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2026, Volume 44, Issue 5
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2026,
44(5):
1-16.
doi: 10.13205/j.hjgc.202605001
Abstract:
As a concentrated area of China's C5 petroleum resin industry， the lower reaches of the Yangtze River Basin face critical bottlenecks in their green and low-carbon transformation due to the high-pollution， refractory wastewater and high carbon emissions generated during production. Aiming to address the problems of low efficiency， high energy consumption， and insufficient resource utilization in traditional petrochemical wastewater treatment technologies， this paper systematically analyzes the sources of wastewater in C5 petroleum resin production from the perspectives of principles and processes. It also reviews the research progress and carbon reduction potential of current petrochemical wastewater treatment technologies in three aspects： new materials， new equipment， and new processes. The significant advantages of integrated processes centered on efficient pretreatment， biological enhancement， and multi-technology coupling in improving treatment efficiency， reducing energy consumption and cost， and strengthening resource recovery are highlighted. Additionally， the study prospects the research priorities for pollution and carbon mitigation through green technological innovation， intelligent upgrading， and other pathways. It provides new solutions for the "near-zero discharge" and resource recycling of C5 petroleum resin wastewater， thereby promoting the green and low-carbon transformation of the petrochemical industry.
As a concentrated area of China's C5 petroleum resin industry， the lower reaches of the Yangtze River Basin face critical bottlenecks in their green and low-carbon transformation due to the high-pollution， refractory wastewater and high carbon emissions generated during production. Aiming to address the problems of low efficiency， high energy consumption， and insufficient resource utilization in traditional petrochemical wastewater treatment technologies， this paper systematically analyzes the sources of wastewater in C5 petroleum resin production from the perspectives of principles and processes. It also reviews the research progress and carbon reduction potential of current petrochemical wastewater treatment technologies in three aspects： new materials， new equipment， and new processes. The significant advantages of integrated processes centered on efficient pretreatment， biological enhancement， and multi-technology coupling in improving treatment efficiency， reducing energy consumption and cost， and strengthening resource recovery are highlighted. Additionally， the study prospects the research priorities for pollution and carbon mitigation through green technological innovation， intelligent upgrading， and other pathways. It provides new solutions for the "near-zero discharge" and resource recycling of C5 petroleum resin wastewater， thereby promoting the green and low-carbon transformation of the petrochemical industry.
2026,
44(5):
17-26.
doi: 10.13205/j.hjgc.202605002
Abstract:
The single-phase partial nitrification and anammox （SPN/A） process has seen limited widespread application due to its slow startup and the difficulties in enriching anaerobic ammonium-oxidizing bacteria （AnAOB）. This study utilized high-ammonia nitrogen wastewater to initiate and enhance the SPN/A process in a pilot-scale integrated fixed-film activated sludge （IFAS） reactor. By establishing an IFAS-SPN/A coupled system based on the symbiotic relationship between the biofilm and sludge， rapid startup of the IFAS reactor and efficient enrichment of AnAOB were achieved. An innovative sludge inoculation strategy was employed： firstly， conventional nitrifying sludge was inoculated to initiate shortcut nitrification and allow ammonia-oxidizing bacteria （AOB） to colonize blank carriers； subsequently， anammox sludge was inoculated to promote the efficient enrichment of AnAOB on the AOB biofilm. The experiment used low-temperature shift condensation water from the synthetic ammonia workshop as the influent， with an average ammonium nitrogen concentration of 2300 mg/L and a COD concentration ranging from 50 to 200 mg/L. The 180-day experiment was divided into three stages： shortcut nitrification startup， SPN/A startup， and load intensification. Ultimately， the system successfully started up SPN/A within 120 days， and through the synergistic action of biofilm and suspended microorganisms， improved the total nitrogen removal efficiency and removal load to （90.21±2.18）% and （0.31±0.07） kg/（m3·d）， respectively. During the load intensification stage， the relative abundance of AnAOB in the two-phase biofilm increased to 18.8% and 35.3%， achieving efficient AnAOB enrichment， while the removal load increased to （0.64±0.11） kg/（m3·d）. This study indicates that stable influent quality is a prerequisite for efficient and stable nitrogen removal in the IFAS-SPN/A coupled system. A surge in the influent ammonium nitrogen concentration is identified as the key factor leading to the imbalance of nitrite nitrogen accumulation and deterioration of the system's nitrogen removal efficiency. The addition of an equalization tank prior to the aeration tank can effectively mitigate the impact of such water quality fluctuations. Furthermore， the "dilution-reconstruction" strategy for treating low-ammonia nitrogen wastewater is beneficial for the rapid recovery of the system's nitrogen removal performance after a deterioration event.
The single-phase partial nitrification and anammox （SPN/A） process has seen limited widespread application due to its slow startup and the difficulties in enriching anaerobic ammonium-oxidizing bacteria （AnAOB）. This study utilized high-ammonia nitrogen wastewater to initiate and enhance the SPN/A process in a pilot-scale integrated fixed-film activated sludge （IFAS） reactor. By establishing an IFAS-SPN/A coupled system based on the symbiotic relationship between the biofilm and sludge， rapid startup of the IFAS reactor and efficient enrichment of AnAOB were achieved. An innovative sludge inoculation strategy was employed： firstly， conventional nitrifying sludge was inoculated to initiate shortcut nitrification and allow ammonia-oxidizing bacteria （AOB） to colonize blank carriers； subsequently， anammox sludge was inoculated to promote the efficient enrichment of AnAOB on the AOB biofilm. The experiment used low-temperature shift condensation water from the synthetic ammonia workshop as the influent， with an average ammonium nitrogen concentration of 2300 mg/L and a COD concentration ranging from 50 to 200 mg/L. The 180-day experiment was divided into three stages： shortcut nitrification startup， SPN/A startup， and load intensification. Ultimately， the system successfully started up SPN/A within 120 days， and through the synergistic action of biofilm and suspended microorganisms， improved the total nitrogen removal efficiency and removal load to （90.21±2.18）% and （0.31±0.07） kg/（m3·d）， respectively. During the load intensification stage， the relative abundance of AnAOB in the two-phase biofilm increased to 18.8% and 35.3%， achieving efficient AnAOB enrichment， while the removal load increased to （0.64±0.11） kg/（m3·d）. This study indicates that stable influent quality is a prerequisite for efficient and stable nitrogen removal in the IFAS-SPN/A coupled system. A surge in the influent ammonium nitrogen concentration is identified as the key factor leading to the imbalance of nitrite nitrogen accumulation and deterioration of the system's nitrogen removal efficiency. The addition of an equalization tank prior to the aeration tank can effectively mitigate the impact of such water quality fluctuations. Furthermore， the "dilution-reconstruction" strategy for treating low-ammonia nitrogen wastewater is beneficial for the rapid recovery of the system's nitrogen removal performance after a deterioration event.
2026,
44(5):
27-36.
doi: 10.13205/j.hjgc.202605003
Abstract:
This study developed a mixed microbial biohybrid system based on Fe2O3 nanoparticles to significantly enhance dark fermentation hydrogen production by improving hydrogenase activity， microbial metabolic activity， and electron transfer efficiency. At a Fe2O3 concentration of 300 mg/L （denoted as S300）， the hydrogen yield attained 2.94 mol H2 per mole of glucose， which was equivalent to 73.5% of the theoretical hydrogen production rate in dark fermentation. This yield was 1.59 times higher than that of the control group （S0） without the addition of Fe2O3 nanoparticles. In the S300 biohybrid， the ATP content and total protein concentration increased by 4.09- and 1.30-fold， respectively； hydrogenase and dehydrogenase activities were enhanced by 24.62% and 63.11%， respectively； and the electron transfer system activity increased by 3.44-fold， accompanied by a significant reduction in charge transfer resistance. Additionally， a gradual increase in Fe2+ concentration from S50 to S300 was identified as a key factor in stimulating hydrogenase activity and enhancing electron transfer efficiency. Microbial community analysis revealed that the relative abundance of the hydrogen-producing genus Clostridium in S300 increased by 9.75 percentage points to 42.60%， playing a pivotal role in enhancing hydrogen production. This study not only proposes an efficient Fe2O3 nanoparticle-based biohybrid strategy but also provides in-depth insights into the synergistic mechanisms between nanomaterials and microorganisms， thereby offering a theoretical and practical foundation for advancing dark fermentation hydrogen production technologies.
This study developed a mixed microbial biohybrid system based on Fe2O3 nanoparticles to significantly enhance dark fermentation hydrogen production by improving hydrogenase activity， microbial metabolic activity， and electron transfer efficiency. At a Fe2O3 concentration of 300 mg/L （denoted as S300）， the hydrogen yield attained 2.94 mol H2 per mole of glucose， which was equivalent to 73.5% of the theoretical hydrogen production rate in dark fermentation. This yield was 1.59 times higher than that of the control group （S0） without the addition of Fe2O3 nanoparticles. In the S300 biohybrid， the ATP content and total protein concentration increased by 4.09- and 1.30-fold， respectively； hydrogenase and dehydrogenase activities were enhanced by 24.62% and 63.11%， respectively； and the electron transfer system activity increased by 3.44-fold， accompanied by a significant reduction in charge transfer resistance. Additionally， a gradual increase in Fe2+ concentration from S50 to S300 was identified as a key factor in stimulating hydrogenase activity and enhancing electron transfer efficiency. Microbial community analysis revealed that the relative abundance of the hydrogen-producing genus Clostridium in S300 increased by 9.75 percentage points to 42.60%， playing a pivotal role in enhancing hydrogen production. This study not only proposes an efficient Fe2O3 nanoparticle-based biohybrid strategy but also provides in-depth insights into the synergistic mechanisms between nanomaterials and microorganisms， thereby offering a theoretical and practical foundation for advancing dark fermentation hydrogen production technologies.
