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2025 Vol. 43, No. 2
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2025, 43(2): 1-10.
doi: 10.13205/j.hjgc.202502001
Abstract:
Currently, the removal efficiency of pollutants in urban and rural water bodies by small-scale wetlands, as well as the influencing factors, remains poorly understood. This study investigated the small-scale wetland network in Liangping, Chongqing to evaluate the efficiency of small-scale wetlands in removing total nitrogen (TN) and total phosphorus (TP) from urban and rural water bodies. Additionally, it explored the effects of topography and hydrology on the nutrient removal process. The results revealed that small-scale wetlands achieved average removal efficiencies of 46.86% for TN and 85.93% for TP. In rural areas, the TN removal efficiency was significantly higher than in urban areas (56.95% vs. 45.19%; P<0.05), while the TP removal efficiency was lower in rural wetlands compared to urban wetlands (68.04% vs. 92.94%; P<0.05). Interestingly, a distinct hump-shaped relationship was observed between nutrient removal efficiency and surface elevation, suggesting an optimal elevation range for wetland performance. Moreover, the interaction between water flow rate and topographic elevation had a significantly positive effect on nutrient removal, outperforming the influence of individual factors. The importance of this study extends beyond its specific findings, as small-scale wetlands represent a critical yet often underutilized tool in sustainable water management. These ecosystems, including micro-drainage systems, ornamental ponds, mixed channels (rivers and sewers), agricultural lands (paddy fields and dryland soil), and small lakes, play an essential role in mitigating non-point source pollution. However, their small size and fragmented nature often result in their being overlooked in larger-scale water management strategies. Research into small-scale wetlands is vital for several reasons. First, they are uniquely positioned to address the challenges of nutrient runoff, particularly in densely populated or agriculturally intensive regions where traditional methods may be insufficient. Secondly, they provide numerous co-benefits, such as habitat provision for wildlife, flood mitigation, and carbon sequestration, enhancing the overall ecological resilience of urban and rural landscapes. Thirdly, these wetlands offer a scalable and cost-effective solution for areas with limited resources or space for large-scale interventions. This study underscores the need to integrate small-scale wetlands into urban and rural planning frameworks. By designing cascading wetland systems based on topographical and hydrological insights, it is possible to optimize nutrient removal processes while preserving the multifunctional benefits of these ecosystems. Future research should be focused on refining our understanding of the mechanisms driving nutrient removal, evaluating the long-term sustainability of such systems, and exploring innovative designs to maximize their ecological and economic values. The findings highlight the strategic importance of protecting and restoring small-scale wetlands as a cornerstone of water quality management and environmental conservation efforts.
Currently, the removal efficiency of pollutants in urban and rural water bodies by small-scale wetlands, as well as the influencing factors, remains poorly understood. This study investigated the small-scale wetland network in Liangping, Chongqing to evaluate the efficiency of small-scale wetlands in removing total nitrogen (TN) and total phosphorus (TP) from urban and rural water bodies. Additionally, it explored the effects of topography and hydrology on the nutrient removal process. The results revealed that small-scale wetlands achieved average removal efficiencies of 46.86% for TN and 85.93% for TP. In rural areas, the TN removal efficiency was significantly higher than in urban areas (56.95% vs. 45.19%; P<0.05), while the TP removal efficiency was lower in rural wetlands compared to urban wetlands (68.04% vs. 92.94%; P<0.05). Interestingly, a distinct hump-shaped relationship was observed between nutrient removal efficiency and surface elevation, suggesting an optimal elevation range for wetland performance. Moreover, the interaction between water flow rate and topographic elevation had a significantly positive effect on nutrient removal, outperforming the influence of individual factors. The importance of this study extends beyond its specific findings, as small-scale wetlands represent a critical yet often underutilized tool in sustainable water management. These ecosystems, including micro-drainage systems, ornamental ponds, mixed channels (rivers and sewers), agricultural lands (paddy fields and dryland soil), and small lakes, play an essential role in mitigating non-point source pollution. However, their small size and fragmented nature often result in their being overlooked in larger-scale water management strategies. Research into small-scale wetlands is vital for several reasons. First, they are uniquely positioned to address the challenges of nutrient runoff, particularly in densely populated or agriculturally intensive regions where traditional methods may be insufficient. Secondly, they provide numerous co-benefits, such as habitat provision for wildlife, flood mitigation, and carbon sequestration, enhancing the overall ecological resilience of urban and rural landscapes. Thirdly, these wetlands offer a scalable and cost-effective solution for areas with limited resources or space for large-scale interventions. This study underscores the need to integrate small-scale wetlands into urban and rural planning frameworks. By designing cascading wetland systems based on topographical and hydrological insights, it is possible to optimize nutrient removal processes while preserving the multifunctional benefits of these ecosystems. Future research should be focused on refining our understanding of the mechanisms driving nutrient removal, evaluating the long-term sustainability of such systems, and exploring innovative designs to maximize their ecological and economic values. The findings highlight the strategic importance of protecting and restoring small-scale wetlands as a cornerstone of water quality management and environmental conservation efforts.
2025, 43(2): 11-20.
doi: 10.13205/j.hjgc.202502002
Abstract:
Understanding the spatial variation of inorganic nitrogen (DIN) and its driving factors in urban small water bodies is helpful for the scientific development of urban small water pollution prevention and control programs. Taking Changsha as the research area, DIN content in 68 small water bodies was randomly sampled and monitored, and spatial differentiation of NH4+-N, NO3--N and DIN content and its influencing factors in small water bodies were discussed. Three circles were divided by their distance from the urban center as ＜5 km, 5 km to 10 km, and ＞10 km. The results showed that the DIN content of small water bodies in the study area had great variability (with a CV value up to 178.42%), and 7.35% were in NH4+-N pollution state. The average NH4+-N, NO3--N and DIN contents in small water bodies in the >10 km circle was higher than those in the <5 km, and 5 km to 10 km circles, which indicated that the NH4+-N, NO3--N and DIN content of small water bodies increased with distance from the urban center. The average NH4+-N and DIN content of small aquaculture water in the suburban area was higher than that of ecological protection, ecological restoration and ecological degradation in the urban center. Further analysis of hierarchical variance decomposition showed that the total contributions of the circle layer and water management mode to the variance variation of NH4+-N, NO3--N and DIN were 59.5%, 49.2% and 68.5%, respectively, which further confirmed that the distance to the urban center and water management mode were the main factors affecting the variation of DIN component content in the study area. Moreover, the urban development trend and the implementation of water environment management measures were not coordinated, and small water bodies were possessing the risk of transferring from urban areas to suburban areas, and it was necessary to further strengthen the overall coordination and planning for risk control.
Understanding the spatial variation of inorganic nitrogen (DIN) and its driving factors in urban small water bodies is helpful for the scientific development of urban small water pollution prevention and control programs. Taking Changsha as the research area, DIN content in 68 small water bodies was randomly sampled and monitored, and spatial differentiation of NH4+-N, NO3--N and DIN content and its influencing factors in small water bodies were discussed. Three circles were divided by their distance from the urban center as ＜5 km, 5 km to 10 km, and ＞10 km. The results showed that the DIN content of small water bodies in the study area had great variability (with a CV value up to 178.42%), and 7.35% were in NH4+-N pollution state. The average NH4+-N, NO3--N and DIN contents in small water bodies in the >10 km circle was higher than those in the <5 km, and 5 km to 10 km circles, which indicated that the NH4+-N, NO3--N and DIN content of small water bodies increased with distance from the urban center. The average NH4+-N and DIN content of small aquaculture water in the suburban area was higher than that of ecological protection, ecological restoration and ecological degradation in the urban center. Further analysis of hierarchical variance decomposition showed that the total contributions of the circle layer and water management mode to the variance variation of NH4+-N, NO3--N and DIN were 59.5%, 49.2% and 68.5%, respectively, which further confirmed that the distance to the urban center and water management mode were the main factors affecting the variation of DIN component content in the study area. Moreover, the urban development trend and the implementation of water environment management measures were not coordinated, and small water bodies were possessing the risk of transferring from urban areas to suburban areas, and it was necessary to further strengthen the overall coordination and planning for risk control.
