by PAC flocs and associated with AOM. FTIR and ICP-MS analyses demonstrated enhanced Mn(II) adsorption via coordination with algal surface functional groups. The combined process reduced the formation of carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs) by 16% and 18.5%, respectively. Notably, trichloromethane (TCM) formation was reduced by 51%, underscoring the process's effectiveness against C-DBPs. Compared to KMnO4 alone, the combined process reduced N-DBPs formation by only 0.6% in the Chlorella sp. system but by 27% in the Pseudoanabaena sp. system. This disparity suggests that DBP formation pathways are differentially regulated by AOM components, which vary with algal species.
  • Research on degradation of methyl orange wastewater with triboelectric nanogenerator (TENG) driven by secondary effluent
    MA Hong-mei, HU Jia-jie, XI Bei-dou, CHEN Yong-zhi, LUO Jie, ZHANG Yong-hui
    China Environmental Science. 2026, 46(3): 1367-1375.
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    The triboelectric nanogenerator (TENG), which was constructed of indium tin oxide (ITO), polytetrafluoroethylene (PTFE), and conductive aluminum tape, was utilized in this study. It was driven by secondary effluent to generate electricity for degrading methyl orange wastewater. Experimental results showed that a maximum output voltage of 23.52V and a current of 2.15μA were achieved by a single TENG unit. When aluminum, iron, copper, and stainless steel were used as electrodes to treat 40mg/L methyl orange wastewater, decolorization rates of 83.21%, 82.88%, 75.27%, and 51.38% were obtained respectively. With aluminum electrodes, decolorization rates exceeding 80% were achieved for methyl orange concentrations<60mg/L, but they declined gradually for methyl orange concentrations>60mg/L, and only 27.85% was reached at 150mg/L. When the number of TENG units was increased from one to six, the decolorization rate was increased from 85.05% to 91.05%. The degradation process was fitted to the first-order kinetic equation: ln(C0/Ct) = 0.027t-0.0815.
  • Migration patterns of Fe2+ and Mn2+ in coal mine water under freezing conditions and their phytotoxicity
    WANG Yue, DUAN Rong-yu, SANG Nan, LI Guang-ke
    China Environmental Science. 2026, 46(3): 1376-1386.
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    Acidic mine drainage (AMD) containing high concentrations of heavy metal ions such as Fe2+ and Mn2+ was treated by a freezing method utilizing the purification effect of ice crystals. The process parameters for removing Fe2+ and Mn2+ from simulated AMD via the freezing method were optimized through single-factor and orthogonal experiments, and the optimal conditions were determined (for Fe2+: freezing temperature of -12℃, initial concentration of 0.9mg/L, freezing radius of 4.25cm; for Mn2+: freezing temperature of -6℃, initial concentration of 1.2mg/L, freezing radius of 5.00cm). The optimized process was then applied to treat actual AMD. The results showed that the removal rates of Fe2+ and Mn2+ from the actual AMD reached 60% and 59%, respectively, which confirmed the effectiveness of the technology. Furthermore, barley seeds and seedlings were used as model plants to evaluate the phytotoxicity of the AMD before and after treatment. The results indicated that, compared with the untreated AMD, the treated AMD did not inhibit the germination of barley seeds or the growth of barley seedlings. This study confirmed that the freezing method can not only effectively remove heavy metal pollutants from AMD but also significantly reduce its biotoxicity.
  • Effectiveness of persulfate slow-release material in remediating fuel contamination in karst water
    LI Wei-xuan, CHEN Yu-dao, DENG Ri-tian, TANG Dong-bo, YANG Wei
    China Environmental Science. 2026, 46(3): 1387-1397.
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    In response to the constrained efficacy of traditional in situ chemical oxidation and enhanced bioremediation in karst groundwater, novel slow-release materials (SRMs) were prepared employing paraffin and concrete as binding agents. Simulated karst column experiments were performed to characterize the release kinetics and assess the removal performance of these SRMs against typical fuel pollutants (BTX). In this study, slow-release materials were prepared using paraffin and concrete as binders. Column experiments simulating a dynamic karst aquatic environment were conducted to investigate the release behavior of these materials and their efficacy in removing typical fuel contaminants (BTX compounds). The results showed that: Paraffin-based slow-release materials exhibited significant media-specific release behaviour, but their initial burst release of persulfate resulted in increased non-target consumption. Concrete-based slow-release materials demonstrated a more stable release profile and achieved a higher nitrate utilization rate in the remediation system. Although ferrous salt activation improved the oxidation efficiency of persulfate, challenges such as short activation duration (<72hours), limited spatial influence, and low ferrous ion utilization (leading to iron hydroxide precipitation) remained. In karst groundwater, the first-order decay rate constant for benzene series concentration under the slow-release dosing method (0.154d-1) was higher than that under the continuous dosing method (0.044d-1), indicating superior removal efficiency with slow-release dosing. The pH buffering effect in the limestone medium delayed persulfate decay, while the sandy medium facilitated the enrichment of functional microorganisms, thereby enhancing bioremediation.
  • Effect of ultraviolet aging on the adsorption of diclofenac by microplastics
    LIU Yi-qing, ZOU Qing-hua, ZHANG You-zhong, HU Hong, CHEN Chuan-zeng
    China Environmental Science. 2026, 46(3): 1398-1406.
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    Taking three types of the most frequently detected microplastics (MPs) in the environment, i.e., polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS), as the research objects, their ultraviolet (UV) aging and the environmental behavior of aged MPs to diclofenac (DCF) were explored in this study. The results indicate that after UV aging, the surface roughness, specific surface area and average pore size of the three MPs increased, while their contact angle and point of zero charge decreased. Moreover, UV aging caused an increase in the oxygen content of MPs, with a significant increase in the content of oxygen-containing functional groups such as carbonyl and hydroxyl. Adsorption experimental results show that different MPs had slightly different adsorption capacities for DCF, and PS exhibited stronger DCF adsorption ability with the adsorption capacity of 0.5626mg/g. The adsorption capacities of UV-aged PE, PVC and PS for DCF were 0.4884, 0.6077and 0.6382mg/g, respectively, which were stronger than that of the original MPs. The adsorption amount of DCF by MPs before and after aging both decreased with increasing pH or the increase in salinity and humic acid concentration. The adsorption process for DCF by MPs was divided into three stages, i.e., liquid film diffusion, particle internal diffusion, and adsorption equilibrium, and the adsorption mechanism mainly involved physical adsorption dominated by hydrophobic interactions, van der Waals forces, hydrogen bonding and electrostatic interactions.
  • Corrosion characteristics and mechanism of water distribution networks under the coupling effect of NaClO and iron-oxidizing bacteria
    ZHU Jing-yu, ZHANG Hui, LIU Sha-sha, FENG Yong-jia, JIA Pei-xin, JI Yi-meng
    China Environmental Science. 2026, 46(3): 1407-1416.
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    This study established a static simulation experimental system, using sodium hypochlorite (NaClO) as a representative disinfectant and iron-oxidizing bacteria (IOB) strain LSS-1as a representative corrosive microorganism, to investigate their combined effects on total iron concentration, corrosion rate, electrochemical characteristics during corrosion, and physicochemical properties of corrosion products. The results indicated that the coupling of NaClO and LSS-1 promoted the corrosion of cast iron coupons. Under the condition of LSS-1 with 4.00mg/L NaClO, the corrosion rate after 30 days increased by 0.06mm/a, and the average total iron concentration increased by 5.76mg/L compared to the condition without LSS-1 and NaClO. Under the coupled condition, the self-corrosion potential (E0) shifted negatively, and the current density (I0) increased. Furthermore, the main corrosion products generated under the coupled condition included α-FeOOH, β-FeOOH, γ-FeOOH, Fe2O3, Fe3O4, and CaCO3.
