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2023 Vol. 41, No. 1
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2023, 41(1): 1-9,111.
doi: 10.13205/j.hjgc.202301001
Abstract:
Three field investigations of water level, velocity, water quality, phytoplankton and zooplankton were carried out in Baidang Lake Basin, Anhui Province in November 2020, and March and June 2021. The key environmental factors affecting the plankton community structure in the Baidang Lake Basin were explored and evaluated for hydrological connectivity. The results showed that the river-lake connectivity of the Baidang Lake Basin was highest in the wet season (June), followed by the normal season (March), and then dry season (November). The dominant species, abundance and biomass of phytoplankton and zooplankton communities showed significant seasonal differences, in which the dominant species of phytoplankton were green algae, diatoms and cyanobacteria, and the dominant species of zooplankton were rotifers and cladocerans. There was a trend of wet season>normal season>dry season in biomass and abundance. The Shannon Wiener and Margalef index of phytoplankton were lowest in the lake area, and highest in the upper reaches of the Yangshi River; while the lowest value of Pielou index was in the lake area, and the highest value was at the entrance of the Luochang River. For the zooplankton, the lowest values of Shannon Wiener index and Margalef index were in the middle reaches of the Luochang River, and the highest value was in the upper reaches of the Luochang River; while Pielou index was the lowest at the entrance of the Yangshi River and the highest at the upper reaches of the Luochang River. Redundancy analysis showed that the key environmental factors affecting the dominant species of phytoplankton were T, DO and TN, while that of the dominant species of zooplankton were TP and HCI. This study clarified the characteristics of the plankton community structure in the Baidang Lake Basin, and revealed the impact of hydrological connectivity on plankton community structure, which provided a scientific basis for further study of ecological health, and protection and restoration of the lake basin.
Three field investigations of water level, velocity, water quality, phytoplankton and zooplankton were carried out in Baidang Lake Basin, Anhui Province in November 2020, and March and June 2021. The key environmental factors affecting the plankton community structure in the Baidang Lake Basin were explored and evaluated for hydrological connectivity. The results showed that the river-lake connectivity of the Baidang Lake Basin was highest in the wet season (June), followed by the normal season (March), and then dry season (November). The dominant species, abundance and biomass of phytoplankton and zooplankton communities showed significant seasonal differences, in which the dominant species of phytoplankton were green algae, diatoms and cyanobacteria, and the dominant species of zooplankton were rotifers and cladocerans. There was a trend of wet season>normal season>dry season in biomass and abundance. The Shannon Wiener and Margalef index of phytoplankton were lowest in the lake area, and highest in the upper reaches of the Yangshi River; while the lowest value of Pielou index was in the lake area, and the highest value was at the entrance of the Luochang River. For the zooplankton, the lowest values of Shannon Wiener index and Margalef index were in the middle reaches of the Luochang River, and the highest value was in the upper reaches of the Luochang River; while Pielou index was the lowest at the entrance of the Yangshi River and the highest at the upper reaches of the Luochang River. Redundancy analysis showed that the key environmental factors affecting the dominant species of phytoplankton were T, DO and TN, while that of the dominant species of zooplankton were TP and HCI. This study clarified the characteristics of the plankton community structure in the Baidang Lake Basin, and revealed the impact of hydrological connectivity on plankton community structure, which provided a scientific basis for further study of ecological health, and protection and restoration of the lake basin.
2023, 41(1): 10-17,131.
doi: 10.13205/j.hjgc.202301002
Abstract:
The Tongling river-lake wetlands were selected to investigate the water environment and plankton population composition in December, 2020, March and June, 2021. Temporal and spatial variations of the plankton community were analyzed. In addition, the effects of environmental factors and sluices density on plankton community structure were investigated. The results showed that 102 species of phytoplankton in 60 genera and 7 phyla were identified, mainly belonging to Cyanophyta and Diatom. Phytoplankton species were mainly found in spring and summer, but less in winter. In total, 3 phyla, 21 genera and 32 species of zooplankton were collected, and rotifers were the dominant type. The structure of the plankton community was jointly affected by environmental factors such as water temperature, dissolved oxygen and total phosphorus and sluices density. The distribution of high-density sluices affected the natural habitats of rivers and lakes, and the density of plankton was high. From the perspectives of long-term protection and ecological restoration of the urban river and lake wetlands, under the condition of ensuring flood control and drainage, properly adjusting the distribution and opening frequency of water conservancy facilities can provide favourable wetland habitat condition for plankton.