2026,
44(5):
37-49.
doi: 10.13205/j.hjgc.202605004
Abstract:
To address the decline in operational performance of sewage pipeline networks in rainy cities of southern China caused by structural defects， stormwater-sewage cross-connections， and external water intrusion， a systematic governance framework comprising precise investigation， dynamic regulation， graded rehabilitation， and smart operation and maintenance was established. A zoned priority evaluation model was developed with comprehensive problem severity （P） and governance contribution （B） as the core indicators， based on which differentiated governance strategies were formulated. Supported by a digital platform， monitoring， assessment， rectification， and verification data were integrated to develop a digital twin system for the pipeline network， and a correlation-based analysis and closed-loop operation and maintenance mechanism linking rainfall， groundwater level， and network hydraulic load was established. A typical urban area in Jiangxi Province was selected as the case study. After implementation， the mean COD concentration of terminal sewage in the study area increased steadily to 230 mg/L above， the average daily external water volume in the dry season decreased by 27.64%， and the sewage collection rate increased to 76%. The results indicate that the proposed framework can effectively support the quality and efficiency improvement of sewage pipeline networks in rainy cities of southern China， and provide a technical reference for similar cities.
To address the decline in operational performance of sewage pipeline networks in rainy cities of southern China caused by structural defects， stormwater-sewage cross-connections， and external water intrusion， a systematic governance framework comprising precise investigation， dynamic regulation， graded rehabilitation， and smart operation and maintenance was established. A zoned priority evaluation model was developed with comprehensive problem severity （P） and governance contribution （B） as the core indicators， based on which differentiated governance strategies were formulated. Supported by a digital platform， monitoring， assessment， rectification， and verification data were integrated to develop a digital twin system for the pipeline network， and a correlation-based analysis and closed-loop operation and maintenance mechanism linking rainfall， groundwater level， and network hydraulic load was established. A typical urban area in Jiangxi Province was selected as the case study. After implementation， the mean COD concentration of terminal sewage in the study area increased steadily to 230 mg/L above， the average daily external water volume in the dry season decreased by 27.64%， and the sewage collection rate increased to 76%. The results indicate that the proposed framework can effectively support the quality and efficiency improvement of sewage pipeline networks in rainy cities of southern China， and provide a technical reference for similar cities.
2026,
44(5):
50-60.
doi: 10.13205/j.hjgc.202605005
Abstract:
This study collected water quality monitoring data from two city-level control monitoring stations within the district from December 2020 to June 2024. The dataset included eight indicators： water temperature， turbidity， pH， conductivity， dissolved oxygen （DO）， ammonia nitrogen （NH4+-N）， total phosphorus （TP）， and permanganate index （CODMn）. To address the water quality prediction issues for city-level monitoring sections in the study area， seasonal trend decomposition （STD）-Bayesian-random forest （RF） model， and STD-Bayesian-XGBoost models were constructed. These models used water temperature， turbidity， pH， conductivity， and seasonal factors as characteristic variables to predict and analyze four key indicators： DO， NH4+-N， TP， and CODMn. STD was applied to smooth and denoise the data while extracting seasonal factors. The Bayesian optimization algorithm was selected to optimize the hyperparameters of the RF and XGBoost models. Evaluation results showed that the STD-Bayesian-XGBoost model yielded smaller bias errors compared to the STD-Bayesian-RF model， achieving better prediction accuracy and superior prediction effect. This study contributes to the research on water quality prediction modeling for river basins in southern China， and provides a technical reference for pollution reduction and carbon emission management in the basin.
This study collected water quality monitoring data from two city-level control monitoring stations within the district from December 2020 to June 2024. The dataset included eight indicators： water temperature， turbidity， pH， conductivity， dissolved oxygen （DO）， ammonia nitrogen （NH4+-N）， total phosphorus （TP）， and permanganate index （CODMn）. To address the water quality prediction issues for city-level monitoring sections in the study area， seasonal trend decomposition （STD）-Bayesian-random forest （RF） model， and STD-Bayesian-XGBoost models were constructed. These models used water temperature， turbidity， pH， conductivity， and seasonal factors as characteristic variables to predict and analyze four key indicators： DO， NH4+-N， TP， and CODMn. STD was applied to smooth and denoise the data while extracting seasonal factors. The Bayesian optimization algorithm was selected to optimize the hyperparameters of the RF and XGBoost models. Evaluation results showed that the STD-Bayesian-XGBoost model yielded smaller bias errors compared to the STD-Bayesian-RF model， achieving better prediction accuracy and superior prediction effect. This study contributes to the research on water quality prediction modeling for river basins in southern China， and provides a technical reference for pollution reduction and carbon emission management in the basin.
2026,
44(5):
61-70.
doi: 10.13205/j.hjgc.202605006
Abstract:
Military ecological and environmental protection constitutes an important component of national ecological and environmental protection. Military activities and operations， such as training and drills， weapons and equipment testing， and combat， are prone to triggering a series of ecological and environmental problems， including greenhouse gas emissions， deterioration of water resources and water quality， vegetation destruction， land degradation， and typical physical and chemical pollution， which have attracted extensive global attention. This study systematically analyzed the eco-environmental impacts of military activities on multiple environmental media （atmosphere， water， and soil） across different periods， and conducted pollution source tracing in multi-media and representative regions. It reviewed the current status of ecological and environmental protection technologies for the three major environmental media， i.e.， atmosphere， water， and soil， and summarized the characteristics and constraints of military ecological and environmental research. Finally， it proposed the research trends and key development directions for military ecological and environmental protection from four dimensions： data monitoring and sharing， research and development of in-situ remediation technologies for military-civilian integrated combined pollution， green construction practices for military facilities， and optimization of management systems.
Military ecological and environmental protection constitutes an important component of national ecological and environmental protection. Military activities and operations， such as training and drills， weapons and equipment testing， and combat， are prone to triggering a series of ecological and environmental problems， including greenhouse gas emissions， deterioration of water resources and water quality， vegetation destruction， land degradation， and typical physical and chemical pollution， which have attracted extensive global attention. This study systematically analyzed the eco-environmental impacts of military activities on multiple environmental media （atmosphere， water， and soil） across different periods， and conducted pollution source tracing in multi-media and representative regions. It reviewed the current status of ecological and environmental protection technologies for the three major environmental media， i.e.， atmosphere， water， and soil， and summarized the characteristics and constraints of military ecological and environmental research. Finally， it proposed the research trends and key development directions for military ecological and environmental protection from four dimensions： data monitoring and sharing， research and development of in-situ remediation technologies for military-civilian integrated combined pollution， green construction practices for military facilities， and optimization of management systems.
2026,
44(5):
71-82.
doi: 10.13205/j.hjgc.202605007
Abstract:
Reservoirs are increasingly recognized as dynamic inland-water components that can function as both sources and sinks of nitrous oxide （N2O）， a potent greenhouse gas and ozone-depleting substance. In sedimentary environments， complete denitrification provides the only known biological pathway for reducing N2O to inert dinitrogen （N2）， and the functional gene nosZ， which encodes nitrous oxide reductase， is widely used as a molecular marker to assess the N2O-reduction potential of microbial communities. However， the community characteristics， spatiotemporal variability， and environmental control of nosZ-type denitrifiers in high-altitude reservoir sediments remain insufficiently understood. This study investigated nosZ-type denitrifying bacterial communities and nosZ gene abundance in surface sediments （0 to 15 cm） collected from 18 reservoirs located in the mainstem Yellow River Basin （10 reservoirs） and its tributary basin， the Huangshui River Basin （8 reservoirs）， in the northeastern Qinghai-Tibet Plateau. Sampling was conducted during the dry season （May 2023） and wet season （August 2023）， and paired sediment and surface-water physicochemical parameters were measured concurrently. High-throughput sequencing targeting the nosZ gene was employed to profile community composition and diversity， while quantitative PCR （qPCR） was used to quantify absolute nosZ gene copy numbers （copies/g dry sediment） as a proxy for functional potential. Multivariate analysis， including redundancy analysis （RDA） and hierarchical partitioning， were applied to identify key environmental drivers shaping community structure. The results showed that：1） nosZ-type denitrifying bacteria in reservoir sediments of the northeastern Qinghai-Tibet Plateau were dominated by Proteobacteria （78.91%）. LEfSe analysis indicated that Paracoccus and Halomonas were biomarkers for the mainstem of the Yellow River Basin， while no biomarkers were detected in the Huangshui River Basin at the genus level. 2） The diversity of nosZ-type denitrifying bacteria in the Huangshui River Basin was higher than that in the mainstem of the Yellow River Basin （P<0.05）， with no significant difference over time （P>0.05）. The abundance of the nosZ gene was spatially higher in the Huangshui River Basin （165.24×105 copies/g） than in the mainstem of the Yellow River Basin （34.43×105 copies/g）. Temporally， it was also higher in the wet season （128.55×105 copies/g） compared to the dry season （61.27×105 copies/g） （P<0.05）. 3） Sediment temperature （17.14%）， pH （16.89%）， total phosphorus （13.83%）， and total nitrogen （11.23%） in water significantly influenced the community structure of nosZ-type denitrifying bacteria in the reservoir sediments of the northeastern Qinghai-Tibet Plateau （P<0.05）. Collectively， these results demonstrated that nosZ-type denitrifiers in reservoir sediments of the northeastern Qinghai-Tibet Plateau exhibit clear basin-dependent patterns and significant seasonal shifts in functional gene abundance， and that thermal regime， pH， and nutrient status are critical determinants of community assembly. This study provides an integrated microbial and environmental baseline for plateau reservoirs， improves mechanistic understanding of sedimentary N2O sinks， and offers scientific support for reservoir N2O mitigation strategies that consider watershed nutrient management and sediment physicochemical conditions.