2025, 43(2): 21-30.
doi: 10.13205/j.hjgc.202502003
Abstract:
Improving urban river water quality is fraught with challenges, such as poor water flow and complex pollution sources, making it a significant difficulty in current water environment enhancement efforts. To achieve a nuanced analysis of the causes of urban river pollution and ensure the precision and reliability of remediation strategies, this study focused on a typical urban river in Ningbo City. Employing three-dimensional fluorescence-parallel factor analysis (EEM-PARAFAC) to examine the composition characteristics of dissolved organic matter (DOM) in the water, this research investigated the seasonal variations in urban river pollution and the rapid source-tracing mechanisms under complex pollution conditions. The findings revealed that the river exhibited high nutrient pollution, with average concentrations of ammonia nitrogen, total nitrogen, and total phosphorus at (2.53±1.16), (6.17±1.57), and (0.40±0.15) mg/L, respectively. During the dry season, the average nutrient concentrations in the water were 1.44 to 1.72 times higher than those in the wet season. Indicators of DOM humification degree, HIX, and SUVA254, suggested a significant accumulation of autochthonous pollutants in the water during the dry season. The correlation between nutrient salts concentrations and protein-like fluorescent components (r=0.07, P > 0.05) was much lower than that with humic-like fluorescent components (r=0.58, P<0.001). This indicated that agricultural non-point source pollution was significantly higher than the impact of domestic sewage, closely linked to the ongoing implementation of sewage interception measures in recent years. Moreover, by comparing the spatial and temporal distribution differences of major pollutants and EEM-PARAFAC fluorescent components, it was confirmed that the abnormal increase in nitrogen and phosphorus concentrations in the upstream river section was directly related to the discharge of farmland tailwater, eliminating the possibility of domestic sewage influencing the downstream residential river section. This underscored the importance of DOM spectral data in assisting the determination of pollution causes. Given the extensive pollution source information contained in DOM spectral data and its straightforward testing process, the research can provide substantial support for improving the water quality of urban rivers in China.
Improving urban river water quality is fraught with challenges, such as poor water flow and complex pollution sources, making it a significant difficulty in current water environment enhancement efforts. To achieve a nuanced analysis of the causes of urban river pollution and ensure the precision and reliability of remediation strategies, this study focused on a typical urban river in Ningbo City. Employing three-dimensional fluorescence-parallel factor analysis (EEM-PARAFAC) to examine the composition characteristics of dissolved organic matter (DOM) in the water, this research investigated the seasonal variations in urban river pollution and the rapid source-tracing mechanisms under complex pollution conditions. The findings revealed that the river exhibited high nutrient pollution, with average concentrations of ammonia nitrogen, total nitrogen, and total phosphorus at (2.53±1.16), (6.17±1.57), and (0.40±0.15) mg/L, respectively. During the dry season, the average nutrient concentrations in the water were 1.44 to 1.72 times higher than those in the wet season. Indicators of DOM humification degree, HIX, and SUVA254, suggested a significant accumulation of autochthonous pollutants in the water during the dry season. The correlation between nutrient salts concentrations and protein-like fluorescent components (r=0.07, P > 0.05) was much lower than that with humic-like fluorescent components (r=0.58, P<0.001). This indicated that agricultural non-point source pollution was significantly higher than the impact of domestic sewage, closely linked to the ongoing implementation of sewage interception measures in recent years. Moreover, by comparing the spatial and temporal distribution differences of major pollutants and EEM-PARAFAC fluorescent components, it was confirmed that the abnormal increase in nitrogen and phosphorus concentrations in the upstream river section was directly related to the discharge of farmland tailwater, eliminating the possibility of domestic sewage influencing the downstream residential river section. This underscored the importance of DOM spectral data in assisting the determination of pollution causes. Given the extensive pollution source information contained in DOM spectral data and its straightforward testing process, the research can provide substantial support for improving the water quality of urban rivers in China.
2025, 43(2): 31-38.
doi: 10.13205/j.hjgc.202502004
Abstract:
Temperature tracing is a widely used method for determining pore water velocity in sediments, based on the thermal diffusion equation. This technique is valuable for understanding fluid dynamics in subsurface environments. However, in practice, the phenomenon of free convection and its associated effects are often overlooked. The assumption that free convection can be ignored is not always justified, and the implications of this assumption have not been thoroughly discussed in the literature. This oversight can lead to inaccuracies in the results obtained from temperature tracing methods. In this paper, a sandbox device was designed to simulate free convection in the sediment-water system to address this issue. This experimental setup provided a controlled environment where the effects of free convection can be systematically observed and quantified. A one-dimensional heat transfer model was developed using the R Language Program to explore the necessity of incorporating free convection effects in application of temperature tracing. This model offered a robust framework for simulating and analyzing heat transfer processes. In the study, the impact of free convection was quantified by introducing an additional thermal diffusion coefficient. This coefficient accounted for the enhanced heat transfer due to the buoyancy-driven movement of fluids. The primary focus was to assess how neglecting free convection affects the inversion results, particularly the velocity estimates. This was done through a detailed parameter sensitivity analysis, which helps understand how variations in model parameters influence the output. The findings revealed that the additional thermal diffusion coefficient can be 1 to 6 times greater than the inherent thermal diffusion coefficient of the saturated water filling material. This indicated a significant potential impact of free convection on temperature tracing results. The sensitivity analysis showed that a 55% deviation in the thermal diffusion coefficient could lead to a 13% error in velocity estimation. Disregarding free convection caused a maximum deviation of 0.012 cm/min in the inversion velocity results, which significantly affected the calculation of heat and pollutant exchange fluxes between sediment and water. Therefore, it is recommended to evaluate the influence of free convection on inversion results before applying the temperature tracing method. This evaluation can be conducted through experimental observation and computational modeling. Based on this assessment, researchers can decide whether to incorporate free convection effects into the heat transfer mechanism. By doing so, they can enhance the accuracy and reliability of the temperature tracing method, providing a more comprehensive understanding of fluid dynamics in sedimentary environments. This approach will lead to better-informed decisions in environmental management and engineering projects.
Temperature tracing is a widely used method for determining pore water velocity in sediments, based on the thermal diffusion equation. This technique is valuable for understanding fluid dynamics in subsurface environments. However, in practice, the phenomenon of free convection and its associated effects are often overlooked. The assumption that free convection can be ignored is not always justified, and the implications of this assumption have not been thoroughly discussed in the literature. This oversight can lead to inaccuracies in the results obtained from temperature tracing methods. In this paper, a sandbox device was designed to simulate free convection in the sediment-water system to address this issue. This experimental setup provided a controlled environment where the effects of free convection can be systematically observed and quantified. A one-dimensional heat transfer model was developed using the R Language Program to explore the necessity of incorporating free convection effects in application of temperature tracing. This model offered a robust framework for simulating and analyzing heat transfer processes. In the study, the impact of free convection was quantified by introducing an additional thermal diffusion coefficient. This coefficient accounted for the enhanced heat transfer due to the buoyancy-driven movement of fluids. The primary focus was to assess how neglecting free convection affects the inversion results, particularly the velocity estimates. This was done through a detailed parameter sensitivity analysis, which helps understand how variations in model parameters influence the output. The findings revealed that the additional thermal diffusion coefficient can be 1 to 6 times greater than the inherent thermal diffusion coefficient of the saturated water filling material. This indicated a significant potential impact of free convection on temperature tracing results. The sensitivity analysis showed that a 55% deviation in the thermal diffusion coefficient could lead to a 13% error in velocity estimation. Disregarding free convection caused a maximum deviation of 0.012 cm/min in the inversion velocity results, which significantly affected the calculation of heat and pollutant exchange fluxes between sediment and water. Therefore, it is recommended to evaluate the influence of free convection on inversion results before applying the temperature tracing method. This evaluation can be conducted through experimental observation and computational modeling. Based on this assessment, researchers can decide whether to incorporate free convection effects into the heat transfer mechanism. By doing so, they can enhance the accuracy and reliability of the temperature tracing method, providing a more comprehensive understanding of fluid dynamics in sedimentary environments. This approach will lead to better-informed decisions in environmental management and engineering projects.