  • Kinetics of reaction between Fe(II)-ligand and c-type cytochrome under acidic conditions
    YIN Yun-lu, CHENG Kuan, WANG Ying, LIU Tong-xu, LI Xiao-min
    China Environmental Science. 2026, 46(3): 1417-1425.
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    The c-type cytochrome (c-Cyts) is a key protein in microbial oxidation of Fe(II). However, the reaction process and influencing factors of ligand-bound Fe(II) with c-Cyts under acidic conditions remain unclear. In this study, Fe(II)-EDTA and a model c-type cytochrome (c-Cyts) were used to investigate the mechanism of microbial Fe(II) oxidation under acidic conditions with various environmental factors, including anoxic/oxic conditions, pH, and initial Fe(II)-EDTA concentration. A stopped-flow spectrophotometer was employed to study the reduction kinetics of c-Cyts, while the electrochemical properties of Fe(II) and the distribution of different Fe(II) species were characterized. Under anoxic conditions, the reduction rate of c-Cyts increased with increasing pH and Fe(II)-EDTA concentration. At 20μmol/L Fe(II)-EDTA, the apparent rate constants (kapp) were 0.841 and 6.802s-1 at pH 3.5 and pH 5.0, respectively. At pH 5.0, the kapp increased to 13.028s-1 when the initial Fe(II)-EDTA concentration increased to 80μmol/L. The increase in pH and Fe(II)-EDTA concentration enhanced the proportion of FeEDTA2- and intensified the redox peaks of Fe(II), indicating greater Fe(II) reactivity and thus a faster c-Cyts reduction rate. Compared to anoxic conditions, c-Cyts reduction was inhibited under oxic conditions. This inhibitory effect of oxygen decreased as the pH increased. At pH 3.5 and 4.0, c-Cyts reduction was completely inhibited. At pH 4.5, the kappdecreased from 5.402s-1 (anoxic) to 1.658s-1 (oxic); and at pH 5.0, the kapp slightly decreased from 6.802s-1 (anoxic) to 6.454s-1 (oxic). This is attributed to the slower reaction between Fe(II)-EDTA and c-Cyts at lower pH, whereas the competing reaction of Fe(II)-EDTA with oxygen is favored, producing reactive oxygen species that further accelerate the reoxidation of reduced c-Cyts. This study elucidates the critical mechanisms of the reaction between Fe(II)-ligand and c-Cyts, providing deeper molecular-level insight into the microbial Fe(II) oxidation process.
    • Solid Waste
  • Sodium citrate and potassium permanganate promote the production of short-chain fatty acids in waste activated sludge and its mechanism
    LUAN Hui-lin, WANG Zheng-jiang, LIANG Kang, LIU Tuo-hong, LUO You-lin, WEN Si-jing, LI Zhen-lun
    China Environmental Science. 2026, 46(3): 1426-1433.
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    In this study, the effect of sodium citrate (CA) combined with potassium permanganate (PM) pretreatment strategy on the acid production efficiency of waste activated sludge (WAS) anaerobic fermentation was investigated, and the promotion mechanism of CA synergistic PM significantly increased the accumulation of short-chain fatty acids (SCFAs). The results showed that, the production of SCFAs after CA and PM pretreatment reached a peak of 15777.54mg COD/L on the 6th day, which was increased by 6.41 times and 3.18 times compared with the control group and the PM group, respectively. At the same time, the proportion of acetic acid in SCFAs was also significantly increased. The reason is that CA and PM pretreatment enhance the structural destruction of extracellular polymer (EPS) in the sludge, release a large amount of soluble organic matter, and provide a richer substrate for microbial metabolism. Microbial community analysis further revealed that pretreatment reduced the overall diversity of microbial communities, significantly enriched functional flora related to hydrolysis and acid production, and inhibited SCFAs-depleting flora.
  • Research progress in remote sensing monitoring and assessment of solid waste
    HAN Zhi-long, WANG Yi-fei, LI Ping, LI Lian-wei, YIN Shou-jing
    China Environmental Science. 2026, 46(3): 1434-1443.
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    Primarily based on relevant literature from the Web of Science core database, it analyses the volume, content, and evolving trends of global and national research publications within this field. From an application perspective, solid waste remote sensing research is categorised into three domains: identification of solid waste disposal sites, site selection and suitability assessment, and environmental impact monitoring of disposal sites. Progress and emerging trends within each domain are systematically examined. Analysis reveals that current landfill identification approaches using low-resolution imagery predominantly employ GIS analysis and index construction, while high-resolution imagery applications frequently utilise deep learning techniques (object recognition, semantic segmentation). For site selection and suitability assessment, GIS platforms are commonly employed to conduct multi- criteria decision analysis integrating remote sensing indices (NDVI, NDWI, etc.) and topographical features (roads, water bodies, residential areas, etc.). Environmental monitoring primarily focuses on vegetation stress, surface thermal anomalies, and methane emissions. Current solid waste remote sensing research faces limitations in operationalising identification applications, lacks universally applicable site selection criteria, and has restricted environmental impact monitoring parameters. Building upon this, recommendations for advancing solid waste remote sensing research are proposed, aligned with environmental management requirements.
    • Soil Pollution Control
  • Quantitative analysis of source-sink and sustainable risk control for heavy metals in soil
    CHEN Wei-sheng, SHI Qing, ZHANG Zhi-ke, LIU Rui-ping, ZHANG Jian, SONG Yi-nan, ZHANG Jing-zhuo, YANG Yang, ZHANG Hao, ZHAO Bin
    China Environmental Science. 2026, 46(3): 1444-1459.
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    The source prevention and control technologies for heavy metals in soil at that time were plagued by problems such as insufficient precision and systematicness. This quantitative analysis methods of soil heavy metal sources and sinks at home and abroad were studied in this paper. Their historical evolution, type characteristics, basic principles, advantages and disadvantages were analyzed, and their roles and intrinsic correlations in source identification and flux analysis were revealed. The results show, after decades of exploration and iteration, source apportionment represented by mathematical statistics, receptor mathematical models, and physicochemical characteristic fingerprints had become the foundation for controlling the sources of heavy metals in soil. However, as the concept of soil pollution prevention and control shifted from traditional investigation and remediation to sustainable risk management of sources and sinks, the importance of precise flux calculation for control effectiveness had become increasingly prominent. In view of this, a "source-sink-end" "three-in-one" risk control system was proposed in this paper: based on scientific "source" identification, centered on flux "sink" characterization, and guaranteed by receptor "end" verification, this system was designed to practice the concept of "prevention first, remediation second", and to promote food security and the sustainable utilization of soil resources.
  • Explainable machine learning for uncovering PFAS adsorption mechanisms in soils
    LIU Bing, ZOU Ke-ke, LIU Hui, SHI Kai-ge, CHEN Yan-min, LU Xin, HAN Shuai-jun, GU Li
    China Environmental Science. 2026, 46(3): 1460-1474.