Reservoirs are increasingly recognized as dynamic inland-water components that can function as both sources and sinks of nitrous oxide （N2O）， a potent greenhouse gas and ozone-depleting substance. In sedimentary environments， complete denitrification provides the only known biological pathway for reducing N2O to inert dinitrogen （N2）， and the functional gene nosZ， which encodes nitrous oxide reductase， is widely used as a molecular marker to assess the N2O-reduction potential of microbial communities. However， the community characteristics， spatiotemporal variability， and environmental control of nosZ-type denitrifiers in high-altitude reservoir sediments remain insufficiently understood. This study investigated nosZ-type denitrifying bacterial communities and nosZ gene abundance in surface sediments （0 to 15 cm） collected from 18 reservoirs located in the mainstem Yellow River Basin （10 reservoirs） and its tributary basin， the Huangshui River Basin （8 reservoirs）， in the northeastern Qinghai-Tibet Plateau. Sampling was conducted during the dry season （May 2023） and wet season （August 2023）， and paired sediment and surface-water physicochemical parameters were measured concurrently. High-throughput sequencing targeting the nosZ gene was employed to profile community composition and diversity， while quantitative PCR （qPCR） was used to quantify absolute nosZ gene copy numbers （copies/g dry sediment） as a proxy for functional potential. Multivariate analysis， including redundancy analysis （RDA） and hierarchical partitioning， were applied to identify key environmental drivers shaping community structure. The results showed that：1） nosZ-type denitrifying bacteria in reservoir sediments of the northeastern Qinghai-Tibet Plateau were dominated by Proteobacteria （78.91%）. LEfSe analysis indicated that Paracoccus and Halomonas were biomarkers for the mainstem of the Yellow River Basin， while no biomarkers were detected in the Huangshui River Basin at the genus level. 2） The diversity of nosZ-type denitrifying bacteria in the Huangshui River Basin was higher than that in the mainstem of the Yellow River Basin （P<0.05）， with no significant difference over time （P>0.05）. The abundance of the nosZ gene was spatially higher in the Huangshui River Basin （165.24×105 copies/g） than in the mainstem of the Yellow River Basin （34.43×105 copies/g）. Temporally， it was also higher in the wet season （128.55×105 copies/g） compared to the dry season （61.27×105 copies/g） （P<0.05）. 3） Sediment temperature （17.14%）， pH （16.89%）， total phosphorus （13.83%）， and total nitrogen （11.23%） in water significantly influenced the community structure of nosZ-type denitrifying bacteria in the reservoir sediments of the northeastern Qinghai-Tibet Plateau （P<0.05）. Collectively， these results demonstrated that nosZ-type denitrifiers in reservoir sediments of the northeastern Qinghai-Tibet Plateau exhibit clear basin-dependent patterns and significant seasonal shifts in functional gene abundance， and that thermal regime， pH， and nutrient status are critical determinants of community assembly. This study provides an integrated microbial and environmental baseline for plateau reservoirs， improves mechanistic understanding of sedimentary N2O sinks， and offers scientific support for reservoir N2O mitigation strategies that consider watershed nutrient management and sediment physicochemical conditions.
2026,
44(5):
83-91.
doi: 10.13205/j.hjgc.202605008
Abstract:
Vegetable production is an important source of greenhouse gas emissions. Conducting carbon footprint accounting and heterogeneity analysis for vegetable production is crucial for achieving the Dual Carbon Goals in agriculture. Previous studies have mostly focused on local regions or single varieties， lacking systematic comparisons of different planting patterns at the national scale， and providing insufficient analysis of their spatial distribution patterns and contributions at each stage. This study was based on the life cycle assessment（LCA） framework and used provincial statistical data from 2018 to 2022 to construct a calculation model covering material inputs， field emissions， and energy consumption. It analyzed the compositional characteristics and spatial distribution patterns of the carbon footprints of different vegetables under open-field and facility farming models. The results show that： 1） The annual average carbon footprint per unit yield of typical vegetables in China ranges from 65.5 to 293.8 g CO2-eq/kg； among these vegetables， open-field radishes have the lowest emission intensity， while open-field green beans have the highest， and significant inter-provincial heterogeneity exists， with the largest regional fluctuations observed for facility eggplants and open-field green beans. 2） The carbon footprint exhibits significant spatial clustering and model differences； fruit vegetables show higher emissions in open-field production in the central and southern regions， and in facility production in the northern regions， while leafy vegetables display a "higher in the south， lower in the north" pattern. 3） Fertilizer production and field N2O emissions are the core sources of the carbon footprint （with a contribution rate as high as 80.4%）； compared with open-field production， irrigation electricity consumption and agricultural film input emissions for facility vegetables increase significantly， reaching up to 57.87%. This study can provide scientific support for developing differentiated green production strategies and precise emission reduction measures in China.
Vegetable production is an important source of greenhouse gas emissions. Conducting carbon footprint accounting and heterogeneity analysis for vegetable production is crucial for achieving the Dual Carbon Goals in agriculture. Previous studies have mostly focused on local regions or single varieties， lacking systematic comparisons of different planting patterns at the national scale， and providing insufficient analysis of their spatial distribution patterns and contributions at each stage. This study was based on the life cycle assessment（LCA） framework and used provincial statistical data from 2018 to 2022 to construct a calculation model covering material inputs， field emissions， and energy consumption. It analyzed the compositional characteristics and spatial distribution patterns of the carbon footprints of different vegetables under open-field and facility farming models. The results show that： 1） The annual average carbon footprint per unit yield of typical vegetables in China ranges from 65.5 to 293.8 g CO2-eq/kg； among these vegetables， open-field radishes have the lowest emission intensity， while open-field green beans have the highest， and significant inter-provincial heterogeneity exists， with the largest regional fluctuations observed for facility eggplants and open-field green beans. 2） The carbon footprint exhibits significant spatial clustering and model differences； fruit vegetables show higher emissions in open-field production in the central and southern regions， and in facility production in the northern regions， while leafy vegetables display a "higher in the south， lower in the north" pattern. 3） Fertilizer production and field N2O emissions are the core sources of the carbon footprint （with a contribution rate as high as 80.4%）； compared with open-field production， irrigation electricity consumption and agricultural film input emissions for facility vegetables increase significantly， reaching up to 57.87%. This study can provide scientific support for developing differentiated green production strategies and precise emission reduction measures in China.
2026,
44(5):
92-102.
doi: 10.13205/j.hjgc.202605009
Abstract:
Reservoir carbon dioxide （CO2） emission forecasting is a key component of the global carbon cycle. Most existing prediction studies are based on machine learning models， where data from large-， medium-， and small-sized reservoirs are used together for model calibration. Neither the model calibration nor the emission forecasting is stratified by reservoir capacity level， thereby ignoring the impact of reservoir size on the carbon cycle mechanism. To address this problem， this study abandoned the traditional full-scale hybrid modeling strategy and constructed a training dataset specifically for large- and medium-sized reservoirs. Using data from large- and medium-sized reservoirs in China， this study established a CO2 emission forecasting model， thoroughly explored the spatiotemporal evolution of CO2 flux across different river basins， and quantitatively identified the leading driving factors. The results showed that CO2 flux of reservoirs in China exhibited significant latitudinal zonation， with values in low-latitude areas in the south significantly higher than those in high-latitude areas in the north. CO2 flux was significantly correlated with reservoir age， latitude， and total phosphorus content. Among these， total phosphorus content was the most strongly correlated driving factor， showing a positive exponential correlation with CO2 flux. However， physical parameters such as reservoir area， pre-impoundment submersion ratio， and average water depth showed no significant correlation with CO2 flux at the national scale， and the dominant influencing factors varied heterogeneously across different basins. The findings of this study provide a theoretical basis for clarifying the carbon emission characteristics of large- and medium-sized reservoirs in China offer scientific support for the management of carbon sinks in reservoirs.
Reservoir carbon dioxide （CO2） emission forecasting is a key component of the global carbon cycle. Most existing prediction studies are based on machine learning models， where data from large-， medium-， and small-sized reservoirs are used together for model calibration. Neither the model calibration nor the emission forecasting is stratified by reservoir capacity level， thereby ignoring the impact of reservoir size on the carbon cycle mechanism. To address this problem， this study abandoned the traditional full-scale hybrid modeling strategy and constructed a training dataset specifically for large- and medium-sized reservoirs. Using data from large- and medium-sized reservoirs in China， this study established a CO2 emission forecasting model， thoroughly explored the spatiotemporal evolution of CO2 flux across different river basins， and quantitatively identified the leading driving factors. The results showed that CO2 flux of reservoirs in China exhibited significant latitudinal zonation， with values in low-latitude areas in the south significantly higher than those in high-latitude areas in the north. CO2 flux was significantly correlated with reservoir age， latitude， and total phosphorus content. Among these， total phosphorus content was the most strongly correlated driving factor， showing a positive exponential correlation with CO2 flux. However， physical parameters such as reservoir area， pre-impoundment submersion ratio， and average water depth showed no significant correlation with CO2 flux at the national scale， and the dominant influencing factors varied heterogeneously across different basins. The findings of this study provide a theoretical basis for clarifying the carbon emission characteristics of large- and medium-sized reservoirs in China offer scientific support for the management of carbon sinks in reservoirs.