2025, 43(2): 39-46.
doi: 10.13205/j.hjgc.202502005
Abstract:
Microorganisms play a crucial role in the water purification process of constructed wetlands. In surface flow constructed wetlands, a large number of microorganisms are attached to the stems of emergent plants, which are closely related to wastewater treatment performance. However, research on the microorganisms on plant stems is still limited. This study established two surface flow constructed wetland systems composed of different plant mixtures (Iris pseudacorus + Canna indica, calamus + Cyperus alternifolius) and one surface flow constructed wetland composed of a single plant species(schoenoplectus), to investigate their nitrogen removal effects from wastewater. By examining the microbial diversity and community structure on the stems of four common wetland plants (Schoenoplectus, calamus, Canna and Cyperus alternifolius), the study analyzed the specificity of microbial communities on different wetland plants and clarified the microbial mechanisms of nitrogen removal in conjunction with the heterotrophic performance tests of plant stems. Results indicated that stem-associated microorganisms contributed approximately 0.25 to 0.6 mg/g fresh weight to the removal of nitrate nitrogen. Schoenoplectus exhibited the best removal efficiency for both ammonia and nitrate nitrogen, with its stem microorganisms contributing 0.58 mg/g, and its microbial community showing higher diversity and abundance than the other plants. From an overall pollutants removal perspective, the combination of Iris pseudacorus and Canna indica was identified as the optimal treatment combination, achieving an ammonia nitrogen removal rate of 83.8% and a total nitrogen removal rate of 51.9%. The predominant microbial communities present in the system were similar, including Pseudomonas, Chryseobacterium, Comamonas, Glutamicibacter, and Aeromonas. These microorganisms synergistically promoted the water purification function of the constructed wetland system. The contribution of stem microorganisms to the nitrate nitrogen removal in surface flow constructed wetlands was approximately 0.2 to 1.0 mg/g fresh weight, and reached its maximum value when the retention time was 70 hours.
Microorganisms play a crucial role in the water purification process of constructed wetlands. In surface flow constructed wetlands, a large number of microorganisms are attached to the stems of emergent plants, which are closely related to wastewater treatment performance. However, research on the microorganisms on plant stems is still limited. This study established two surface flow constructed wetland systems composed of different plant mixtures (Iris pseudacorus + Canna indica, calamus + Cyperus alternifolius) and one surface flow constructed wetland composed of a single plant species(schoenoplectus), to investigate their nitrogen removal effects from wastewater. By examining the microbial diversity and community structure on the stems of four common wetland plants (Schoenoplectus, calamus, Canna and Cyperus alternifolius), the study analyzed the specificity of microbial communities on different wetland plants and clarified the microbial mechanisms of nitrogen removal in conjunction with the heterotrophic performance tests of plant stems. Results indicated that stem-associated microorganisms contributed approximately 0.25 to 0.6 mg/g fresh weight to the removal of nitrate nitrogen. Schoenoplectus exhibited the best removal efficiency for both ammonia and nitrate nitrogen, with its stem microorganisms contributing 0.58 mg/g, and its microbial community showing higher diversity and abundance than the other plants. From an overall pollutants removal perspective, the combination of Iris pseudacorus and Canna indica was identified as the optimal treatment combination, achieving an ammonia nitrogen removal rate of 83.8% and a total nitrogen removal rate of 51.9%. The predominant microbial communities present in the system were similar, including Pseudomonas, Chryseobacterium, Comamonas, Glutamicibacter, and Aeromonas. These microorganisms synergistically promoted the water purification function of the constructed wetland system. The contribution of stem microorganisms to the nitrate nitrogen removal in surface flow constructed wetlands was approximately 0.2 to 1.0 mg/g fresh weight, and reached its maximum value when the retention time was 70 hours.
2025, 43(2): 47-61.
doi: 10.13205/j.hjgc.202502006
Abstract:
The sewage treatment and reuse situation, and water reuse potential in 9 provinces (autonomous regions, municipalities) and 51 selected cities in the upper reaches of the Yangtze River Basin were systematically analyzed. The reclaimed water utilization policy, planning, and upgrading plan of typical areas in the upper reaches of the Yangtze River, were discussed, taking Luzhou City, Sichuan Province as an example. In 2021, the total amount of reclaimed water used by the 51 selected cities in the upper reaches of the Yangtze River Basin was 1.01 billion m3, and it was estimated that there will be a potential growth of 0.67 billion to 1.34 billion m3 per year in the future. There were significant differences in reclaimed water reuse quantity and rate among the selected cities in the upper reaches of the Yangtze River Basin. The water reuse rates of 28 upstream cities of the Yangtze River Basin were less than 25%, and obviously there is huge room for improvement. Through the analysis of the pricing strategy of reclaimed water in Luzhou City, the discussion on the operation mode of sewage treatment and reuse, and the analysis of relevant policies, the objective based analysis and process planning of the policy formulation of reclaimed water use was proposed, to further standardize and improve the utilization rate. In general, the policy formulation of reclaimed water utilization proposed in this paper is not only applicable to Luzhou City, but also provides a useful reference for other important cities in the upper reaches of the Yangtze River. Through scientific and reasonable pricing mechanism, flexible and diversified operation mode and systematic policy guarantee, it can effectively improve the utilization efficiency of reclaimed water, and promote the sustainable development of regional water resources, and contribute to the realization of the goal of ecological civilization construction.
The sewage treatment and reuse situation, and water reuse potential in 9 provinces (autonomous regions, municipalities) and 51 selected cities in the upper reaches of the Yangtze River Basin were systematically analyzed. The reclaimed water utilization policy, planning, and upgrading plan of typical areas in the upper reaches of the Yangtze River, were discussed, taking Luzhou City, Sichuan Province as an example. In 2021, the total amount of reclaimed water used by the 51 selected cities in the upper reaches of the Yangtze River Basin was 1.01 billion m3, and it was estimated that there will be a potential growth of 0.67 billion to 1.34 billion m3 per year in the future. There were significant differences in reclaimed water reuse quantity and rate among the selected cities in the upper reaches of the Yangtze River Basin. The water reuse rates of 28 upstream cities of the Yangtze River Basin were less than 25%, and obviously there is huge room for improvement. Through the analysis of the pricing strategy of reclaimed water in Luzhou City, the discussion on the operation mode of sewage treatment and reuse, and the analysis of relevant policies, the objective based analysis and process planning of the policy formulation of reclaimed water use was proposed, to further standardize and improve the utilization rate. In general, the policy formulation of reclaimed water utilization proposed in this paper is not only applicable to Luzhou City, but also provides a useful reference for other important cities in the upper reaches of the Yangtze River. Through scientific and reasonable pricing mechanism, flexible and diversified operation mode and systematic policy guarantee, it can effectively improve the utilization efficiency of reclaimed water, and promote the sustainable development of regional water resources, and contribute to the realization of the goal of ecological civilization construction.
2025, 43(2): 62-73.
doi: 10.13205/j.hjgc.202502007
Abstract:
It is significant for sponge city construction to predict the pollution of initial rainwater runoff in line with regional and precipitation characteristics. In this paper, a vast amount of extensive and long-term data concerning various aspects such as urban characteristics, precipitation features, the nature and properties of underlying surfaces, and the quality of initial rainwater were meticulously collected. Thirteen typical cities located in the Yangtze River Basin were clustered and grouped based on their complex degrees of similarity and dissimilarity. The rationality and validity of the clustering results were carefully verified and authenticated through principal coordinate analysis. Subsequently, the statistical characteristics of the pollution of initial rainwater runoff in different types of cities were thoroughly investigated and explored, and the underlying and influential driving factors were dissected and analyzed in detail. This involved not only a comprehensive examination of the correlation between different variables but also an exploration of the potential mechanisms. Eventually, a highly sophisticated random forest regression model specifically designed for predicting the pollution of initial rainwater runoff was established and then validated and verified with the measured data obtained from Nanjing. The results and findings indicated that the cities in the Yangtze River Basin can be effectively categorized into three distinct types according to terrain, climate, economy and the specific situation of initial rainwater pollution. Annual precipitation, single precipitation, average rainfall intensity, dry period duration before rainfall and impermeability degree of underlying surfaces are the principal factors on pollutants concentration in initial rainwater runoff. The fitting R-squared values of the random forest regression model were all greater than 0.68, and the errors between the measured values in Nanjing and the predicted results of the random forest were all within 15%, which convincingly demonstrated that the predicted results are relatively accurate and reliable. This research made full use of the data on regional and precipitation characteristics in specific areas to establish a machine-learning prediction model, thereby presenting a novel approach for predicting the pollution of initial rainwater surface runoff in different types of cities in the Yangtze River Basin. Moreover, it may inspire more studies on the relationship between urban characteristics, precipitation and the pollution of initial rainwater runoff in urban areas.