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    The soil-water partition coefficient (Kd) of per- and polyfluoroalkyl substances (PFAS) was predicted using machine learning (ML) models, and their partitioning behavior in soils was elucidated. A dataset comprising 1,227 samples of 47 PFAS was employed, with 16 PFAS physicochemical properties and soil parameters used as input features. It was demonstrated that the lgKd values ranged from -1.40 to 3.95. When the number of CF2 groups exceeded 5and the molecular weight (MW) was greater than 400g/mol, significant linear relationships were observed between lgKd and both the CF2 number and MW, with R2 values of 0.96 and 0.94, respectively. The influence of soil properties on PFAS adsorption was found to be dependent on the type of PFAS: non-zwitterionic PFAS were mainly affected by organic carbon content and silt content, whereas zwitterionic PFAS were primarily influenced by silt and sand content. After parameter optimization, the ML model exhibited good predictive performance, achieving an R2 of 0.85, an RMSE of 0.35, and an MAE of 0.26. MW, organic carbon content, water solubility (lgS), and net charge density were identified as the most important features, with contribution rates of 31.6%, 29.8%, 19.7%, and 10.0%, respectively. Three-dimensional interaction analysis indicated that when soils with high organic carbon content, high cation exchange capacity (CEC), and low pH were combined with PFAS of large MW, lgKd exceeded 0.40, reflecting strong adsorption. Conversely, under conditions where CEC was below 8.00 cmol/kg, organic matter content was less than 1.00%, and MW was below 380g/mol, lgKd was lower than 0.40, indicating weaker adsorption and higher potential for environmental migration. The findings provide a reliable tool for predicting the adsorption behavior of PFAS.
  • Electrode loaded ferrihydrite enhances the performance of the soil microbial electrochemical system in the remediation of petroleum hydrocarbon-contaminated soil
    YU Xin, ZHANG Xiao-lin, QU Yong-shuai, ZHONG Peng-ju, LU jia-jun, LI Xiao-jing
    China Environmental Science. 2026, 46(3): 1475-1485.
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    To investigate the enhanced effect of ferrihydrite-loaded electrodes on the degradation of organic pollutants in petroleum-contaminated soil using a Microbial Electrochemical System (MES), and to elucidate the underlying synergistic mechanisms, a single-chamber soil MES reactor was constructed. Using oil-contaminated soil as the experimental medium, we compared the performance of the original soil, the conventional electrode setup, and the ferrihydrite-loaded electrode setup. The system's effectiveness was evaluated through electrochemical analysis, assessment of soil carbon degradation and transformation, characterization of iron forms, and determination of enzyme activity. Results indicate that loading electrodes with ferrihydrite significantly improved the system's electrochemical performance, with cumulative charge output increasing by 18%. The carbon degradation capacity was also enhanced, with the total carbon degradation rate increasing by up to 11%, effectively promoting the transformation of recalcitrant carbon, such as humus, into more labile forms. Ferrihydrite facilitated the iron cycle, with iron ion content increasing by up to 28%, thereby enhancing the Fe(II)/Fe(III) redox cycling and strengthening the coupling between carbon and nitrogen transformations. Additionally, the bioelectric field accelerated the phase transformation of ferrihydrite into goethite and hematite. The presence of ferrihydrite stimulated microbial secretion of degradative enzymes, significantly increasing the activity of key enzymes involved in pollutant degradation. Mantel test results further reveal that dehydrogenase and polyphenol oxidase served as the primary drivers of carbon mineralization.
    • Environmental Ecology
  • Machine learning-based identification and contribution analysis of dominant factors driving algal blooms in the Xiangxi Bay
    YANG Jing, YANG Zhong-yong, HE Yu-fang, XIONG Li-wei, HU Yi-ling, JI Dao-bin
    China Environmental Science. 2026, 46(3): 1486-1498.
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    Algal blooms are a major ecological and environmental issue in the tributary bays of the Three Gorges Reservoir. To identify the dominant environmental factors driving algal blooms in the Xiangxi Bay, this study utilized high-frequency monitoring data collected from August 9 to August 30, 2024, with chlorophyll-a (Chl.a) concentration as the bloom indicator. Three machine learning models—Random Forest (RF), Support Vector Regression (SVR), and Partial Least Squares Regression (PLS)—were applied to identify key driving factors. The results showed that algal blooms in Xiangxi Bay exhibited pronounced diurnal variation, with nighttime stable stratification and low disturbance favoring bloom formation, while daytime disturbances and high temperatures inhibited algal accumulation. Water velocity (WV) and air temperature (AT) were identified as immediate driving factors, with contribution rates of 27.1% and 18.1%, respectively. specific conductivity (SP) served as an important regulating factor (17.1%), while dissolved oxygen (DO), pH, and water temperature (WT) were secondary feedback factors. Moreover, the impacts of these factors on Algal blooms exhibited significant nonlinearity and lagged response characteristics.
  • Spring-summer dynamics of chlorophyll-a and its hydrological and water quality drivers at the dam forebay of Huating lake reservoir
    DONG Jiang, FAN Zhong-ya, HUANG Lu, LI Dan, YANG Meng-di, QIU Yi-xuan, WANG Biao, DUAN Bin, WANG Wen-cai
    China Environmental Science. 2026, 46(3): 1499-1508.
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    Using high-frequency continuous monitoring data collected at the dam forebay of Huating Lake from April to June 2022, this study quantified chlorophyll-a (Chl.a) dynamics and examined its phase-dependent responses to hydrological and water-quality drivers during phytoplankton growth and decline stages. Principal component analysis, multivariate correlation analysis, and partial least squares structural equation modeling (PLS-SEM) were integrated to disentangle the relative contributions and interaction pathways of these drivers. Chl.a concentrations ranged from 6.54 to 65.90µg/L (mean: (34.62±12.14)µg/L), exhibiting a pronounced unimodal temporal pattern. The dominant controls on Chl.a differed substantially between growth and decline phases. During the growth phase, Chl.a variability was primarily driven by the combined effects of nutrient availability—especially total phosphorus (TP) and permanganate index (CODMn)—and hydrological processes, including water-level fluctuations and outflow discharge. In contrast, Chl.a dynamics during the decline phase were mainly regulated by pH and total nitrogen (TN), indicating a shift in controlling mechanisms across phytoplankton life stages. PLS-SEM results showed that water-quality factors exerted significant positive direct effects on Chl.a in both phases (standardized path coefficients: 0.729 in the growth phase and 0.941 in the decline phase). Hydrological factors did not directly affect Chl.a but influenced it indirectly through water-quality pathways, producing a negative indirect effect during the growth phase (-0.780) and a positive indirect effect during the decline phase (0.583). Variable-level analysis identified CODMn and TP, together with outflow discharge and water level, as key drivers during the growth phase, whereas pH, TP, TN, CODMn, and water level dominated during the decline phase.
  • Time-series monitoring and prediction of cyanobacteria blooms based on FY3D/MERSI data
    ZHANG Ruo-lin, WANG Meng, MENG Qing-yan, SUN Yun-xiao, YUAN Xi-tun, ZHANG Lin-lin, WU Han-tian, SUN Zhen-hui, WANG Jia-long
    China Environmental Science. 2026, 46(3): 1509-1521.