Research on colonization requirements of submerged macrophytes based on underwater light environment
2026,
44(5):
103-111.
doi: 10.13205/j.hjgc.202605010
Abstract:
The underwater light environment is one of the key limiting factors for the colonization of submerged macrophytes and the ecological restoration of shallow lakes. Previous studies have rarely quantitatively determined the contribution characteristics of aquatic environmental factors in the relationship between water quality， underwater light environment， and submerged macrophyte colonization. They have also failed to comprehensively consider the correlations among various aquatic environmental factors or to clarify the parameter thresholds that meet the requirements for submerged macrophyte colonization. Taking a typical national wetland nature reserve as the study area， this study measured indicators including photosynthetically active radiation， light attenuation coefficient， euphotic depth， water transparency， total suspended solids， chlorophyll-a， total nitrogen， and total phosphorus. A simulation model of the underwater light attenuation coefficient was established， the spatial distribution patterns of aquatic environmental factors were quantitatively analyzed， the contribution rates of aquatic environmental factors to light attenuation were quantified， and the thresholds of key parameters were determined. The results showed that the average light attenuation coefficient in the study area was （10.31±3.76） m-1； the euphotic depth ［（0.53±0.24） m］ was lower than the average water depth ［（0.94±0.29） m］， exhibiting a heterogeneous pattern of being shallower in the west and deeper in the east. Total suspended solids and chlorophyll-a were the main direct influencing factors， while total nitrogen was the main indirect influencing factor. To achieve effective colonization of submerged macrophytes under the condition of average water depth， the euphotic depth should be ≥ 0.94 m， corresponding to the water transparency ≥ 0.41 m， light attenuation coefficient ≤ 4.95 m-1， and chlorophyll-a ≤ 3.8 μg/L.
The underwater light environment is one of the key limiting factors for the colonization of submerged macrophytes and the ecological restoration of shallow lakes. Previous studies have rarely quantitatively determined the contribution characteristics of aquatic environmental factors in the relationship between water quality， underwater light environment， and submerged macrophyte colonization. They have also failed to comprehensively consider the correlations among various aquatic environmental factors or to clarify the parameter thresholds that meet the requirements for submerged macrophyte colonization. Taking a typical national wetland nature reserve as the study area， this study measured indicators including photosynthetically active radiation， light attenuation coefficient， euphotic depth， water transparency， total suspended solids， chlorophyll-a， total nitrogen， and total phosphorus. A simulation model of the underwater light attenuation coefficient was established， the spatial distribution patterns of aquatic environmental factors were quantitatively analyzed， the contribution rates of aquatic environmental factors to light attenuation were quantified， and the thresholds of key parameters were determined. The results showed that the average light attenuation coefficient in the study area was （10.31±3.76） m-1； the euphotic depth ［（0.53±0.24） m］ was lower than the average water depth ［（0.94±0.29） m］， exhibiting a heterogeneous pattern of being shallower in the west and deeper in the east. Total suspended solids and chlorophyll-a were the main direct influencing factors， while total nitrogen was the main indirect influencing factor. To achieve effective colonization of submerged macrophytes under the condition of average water depth， the euphotic depth should be ≥ 0.94 m， corresponding to the water transparency ≥ 0.41 m， light attenuation coefficient ≤ 4.95 m-1， and chlorophyll-a ≤ 3.8 μg/L.
2026,
44(5):
112-121.
doi: 10.13205/j.hjgc.202605011
Abstract:
Phytoplankton are highly sensitive to environmental changes and respond rapidly. Their community dynamics serve as important early warning indicators of lake ecosystem conditions. Previous studies have focused on qualitatively analyzing the combined effects of multiple physicochemical water quality factors on phytoplankton communities； however， few have quantitatively distinguished between the direct and indirect effects of different physicochemical water quality factors on these communities. This study used correlation analysis， redundancy analysis， and structural equation modeling to explore the spatial distribution characteristics of phytoplankton communities in Baiyangdian Lake and their driving factors. A total of 113 species belonging to 57 genera and 7 phyla were recorded. Phytoplankton density showed significant seasonal and spatial variability， reaching its maximum in summer. Diatoms and green algae dominated in spring， transitioning to cyanobacterial dominance in summer and autumn， and then reverting to green algae dominance in winter. Structural equation modeling revealed that water temperature had a total positive effect on phytoplankton biomass （β = 0.96）， consisting of a direct positive effect （β = 0.94， P < 0.05） and an indirect positive effect via increased abundance （β = 0.02）. Total nitrogen had a negative total effect on phytoplankton biomass （β = -0.96）， consisting of a direct negative effect （β = -0.95， P < 0.05） and an indirect negative effect via reduced abundance （β = -0.01）. Total nitrogen exerted a negative effect on abundance （β = -0.15， P < 0.05）. This study provides a scientific basis for ecosystem health assessment， eutrophication control strategies， and biodiversity protection in Baiyangdian Lake.
Phytoplankton are highly sensitive to environmental changes and respond rapidly. Their community dynamics serve as important early warning indicators of lake ecosystem conditions. Previous studies have focused on qualitatively analyzing the combined effects of multiple physicochemical water quality factors on phytoplankton communities； however， few have quantitatively distinguished between the direct and indirect effects of different physicochemical water quality factors on these communities. This study used correlation analysis， redundancy analysis， and structural equation modeling to explore the spatial distribution characteristics of phytoplankton communities in Baiyangdian Lake and their driving factors. A total of 113 species belonging to 57 genera and 7 phyla were recorded. Phytoplankton density showed significant seasonal and spatial variability， reaching its maximum in summer. Diatoms and green algae dominated in spring， transitioning to cyanobacterial dominance in summer and autumn， and then reverting to green algae dominance in winter. Structural equation modeling revealed that water temperature had a total positive effect on phytoplankton biomass （β = 0.96）， consisting of a direct positive effect （β = 0.94， P < 0.05） and an indirect positive effect via increased abundance （β = 0.02）. Total nitrogen had a negative total effect on phytoplankton biomass （β = -0.96）， consisting of a direct negative effect （β = -0.95， P < 0.05） and an indirect negative effect via reduced abundance （β = -0.01）. Total nitrogen exerted a negative effect on abundance （β = -0.15， P < 0.05）. This study provides a scientific basis for ecosystem health assessment， eutrophication control strategies， and biodiversity protection in Baiyangdian Lake.
2026,
44(5):
122-131.
doi: 10.13205/j.hjgc.202605012
Abstract:
The water extraction process of large-scale infiltration galleries can significantly alter the exchange dynamics between surface water and groundwater. However， the existing models often simplify the gallery as a boundary condition or adopt a loosely coupling schemes， and are typically constrained by iterative exchange algorithms， which often fail to accurately capture the dynamic water flux interactions and transient responses among system components. To address this limitation， this study focused on the large riverbed infiltration and purification water supply project in Shijiazhuang， China， and established an integrated three-domain fully coupled numerical model—encompassing surface water， groundwater， and the infiltration gallery—using the dual-node coupling approach in HydroGeoSphere. The model set two upstream inflow scenarios （wet season and dry season conditions） and simulated the characteristics of regional groundwater level evolution and the water exchange processes among various domains under two operational modes： single-pump extraction at 1000 m3/h and no pumping. Simulation results showed that groundwater levels declined markedly under pumping， with the most pronounced response occurring during the dry season， where the maximum drawdown reached approximately 1.24 m. Monitoring wells near the gallery showed an obviously earlier hydraulic response to pumping， reaching peak drawdown rates about 2 to 3 days sooner than wells located farther away. Further analysis of water exchange characteristics at steady-state balance revealed significant differences across scenarios： overall， surface water contributed more recharge to groundwater during the wet season than in the dry season， and the water exchange between the infiltration gallery and the aquifer was substantially enhanced under pumping conditions. Spatially， the water exchange was concentrated primarily around the transverse and longitudinal gallery sections， consistent with the localized enhancement of permeability induced by the perforated structure of the gallery. These findings revealed the groundwater dynamics and multi-domain interaction mechanisms under operational conditions of large-scale infiltration galleries， providing a theoretical basis for the planning， design， and sustainable operation of similar riverbed infiltration water supply systems.
The water extraction process of large-scale infiltration galleries can significantly alter the exchange dynamics between surface water and groundwater. However， the existing models often simplify the gallery as a boundary condition or adopt a loosely coupling schemes， and are typically constrained by iterative exchange algorithms， which often fail to accurately capture the dynamic water flux interactions and transient responses among system components. To address this limitation， this study focused on the large riverbed infiltration and purification water supply project in Shijiazhuang， China， and established an integrated three-domain fully coupled numerical model—encompassing surface water， groundwater， and the infiltration gallery—using the dual-node coupling approach in HydroGeoSphere. The model set two upstream inflow scenarios （wet season and dry season conditions） and simulated the characteristics of regional groundwater level evolution and the water exchange processes among various domains under two operational modes： single-pump extraction at 1000 m3/h and no pumping. Simulation results showed that groundwater levels declined markedly under pumping， with the most pronounced response occurring during the dry season， where the maximum drawdown reached approximately 1.24 m. Monitoring wells near the gallery showed an obviously earlier hydraulic response to pumping， reaching peak drawdown rates about 2 to 3 days sooner than wells located farther away. Further analysis of water exchange characteristics at steady-state balance revealed significant differences across scenarios： overall， surface water contributed more recharge to groundwater during the wet season than in the dry season， and the water exchange between the infiltration gallery and the aquifer was substantially enhanced under pumping conditions. Spatially， the water exchange was concentrated primarily around the transverse and longitudinal gallery sections， consistent with the localized enhancement of permeability induced by the perforated structure of the gallery. These findings revealed the groundwater dynamics and multi-domain interaction mechanisms under operational conditions of large-scale infiltration galleries， providing a theoretical basis for the planning， design， and sustainable operation of similar riverbed infiltration water supply systems.