It is significant for sponge city construction to predict the pollution of initial rainwater runoff in line with regional and precipitation characteristics. In this paper, a vast amount of extensive and long-term data concerning various aspects such as urban characteristics, precipitation features, the nature and properties of underlying surfaces, and the quality of initial rainwater were meticulously collected. Thirteen typical cities located in the Yangtze River Basin were clustered and grouped based on their complex degrees of similarity and dissimilarity. The rationality and validity of the clustering results were carefully verified and authenticated through principal coordinate analysis. Subsequently, the statistical characteristics of the pollution of initial rainwater runoff in different types of cities were thoroughly investigated and explored, and the underlying and influential driving factors were dissected and analyzed in detail. This involved not only a comprehensive examination of the correlation between different variables but also an exploration of the potential mechanisms. Eventually, a highly sophisticated random forest regression model specifically designed for predicting the pollution of initial rainwater runoff was established and then validated and verified with the measured data obtained from Nanjing. The results and findings indicated that the cities in the Yangtze River Basin can be effectively categorized into three distinct types according to terrain, climate, economy and the specific situation of initial rainwater pollution. Annual precipitation, single precipitation, average rainfall intensity, dry period duration before rainfall and impermeability degree of underlying surfaces are the principal factors on pollutants concentration in initial rainwater runoff. The fitting R-squared values of the random forest regression model were all greater than 0.68, and the errors between the measured values in Nanjing and the predicted results of the random forest were all within 15%, which convincingly demonstrated that the predicted results are relatively accurate and reliable. This research made full use of the data on regional and precipitation characteristics in specific areas to establish a machine-learning prediction model, thereby presenting a novel approach for predicting the pollution of initial rainwater surface runoff in different types of cities in the Yangtze River Basin. Moreover, it may inspire more studies on the relationship between urban characteristics, precipitation and the pollution of initial rainwater runoff in urban areas.
2025, 43(2): 74-86.
doi: 10.13205/j.hjgc.202502008
Abstract:
To reveal the spatiotemporal evolution characteristics and influencing factors of surface water quality in the Niulan River Basin (Kunming section), this study evaluated the water quality during wet and dry seasons at 15 monitoring sites using the single-factor assessment method. Optimal parameters-based geographical detector analysis was employed to investigate the impacts of natural and anthropogenic factors on water quality at sub-watershed and riparian zone scales. The results demonstrated significant spatiotemporal heterogeneity in water quality, with total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD), and ammonia nitrogen (NH3-N) identified as primary pollutants. During the dry season, 13%, 20%, and 53% of sampling sites exceeded Class III limiting values of Surface Water Environmental Quality Standard (GB 3838—2002) for COD, NH3-N, and TP respectively, while these exceedance rates significantly increased to 53%, 40%, and 67% in the rainy season. Spatiotemporal analysis revealed poorer water quality during rainy seasons, with Class Ⅲ-exceeding sections predominantly distributed in upstream areas and tributaries, particularly showing severe TP contamination. Geographical detector analysis indicated that water quality variations resulted from multi-scale interactions between natural and anthropogenic factors. Anthropogenic factors (particularly road density and population density) dominated at sub-watershed scales, while natural factors (vegetation cover types and topographic features) exhibited enhanced pollutant interception effects at riparian zone scales. Factor interactions generally demonstrated dual-factor enhancement effects. Notably, certain factors showed threshold-specific impacts on water quality parameters, as exemplified by TP exceedances corresponding to specific ranges or types of influencing factors. The study recommends implementing comprehensive water pollution control strategies across spatial-temporal scales, incorporating factor-specific carrying capacity assessments tailored to basin characteristics.
To reveal the spatiotemporal evolution characteristics and influencing factors of surface water quality in the Niulan River Basin (Kunming section), this study evaluated the water quality during wet and dry seasons at 15 monitoring sites using the single-factor assessment method. Optimal parameters-based geographical detector analysis was employed to investigate the impacts of natural and anthropogenic factors on water quality at sub-watershed and riparian zone scales. The results demonstrated significant spatiotemporal heterogeneity in water quality, with total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD), and ammonia nitrogen (NH3-N) identified as primary pollutants. During the dry season, 13%, 20%, and 53% of sampling sites exceeded Class III limiting values of Surface Water Environmental Quality Standard (GB 3838—2002) for COD, NH3-N, and TP respectively, while these exceedance rates significantly increased to 53%, 40%, and 67% in the rainy season. Spatiotemporal analysis revealed poorer water quality during rainy seasons, with Class Ⅲ-exceeding sections predominantly distributed in upstream areas and tributaries, particularly showing severe TP contamination. Geographical detector analysis indicated that water quality variations resulted from multi-scale interactions between natural and anthropogenic factors. Anthropogenic factors (particularly road density and population density) dominated at sub-watershed scales, while natural factors (vegetation cover types and topographic features) exhibited enhanced pollutant interception effects at riparian zone scales. Factor interactions generally demonstrated dual-factor enhancement effects. Notably, certain factors showed threshold-specific impacts on water quality parameters, as exemplified by TP exceedances corresponding to specific ranges or types of influencing factors. The study recommends implementing comprehensive water pollution control strategies across spatial-temporal scales, incorporating factor-specific carrying capacity assessments tailored to basin characteristics.
2025, 43(2): 87-95.
doi: 10.13205/j.hjgc.202502009
Abstract:
The Yongding River is one of the main water sources in the Beijing Tianjin Hebei Region. Understanding the hydrochemical characteristics and ion sources of the Yongding River basin is of great significance for water resource management and social development in the Beijing Tianjin Hebei Region. This study comprehensively utilized the mass balance method and ion ratio method to analyze the hydrochemical characteristics and main ion sources in the mainstream and tributaries from the Guanting Reservoir to the mouth of the Yongding River. The results indicated that the main hydrochemical types of the Yongding River in spring were SO4·Cl-Na and HCO3-Ca. The river water was slightly alkaline, with high values of EC and TDS, and the average values of tributaries were higher than those of the mainstream. The spatial variation of ions’ concentration in river water was significant, and the concentrations of Na+、K+、Cl-、NO3- in the mainstream of Yongding River showed an upward trend from upstream to downstream, with the highest mean value in the Coastal Plain Section(CPS) in the river. The sources of river water ions in various locations were mainly controlled by atmospheric precipitation (2.19% to 11.38%), human activities (0.06% to 50.69%), evaporite dissolution (6.47% to 52.13%), silicate rock weathering (5.74% to 71.23%), and carbonate rock weathering (0.24% to 60.06%) inputs, with rock weathering being the main source of river ions in spring. The contribution rate of rock weathering in the upstream Mountain Gorge Section (MGS) and Urban Plain Section (UPS) (85%) was significantly higher than that in the middle and lower reaches (71.5%), where human activities contributed more. The impact of urban domestic sewage on the Yongding River in spring was more significant, while the impact of agriculture and industry on the river was limited.