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    Conventional remote sensing platforms like Landsat and Sentinel face inherent limitations in achieving continuous dynamic monitoring of cyanobacterial blooms due to their inadequate temporal resolution. Similarly, existing FY satellite-based monitoring and prediction approaches are constrained by unidimensional analyses and oversimplified models dependent on single-variable inputs. To overcome these challenges, this study developed a comprehensive multidimensional monitoring and prediction system utilizing high-temporal-resolution FY3D/MERSI data for Taihu Lake cyanobacterial blooms. Our methodology integrated spectral indices with an optimized Otsu algorithm for accurate bloom detection, coupled with innovative dual-scale (pixel and sub-pixel) quantification techniques. Through this framework, we conducted systematic multidimensional analysis of Taihu Lake's cyanobacterial blooms (2019~2023), examining critical parameters including bloom intensity, frequency patterns, and outbreak severity dynamics. Concurrently, integrating meteorological and water quality factors, we constructed a BP neural network model to predict bloom areas. Validation analyses demonstrated the strong performance of FY3D/MERSI data in cyanobacterial bloom extraction, showing excellent agreement with in-situ measurements (R2 = 0.98, RMSE = 21.6km2). Cyanobacterial bloom areas in Lake Tai exhibited seasonal double-peak patterns, with peaks occurring in May and October. Bloom severity predominantly ranged from mild to moderate, while severe blooms remained at low levels throughout the year. Outbreak frequency was significantly higher in the western, southern coastal, and central lake areas than in the eastern region, and higher frequencies occurred during summer and autumn. Inter annual outbreak intensity showed a gradual decreasing trend, with the proportion of “no cyanobacterial blooms” rising to 89% in 2023. Correlation analysis indicated that factors such as temperature and relative humidity promote bloom outbreaks, while turbidity and fluorescent dissolved organic matter exerted inhibitory effects. The BP neural network model demonstrated robust predictive capability, achieving a root mean square error (RMSE) of 27.07km2 and a Pearson correlation coefficient (r) of 0.94 on the validation set. Notably, 83% of predictions fell within ±25km2 of observed values. These metrics collectively confirm the model's effectiveness in capturing the dynamic spatiotemporal trends of cyanobacterial bloom areas.
  • Sulfur reduction-oxidation functional microorganisms and vertical distribution characteristics in grass carp aquaculture pond sediments
    WU Zhao-xing, TIAN Zhao-hui, CHEN Yan, PAN Zhe
    China Environmental Science. 2026, 46(3): 1522-1532.
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    The present study was conducted in typical grass carp aquaculture ponds in northern China. The characteristics of the vertical distribution of environmental factors, key sulfur reduction-oxidation functional genes, and microbial communities were analyzed through in-situ measurement, physicochemical analysis, and metagenomic sequencing. The results showed that the sulfur-reducing functional genes (sat, aprA, asrA, phsA) and microorganisms (g_NA_c_Deltaproteobacteria) were enriched, whereas sulfur-oxidizing functional genes (fccB, sqr) and microorganisms (g_Thiobacillus, g_Thioalkalivibrio, g_NA_o_Hydrogenophilales) were reduced in grass carp pond sediments compared with control pond. As for the vertical distribution, the abundances of sulfur reduction-oxidation genes (dsrA, asrA, fccB, phsA, soxX/Z) and their dominant genera significantly decreased along sediment depth in both grass carp and control ponds (P < 0.05). The network analysis indicated that the interactions of sulfur reduction-oxidation functional microflora were decreased in grass carp ponds compared with control ponds. Mantel tests revealed that TN, ORP, NH+ 4, and TOC were significantly positively correlated with genes and microbial communities involved in sulfur reduction-oxidation (P < 0.05). The removal of organic matter, as well as the improvement of redox conditions in sediment might be effective ways to mitigate the risks of sulfide accumulation and water quality deterioration in grass carp aquaculture ponds.
  • Copper isotope fractionation and transformation at the acid mine drainage-sediment interface in mining areas
    LIU De-hong, CAO Kai-wen, LIAO Wen, HOU Dong-mei, ZHONG Song-xiong
    China Environmental Science. 2026, 46(3): 1533-1542.
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    The heavy metal copper (Cu) in acid mine drainage (AMD) is an essential element for organisms but potentially toxic. To control its environmental impact, it is necessary to investigate the factors that influence Cu migration in AMD-sediment interfaces. This study investigated the isotopic composition and fractionation characteristics of Cu in AMD systems from three different mining areas in central China. By coupling these isotopic signatures with detailed physicochemical analyses, we elucidated the key factors and mechanisms controlling Cu adsorption and migration. The results revealed that the Cu isotope fractionation between solutions and sediments in the Dingjiashan gold-copper-sulfur mining area, the Guanchao lead-zinc mining area, and the Qiaolichong polymetallic mining area ranged from (0.3±0.01)‰ to (1.5±0.07)‰, (0.61±0.01)‰, and (1.03±0.02)‰, respectively. This indicates that Cu isotope fractionation in AMD systems varies across mining areas and at different locations within the same mining area. The trends in the primary Cu species in sediments are consistent with those in AMD systems, and exhibit a clear pattern: as sediment Fe-oxide content and the proportion of Fe-/Mn-oxide-bound Cu increase, the isotopic fractionation magnitude decreases; conversely, elevated sulfur/organic matters and a larger fraction of organic- sulfide-bound Cu amplify the fractionation scale, confirming that mineral adsorption and organic-sulfur complexation are the key factors governing Cu mobility and transformation in AMD systems. These results suggest that the characteristics of Cu stable isotope fractionation may serve as a potential tool to explore the key factors controlling Cu migration in AMD systems across different mining areas.
  • Source apportionment methods for upstream inflows of nitrate nitrogen in the reservoir using stable isotopes
    WEI Jian, CHEN Li-li, CHEN Jun-jun, XIE Rong-rong, LI Jia-bing, MA Xiao-dan, WU Qiong-yao, SHI Cheng-chun
    China Environmental Science. 2026, 46(3): 1543-1553.
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    In this study, the ShuiKou Reservoir (SR) in the Min River Basin and its upstream inflows (T1~T3) were selected as the research area. The Bayesian Isotope Mixing Model (MixSIAR) was employed to conduct source apportionment of nitrate contributions during both non-flood and flood seasons. Two approaches were implemented: conventional nitrate nitrogen-oxygen isotopes and a newly developed "water hydrogen-oxygen stable isotope-nitrate concentration" method. The results from both methods were validated through a complete mixing model and the deviation information criterion (DIC) values from MixSIAR. The findings revealed that nitrate nitrogen concentrations in non-flood seasons exceeded those in flood seasons. Among the upstream inflows, the Shaxi River (T3), which is adjacent to an industrial area and has the highest proportion of construction land in its vicinity, demonstrated the most severe nitrate pollution. During flood seasons, a decline of δ18O-NO3- values in T3and SR were observed, alongside a reduction in both water δ18O-H2O and δD-H2O values within the entire research area. The results indicated that rainfall with lower δ18O-H2O and δD-H2O signatures brought pollutants with lower δ18O-NO3- to the research area. Secondly, both methods showed comparable source apportionment results during flood seasons (maximum error 13.04%), but exhibited significant discrepancies in non-flood seasons. Conventional isotope analysis under 0fractionation yielded contributions: T2 (49.4%) > T3 (26.1%) > T1 (24.5%), whereas the new method indicated: T3 (44.8%) > T1 (29.6%) > T2 (25.6%). Thirdly, the novel method demonstrated superior reliability, with lower DIC than those obtained using conventional methods under different fractionation. The nitrate concentration errors validated by the complete mixing model at merely 1.22% (flood season) and 0.89% (non-flood season). Those further confirmed its highest credibility. This methodology shows potential for extension to other pollutant source tracking studies, providing solution for watershed water quantity-quality integration and pollution control management.