2026,
44(5):
132-141.
doi: 10.13205/j.hjgc.202605013
Abstract:
Against the backdrop of intensifying global eutrophication， algal blooms trigger substantial releases and accumulation of algal-derived dissolved organic matter （ADOM）， significantly impacting aquatic carbon cycling and pollutant transport. Among these， the adsorption and sequestration of dissolved organic matter （DOM） by iron minerals，particularly ferrihydrite，constitutes a pivotal process regulating its environmental fate. However， the adsorption fractionation behaviors of ADOM under varying environmental conditions remains poorly understood. Consequently， this study systematically investigates the effects of pH （2.0 to 10.0） and initial dissolved organic carbon （DOC） concentration （2 to 100 mg C/L） on the adsorption amount and selectivity of ADOM onto ferrihydrite. The fractionation patterns were elucidated using ultraviolet-visible spectroscopy （UV-Vis） and three-dimensional fluorescence spectroscopy-parallel factor analysis （EEM-PARAFAC）. Results indicate that pH and DOC concentration not only regulated ADOM adsorption onto ferrihydrite but also significantly influenced its fractionation effect. Within the pH range of 2.0 to 7.0， adsorption capacity increased with rising pH， peaking at pH=7.0 （21.59 mg C/g）， declining at pH > 7.0 due to enhanced electrostatic repulsion. UV-Vis and EEM analysis revealed that within the pH range of 3.0 to 9.0， the selective fractionation of ferrihydrite towards highly aromatic， high-molecular-weight chromophoric DOM （CDOM） components and relatively highly humic， biogenic protein-like/aromatic amino acid fluorescent DOM （FDOM） progressively intensified with the increasing pH. Furthermore， with DOC concentration increasing， adsorption capacity exhibited non-linear growth， higher molecular weight components with low aromaticity and lower molecular weight， alongside FDOM of protein-like/aromatic amino acid with lower humification and stronger autotrophic characteristics， progressively intensified. This study demonstrates that in water bodies dominated by ADOM， such as eutrophic lakes， ferrihydrite can effectively sequester the active components of ADOM through pH-dependent and concentration-dependent selective adsorption， which may potentially have an impact on the composition and reactivity of DOM. This can provide fundamental data for a deeper understanding of the autochthonous carbon sequestration process mediated by iron minerals in eutrophic water bodies.
Against the backdrop of intensifying global eutrophication， algal blooms trigger substantial releases and accumulation of algal-derived dissolved organic matter （ADOM）， significantly impacting aquatic carbon cycling and pollutant transport. Among these， the adsorption and sequestration of dissolved organic matter （DOM） by iron minerals，particularly ferrihydrite，constitutes a pivotal process regulating its environmental fate. However， the adsorption fractionation behaviors of ADOM under varying environmental conditions remains poorly understood. Consequently， this study systematically investigates the effects of pH （2.0 to 10.0） and initial dissolved organic carbon （DOC） concentration （2 to 100 mg C/L） on the adsorption amount and selectivity of ADOM onto ferrihydrite. The fractionation patterns were elucidated using ultraviolet-visible spectroscopy （UV-Vis） and three-dimensional fluorescence spectroscopy-parallel factor analysis （EEM-PARAFAC）. Results indicate that pH and DOC concentration not only regulated ADOM adsorption onto ferrihydrite but also significantly influenced its fractionation effect. Within the pH range of 2.0 to 7.0， adsorption capacity increased with rising pH， peaking at pH=7.0 （21.59 mg C/g）， declining at pH > 7.0 due to enhanced electrostatic repulsion. UV-Vis and EEM analysis revealed that within the pH range of 3.0 to 9.0， the selective fractionation of ferrihydrite towards highly aromatic， high-molecular-weight chromophoric DOM （CDOM） components and relatively highly humic， biogenic protein-like/aromatic amino acid fluorescent DOM （FDOM） progressively intensified with the increasing pH. Furthermore， with DOC concentration increasing， adsorption capacity exhibited non-linear growth， higher molecular weight components with low aromaticity and lower molecular weight， alongside FDOM of protein-like/aromatic amino acid with lower humification and stronger autotrophic characteristics， progressively intensified. This study demonstrates that in water bodies dominated by ADOM， such as eutrophic lakes， ferrihydrite can effectively sequester the active components of ADOM through pH-dependent and concentration-dependent selective adsorption， which may potentially have an impact on the composition and reactivity of DOM. This can provide fundamental data for a deeper understanding of the autochthonous carbon sequestration process mediated by iron minerals in eutrophic water bodies.
2026,
44(5):
142-150.
doi: 10.13205/j.hjgc.202605014
Abstract:
Chlorinated aliphatic hydrocarbons （CAHs） are one of the primary contaminants in groundwater at industrial sites in China. A pilot-scale study was conducted at a contaminated site in southwest China to verify the effectiveness of in-situ anaerobic bioremediation for CAHs-contaminated groundwater， using an anaerobic bioaugmentation culture named BS-1. The contaminated groundwater was located in a low-permeability bedrock fracture zone with a depth of up to 40 m. This study involved the injection of carbon sources， nutrients， and dechlorinating bacteria， and lasted for 399 days after the initial injection. First， sodium citrate and emulsified oil as carbon sources， mixed with some nutrients， were injected through injection wells and direct-push injection points to create a favourable geochemical environment for microbial growth. Then， the BS-1 culture， containing the dechlorinating bacteria Dehalococcoides， Desulfitobacterium， and Dehalogenimonas， was injected into the target treatment zone. Following each liquid injection， pressurized nitrogen gas was injected. The results showed that： 1） the injection of liquid amendments followed by gas injection effectively distributed the nutrients and bacteria in the low-permeability aquifer， and the radius of influence zone reached 5.0 m； 2） two types of carbon sources （slow-release and soluble） maintained the groundwater in an anaerobic state over the long term （ORP less than -100 mV） and provided sufficient electron donors for reductive dechlorination by dechlorinating bacteria； 3） emulsified vegetable oil was used as a slow-release carbon source for the growth of anaerobic dechlorinating bacteria and reduced the injection frequency of electron donors； 4） the target CAHs， including vinyl chloride， cis-1，2-dichloroethylene， trichloroethylene， and chloroform， were effectively dechlorinated to innocuous end products by the BS-1 culture， with removal efficiencies exceeding 95%. This study provides a green， economical， and effective solution for the remediation of CAHs-contaminated sites in China. The self-developed bioremediation material and technologies have huge application potential in remediation engineering.
Chlorinated aliphatic hydrocarbons （CAHs） are one of the primary contaminants in groundwater at industrial sites in China. A pilot-scale study was conducted at a contaminated site in southwest China to verify the effectiveness of in-situ anaerobic bioremediation for CAHs-contaminated groundwater， using an anaerobic bioaugmentation culture named BS-1. The contaminated groundwater was located in a low-permeability bedrock fracture zone with a depth of up to 40 m. This study involved the injection of carbon sources， nutrients， and dechlorinating bacteria， and lasted for 399 days after the initial injection. First， sodium citrate and emulsified oil as carbon sources， mixed with some nutrients， were injected through injection wells and direct-push injection points to create a favourable geochemical environment for microbial growth. Then， the BS-1 culture， containing the dechlorinating bacteria Dehalococcoides， Desulfitobacterium， and Dehalogenimonas， was injected into the target treatment zone. Following each liquid injection， pressurized nitrogen gas was injected. The results showed that： 1） the injection of liquid amendments followed by gas injection effectively distributed the nutrients and bacteria in the low-permeability aquifer， and the radius of influence zone reached 5.0 m； 2） two types of carbon sources （slow-release and soluble） maintained the groundwater in an anaerobic state over the long term （ORP less than -100 mV） and provided sufficient electron donors for reductive dechlorination by dechlorinating bacteria； 3） emulsified vegetable oil was used as a slow-release carbon source for the growth of anaerobic dechlorinating bacteria and reduced the injection frequency of electron donors； 4） the target CAHs， including vinyl chloride， cis-1，2-dichloroethylene， trichloroethylene， and chloroform， were effectively dechlorinated to innocuous end products by the BS-1 culture， with removal efficiencies exceeding 95%. This study provides a green， economical， and effective solution for the remediation of CAHs-contaminated sites in China. The self-developed bioremediation material and technologies have huge application potential in remediation engineering.
2026,
44(5):
151-160.
doi: 10.13205/j.hjgc.202605015
Abstract:
In 2023， the National Greenhouse Gas （GHG） Voluntary Emission Reduction Trading Market in China was relaunched， using the China Certified Emission Reduction （CCER） as its trading unit. As an important supplement to the national carbon market， the CCER mechanism aims to further stimulate emission reduction efforts， especially within key sectors such as offshore wind power. This study systematically evaluated the effectiveness of CO2 and major air pollutant emission reductions in China's offshore wind power industry， and examined its economic feasibility within the framework of the CCER policy. Specifically， this research adopted the CCER methodology， utilized both baseline scenario analysis and empirical data from 2020 and projections for 2025， and quantitatively estimated the reduction of CO2 emissions as well as principal air pollutants （including particulate matter， sulfur dioxide， and nitrogen oxides） achieved by the offshore wind sector. The assessment process involved constructing detailed emission inventories for different coastal provinces， applying authoritative grid emission factors， and calculating corresponding emission reductions attributable to offshore wind power expansion. Then， this study comprehensively evaluated the economic viability of the industry by accounting for the levelized cost of electricity （LCOE）， additional revenues generated through CCER transactions， and the external environmental benefits associated with lower pollutant discharge. The analysis further considered the dynamic interplay between market-based carbon pricing and evolving operational costs. The results of this research provide four significant policy insights for the strategic development of China’s offshore wind industry. First， while the sector demonstrated a consistently positive trend in emission reduction performance and economic-environmental contribution， it might face the risk of financial deficits by 2025 in the absence of CCER subsidies. Second， economically developed coastal provinces exhibit greater potential for the development of the offshore wind power industry due to their resource， infrastructure， and policy advantages. Third， profitability analysis for 2020 and 2025 indicates that with appropriate policy support， the offshore wind power sector could achieve sustainable economic returns. Fourth， among various air pollutants， the development of the offshore wind industry results in the largest reduction in nitrogen oxides， while the reduction of sulfur dioxide yield the most significant co-benefits. Overall， this study offers important evidence and actionable policy recommendations for planning and regulating the future growth of China's offshore wind power sector， providing a robust analytical basis for both academic research and practical decision-making.