The Yongding River is one of the main water sources in the Beijing Tianjin Hebei Region. Understanding the hydrochemical characteristics and ion sources of the Yongding River basin is of great significance for water resource management and social development in the Beijing Tianjin Hebei Region. This study comprehensively utilized the mass balance method and ion ratio method to analyze the hydrochemical characteristics and main ion sources in the mainstream and tributaries from the Guanting Reservoir to the mouth of the Yongding River. The results indicated that the main hydrochemical types of the Yongding River in spring were SO4·Cl-Na and HCO3-Ca. The river water was slightly alkaline, with high values of EC and TDS, and the average values of tributaries were higher than those of the mainstream. The spatial variation of ions’ concentration in river water was significant, and the concentrations of Na+、K+、Cl-、NO3- in the mainstream of Yongding River showed an upward trend from upstream to downstream, with the highest mean value in the Coastal Plain Section(CPS) in the river. The sources of river water ions in various locations were mainly controlled by atmospheric precipitation (2.19% to 11.38%), human activities (0.06% to 50.69%), evaporite dissolution (6.47% to 52.13%), silicate rock weathering (5.74% to 71.23%), and carbonate rock weathering (0.24% to 60.06%) inputs, with rock weathering being the main source of river ions in spring. The contribution rate of rock weathering in the upstream Mountain Gorge Section (MGS) and Urban Plain Section (UPS) (85%) was significantly higher than that in the middle and lower reaches (71.5%), where human activities contributed more. The impact of urban domestic sewage on the Yongding River in spring was more significant, while the impact of agriculture and industry on the river was limited.
2025, 43(2): 96-104.
doi: 10.13205/j.hjgc.202502010
Abstract:
In order to investigate the structure of zooplankton community in Pengxi River basin, Yunyang County, Chongqing and clarify its correlation with saline-alkali of the water body, a study on zooplankton biodiversity was carried out in June 2023. The results showed that 31 species of zooplankton belonging to 4 classes were collected, including 22 species of Cladocera, 4 species of Rotifer, 3 species of Copepod, 1 species of insect, and 1 species of Oligochaeta. The total density was 70.8 ind./L to 270 ind./L, and the total biomass was 1.13 mg/L to 4.02 mg/L; among which Cladocera was the most abundant, and the level of species diversity was significantly higher than that of other species. The Shannon-Wiener diversity index and Pielou evenness index of zooplankton ranged from 0.919 to 2.335, and 0.300 to 0.780, respectively. 7 dominant species were found, among which Cyclops, Harpacticoida, and Daphnia vulgaris were similar in habitat selection and had higher niche overlap. The results of correlation analysis showed that total salinity, total alkalinity, and total phosphorus were the main environmental factors affecting the changes in zooplankton community structure. To some extent, the nutrients of water might mitigate the alkalinity and salinity constraints for some zooplankton. Therefore, controlling the input of salt pollutants in the basin was crucial to maintaining the stability of the zooplankton community structure in the basin.
In order to investigate the structure of zooplankton community in Pengxi River basin, Yunyang County, Chongqing and clarify its correlation with saline-alkali of the water body, a study on zooplankton biodiversity was carried out in June 2023. The results showed that 31 species of zooplankton belonging to 4 classes were collected, including 22 species of Cladocera, 4 species of Rotifer, 3 species of Copepod, 1 species of insect, and 1 species of Oligochaeta. The total density was 70.8 ind./L to 270 ind./L, and the total biomass was 1.13 mg/L to 4.02 mg/L; among which Cladocera was the most abundant, and the level of species diversity was significantly higher than that of other species. The Shannon-Wiener diversity index and Pielou evenness index of zooplankton ranged from 0.919 to 2.335, and 0.300 to 0.780, respectively. 7 dominant species were found, among which Cyclops, Harpacticoida, and Daphnia vulgaris were similar in habitat selection and had higher niche overlap. The results of correlation analysis showed that total salinity, total alkalinity, and total phosphorus were the main environmental factors affecting the changes in zooplankton community structure. To some extent, the nutrients of water might mitigate the alkalinity and salinity constraints for some zooplankton. Therefore, controlling the input of salt pollutants in the basin was crucial to maintaining the stability of the zooplankton community structure in the basin.
2025, 43(2): 105-113.
doi: 10.13205/j.hjgc.202502011
Abstract:
The purpose of this study was to provide a scientific basis for the formulation of emergency plans for the emergency water pollution events of alpine river watershed represented by the Pudu River Basin. Taking the Pudu River (Dianchi-Haikou Section), a first-level tributary of the upper reaches of the Yangtze River in Kunming as an example, the emergency spaces and facilities available for water pollution emergencies along the riverside were investigated, and their use strategy was analyzed. The accident situation was set up according to the characteristics of risk sources, and the mathematical model of pollutant diffusion and transport in river channels was established to determine the optimal emergency response plan for water pollution emergencies in the river basin. According to the amount of pollutants in accident leakage, the hydrological characteristics of the river, and on the premise of ensuring the water quality of the downstream protection target complying with the standard, the water quality model was used for the reverse calculation to determine the number of needed emergency spaces and facilities, as well as the launching sequence, and the space volume and location required for temporary emergency facilities. The results showed that Haikou Bridge Q1, gate dam Z1, and pit T1 along the river, diversion power station Y, and island J should be applied to formulate the emergency spaces to reduce pollutants. The emergency space could set aside a 24-minute buffer time for emergency response, and the pollution clusters were controlled, to prevent excessive pollution levels in the protection target, the section at the junction of Xishan District and Anning City (9500 m downstream from the leak point).
The purpose of this study was to provide a scientific basis for the formulation of emergency plans for the emergency water pollution events of alpine river watershed represented by the Pudu River Basin. Taking the Pudu River (Dianchi-Haikou Section), a first-level tributary of the upper reaches of the Yangtze River in Kunming as an example, the emergency spaces and facilities available for water pollution emergencies along the riverside were investigated, and their use strategy was analyzed. The accident situation was set up according to the characteristics of risk sources, and the mathematical model of pollutant diffusion and transport in river channels was established to determine the optimal emergency response plan for water pollution emergencies in the river basin. According to the amount of pollutants in accident leakage, the hydrological characteristics of the river, and on the premise of ensuring the water quality of the downstream protection target complying with the standard, the water quality model was used for the reverse calculation to determine the number of needed emergency spaces and facilities, as well as the launching sequence, and the space volume and location required for temporary emergency facilities. The results showed that Haikou Bridge Q1, gate dam Z1, and pit T1 along the river, diversion power station Y, and island J should be applied to formulate the emergency spaces to reduce pollutants. The emergency space could set aside a 24-minute buffer time for emergency response, and the pollution clusters were controlled, to prevent excessive pollution levels in the protection target, the section at the junction of Xishan District and Anning City (9500 m downstream from the leak point).
2025, 43(2): 114-125.
doi: 10.13205/j.hjgc.202502012
Abstract:
Taihu Lake’s blue-green algae blooms have been a persistent environmental issue, with the associated odors becoming increasingly concerning, due to their impact on water quality and ecological health. The blooms are influenced by a complex interplay of factors including nutrient input, water temperature, and alterations in the food chain, which underscores the complexity of managing these ecosystems. Furthermore, the odors produced during algae metabolism not only affect the aesthetic quality of the water but also pose potential health risks, highlighting the urgency of addressing the algal blooms and their metabolic byproducts. The ecological risk management of Taihu Lake requires a comprehensive approach that considers the biological and chemical aspects of the blooms, as well as the potential impacts on human health and the environment. The Gonghu Bay, a hotspot for algal blooms in the past, was selected as the study area for investigating changes in algae and algogenic odors in Taihu Lake during the summer of 2023. The collected water samples provide crucial data on the current state of algal populations and the associated odors, helping to understand the ecological health of the lake. In-situ and laboratory works were conducted to analyze the water samples, including evaluating the water quality index (WQI) and trophic level index (TLI), monitoring the algal density and community composition, and determining the concentrations of six odors. The WQI and TLI are critical tools for assessing the overall health and trophic state of the water body, providing a comprehensive understanding of water quality parameters and nutrient levels that can influence algal growth. The target odors were dimethyl trisulfide (DMTS), 2-methylisoborneol (2-MIB), citral (CIT), 2,4,6-trichlorotoluene (TCA), geosmin (GSM), and β-ionone (BI). The results showed that the water quality in Gonghu Bay during the summer of 2023 was relatively better in June and July, but became deteriorated in August. The values of WQI and TLI in August were 70.1±5.0 and 58.1±4.1, respectively, which could be attributed to the higher concentrations of TN and NH4+-N. The average algal density (1.27×107 cells/L) was significantly lower than those in previous years. Cyanophyta was still the primary algae at the phylum level, but the proportion of filamentous cyanobacteria increased significantly and the genus Pseudanabaena was the dominant one. A total of four odors (2-MIB, CIT, TCA, and BI) were detected in the surface water of Gonghu Bay and their concentrations were low in June and July. However, the total concentrations of these odors in August could be up to (556.3±64.6) ng/L, implying that odors in Taihu Lake still require attention. Based on the correlation analysis, the genera Pseudanabaena and Aphanocapsa were identified as the potential sources of TCA, in which the genus Aphanocapsa was also thought of as one of the sources of BI. These odor-producing algal genera were significantly positively correlated with TN in water. The risk quotients (RQ) of odors were below 0.1 in June and July, indicating low ecological risk, but the ecological risk was moderate (RQ=0.86) in August, likely due to the high concentration of TCA. Therefore, it is necessary to carry out effective monitoring and preventive measures for the TCA and its related algae in Taihu Lake.