  • Mechanism of algal removal in the EP-BiOBr/ZnFe2O4 floating photocatalytic system
    HU Lei, ZHANG Dong-yuan, DING Ning, LIU Hong
    China Environmental Science. 2026, 46(3): 1554-1567.
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    A floating-type EP-BiOBr/ZnFe2O4 (EP-BFO) photocatalyst with a type-II heterojunction was successfully synthesized via the hydrothermal method. Characterization techniques including SEM, XRD, XPS, and UV-Vis DRS were employed to analyze the morphology, elemental composition, and chemical valence states of the photocatalyst. Results indicate that EP-BFO exhibits a three-dimensional porous structure, broad spectral response (200~700nm), and an optimized band structure (Eg = 2.08eV). Its oxygen vacancies and heterojunction interface effectively promote photogenerated charge separation. The removal efficiency of EP-BFO against Microcystis aeruginosa under visible light was investigated, along with its removal mechanism. Results demonstrated that EP-BFO achieved a removal rate of 93.6% for Microcystis aeruginosa under visible light, with a reaction rate constant (0.4191h-1) significantly superior to that of single-component catalysts. When tested in complex aquatic environments containing 10mg/L humic acid or fulvic acid, EP-BFO still maintained an 82% removal rate. Radical scavenging experiments indicated that superoxide radicals (·O2-) and holes (h+) were the primary active species. Concurrently, the active species generated during photocatalysis caused damage to algal cell membranes (ion leakage, MDA accumulation) and photosynthetic systems (degradation of phycobiliproteins) through oxidative processes.
  • Net phosphorus input and influencing factors of human activities in different ecological types of agricultural-pastoral ecotone
    JIN Sheng-yuan, LU Yu-qi, LEI Qiu-liang, DU Xin-zhong, ZHANG Tian-peng, LIU Huan, HOU Yi-zhan, LUO Jia-fa, LIU Hong-bin
    China Environmental Science. 2026, 46(3): 1568-1576.
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    In order to explore the impact of human activities on net phosphorus input in different ecological types in the agricultural-pastoral ecotone in northern China, the statistical data of 23 prefecture-level cities in 7 provinces involved in the northern agricultural-pastoral ecotone from 1985~2020 were collected based on the net phosphorus input model of human activities (NAPI), and the development trend of NAPI in the region was analyzed. The results show that the NAPI change in the northern agropastoral zone shows a downward trend as a whole, increasing due to fertilizer application and food intake in 1985~2015, and decreasing due to agricultural restructuring in 2015~2020, but Liaoning and Ningxia are inconsistent with the overall trend due to agricultural restructuring in only some areas; In terms of NAPI composition, phosphorus fertilizer input accounted for the highest proportion of NAPI, more than 50%, followed by food phosphorus, accounting for 30%~40%. In terms of influencing factors, NAPI was positively correlated with population density, cultivated land area, and livestock and poultry volume per unit area (P<0.001).Therefore, the adjustment of agricultural structure in the northern agricultural-pastoral ecotone has effectively reduced the net phosphorus input of human activities.
  • Spatiotemporal patterns and evolutionary trajectory of terrestrial ecosystem carbon storage in Southwest China from 1980 to 2020
    WANG Fang, XIANG Shou-yi, REN Jin-tong
    China Environmental Science. 2026, 46(3): 1577-1592.
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    Taking the southwestern region of China as a representative case, the spatiotemporal evolution and driving mechanisms of terrestrial ecosystem carbon storage were systematically investigated through the integrated application of the InVEST model, Theil index, spatial autocorrelation, and geographical detector. The findings revealed that: ①Terrestrial carbon storage was reduced by 2.048Pg C during 1980~2020, showing a phased characteristic of accelerated decline followed by gradual recovery. The most pronounced reduction was observed between 1990 and 2000, with a distinct spatial pattern of higher values in the west and lower values in the east. Land use conversions were found to have significantly impacted carbon storage before 2000, while this effect was substantially weakened thereafter. The transformation from cropland to forestland was identified as the principal pathway for carbon sequestration, whereas grassland degradation to unused land was recognized as the major route for carbon loss. In addition, cropland conversion to construction land was shown to constitute a persistent pressure on carbon storage. ②Carbon density evolution exhibited a transition from decline to increase, with expanding areas surpassing declining zones as the dominant pattern after 2000. Theil index analysis indicated a general convergence in overall regional carbon density disparities, while heterogeneity at municipal and county levels within provinces was progressively intensified. Spatial aggregation patterns underwent significant reorganization: the western Sichuan Plateau was characterized by a shift from high-value to low-value clustering accompanied by notable northward migration; Tibet transitioned from high-high to low-low aggregation; and a new high-value cluster emerged in the Yunnan-Guizhou border area during 2010~2020. ③ GDP was identified as the dominant determinant of carbon storage variation. The interactive effects among GDP, soil type, and population density with other environmental factors were demonstrated to constitute the primary combination governing regional differentiations in carbon storage. Over the 40-year period, the dominant driving mechanism was observed to transition from spatial dependency-oriented to ecological stress-dominated.
  • A review of manganese-dependent anaerobic methane oxidation
    YU Xin, CHENG Cheng, LIU Yu-nan, WANG Yu-qi, CAI Yan-bo, TAO Yuan-hong, HE Qiang
    China Environmental Science. 2026, 46(3): 1593-1604.
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    Manganese-dependent anaerobic oxidation of methane (Mn-AOM) is a non-canonical methane sink. Here, we synthesize its conceptual origins, environmental occurrence and activity, microorganisms and electron-transfer routes underpinning the process. Mn-AOM has been reported in sulfur-depleted marine sediments, freshwater environments, and constructed wetlands, with niche-dependent differences in rates and community composition. In marine settings, Mn-AOM is mainly associated with ANME-1 and ANME-2 archaea, whereas freshwater Mn-AOM is dominated by ANME-2d lineages, including Ca. M. manganicus, Ca. M. manganireducens, Ca. M. nitroreducens, and Ca. M. sp. BLZ1. Proposed electron-transfer mechanisms involve multi-heme c-type cytochromes, soluble electron shuttles, and syntrophic interactions with partner bacteria, and may further couple to cryptic sulfur cycling or co-utilization of nitrate as an electron acceptor. Collectively, Mn-AOM expands current frameworks of methane biogeochemistry and holds promise for water and wastewater treatment, warranting future efforts in molecular resolution, quantitative ecological assessment, and engineering translation.
  • Characteristics and mechanisms of methane emissions from slurry lagoons in concentrated animal feeding operations in North China during autumn and winter
    ZHANG Hao-rui, XU Hua-sheng, ZHANG Zhuo-yi, TIAN Yan-feng, LI Xin, LIN Li-hong, WANG Yue, ZHU Zhi-ping
    China Environmental Science. 2026, 46(3): 1605-1616.