In 2023， the National Greenhouse Gas （GHG） Voluntary Emission Reduction Trading Market in China was relaunched， using the China Certified Emission Reduction （CCER） as its trading unit. As an important supplement to the national carbon market， the CCER mechanism aims to further stimulate emission reduction efforts， especially within key sectors such as offshore wind power. This study systematically evaluated the effectiveness of CO2 and major air pollutant emission reductions in China's offshore wind power industry， and examined its economic feasibility within the framework of the CCER policy. Specifically， this research adopted the CCER methodology， utilized both baseline scenario analysis and empirical data from 2020 and projections for 2025， and quantitatively estimated the reduction of CO2 emissions as well as principal air pollutants （including particulate matter， sulfur dioxide， and nitrogen oxides） achieved by the offshore wind sector. The assessment process involved constructing detailed emission inventories for different coastal provinces， applying authoritative grid emission factors， and calculating corresponding emission reductions attributable to offshore wind power expansion. Then， this study comprehensively evaluated the economic viability of the industry by accounting for the levelized cost of electricity （LCOE）， additional revenues generated through CCER transactions， and the external environmental benefits associated with lower pollutant discharge. The analysis further considered the dynamic interplay between market-based carbon pricing and evolving operational costs. The results of this research provide four significant policy insights for the strategic development of China’s offshore wind industry. First， while the sector demonstrated a consistently positive trend in emission reduction performance and economic-environmental contribution， it might face the risk of financial deficits by 2025 in the absence of CCER subsidies. Second， economically developed coastal provinces exhibit greater potential for the development of the offshore wind power industry due to their resource， infrastructure， and policy advantages. Third， profitability analysis for 2020 and 2025 indicates that with appropriate policy support， the offshore wind power sector could achieve sustainable economic returns. Fourth， among various air pollutants， the development of the offshore wind industry results in the largest reduction in nitrogen oxides， while the reduction of sulfur dioxide yield the most significant co-benefits. Overall， this study offers important evidence and actionable policy recommendations for planning and regulating the future growth of China's offshore wind power sector， providing a robust analytical basis for both academic research and practical decision-making.
2026,
44(5):
161-170.
doi: 10.13205/j.hjgc.202605016
Abstract:
BiOX （X = Cl， Br， I） photocatalytic materials were prepared by a chemical precipitation method. Their structures and properties were characterized using scanning electron microscopy， X-ray diffraction， X-ray photoelectron spectroscopy， nitrogen adsorption-desorption， and ultraviolet-visible diffuse reflectance spectroscopy. The results showed that BiOBr possesses a flower-like nanomicrosphere structure composed of nanosheets， which gives it a more three-dimensional morphology， a larger specific surface area， and a moderate light absorption range， resulting in superior visible light absorption. Consequently， BiOBr exhibited the best photocatalytic degradation of NO under xenon lamp irradiation. In addition， this study investigated the effects of light intensity， NO flow rate， and oxygen concentration on the NO degradation performance of BiOBr. The experimental results showed that the optimal NO removal rate of 58% was achieved under the conditions of a light source distance of 15 cm， an NO flow rate of 15 mL/min， and in the presence of oxygen. These findings provide an important experimental basis for the application of BiOBr in the photocatalytic degradation of NO.
BiOX （X = Cl， Br， I） photocatalytic materials were prepared by a chemical precipitation method. Their structures and properties were characterized using scanning electron microscopy， X-ray diffraction， X-ray photoelectron spectroscopy， nitrogen adsorption-desorption， and ultraviolet-visible diffuse reflectance spectroscopy. The results showed that BiOBr possesses a flower-like nanomicrosphere structure composed of nanosheets， which gives it a more three-dimensional morphology， a larger specific surface area， and a moderate light absorption range， resulting in superior visible light absorption. Consequently， BiOBr exhibited the best photocatalytic degradation of NO under xenon lamp irradiation. In addition， this study investigated the effects of light intensity， NO flow rate， and oxygen concentration on the NO degradation performance of BiOBr. The experimental results showed that the optimal NO removal rate of 58% was achieved under the conditions of a light source distance of 15 cm， an NO flow rate of 15 mL/min， and in the presence of oxygen. These findings provide an important experimental basis for the application of BiOBr in the photocatalytic degradation of NO.
2026,
44(5):
171-178.
doi: 10.13205/j.hjgc.202605017
Abstract:
In response to the increasingly severe dust pollution control challenges in the current industrial field， this paper innovatively proposed a electrostatic dust collector with magnetic enhancement and wire mesh filtration. By introducing an external magnetic field， this technology physically enhances the traditional electrostatic dedusting process. A systematic comparative analysis was conducted on the variation patterns of discharge characteristics and dust removal efficiency before and after the magnetic field intervention. The experiments investigated the impact of wire mesh structural parameters on dust removal performance， focusing on three core factors： pore sizes of the metal wire mesh （1， 2， 3 mm）， number of stacked wire mesh layers（1， 2， 3）， and the type of composite filtration material coated on the wire mesh surface （polyethylene filter mesh， polyamide mesh）. Concurrently， the effects of airflow velocity （1 to 5 m/s）， inlet flow direction （forward/reverse direction）， and dust type （fly ash， coal combustion dust， cement ash） on the removal efficiency were systematically tested. The experimental results showed that the optimized magnetic field-wire mesh coupling structure could significantly enhance the charging and capture efficiency of fine dust， providing a feasible technical solution for efficient industrial flue gas dedusting.
In response to the increasingly severe dust pollution control challenges in the current industrial field， this paper innovatively proposed a electrostatic dust collector with magnetic enhancement and wire mesh filtration. By introducing an external magnetic field， this technology physically enhances the traditional electrostatic dedusting process. A systematic comparative analysis was conducted on the variation patterns of discharge characteristics and dust removal efficiency before and after the magnetic field intervention. The experiments investigated the impact of wire mesh structural parameters on dust removal performance， focusing on three core factors： pore sizes of the metal wire mesh （1， 2， 3 mm）， number of stacked wire mesh layers（1， 2， 3）， and the type of composite filtration material coated on the wire mesh surface （polyethylene filter mesh， polyamide mesh）. Concurrently， the effects of airflow velocity （1 to 5 m/s）， inlet flow direction （forward/reverse direction）， and dust type （fly ash， coal combustion dust， cement ash） on the removal efficiency were systematically tested. The experimental results showed that the optimized magnetic field-wire mesh coupling structure could significantly enhance the charging and capture efficiency of fine dust， providing a feasible technical solution for efficient industrial flue gas dedusting.
2026,
44(5):
179-184.
doi: 10.13205/j.hjgc.202605018
Abstract:
To address the issue that the existing temporal emission allocation coefficients for oil storage， transportation， and sales sources struggle to adapt to the temperature variation characteristics in regions with distinct four seasons， this study took a large oil depot in Northwest China as the research object. A method for establishing VOCs temporal emission allocation coefficients that accounted for temperature changes was proposed， revealing the dynamic response relationship between VOCs emissions from oil depots and temperature variations. Based on this dynamic emission pattern， the atmospheric environmental protection distance was calculated and compared with that obtained using the traditional method based on constant emission source strength. The findings indicated that the proposed method for calculating time-dependent emission coefficients of VOCs in oil depots considering temperature variations demonstrated distinct patterns across different temperature ranges. A positive correlation was observed between ambient temperature and VOCs emission coefficients in these facilities. The coefficient reached its maximum value of 0.068 when temperatures exceeded 14 ℃， while it dropped to a minimum of 0.007 at temperatures below 8.5 ℃. Notably， daily VOCs emissions from oil storage facilities in summer were significantly higher than those in other seasons， with summer total emissions approximately 8.68 times greater than winter levels—a finding that aligned more closely with local environmental realities. In contrast， the conventional calculation method， which assumes a constant emission source strength， tends to obscure peak simulated concentrations， leading to an underestimation of the atmospheric environmental protection distance. This underestimation poses potential risks to the health and safety of residents near oil depots.
To address the issue that the existing temporal emission allocation coefficients for oil storage， transportation， and sales sources struggle to adapt to the temperature variation characteristics in regions with distinct four seasons， this study took a large oil depot in Northwest China as the research object. A method for establishing VOCs temporal emission allocation coefficients that accounted for temperature changes was proposed， revealing the dynamic response relationship between VOCs emissions from oil depots and temperature variations. Based on this dynamic emission pattern， the atmospheric environmental protection distance was calculated and compared with that obtained using the traditional method based on constant emission source strength. The findings indicated that the proposed method for calculating time-dependent emission coefficients of VOCs in oil depots considering temperature variations demonstrated distinct patterns across different temperature ranges. A positive correlation was observed between ambient temperature and VOCs emission coefficients in these facilities. The coefficient reached its maximum value of 0.068 when temperatures exceeded 14 ℃， while it dropped to a minimum of 0.007 at temperatures below 8.5 ℃. Notably， daily VOCs emissions from oil storage facilities in summer were significantly higher than those in other seasons， with summer total emissions approximately 8.68 times greater than winter levels—a finding that aligned more closely with local environmental realities. In contrast， the conventional calculation method， which assumes a constant emission source strength， tends to obscure peak simulated concentrations， leading to an underestimation of the atmospheric environmental protection distance. This underestimation poses potential risks to the health and safety of residents near oil depots.