Taihu Lake’s blue-green algae blooms have been a persistent environmental issue, with the associated odors becoming increasingly concerning, due to their impact on water quality and ecological health. The blooms are influenced by a complex interplay of factors including nutrient input, water temperature, and alterations in the food chain, which underscores the complexity of managing these ecosystems. Furthermore, the odors produced during algae metabolism not only affect the aesthetic quality of the water but also pose potential health risks, highlighting the urgency of addressing the algal blooms and their metabolic byproducts. The ecological risk management of Taihu Lake requires a comprehensive approach that considers the biological and chemical aspects of the blooms, as well as the potential impacts on human health and the environment. The Gonghu Bay, a hotspot for algal blooms in the past, was selected as the study area for investigating changes in algae and algogenic odors in Taihu Lake during the summer of 2023. The collected water samples provide crucial data on the current state of algal populations and the associated odors, helping to understand the ecological health of the lake. In-situ and laboratory works were conducted to analyze the water samples, including evaluating the water quality index (WQI) and trophic level index (TLI), monitoring the algal density and community composition, and determining the concentrations of six odors. The WQI and TLI are critical tools for assessing the overall health and trophic state of the water body, providing a comprehensive understanding of water quality parameters and nutrient levels that can influence algal growth. The target odors were dimethyl trisulfide (DMTS), 2-methylisoborneol (2-MIB), citral (CIT), 2,4,6-trichlorotoluene (TCA), geosmin (GSM), and β-ionone (BI). The results showed that the water quality in Gonghu Bay during the summer of 2023 was relatively better in June and July, but became deteriorated in August. The values of WQI and TLI in August were 70.1±5.0 and 58.1±4.1, respectively, which could be attributed to the higher concentrations of TN and NH4+-N. The average algal density (1.27×107 cells/L) was significantly lower than those in previous years. Cyanophyta was still the primary algae at the phylum level, but the proportion of filamentous cyanobacteria increased significantly and the genus Pseudanabaena was the dominant one. A total of four odors (2-MIB, CIT, TCA, and BI) were detected in the surface water of Gonghu Bay and their concentrations were low in June and July. However, the total concentrations of these odors in August could be up to (556.3±64.6) ng/L, implying that odors in Taihu Lake still require attention. Based on the correlation analysis, the genera Pseudanabaena and Aphanocapsa were identified as the potential sources of TCA, in which the genus Aphanocapsa was also thought of as one of the sources of BI. These odor-producing algal genera were significantly positively correlated with TN in water. The risk quotients (RQ) of odors were below 0.1 in June and July, indicating low ecological risk, but the ecological risk was moderate (RQ=0.86) in August, likely due to the high concentration of TCA. Therefore, it is necessary to carry out effective monitoring and preventive measures for the TCA and its related algae in Taihu Lake.
2025, 43(2): 126-137.
doi: 10.13205/j.hjgc.202502013
Abstract:
Lanthanum-modified bentonite (LMB) is widely used to control the release of endogenous phosphorus in many water bodies worldwide due to its strong affinity to phosphate. In this paper, several field application cases of LMB at home and abroad were reviewed, and short-term and long-term water quality changes, ecological effects and long-term effectiveness of LMB after application were summarized, to provide references for the development of similar chemical covering materials and treatment of lake internal sources. Based on the mechanism of endogenous phosphorus control by LMB, this review discussed the concentration and distribution changes of lanthanum and phosphorus in water and sediment and their effects on water ecology after applying LMB in some natural water bodies. The analysis indicated that the effectiveness of LMB in immobilizing phosphorus is determined by the physicochemical properties of the water body, such as pH, alkalinity, hardness, concentration of competing anions, and DOC concentration. Additionally, factors like wind and benthic organism disturbances, lake morphology, dosage of the remediation agent, and hydrological and climatic conditions can also affect the long-term efficacy of LMB remediation. Furthermore, there is a risk of lanthanum leaching in water bodies with low alkalinity and hardness, and whether lanthanum will be bioaccumulated in the food chain still requires further long-term monitoring and analysis. In conclusion, before applying LMB in natural water bodies, it is essential to comprehensively understand the hydrological and geographical environment of the target water body, as well as its physicochemical properties, and then estimate the potential risk through extensive experimentation.
Lanthanum-modified bentonite (LMB) is widely used to control the release of endogenous phosphorus in many water bodies worldwide due to its strong affinity to phosphate. In this paper, several field application cases of LMB at home and abroad were reviewed, and short-term and long-term water quality changes, ecological effects and long-term effectiveness of LMB after application were summarized, to provide references for the development of similar chemical covering materials and treatment of lake internal sources. Based on the mechanism of endogenous phosphorus control by LMB, this review discussed the concentration and distribution changes of lanthanum and phosphorus in water and sediment and their effects on water ecology after applying LMB in some natural water bodies. The analysis indicated that the effectiveness of LMB in immobilizing phosphorus is determined by the physicochemical properties of the water body, such as pH, alkalinity, hardness, concentration of competing anions, and DOC concentration. Additionally, factors like wind and benthic organism disturbances, lake morphology, dosage of the remediation agent, and hydrological and climatic conditions can also affect the long-term efficacy of LMB remediation. Furthermore, there is a risk of lanthanum leaching in water bodies with low alkalinity and hardness, and whether lanthanum will be bioaccumulated in the food chain still requires further long-term monitoring and analysis. In conclusion, before applying LMB in natural water bodies, it is essential to comprehensively understand the hydrological and geographical environment of the target water body, as well as its physicochemical properties, and then estimate the potential risk through extensive experimentation.
2025, 43(2): 138-147.
doi: 10.13205/j.hjgc.202502014
Abstract:
The forms of phosphorus in sediments are influenced by various physical, chemical, and biological factors, with microorganisms playing a key role in driving the migration and transformation of phosphorus in sediments. However, studies on the impact of microorganisms on phosphorus forms in sediments remain insufficient. This study focused on the Xiangxi River, a tributary of the Three Gorges Reservoir, by establishing five sampling sites in the river’s bay. Sediment samples were collected during different periods to analyze phosphorus forms and to explore the relationship between changes in sediment microbial community structure and phosphorus storage forms in conjunction with physicochemical factors of the sediments. The results indicated that the total phosphorus content in the sediments of the Xiangxi River ranged from 324.21 mg/kg to 1385.05 mg/kg, with an average content of 869.56 mg/kg, where HCl-P was the dominant phosphorus form. The main dominant microbial communities in the sediments were Proteobacteria, Cyanobacteria, and Bacteroidota. Proteobacteria’s relative abundance showed a significant negative correlation with OP and HCl-P, and the dominant phosphorus-reducing genera within Proteobacteria can enhance the dissolution and release of HCl-P and OP. Cyanobacteria’s relative abundance exhibited a significant negative correlation with OP and NaOH-P, promoting the release of OP and NaOH-P through positive feedback mechanisms. Desulfobacterota’s relative abundance showed a significant negative correlation with NaOH-P, with Geothermobacter in Desulfobacterota facilitating the release of NaOH-P through iron reduction.