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    CH4 emission fluxes from five animal slurry lagoons in North China were quantified using the dynamic chamber method between October and November 2024. Meteorological conditions, water quality parameters, and microbial data were collected to identify key drivers and explore underlying mechanisms. Methane emission fluxes from the five lagoons ranged from 4.3 to 99.8g/(m2·d). The second-stage lagoon at the Miyun pig farm (MY_L2) exhibited significantly lower emissions, which was attributed to extensive organic matter degradation in the on-farm deep-pit system and the preceding black-film biogas digester. Methane emission fluxes showed a strong positive correlation with acetic acid concentration (r=0.74, P<0.01) and a strong negative correlation with pH (r=-0.70, P<0.01). The diurnal (24h) variation in CH4 emission flux was significantly positively correlated with air temperature (r=0.83, P<0.05). The abundance of the methanogenic marker gene mcrA in the lagoons (1.9×107 to 4.4×108copies/mL) was substantially higher than that of the methanotrophic marker gene pmoA (4.9×104 to 5.1×106copies/mL), indicating a high CH4 emission potential under open-air storage conditions. Among the five slurry lagoons, three were dominated by the acetoclastic methanogenic archaea, Methanosarcina and Methanosaeta. These lagoons were also enriched with acetogenic bacteria as well as hydrolytic and fermentative bacteria that degrade complex organic matter, thereby providing essential substrates for acetoclastic methanogenesis. In contrast, the lagoon with the highest CH4 emissions was dominated by the hydrogenotrophic methanogen Methanobrevibacter and was enriched with acetate-consuming bacteria, which may creat competitive inhibition of acetoclastic methanogens. The remaining lagoon exhibited a balanced coexistence of acetoclastic and hydrogenotrophic methanogens, potentially facilitated by Clostridium species capable of concurrently supplying acetate and H2/CO2. Shifts in the community structure of acetoclastic methanogens (P<0.05) and overall bacterial communities (P<0.01) across the lagoons significantly influenced the CH4 emissions. To effectively mitigate CH4 emissions, strategies should encompass not only front-end manure management (e.g., in-house manure removal practices and solid-liquid separation), but also the development of technologies to regulate lagoon pH or reducing acetic acid (acetate) concentrations.
  • Effects and mechanisms of attached biofilms on aquatic nitrogen transformation and N2O emission
    ZHANG Guan-jie, ZHOU Ying-ping, XIAO Lin
    China Environmental Science. 2026, 46(3): 1617-1624.
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    The effects and mechanisms of high ammonium (NH4+) stress on nitrogen transformation and nitrous oxide (N2O) emissions of attached biofilms on different substrate were investigated. Under high ammonium-nitrogen conditions, the nitrification potential of epiphytic biofilms associated with Vallisneria natans and Ceratophyllum demersum increased by 27.1-fold and 10.2-fold, respectively, whereas denitrification was suppressed, resulting in nitrogen accumulation. High NH4+ levels promoted N2O emissions associated with nitrification; however, N2O production during nitrification accounted for only up to 1.28% of that from denitrification, and denitrification was the main pathway of N2O emissions. Under high NH4+ stress, the increased abundances of nitrifying bacteria and genes but decreased denitrifiers contributed to changes in nitrogen transformation activities. Concurrently, the N2O emission potential (nirS/nosZ and nirK/nosZ) increased by 90% and 59%, which enhanced N2O emissions. Notably, artificial plant biofilms exhibited the highest nitrification and denitrification activities, whereas N2O emission from attached biofilms on Vallisneria natans was only 65.92%~82.76% of those from artificial plants and Ceratophyllum demersum L., suggesting dual regulation by functional microbial composition and microenvironment.
  • Research progress on the mechanism of photosynthetic carbon metabolism in microalgae based on cyclic electron transport
    LIU Ya-qi, ZHENG Meng-qi, ZHU Hong-yun, WANG Wei, GAO Yu-hang, XIE Bing-han, XU Peng, HU Zhen-hu
    China Environmental Science. 2026, 46(3): 1625-1637.
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    Imbalance in photosynthetic electron transport caused by environmental stress impairs carbon assimilation, triggering CO₂ release through processes like photorespiration. This exacerbates net carbon emissions and severely undermines microalgae's carbon sink function. As an energy allocation mechanism responding to environmental stress, cyclic electron transport (CET) compensates for the energy supply ratio of linear electron transport (LET) by independently regulating ATP synthesis, thereby safeguarding the photosynthetic system and maintaining its functionality. This review elucidates the activation mechanisms and photoprotective roles of CET in microalgae under various stress conditions, including high light, nutrient deficiency, CO₂ limitation, and toxic environments such as heavy metals, organic pollutants, and emerging contaminants. It discusses how CET synergizes photoprotection with carbon fixation by dynamically elevating the ATP/NADPH ratio, thereby regulating Calvin cycle efficiency and directing carbon metabolic flux. Finally, the paper prospects future research directions for enhancing microalgal carbon sequestration under environmental stresses through CET regulation, aiming to provide references for improving microalgal carbon sink capacity and advancing environmental engineering practices like carbon-neutral water remediation.
    • Environmental Toxicology and Environmental Health
  • Study on the interaction of pentachlorothiophenol with Chinese rare minnow transthyretin
    ZHAO Song-shan, ZHANG Jia-wei, ZHANG Zheng, LIU Hui-hui, YANG Xian-hai
    China Environmental Science. 2026, 46(3): 1638-1645.
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    In this study, the pentachlorothiophenol (PCTP) and Chinese rare minnow (Gobiocypris rarus) transthyretin were selected as the objects of study. We determined the potential binding affinity data of pentachlorothiophenol on Chinese rare minnow transthyretin, revealed the underlying molecular recognition mechanism between pentachlorothiophenol and the protein, and derived the binary classification models for distinguishing whether a given substance was a potential Chinese rare minnow transthyretin disruptor or not by using the Chinese rare minnow transthyretin disrupting data measured in this study and previous studies. The experimental results indicated that the observed water solubility value of pentachlorothiophenol was (0.636 ± 0.0871) mg/L (25℃). The relative competing potency of pentachlorothiophenol with 3,3',5,5'-Tetraiodo-L-thyronine (T4) binding to Chinese rare minnow transthyretin (logRP) was (0.0200 ± 0.0533), implying that pentachlorothiophenol was a high potency Chinese rare minnow transthyretin disruptor. The molecular simulation results documented that the binding interaction between pentachlorothiophenol and Chinese rare minnow transthyretin was controlled by the halogen hydrogen bond, halogen bond, and hydrophobic interactions. In the modelling, three optimum binary classification models (i.e. k nearest neighbour model, random forest model, decision tree model) were successfully developed. The statistical parameters (e.g. predictive accuracy (Q)) values of those optimum models were 1, highlighting that those optimum models had great classification performance. Finally, the tool named “TTR Profiler” that used to identify potential transthyretin disruptors was updated by integrating the newly developed optimum models, which means that the application domain of the related models in the new tool covered the thiophenols.
  • Protective effect of astaxanthin on the mitochondrial lesions induced by arsenic in HT-22 cells
    CHEN Yao, YU Man, LIU Ying-jie, ZHANG Yi-xin, REN Hang, WANG Mei
    China Environmental Science. 2026, 46(3): 1646-1654.