2026,
44(5):
185-193.
doi: 10.13205/j.hjgc.202605019
Abstract:
The utilization of food waste as a fermentation substrate can effectively reduce the substrate cost of lactic acid production industrialization， and the synergistic fermentation of leachate could promote the production of lactic acid. However， the effect of magnesium ions in leachate on lactic acid production during fermentation， on metabolic processes， and on key functional bacterial communities remain unclear and require further exploration. This article explored the effect of adding an appropriate amount of magnesium ions on lactic acid fermentation when food waste was used as the substrate. The results showed that the optimal dosage of magnesium ion concentration was 750 mg/L， and the lactate yield and L-lactic acid optical activity respectively reached （37.4±0.5） g COD/L and （96.3±0.9）%. Mechanistic studies revealed that the addition of magnesium ions could accelerate substrate dissolution， significantly enhance the activity of key hydrolytic enzymes （α-glucosidase， amylase， and protease） and L-lactic acid producing enzymes， and increase both the hydrolysis rate and the lactate production rate. Simultaneously， the relative activity of lactate-consuming enzymes decreases， slowing down the rate of lactate consumption. When the magnesium ion dosage was 750 mg/L， the relative abundance of Enterococcus and Streptococcus was 65.0%（2.2 times that of the Blank group） and 18.7% （37.8% of the Bank group）， respectively. But the total relative abundance reached 83.7%， which increased lactate production and L-lactic acid optical activity. Finally， metabolic pathway prediction and functional genes further revealed that the addition of magnesium ions can increase the relative abundance of carbohydrate metabolic pathways and genes encoding lactate dehydrogenase. This study can provide technical support for the resource utilization of food waste.
The utilization of food waste as a fermentation substrate can effectively reduce the substrate cost of lactic acid production industrialization， and the synergistic fermentation of leachate could promote the production of lactic acid. However， the effect of magnesium ions in leachate on lactic acid production during fermentation， on metabolic processes， and on key functional bacterial communities remain unclear and require further exploration. This article explored the effect of adding an appropriate amount of magnesium ions on lactic acid fermentation when food waste was used as the substrate. The results showed that the optimal dosage of magnesium ion concentration was 750 mg/L， and the lactate yield and L-lactic acid optical activity respectively reached （37.4±0.5） g COD/L and （96.3±0.9）%. Mechanistic studies revealed that the addition of magnesium ions could accelerate substrate dissolution， significantly enhance the activity of key hydrolytic enzymes （α-glucosidase， amylase， and protease） and L-lactic acid producing enzymes， and increase both the hydrolysis rate and the lactate production rate. Simultaneously， the relative activity of lactate-consuming enzymes decreases， slowing down the rate of lactate consumption. When the magnesium ion dosage was 750 mg/L， the relative abundance of Enterococcus and Streptococcus was 65.0%（2.2 times that of the Blank group） and 18.7% （37.8% of the Bank group）， respectively. But the total relative abundance reached 83.7%， which increased lactate production and L-lactic acid optical activity. Finally， metabolic pathway prediction and functional genes further revealed that the addition of magnesium ions can increase the relative abundance of carbohydrate metabolic pathways and genes encoding lactate dehydrogenase. This study can provide technical support for the resource utilization of food waste.
2026,
44(5):
194-204.
doi: 10.13205/j.hjgc.202605020
Abstract:
To address the issue of high carbon dioxide （CO2） emission proportion in the industrial sector， distiller's grain waste can be used to prepare biochar， which is then used to adsorb CO2 from industrial flue gas， thereby achieving the goal of carbon emission reduction. Owing to its porous structure， biochar can serve as a solid adsorbent for CO2 capture； however， it still has drawbacks， such as weak pore adsorption capacity and difficulties in achieving selective capture of CO2 from flue gas at high temperatures. To solve the aforementioned problems， in this study， distiller's grain pyrolysis biochar was used as the raw material， and pore-forming of biochar and simultaneous amine loading were carried out through ash self-templating and particle self-assembly methods， resulting in the preparation of amine-functionalized hierarchical porous carbon spheres. The results showed that the amine loading amount in the biochar spheres increased significantly， providing more CO2 adsorption sites， and part of the macroporous structure was retained （the total pore volume after amine loading remained between 0.0030 cm3/g and 0.0066 cm3/g）， which was conducive to improving the morphological stability and CO2 mass transfer rate. In particular， the 0.2PW-K-CNF-PEI carbon sphere exhibited excellent CO2 adsorption capacity （1.03 mmol/g） at 100 ℃， a high CO2 diffusion coefficient （0.0495 min-1）， and superior selective CO2 adsorption capacity （44 mg/g） at 80 ℃. This study provides a solution for the resource utilization of distiller's grain by-products and CO2 capture from low-temperature flue gas.
To address the issue of high carbon dioxide （CO2） emission proportion in the industrial sector， distiller's grain waste can be used to prepare biochar， which is then used to adsorb CO2 from industrial flue gas， thereby achieving the goal of carbon emission reduction. Owing to its porous structure， biochar can serve as a solid adsorbent for CO2 capture； however， it still has drawbacks， such as weak pore adsorption capacity and difficulties in achieving selective capture of CO2 from flue gas at high temperatures. To solve the aforementioned problems， in this study， distiller's grain pyrolysis biochar was used as the raw material， and pore-forming of biochar and simultaneous amine loading were carried out through ash self-templating and particle self-assembly methods， resulting in the preparation of amine-functionalized hierarchical porous carbon spheres. The results showed that the amine loading amount in the biochar spheres increased significantly， providing more CO2 adsorption sites， and part of the macroporous structure was retained （the total pore volume after amine loading remained between 0.0030 cm3/g and 0.0066 cm3/g）， which was conducive to improving the morphological stability and CO2 mass transfer rate. In particular， the 0.2PW-K-CNF-PEI carbon sphere exhibited excellent CO2 adsorption capacity （1.03 mmol/g） at 100 ℃， a high CO2 diffusion coefficient （0.0495 min-1）， and superior selective CO2 adsorption capacity （44 mg/g） at 80 ℃. This study provides a solution for the resource utilization of distiller's grain by-products and CO2 capture from low-temperature flue gas.
2026,
44(5):
205-214.
doi: 10.13205/j.hjgc.202605021
Abstract:
The digestate of anaerobic digestion of food waste can be separated into residues and filtrate. The filtrate still contains a high content of nutrients and carbon， making it a feasible resource for utilization. The pyrolysis of the residues into biochar for secondary use has gained widespread attention. This study prepared biochar from food waste digestate as an electrode active material for the flow-electrode capacitive deionization （FCDI） system， and investigated its nitrogen and phosporus removal performance， with activated carbon as a control group. The results showed that biochar modified with zinc chloride significantly improved its surface area， adsorption properties， capacitance， and resistance. The optimal mass fraction of the modified biochar in the electrode liquid was 7.5%， and the removal efficiencies of NH4+-N and reactive phosphorus （RP） in the simulated digestate were 47.7% and 55.2%， respectively， when the FCDI system ran for 12 h. The results indicated the performances of the FCDI systems with activated carbon， modified biochar in nitrogen and phosphorus removal were evidently better than the system with unmodified biochar. The continuous operation of the FCDI system with digestate filtrate derived from anaerobic digestion of food waste showed the highest removal efficiencies of NH4+-N and RP at 32.2% and 26.2%， respectively， which were poorer than that of the system with simulated digestate filtrate. The undermined performance might be related to the presence of peptides and amino acids in the actual digestate， which were prone to block the ion-exchange membrane channels and increase resistance， subsequently mitigating ion transfer， charge transport， and reducing the deionization performance of the FCDI system.
The digestate of anaerobic digestion of food waste can be separated into residues and filtrate. The filtrate still contains a high content of nutrients and carbon， making it a feasible resource for utilization. The pyrolysis of the residues into biochar for secondary use has gained widespread attention. This study prepared biochar from food waste digestate as an electrode active material for the flow-electrode capacitive deionization （FCDI） system， and investigated its nitrogen and phosporus removal performance， with activated carbon as a control group. The results showed that biochar modified with zinc chloride significantly improved its surface area， adsorption properties， capacitance， and resistance. The optimal mass fraction of the modified biochar in the electrode liquid was 7.5%， and the removal efficiencies of NH4+-N and reactive phosphorus （RP） in the simulated digestate were 47.7% and 55.2%， respectively， when the FCDI system ran for 12 h. The results indicated the performances of the FCDI systems with activated carbon， modified biochar in nitrogen and phosphorus removal were evidently better than the system with unmodified biochar. The continuous operation of the FCDI system with digestate filtrate derived from anaerobic digestion of food waste showed the highest removal efficiencies of NH4+-N and RP at 32.2% and 26.2%， respectively， which were poorer than that of the system with simulated digestate filtrate. The undermined performance might be related to the presence of peptides and amino acids in the actual digestate， which were prone to block the ion-exchange membrane channels and increase resistance， subsequently mitigating ion transfer， charge transport， and reducing the deionization performance of the FCDI system.
2026,
44(5):
215-224.
doi: 10.13205/j.hjgc.202605022
Abstract:
As an alkaline industrial solid waste produced in the process of acetylene production from the chlor-alkali industry， the long-term storage of carbide slag poses serious ecological and environmental risks， which urgently require efficient disposal. In this paper， the technical pathways and application progress of carbon dioxide fixation by carbide slag mineralization are systematically reviewed. Based on the high-active phase characteristics dominated by calcium hydroxide， the reaction mechanisms of gas-solid/liquid-solid direct carbonization and ammonium salt cyclic leaching-carbonation indirect carbonization are elaborated. The mineralization process has been optimized through process parameter regulation， amino acid modification， and multi-solid waste coordination， which significantly improves reaction efficiency and product performance and enables the controllable synthesis of high-value-added calcium carbonate products. The analysis of the environmental and economic benefits of the mineralized products confirms that the technology exhibits good economic feasibility while achieving CO2 fixation. The CO2 mineralization process of carbide slag synchronously achieves the dual goal of solid waste resource utilization and carbon emission reduction. The derived lightweight fillers and low-carbon cementitious materials possess both environmental and economic potential， which provides theoretical and application support for the “waste-to-waste” carbon emission reduction technology system.