The forms of phosphorus in sediments are influenced by various physical, chemical, and biological factors, with microorganisms playing a key role in driving the migration and transformation of phosphorus in sediments. However, studies on the impact of microorganisms on phosphorus forms in sediments remain insufficient. This study focused on the Xiangxi River, a tributary of the Three Gorges Reservoir, by establishing five sampling sites in the river’s bay. Sediment samples were collected during different periods to analyze phosphorus forms and to explore the relationship between changes in sediment microbial community structure and phosphorus storage forms in conjunction with physicochemical factors of the sediments. The results indicated that the total phosphorus content in the sediments of the Xiangxi River ranged from 324.21 mg/kg to 1385.05 mg/kg, with an average content of 869.56 mg/kg, where HCl-P was the dominant phosphorus form. The main dominant microbial communities in the sediments were Proteobacteria, Cyanobacteria, and Bacteroidota. Proteobacteria’s relative abundance showed a significant negative correlation with OP and HCl-P, and the dominant phosphorus-reducing genera within Proteobacteria can enhance the dissolution and release of HCl-P and OP. Cyanobacteria’s relative abundance exhibited a significant negative correlation with OP and NaOH-P, promoting the release of OP and NaOH-P through positive feedback mechanisms. Desulfobacterota’s relative abundance showed a significant negative correlation with NaOH-P, with Geothermobacter in Desulfobacterota facilitating the release of NaOH-P through iron reduction.
2025, 43(2): 148-156.
doi: 10.13205/j.hjgc.202502015
Abstract:
Many reservoirs in north China are facing the issue of excessive fluoride concentration over the water quality standards, which severely impacts the regional ecological environment and human health. Leveraging the urgent need to restore the water source of the Guanting Reservoir, combined with the current situation of excessive fluoride concentration in the reservoir area, a comprehensive approach utilizing methods such as water-salt balance analysis, correlation analysis, and scenario analysis was employed to explore the ways and measures for restoring the water source of Guanting Reservoir from the perspective of fluoride. Research findings indicate that the average fluoride concentration in the Guanting Reservoir area is 1.23 mg/L over multiple years, slightly higher than the fluoride concentrations at the No.8 Bridge and East Bridge inlet tributary. The No.8 Bridge and East Bridge inlet tributary are the main contributors to the reservoir area’s water volume and fluoride, accounting for 66.69% and 52.31% of the total inflow, respectively. Additionally, fluoride released from reservoir sediment accounts for approximately 27.54% of the total inflow, making it the second largest source of pollution following the No.8 Bridge inlet tributary. By taking a single measure, like reducing the fluoride concentration in the water of the No.8 Bridge inlet tributary to 0.63 mg/L, dredging 75.42% of the reservoir area, or taking a comprehensive measure, including increasing water replenishment amount by 50%, reducing the fluoride concentration of replenishment water by 50%, and dredging 50% the reservoir area, the fluoride in the reservoir area can all be maintained at the level of Class Ⅱ spcified in Surface Water Environmental Quality GB 3838—2022. It is necessary to comprehensively adopt water replenishment, water quality improvement, and ecological dredging to ensure the stable attainment of water source requirements in the reservoir area.
Many reservoirs in north China are facing the issue of excessive fluoride concentration over the water quality standards, which severely impacts the regional ecological environment and human health. Leveraging the urgent need to restore the water source of the Guanting Reservoir, combined with the current situation of excessive fluoride concentration in the reservoir area, a comprehensive approach utilizing methods such as water-salt balance analysis, correlation analysis, and scenario analysis was employed to explore the ways and measures for restoring the water source of Guanting Reservoir from the perspective of fluoride. Research findings indicate that the average fluoride concentration in the Guanting Reservoir area is 1.23 mg/L over multiple years, slightly higher than the fluoride concentrations at the No.8 Bridge and East Bridge inlet tributary. The No.8 Bridge and East Bridge inlet tributary are the main contributors to the reservoir area’s water volume and fluoride, accounting for 66.69% and 52.31% of the total inflow, respectively. Additionally, fluoride released from reservoir sediment accounts for approximately 27.54% of the total inflow, making it the second largest source of pollution following the No.8 Bridge inlet tributary. By taking a single measure, like reducing the fluoride concentration in the water of the No.8 Bridge inlet tributary to 0.63 mg/L, dredging 75.42% of the reservoir area, or taking a comprehensive measure, including increasing water replenishment amount by 50%, reducing the fluoride concentration of replenishment water by 50%, and dredging 50% the reservoir area, the fluoride in the reservoir area can all be maintained at the level of Class Ⅱ spcified in Surface Water Environmental Quality GB 3838—2022. It is necessary to comprehensively adopt water replenishment, water quality improvement, and ecological dredging to ensure the stable attainment of water source requirements in the reservoir area.
2025, 43(2): 157-166.
doi: 10.13205/j.hjgc.202502016
Abstract:
In this paper, sediment pollution assessment and nitrogen and phosphorus release risk study in different areas of the Taihu Lake were conducted to assess the impact of nitrogen and phosphorus nutrient exchange flux in the Taihu Lake sediments on the overlying water quality. The results showed that the contents of TN (total nitrogen) and TP (total phosphorus) in the sediment of the Taihu Lake were high, especially the TN content was between 1.85 g/kg and 3.57 g/kg. According to the comprehensive pollution index evaluation, it was at the level of heavy pollution. TP content was between 0.15 g/kg and 1.40 g/kg. According to the comprehensive pollution index assessment, the sediment of the grass type lake areas (Eastern and Southern Taihu Lake) was at a clean level. The concentrations of NH4+-N and dissolved phosphorus (TDP) in pore water of surface sediments were much higher than those in the overlying water in different lake areas. The release rates of NH4+-N and TDP in Meiliang Bay of the algal lake area were 125.86 mg/(m2·d) and 4.88 mg/(m2·d), respectively. The NH4+-N release rate of Eastern Taihu Lake in the grass-type lake area was 42.46 mg/(m2·d), and the TDP release rate was 3.93 mg/(m2·d). The release rates of NH4+-N and TDP at the surface sediment water interface in the algae-type lake area were higher than those in the grass-type lake area. It could be seen that each lake area of the Taihu Lake had a great risk of endogenous release of nitrogen and phosphorus, of which the risk of endogenous release in the algae-type lake area was higher than that in the grass-type lake area. The endogenous release of nitrogen and phosphorus from moderately and severely polluted sediments in the Taihu Lake area was the main reason for eutrophication. We could comprehensively reduce the nutrient load in the lake and enhance the purification effect of the Taihu Lake on water pollutants through external pollution control measures, combined with in-situ coverage technology, ecosystem restoration, aeration and reaeration, environmental dredging of sediment, passivation of sediment and other internal governance methods.
In this paper, sediment pollution assessment and nitrogen and phosphorus release risk study in different areas of the Taihu Lake were conducted to assess the impact of nitrogen and phosphorus nutrient exchange flux in the Taihu Lake sediments on the overlying water quality. The results showed that the contents of TN (total nitrogen) and TP (total phosphorus) in the sediment of the Taihu Lake were high, especially the TN content was between 1.85 g/kg and 3.57 g/kg. According to the comprehensive pollution index evaluation, it was at the level of heavy pollution. TP content was between 0.15 g/kg and 1.40 g/kg. According to the comprehensive pollution index assessment, the sediment of the grass type lake areas (Eastern and Southern Taihu Lake) was at a clean level. The concentrations of NH4+-N and dissolved phosphorus (TDP) in pore water of surface sediments were much higher than those in the overlying water in different lake areas. The release rates of NH4+-N and TDP in Meiliang Bay of the algal lake area were 125.86 mg/(m2·d) and 4.88 mg/(m2·d), respectively. The NH4+-N release rate of Eastern Taihu Lake in the grass-type lake area was 42.46 mg/(m2·d), and the TDP release rate was 3.93 mg/(m2·d). The release rates of NH4+-N and TDP at the surface sediment water interface in the algae-type lake area were higher than those in the grass-type lake area. It could be seen that each lake area of the Taihu Lake had a great risk of endogenous release of nitrogen and phosphorus, of which the risk of endogenous release in the algae-type lake area was higher than that in the grass-type lake area. The endogenous release of nitrogen and phosphorus from moderately and severely polluted sediments in the Taihu Lake area was the main reason for eutrophication. We could comprehensively reduce the nutrient load in the lake and enhance the purification effect of the Taihu Lake on water pollutants through external pollution control measures, combined with in-situ coverage technology, ecosystem restoration, aeration and reaeration, environmental dredging of sediment, passivation of sediment and other internal governance methods.