The Tongling river-lake wetlands were selected to investigate the water environment and plankton population composition in December, 2020, March and June, 2021. Temporal and spatial variations of the plankton community were analyzed. In addition, the effects of environmental factors and sluices density on plankton community structure were investigated. The results showed that 102 species of phytoplankton in 60 genera and 7 phyla were identified, mainly belonging to Cyanophyta and Diatom. Phytoplankton species were mainly found in spring and summer, but less in winter. In total, 3 phyla, 21 genera and 32 species of zooplankton were collected, and rotifers were the dominant type. The structure of the plankton community was jointly affected by environmental factors such as water temperature, dissolved oxygen and total phosphorus and sluices density. The distribution of high-density sluices affected the natural habitats of rivers and lakes, and the density of plankton was high. From the perspectives of long-term protection and ecological restoration of the urban river and lake wetlands, under the condition of ensuring flood control and drainage, properly adjusting the distribution and opening frequency of water conservancy facilities can provide favourable wetland habitat condition for plankton.
2023, 41(1): 18-25.
doi: 10.13205/j.hjgc.202301003
Abstract:
To understand the environmental variables responsible for regulating epipelic algal community composition and biomass in the surface sediment, habitat-linked heterogeneity in algal taxon-specific pigments[chlorophyll a(Chl.a), chlorophyll b(Chl.b), fucoxanthin(Fuco), zeaxanthin(Zea)] in surface sediment were investigated in the Lake Taihu by using high-performance liquid chromatography in different seasons. At the same time, the concentrations of nitrogen and phosphorus and other physical and chemical indexes in the environment were determined by conventional methods. The result showed that total nitrogen, total phosphorus and dissolved total phosphorus concentrations in the water body varied significantly in space (P<0.05) and were in an order of Meiliang bay>Gonghu bay>Xukou bay. In addition, the concentrations of TP and iron-bound phosphorus (Fe-P) from surface sediments in Xukou bay were significantly lower than those in Meiliang bay and Gonghu bay (P<0.05). The epipelic algal biomass in the surface sediment was the highest in Gonghu bay with a value of (12.79±3.69) μg Chl.a/g, while the value of (2.46±1.14) μg Chl.a/g was the lowest in Xukou bay. Algal biomass in the surface sediment varied in an order of Gonghu bay>Meiliang bay>Xukou bay in autumn and summer, and in an order of Meiliang bay>Gonghu bay>Xukou bay in spring. In Xukou bay and Meiliang bay, algal biomass and Chl.b in the surface sediment was higher in spring and lower in summer and autumn, while in Gonghu bay, algal biomass in the surface sediment was high in autumn, followed by summer and spring. Based on pigment ratios of Chl.b (Fuco, Zea) to Chl.a, the algal community was dominated by diatom, followed by cyanobacteria in the surface sediments of Lake Taihu. The results of redundancy analysis (RDA) showed that the phosphorus in the surface sediment, especially the concentration of inorganic phosphorus, was the major environmental factor affecting the development of epipelic algae. The results can provide references for further understanding the ecological functions of epipelic algae and eutrophication control in the Taihu Lake.