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    This study focused on the protective mechanism of astaxanthin (AST) against arsenic-induced mitochondrial-dependent apoptosis in mouse hippocampal neuronal cells (HT-22). An in vitro sodium arsenite (NaAsO2) exposure model was established in HT-22cells, including control, NaAsO2-exposed (4, 6, 8, 10μmol/L), AST-treated (2μmol/L), and AST-intervened (2μmol/L AST + 10μmol/L NaAsO2) groups, so as to evaluate the effects of AST intervention on arsenic-induced neural lesions. DCFH-DA was used to detect the level of reactive oxygen species (ROS). An ATP kit was used to assess the energy metabolism of mitochondria via ATP production. The levels of protein, including PGAM5 and signaling pathways of mitochondrial dynamics (fission/fusion), autophagy, and apoptosis, was analyzed by Western blot. Results showed that NaAsO2 exposure significantly induced increased generation of ROS (P<0.05), decreased synthesis of ATP (P<0.05), activation of PGAM5, up-regulation of p-Drp1-Ser616, and down-regulation of p-Drp1-Ser637 and mitochondrial fusion proteins (OPA1, MFN1), leading to excessive mitochondrial fission. Intervention by AST effectively reversed these effects (P<0.05), which were demonstrated by the inhibition of PGAM5-mediated mitochondrial fission, alleviation of oxidative stress, and reversion of energy metabolism. It is supposed that AST plays a role in AMPK-mTOR-dependent autophagy and mitochondrial apoptosis. On one hand, AST inhibited AMPK phosphorylation which subsequently activated mTOR and down-regulated LC3II/LC3I ratio (autophagy marker); on the other hand, AST down-regulated pro-apoptotic proteins (Bax, cleaved-caspase-3), and upregulated anti-apoptotic Bcl-2 (P<0.05), thereby regulating AMPK-mTOR-dependent autophagy and mitochondrial apoptosis. This study suggests that AST protects against NaAsO2-induced neurotoxicity by targeting PGAM5through the recovery of mitochondrial dynamics, improvement of energy metabolism, and regulation of AMPK-mTOR-autophagy-apoptosis axis, providing highlights on potential therapeutic strategies for arsenic-related neuronal damage.
  • Study on oxidative potential of typical species in atmospheric bioaerosol and its influencing factors
    SHI Hao-ke, ZHAO Jin-peng, LI Yan-peng
    China Environmental Science. 2026, 46(3): 1655-1662.
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    The oxidation potential of common bacterial and fungal aerosols in the atmosphere as well as their key influential factors was evaluated using the dithiothreitol (DTT) method. The results showed that bioaerosols induced reactive oxygen species (ROS) production, varying along the microorganism type, species, and concentration. The oxidative potential of fungi was approximately 2 to 3 times higher than that of bacteria. When the test bioaerosl concentrations were set highest (105CFU/mL), Staphylococcus aureus [(0.41 ± 0.06) nmol/(min·mL)] and Penicillium [(1.32 ± 0.11) nmol/(min·mL)] exhibited the strongest oxidative potential, averaging about 1.5times higher than other bacteria and fungi. The oxidation potential of bioaerosols was also significantly associated with their activity and chemical components. Microbial activity was a key factor regulating oxidative potential, with inactivation treatment reducing it by up to 40%. The consumption rate of DTT when biological components (Staphylococcus aureus/Penicillium) and chemical components (Cu/1, 4-NQ) were simultaneously present in the system was lower than that of the single component. It indicated that there was an interaction between the two components that inhibited the DTT consumption reaction.
  • Research progress on the associations between emerging contaminants and non-communicable diseases
    GUO Yu-qian, GAO Ya, GUO Chang-sheng, WU Rong-shan, FAN Jing-pu, ZHANG Yan, XU Jian
    China Environmental Science. 2026, 46(3): 1663-1672.
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    A bibliometric and visualization analysis using CiteSpace was performed on publications concerning emerging contaminants (ECs) and non-communicable diseases (NCDs) retrieved from the Web of Science Core Collection for the period 2005~2025, with the aim of mapping the field’s evolution and identifying research frontiers. Publication output increased substantially over the study period, with accelerated growth after 2014, coinciding with intensified policy initiatives to regulate newly listed pollutants under the Stockholm Convention on Persistent Organic Pollutants. In addition, the University of California, the U.S. National Institutes of Health, and the Chinese Academy of Sciences were among the most productive institutions, and relevant studies were predominantly published in international journals, including Environmental Health Perspectives and Environmental Science & Technology. The disciplinary landscape was dominated by Environmental Sciences, Toxicology, and Public Environmental Occupational Health, with public health serving as a critical bridge between environmental exposure assessment and disease-related mechanisms. Earlier work largely examined links between endocrine disrupting chemicals (EDCs) and disinfection by products (DBPs) and cancer, whereas recent studies have increasingly emphasized metabolic disorders associated with per- and polyfluoroalkyl substances (PFAS) and nanoparticles, alongside mechanistic themes involving the gut microbiota and inflammation. Future research should prioritize elucidating toxicological pathways and constructing integrative multi-omics frameworks to better explain the pathogenesis of NCDs.
  • Application and perspective to metagenomics in the pollution of marine antibiotic resistance
    MA Jian-qiao, CAI Yi-wei, LI Gui-ying, AN Tai-cheng
    China Environmental Science. 2026, 46(3): 1673-1681.
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    This review summarizes the applications and future prospects of metagenomics in studying antibiotic resistance pollution in marine environments. Results demonstrate that metagenomic analysis enables comprehensive characterization of genetic composition in marine microbial communities, particularly regarding the distribution, diversity, and spatiotemporal dynamics of antibiotic resistance genes (ARGs). The analysis reveals that ARGs are ubiquitously present in marine waters, sediments, and organisms, influenced by multiple factors including pollution sources, environmental conditions, and anthropogenic activities. Metagenomics not only elucidates ARG dissemination mechanisms but also provides scientific foundations for ecological risk assessment and pollution mitigation; however, limitations persist in functional validation and interpretation of environmental driving mechanisms. Future research should leverage multi-omics integration, third-generation sequencing technologies, and advanced bioinformatics tools to enhance the depth and precision of marine ARG pollution studies. Concurrently, integration with big data, machine learning, and artificial intelligence technologies will establish metagenomics as an irreplaceable tool in marine antibiotic resistance research, offering critical insights for combating the global antibiotic resistance crisis.
    • Carbon Emission Control
  • Study on the evolutionary characteristics and driving mechanisms of China’s carbon emissions from a consumption-based perspective
    LI Wen-qing, HE Guo-hua, YANG Qing-hai, LIN Lü, YAN Zeng-min, XIAO Chan, LIU Lü-liu
    China Environmental Science. 2026, 46(3): 1682-1693.
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    This study adopts a consumption-based perspective and, drawing on long time-series input-output data from 189economies around the world, calculates the scale embodied carbon transfers in China (referring specifically to China’s mainland and excluding Hong Kong, Macao, and Taiwan) from 1997 to 2021. It identifies the characteristics of consumption-based carbon emissions of eight industries: agriculture; mining and quarrying; light industries; heavy industries; machinery and equipment manufacturing; electricity, gas, and water supply; other industries; and living and tertiary industries. Furthermore, it analyzes the key drivers of changes in consumption-based carbon emissions across different periods. The findings reveal that from 1997 to 2021, China consistently remained a net exporter of embodied carbon emissions, with light industries, heavy industries, and machinery and equipment manufacturing serving as the main sources of embodied carbon exports. The United States, Japan, and China’s Hong Kong were the main destinations of these exports. In 2021, China’s consumption-based carbon emissions totaled 10,156million tons, 1,289million tons lower than its production-based emissions, indicating that under the consumption-based perspective, China’s carbon emission responsibility is 11.26% lower than that under the production-based perspective. In terms of driving factors, the increase in consumption scale was the main factor driving the growth of China’s consumption-based carbon emissions from 1997 to 2021, with a contribution rate of 159.31%. Changes in population size, improvements in energy utilization efficiency, and adjustments in the energy structure contributed 11.04%, -63.40%, and -6.96%, respectively, to changes in consumption-based carbon emissions. Based on these results, the study discusses the unfairness of assigning carbon emission responsibility under the production-based perspective, highlights key areas of focus for China’s carbon emission reduction efforts, and demonstrates the reliability of the findings.