2025, 43(2): 167-176.
doi: 10.13205/j.hjgc.202502017
Abstract:
With the loss of global coastal wetland areas and the continuous degradation of its ecosystem functions, improving the functions of coastal wetland ecosystems through coastal restoration incorporating hydrological connectivity has become a significant global strategy. This paper reviewed 7,225 articles from the Web of Science database (1950 to 2024), revealed the spatiotemporal distribution characteristics of global coastal restoration projects using hydrological connectivity, and elucidated the main methods of landward and seaward hydrological connectivity restoration. The research on coastal restoration using hydrological connectivity began in the 1970s, and the number of global research papers started to increase after the 1990s. The United States has the highest number of research papers in this field, accounting for more than one-third of the global total. China ranks the second in the number of research papers. Landward hydrological connectivity ecological restoration mainly focuses on the regulation of runoff, sediment transport, and landward nutrient transport, while seaward hydrological connectivity restoration techniques primarily include managing realignment or retreat, regulating tidal exchange, and controlling reduced tide. Furthermore, this paper clarifies the mechanisms and research progress of the impact of coastal restoration based on hydrological connectivity on key ecosystem functions, such as primary productivity, coastal protection, carbon storage, and biodiversity conservation. From the perspectives of numerous influencing factors, lengthy restoration periods, highly variable response processes, and complex functional trade-offs, this paper summarizes the current challenges of enhancing ecosystem functions using coastal restoration based on hydrological connectivity. Future research trends are anticipated in light of the current research progress and existing problems, which can support addressing the fundamental scientific issues faced in enhancing coastal wetland ecosystem functions. In the future, we should focus on utilizing new technologies and big data analysis to reveal the mechanisms behind the enhancement of ecosystem functions, constructing predictive models for ecosystem functions enhancement that integrate hydrological, geomorphological, and ecological dynamic processes, conducting cost-benefit analyses to ensure the sustainability of coastal wetland restoration, and serving national needs and international programs to foster international big science research plans and projects.
With the loss of global coastal wetland areas and the continuous degradation of its ecosystem functions, improving the functions of coastal wetland ecosystems through coastal restoration incorporating hydrological connectivity has become a significant global strategy. This paper reviewed 7,225 articles from the Web of Science database (1950 to 2024), revealed the spatiotemporal distribution characteristics of global coastal restoration projects using hydrological connectivity, and elucidated the main methods of landward and seaward hydrological connectivity restoration. The research on coastal restoration using hydrological connectivity began in the 1970s, and the number of global research papers started to increase after the 1990s. The United States has the highest number of research papers in this field, accounting for more than one-third of the global total. China ranks the second in the number of research papers. Landward hydrological connectivity ecological restoration mainly focuses on the regulation of runoff, sediment transport, and landward nutrient transport, while seaward hydrological connectivity restoration techniques primarily include managing realignment or retreat, regulating tidal exchange, and controlling reduced tide. Furthermore, this paper clarifies the mechanisms and research progress of the impact of coastal restoration based on hydrological connectivity on key ecosystem functions, such as primary productivity, coastal protection, carbon storage, and biodiversity conservation. From the perspectives of numerous influencing factors, lengthy restoration periods, highly variable response processes, and complex functional trade-offs, this paper summarizes the current challenges of enhancing ecosystem functions using coastal restoration based on hydrological connectivity. Future research trends are anticipated in light of the current research progress and existing problems, which can support addressing the fundamental scientific issues faced in enhancing coastal wetland ecosystem functions. In the future, we should focus on utilizing new technologies and big data analysis to reveal the mechanisms behind the enhancement of ecosystem functions, constructing predictive models for ecosystem functions enhancement that integrate hydrological, geomorphological, and ecological dynamic processes, conducting cost-benefit analyses to ensure the sustainability of coastal wetland restoration, and serving national needs and international programs to foster international big science research plans and projects.
2025, 43(2): 177-185.
doi: 10.13205/j.hjgc.202502018
Abstract:
Mangroves are located at the key intersections on the sea-to-land ecological corridor, playing a pivotal role in sustaining maritime hydrology-biology connectivity. Limited by data availability and observation technology during typhoon events, the capacity of mangroves to regulate hydrodynamic processes and deliver coastal protection functions as a consequence, remains unclear till now, which would hamper further engineering practice in coastal protection. In this study, we set the mangroves on Hailing Island, Guangdong Province, China, as a representative case, to investigate the attenuation of storm surge and wave heights by mangrove forests, under typhoon conditions (super typhoon Yagi in 2024). The analysis used a coupled Delft3D FM-Delft3D model framework, validated with in-situ measurements collected during the event. The results revealed that the coupled model successfully simulated the storm surge and wave propagation processes across the environmental gradient from open sea to mudflat, and further into the mangrove forest. The wave height attenuation rate of mangroves ranged from 0.28% to 0.64% per meter, and the water level attenuation rate varied between 1.46 cm and 18.69 cm per kilometer, outperforming the attenuation rates in mudflat and unvegetated scenarios. Furthermore, the contribution of mangrove vegetation to wave height attenuation ranged from 43% to 69%, markedly higher than its contribution to water level attenuation, which ranged from 0.2% to 32%. This study highlights the variability in attenuation capacities of mangrove forests for storm surges and wave heights under typhoon conditions. These findings provide valuable scientific evidence supporting the integration of mangroves into nature-based coastal defense strategies, highlighting that the conservation and restoration of mangrove ecosystems offer sustainable solutions to mitigate the impacts of extreme weather events and would consequently contribute to long-term coastal resilience and disaster risk reduction.
Mangroves are located at the key intersections on the sea-to-land ecological corridor, playing a pivotal role in sustaining maritime hydrology-biology connectivity. Limited by data availability and observation technology during typhoon events, the capacity of mangroves to regulate hydrodynamic processes and deliver coastal protection functions as a consequence, remains unclear till now, which would hamper further engineering practice in coastal protection. In this study, we set the mangroves on Hailing Island, Guangdong Province, China, as a representative case, to investigate the attenuation of storm surge and wave heights by mangrove forests, under typhoon conditions (super typhoon Yagi in 2024). The analysis used a coupled Delft3D FM-Delft3D model framework, validated with in-situ measurements collected during the event. The results revealed that the coupled model successfully simulated the storm surge and wave propagation processes across the environmental gradient from open sea to mudflat, and further into the mangrove forest. The wave height attenuation rate of mangroves ranged from 0.28% to 0.64% per meter, and the water level attenuation rate varied between 1.46 cm and 18.69 cm per kilometer, outperforming the attenuation rates in mudflat and unvegetated scenarios. Furthermore, the contribution of mangrove vegetation to wave height attenuation ranged from 43% to 69%, markedly higher than its contribution to water level attenuation, which ranged from 0.2% to 32%. This study highlights the variability in attenuation capacities of mangrove forests for storm surges and wave heights under typhoon conditions. These findings provide valuable scientific evidence supporting the integration of mangroves into nature-based coastal defense strategies, highlighting that the conservation and restoration of mangrove ecosystems offer sustainable solutions to mitigate the impacts of extreme weather events and would consequently contribute to long-term coastal resilience and disaster risk reduction.