To understand the environmental variables responsible for regulating epipelic algal community composition and biomass in the surface sediment, habitat-linked heterogeneity in algal taxon-specific pigments[chlorophyll a(Chl.a), chlorophyll b(Chl.b), fucoxanthin(Fuco), zeaxanthin(Zea)] in surface sediment were investigated in the Lake Taihu by using high-performance liquid chromatography in different seasons. At the same time, the concentrations of nitrogen and phosphorus and other physical and chemical indexes in the environment were determined by conventional methods. The result showed that total nitrogen, total phosphorus and dissolved total phosphorus concentrations in the water body varied significantly in space (P<0.05) and were in an order of Meiliang bay>Gonghu bay>Xukou bay. In addition, the concentrations of TP and iron-bound phosphorus (Fe-P) from surface sediments in Xukou bay were significantly lower than those in Meiliang bay and Gonghu bay (P<0.05). The epipelic algal biomass in the surface sediment was the highest in Gonghu bay with a value of (12.79±3.69) μg Chl.a/g, while the value of (2.46±1.14) μg Chl.a/g was the lowest in Xukou bay. Algal biomass in the surface sediment varied in an order of Gonghu bay>Meiliang bay>Xukou bay in autumn and summer, and in an order of Meiliang bay>Gonghu bay>Xukou bay in spring. In Xukou bay and Meiliang bay, algal biomass and Chl.b in the surface sediment was higher in spring and lower in summer and autumn, while in Gonghu bay, algal biomass in the surface sediment was high in autumn, followed by summer and spring. Based on pigment ratios of Chl.b (Fuco, Zea) to Chl.a, the algal community was dominated by diatom, followed by cyanobacteria in the surface sediments of Lake Taihu. The results of redundancy analysis (RDA) showed that the phosphorus in the surface sediment, especially the concentration of inorganic phosphorus, was the major environmental factor affecting the development of epipelic algae. The results can provide references for further understanding the ecological functions of epipelic algae and eutrophication control in the Taihu Lake.
2023, 41(1): 26-34.
doi: 10.13205/j.hjgc.202301004
Abstract:
In order to explore the toxicity effect of organic modified layered double hydroxide (O-LDH) combined with methyl orange (MO) on microalgae, Chlorella vulgaris was selected as the experimental algae species in this study. The effects of single and combined exposure of O-LDH and MO on growth inhibition, chlorophyll content and cell structure of C. vulgaris were investigated. The adsorption and toxicity mechanism of O-LDH and MO on C. vulgaris were investigated by measuring residual MO concentration and cell surface potential of algae. The results were as follows:1) the fitting results of 96 h growth inhibition rate of algae by O-LDH and MO were in accordance with the Logistic model (R2>0.99), the EC50-96h values were 122.18, 26.73 mg/L, respectively, and the inhibition effect of MO on C. vulgaris was greater than that of O-LDH. 2) the toxicity mechanisms of O-LDH to C. vulgaris included the shading effect caused by the aggregation of nanolamellae on the surface of microalgae cells and the oxidative damage caused by the fragmentation of cell structure by nanolamellae. 3) at low concentrations of O-LDH (0~50 mg/L), O-LDH in the solution was strongly adsorbed by microalgal cells, resulting in enhanced combined toxicity of O-LDH and MO to C. vulgaris. At high concentrations of O-LDH (50~500 mg/L), O-LDH and the products of MO adsorbed by O-LDH in the solution competed for charge sites on the surface of microalgal cells, and the hydrophobic layer was formed on the surface of O-LDH after adsorbing MO, which weakened the shadow effect of O-LDH on microalgae cells and reduced oxidative damage, leading to weakened combined toxicity of O-LDH and MO to C. vulgaris.
In order to explore the toxicity effect of organic modified layered double hydroxide (O-LDH) combined with methyl orange (MO) on microalgae, Chlorella vulgaris was selected as the experimental algae species in this study. The effects of single and combined exposure of O-LDH and MO on growth inhibition, chlorophyll content and cell structure of C. vulgaris were investigated. The adsorption and toxicity mechanism of O-LDH and MO on C. vulgaris were investigated by measuring residual MO concentration and cell surface potential of algae. The results were as follows:1) the fitting results of 96 h growth inhibition rate of algae by O-LDH and MO were in accordance with the Logistic model (R2>0.99), the EC50-96h values were 122.18, 26.73 mg/L, respectively, and the inhibition effect of MO on C. vulgaris was greater than that of O-LDH. 2) the toxicity mechanisms of O-LDH to C. vulgaris included the shading effect caused by the aggregation of nanolamellae on the surface of microalgae cells and the oxidative damage caused by the fragmentation of cell structure by nanolamellae. 3) at low concentrations of O-LDH (0~50 mg/L), O-LDH in the solution was strongly adsorbed by microalgal cells, resulting in enhanced combined toxicity of O-LDH and MO to C. vulgaris. At high concentrations of O-LDH (50~500 mg/L), O-LDH and the products of MO adsorbed by O-LDH in the solution competed for charge sites on the surface of microalgal cells, and the hydrophobic layer was formed on the surface of O-LDH after adsorbing MO, which weakened the shadow effect of O-LDH on microalgae cells and reduced oxidative damage, leading to weakened combined toxicity of O-LDH and MO to C. vulgaris.