  • Spatio-temporal patterns and evolutionary characteristics of provincial carbon lock-in in China
    HU Xi-wu, LI Zhong-hao, ZHANG Qian
    China Environmental Science. 2026, 46(3): 1694-1709.
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    The carbon lock-in effect represents a systematic challenge to achieve the goal of carbon peaking and carbon neutrality. Identifying its spatio-temporal evolution patterns and regional transmission mechanisms is of great significance for facilitating China's low-carbon transformation. Based on an improved evaluation system, the study measured the carbon lock-in levels of 30 provinces in China from 2002 to 2022. Spatio-temporal analysis method was employed to depict their spatial patterns and evolutionary laws, and further explore their spatial association mechanisms and evolutionary trends. The results show that: The national carbon lock-in level exhibits a three-stage trend overall: a slow decline, accelerated unlocking, and gentle fluctuation. It also demonstrates an evolutionary characteristic of "eastern regions taking the lead in unlocking, central regions undergoing rapid transformation, and western regions following suit continuously" in spatial patterns. Moreover, a comprehensive spatio-temporal analysis indicates that the degree of national carbon lock-in discretization has increased, regional disparities have expanded, and a multi-polarization tendency is evident. Carbon lock-in demonstrates a significant positive spatial spillover effect. The growth rate of fixed asset investment has a positive influence on carbon lock-in in adjacent areas, while the urbanization rate and the proportion of labor compensation have substantial negative impacts. The inter-provincial carbon lock-in network interaction shows a three-stage evolutionary trend bounded by the Hu Huanyong Line and transmission characteristics of "continuous deepening of inter-provincial connections, significant polarization of hub nodes, and explicit regional transmission paths". The differentiated evolution of functional interactions between northern and southern blocks bounded by the Qinling-Huaihe Line is obvious. The prediction results indicate that the carbon lock-in level is under pressure from diminishing marginal returns and faces risks of local rebound. The key to breaking the carbon lock-in network lies in the provinces with high betweenness centrality.
  • Analysis of spatial and temporal characteristics and influencing factors of carbon emissions from road transportation in China
    YANG Wen-zhuo, WANG Yuan, CHEN Han-lu, DONG Zhan-feng
    China Environmental Science. 2026, 46(3): 1710-1724.
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    With the continuous increase in carbon emissions from road transportation and significant regional differences, understanding the spatio-temporal evolution patterns and influencing factors of carbon emissions from road transportation in China is crucial for energy conservation and carbon reduction in this sector. Based on the calculation of carbon emissions from road transportation in 31 provinces of China from 2003 to 2022, this study uses slope values, Theil index, and integrates XGBoost-SHAP to construct an interpretable machine learning model to analyze the temporal characteristics, spatial differences, and influencing factors of carbon emissions from road transportation in China and its eastern, central, and western regions. The results show that: The combined carbon emissions from small and medium-sized passenger cars and heavy-duty trucks account for over 80%, while the proportion of light-duty trucks first increases and then stabilizes, and that of medium-duty trucks continuously decreases. The proportions of medium and large-sized passenger cars, buses, and taxis are relatively low and show a downward trend. The carbon emissions from road transportation in China exhibit a phased characteristic of "rapid growth-decelerating growth". The eastern region had a relatively fast growth rate in the early stage, but it has been continuously decelerating in the later stage; the central region's growth rate surpassed that of the eastern region in the later stage; the western region has a low base but the fastest growth rate. The overall spatial pattern of carbon emissions from road transportation in China is "expansion in the east-increase in the central-stability in the west", with high-emission continuous belts formed successively in the eastern coastal areas and the central hinterland. The differences in carbon emissions from road transportation between regions are gradually decreasing, while the differences within regions are significantly increasing. The differences among provinces within the eastern and western regions are significant, while those in the central region are the smallest and remain stable. (4) At the national level, the turnover volume of road freight is the primary factor and has a significant driving effect on carbon emissions from road traffic, followed by the total population and the number of motor vehicles per 10,000people, moreover, each significant factor shows a synergistic effect of increasing emissions. At the regional level, the turnover volume of road freight remains the most significant factor in the eastern and western regions, but it is not significant in the central region. The contribution rate of motor vehicles per 10,000people and per capita GDP in the central region has significantly increased compared to the eastern and western regions.
  • Research on carbon emission prediction of transportation industry based on MVMD decomposition
    WANG Qing-rong, LIU Xin-kang, ZHU Chang-feng, WANG Jun-jie
    China Environmental Science. 2026, 46(3): 1725-1735.
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    To address the issue of volatility and nonlinearity in carbon emission data sequences from the transportation sector affecting prediction accuracy,this study proposes a carbon emission prediction model that integrates Multivariate Variational Mode Decomposition (MVMD), differential multi-head attention mechanism,improved iTransformer,and LSTM enhanced by Sparrow Search Algorithm(SSA). First, MVMD was introduced to decompose the transportation carbon emission feature data sequence into modal components of different frequencies. Sample entropy was then used to quantify the complexity of each component, which was categorized into high- and low-frequency data based on entropy values, thereby further mitigating the volatility and nonlinearity of the carbon emission data sequence. Subsequently, SSA-LSTM was employed to predict low-frequency data, capturing long-range dependencies, while LSTM combined with the improved iTransformer was applied to rapidly denoise and fit high-frequency data to avoid interference with the primary trend. Finally, the prediction results of high- and low-frequency data were combined using weights calculated based on the sizes of sample entropy values. The model was validated using carbon emission data from China's transportation sector from 2000 to 2022. The results showed that the proposed model achieved a root mean square error (RMSE), mean square error (MSE), and mean absolute percentage error (MAPE) of 10.31x106t, 106.35x106t, and 0.97%, respectively, outperforming other comparative models and confirming its effectiveness.
  • Carbon reduction potential assessment of typical waste photovoltaic panel recycling technologies under life cycle assessment
    ZHAO Da-ming, MIAO Bo, WU Yang, WANG Zhong-qiang, CUI Tian-ao, LIU Zhe, LV Long-yi, GAO Wen-fang
    China Environmental Science. 2026, 46(3): 1736-1746.
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    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.
    • Environmental Impact Assessment and Management
  • Regional variations and the dynamic evolution of water environment governance efficiency in the Yangtze River Delta urban agglomeration
    FU Hui-shan, LI Jia-lin, LIU Yong-chao, CAO Luo-dan, ZHU Xiao, KONG Jiang-tao
    China Environmental Science. 2026, 46(3): 1747-1763.
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    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.
  • A review on value realization of ecological products
    LIU Guo-bo, LIU Gui-huan, WANG Xia-hui
    China Environmental Science. 2026, 46(3): 1764-1776.
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    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.
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