As an alkaline industrial solid waste produced in the process of acetylene production from the chlor-alkali industry， the long-term storage of carbide slag poses serious ecological and environmental risks， which urgently require efficient disposal. In this paper， the technical pathways and application progress of carbon dioxide fixation by carbide slag mineralization are systematically reviewed. Based on the high-active phase characteristics dominated by calcium hydroxide， the reaction mechanisms of gas-solid/liquid-solid direct carbonization and ammonium salt cyclic leaching-carbonation indirect carbonization are elaborated. The mineralization process has been optimized through process parameter regulation， amino acid modification， and multi-solid waste coordination， which significantly improves reaction efficiency and product performance and enables the controllable synthesis of high-value-added calcium carbonate products. The analysis of the environmental and economic benefits of the mineralized products confirms that the technology exhibits good economic feasibility while achieving CO2 fixation. The CO2 mineralization process of carbide slag synchronously achieves the dual goal of solid waste resource utilization and carbon emission reduction. The derived lightweight fillers and low-carbon cementitious materials possess both environmental and economic potential， which provides theoretical and application support for the “waste-to-waste” carbon emission reduction technology system.
2026,
44(5):
225-235.
doi: 10.13205/j.hjgc.202605023
Abstract:
Identifying the characteristics of carbon emissions and driving forces of the railway sector is essential for formulating effective measures to develop a green and low-carbon railway industry. It is of great importance for the achievement of national strategic goals such as “a country with strong transportation network” and “carbon peak and carbon neutrality”. This study systematically evaluated the direct and indirect carbon emissions from 2016 to 2021 generated by the railway sector of China， and analyzed the spatiotemporal dynamic changes of the carbon emissions. On this basis， by adopting the LMDI model， the key factors affecting the carbon emissions of railway sector were discerned. Moreover， the variations in the dominant factors of the carbon emissions over time， and the spatial heterogeneities in the dominant factors of the carbon emissions of the 18 railway bureaus， were analyzed. The results show that： 1）During the periods from 2016 to 2021， the carbon emissions of China's railway sector showed an overall upward trend， increasing from 57.7486 million tons to 64.2084 million tons， by 11.2%. The Shanghai Bureau， Beijing Bureau， Zhengzhou Bureau， Chengdu Bureau and Guangzhou Bureau substantially contributed to the increases of railway carbon emissions. In spatial， the carbon emissions of the 18 railway bureaus were characterized by lower emissions in the west and higher emissions in the east， mainly due to the regional differences in the socio-economic development， industrial structure and population density； 2）During 2016 to 2021， the decline in energy consumption intensity reduced the carbon emissions of the railway sector by 18.8654 million tons， while the changes in carbon emission intensity， economic benefits of per unit passenger and freight turnover， and operating capacity led to an increase of a sum of 25.3252 million tons of carbon emissions. When decomposing the contributions of each factor by sub-periods， it can be found that the impacts of these factors on the carbon emissions changed over time. Only the factor of carbon emission intensity showed a promoting effect in all sub-periods， the other three factors， as energy consumption intensity， economic benefits of per unit passenger and freight turnover， and operating capacity， had a conversion between promoting and inhibiting effects in different sub-periods. 3）Due to the differences in regional socio-economic development， population density， industrial structure and energy structure， the dominant influencing factors of carbon emissions of 18 railway bureaus were different. For the railway bureaus with high passenger and freight volume， the increase in operating capacity was the main reason for the increasing carbon emissions. For the railway bureaus with rapid socio-economic development level， the economic benefit of unit passenger and freight turnover was the main factor to promote the increase in carbon emissions. 4）The carbon emissions of railway sector can be reduced by measures of cutting down the empty-loading ratio， optimizing the energy structure， and the differentiation strategy considering the real situation of each railway bureau.
Identifying the characteristics of carbon emissions and driving forces of the railway sector is essential for formulating effective measures to develop a green and low-carbon railway industry. It is of great importance for the achievement of national strategic goals such as “a country with strong transportation network” and “carbon peak and carbon neutrality”. This study systematically evaluated the direct and indirect carbon emissions from 2016 to 2021 generated by the railway sector of China， and analyzed the spatiotemporal dynamic changes of the carbon emissions. On this basis， by adopting the LMDI model， the key factors affecting the carbon emissions of railway sector were discerned. Moreover， the variations in the dominant factors of the carbon emissions over time， and the spatial heterogeneities in the dominant factors of the carbon emissions of the 18 railway bureaus， were analyzed. The results show that： 1）During the periods from 2016 to 2021， the carbon emissions of China's railway sector showed an overall upward trend， increasing from 57.7486 million tons to 64.2084 million tons， by 11.2%. The Shanghai Bureau， Beijing Bureau， Zhengzhou Bureau， Chengdu Bureau and Guangzhou Bureau substantially contributed to the increases of railway carbon emissions. In spatial， the carbon emissions of the 18 railway bureaus were characterized by lower emissions in the west and higher emissions in the east， mainly due to the regional differences in the socio-economic development， industrial structure and population density； 2）During 2016 to 2021， the decline in energy consumption intensity reduced the carbon emissions of the railway sector by 18.8654 million tons， while the changes in carbon emission intensity， economic benefits of per unit passenger and freight turnover， and operating capacity led to an increase of a sum of 25.3252 million tons of carbon emissions. When decomposing the contributions of each factor by sub-periods， it can be found that the impacts of these factors on the carbon emissions changed over time. Only the factor of carbon emission intensity showed a promoting effect in all sub-periods， the other three factors， as energy consumption intensity， economic benefits of per unit passenger and freight turnover， and operating capacity， had a conversion between promoting and inhibiting effects in different sub-periods. 3）Due to the differences in regional socio-economic development， population density， industrial structure and energy structure， the dominant influencing factors of carbon emissions of 18 railway bureaus were different. For the railway bureaus with high passenger and freight volume， the increase in operating capacity was the main reason for the increasing carbon emissions. For the railway bureaus with rapid socio-economic development level， the economic benefit of unit passenger and freight turnover was the main factor to promote the increase in carbon emissions. 4）The carbon emissions of railway sector can be reduced by measures of cutting down the empty-loading ratio， optimizing the energy structure， and the differentiation strategy considering the real situation of each railway bureau.
2026,
44(5):
236-244.
doi: 10.13205/j.hjgc.202605024
Abstract:
The refined quantification of carbon footprint of engineering construction projects serves as a key pillar for formulating targeted carbon reduction strategies and advancing low-carbon development in the industry during the materialization phase. In this study， material flow analysis （MFA） was integrated with the emission factor method to establish a panoramic carbon flow model for engineering projects. Construction activities were categorized into two types： processing and construction， and office and daily operations. The material flow and carbon flow relationships within the defined system boundary and with external systems were clarified， and an empirical analysis was conducted using the Hejiawan Bridge of Section 11 of the Xiyu High-Speed Railway as the case. The results demonstrate that the total carbon flow of the Hejiawan Bridge amounts to 27，482，432.11 kg CO2eq， of which direct carbon flow （including fuel oil， gasoline， etc.） accounts for 7.6%， and indirect carbon flow （including products， transportation， electricity consumption， etc.） accounts for 92.4%. From the perspective of material flow， the total carbon flow is composed of five categories： product carbon flow （72.88%）， resource and energy carbon flow （25.73%）， transportation carbon flow （1.04%）， waste carbon flow （0.35%）， and service carbon flow （0.01%）. In terms of the scope of carbon emission activities， carbon flow associated with construction accounts for 99.17%， while that related to office and daily operations accounts for 0.46%. Two indicators， namely material consumption carbon flow rate and energy consumption carbon flow rate， were proposed for the first time for the carbon flow assessment of bridge construction. A comparative analysis was performed on five girder bridges. The results indicate that the material consumption carbon flow rate of the Hejiawan Bridge is 3.91 kg CO2eq/kg， ranking the highest among bridges of the same type， while its energy consumption carbon flow rate is 13.40 kg CO2eq/kg ec， which falls at a medium level. The assessment reveals that the material consumption of the bridge is relatively high. Carbon reduction potential can be explored and targeted emission reduction pathways can be designed by considering factors such as the bridge structure and construction geological conditions.
The refined quantification of carbon footprint of engineering construction projects serves as a key pillar for formulating targeted carbon reduction strategies and advancing low-carbon development in the industry during the materialization phase. In this study， material flow analysis （MFA） was integrated with the emission factor method to establish a panoramic carbon flow model for engineering projects. Construction activities were categorized into two types： processing and construction， and office and daily operations. The material flow and carbon flow relationships within the defined system boundary and with external systems were clarified， and an empirical analysis was conducted using the Hejiawan Bridge of Section 11 of the Xiyu High-Speed Railway as the case. The results demonstrate that the total carbon flow of the Hejiawan Bridge amounts to 27，482，432.11 kg CO2eq， of which direct carbon flow （including fuel oil， gasoline， etc.） accounts for 7.6%， and indirect carbon flow （including products， transportation， electricity consumption， etc.） accounts for 92.4%. From the perspective of material flow， the total carbon flow is composed of five categories： product carbon flow （72.88%）， resource and energy carbon flow （25.73%）， transportation carbon flow （1.04%）， waste carbon flow （0.35%）， and service carbon flow （0.01%）. In terms of the scope of carbon emission activities， carbon flow associated with construction accounts for 99.17%， while that related to office and daily operations accounts for 0.46%. Two indicators， namely material consumption carbon flow rate and energy consumption carbon flow rate， were proposed for the first time for the carbon flow assessment of bridge construction. A comparative analysis was performed on five girder bridges. The results indicate that the material consumption carbon flow rate of the Hejiawan Bridge is 3.91 kg CO2eq/kg， ranking the highest among bridges of the same type， while its energy consumption carbon flow rate is 13.40 kg CO2eq/kg ec， which falls at a medium level. The assessment reveals that the material consumption of the bridge is relatively high. Carbon reduction potential can be explored and targeted emission reduction pathways can be designed by considering factors such as the bridge structure and construction geological conditions.