2023, 41(1): 35-41.
doi: 10.13205/j.hjgc.202301005
Abstract:
The allelopathic substance artemisinin has been proven to be effective in controlling cyanobacterial blooms. In order to explore whether the stress of artemisinin on Microcystis aeruginosa is affected by salinity, we studied the effects of artemisinin on the growth, chlorophyll-a content, and chlorophyll fluorescence parameters of Microcystis aeruginosa under different salinity conditions (0~15‰). The results showed that Microcystis aeruginosa had a certain salinity adaptability. Salinity of 5‰ could promote the growth, but the salinity above 10‰ had a significant inhibitory effect on the growth of Microcystis aeruginosa. After the addition of artemisinin, the promoting effect of low salinity on algae disappeared, the salinity strengthened the inhibition of artemisinin on Microcystis aeruginosa and the damage to the photosynthetic system, which was reflected in the destruction of photosynthetic pigments and photosynthetic structure, the reduction of photosynthetic reaction center activity, and the decreasing of electron transport capacity of PSⅡ receptor side. The research results could provide reference for the application of artemisinin in brackish water.
The allelopathic substance artemisinin has been proven to be effective in controlling cyanobacterial blooms. In order to explore whether the stress of artemisinin on Microcystis aeruginosa is affected by salinity, we studied the effects of artemisinin on the growth, chlorophyll-a content, and chlorophyll fluorescence parameters of Microcystis aeruginosa under different salinity conditions (0~15‰). The results showed that Microcystis aeruginosa had a certain salinity adaptability. Salinity of 5‰ could promote the growth, but the salinity above 10‰ had a significant inhibitory effect on the growth of Microcystis aeruginosa. After the addition of artemisinin, the promoting effect of low salinity on algae disappeared, the salinity strengthened the inhibition of artemisinin on Microcystis aeruginosa and the damage to the photosynthetic system, which was reflected in the destruction of photosynthetic pigments and photosynthetic structure, the reduction of photosynthetic reaction center activity, and the decreasing of electron transport capacity of PSⅡ receptor side. The research results could provide reference for the application of artemisinin in brackish water.
2023, 41(1): 42-50.
doi: 10.13205/j.hjgc.202301006
Abstract:
To explore the research progress, hot spots and future development trend of sediment microplastics, taking the core collection of Web of Science and the literature of CNKI (China National Knowledge Network) as data sources, the visual analysis was carried out from the aspects of annual publication volume, author group, publication organization, keyword clustering and emergence using the citespace knowledge map analysis tool. The results showed that the researches on sediment microplastics were in a rapid development stage, and the main feature was the rapid growth of foreign literatures. China's researches in this field had important international influence, and the number of papers published ranks first. The number of papers published by the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences, and East China Normal University ranks in the top three. The author group analysis showed the characteristics of many and scattered, and the author with the highest number of papers was from the Chinese Academy of Sciences. The results of keyword cluster analysis and emergent word analysis indicated that the current researches on microplastics in sediments mainly focused on the quantitative methods, biological intake and enrichment of microplastics in marine sediments, while the unified quantitative analysis methods of microplastics in freshwater sediments, the toxic effect of microplastics on organisms and their combined toxic effect with the typical pollutants will be important directions and hotspots for future research.
To explore the research progress, hot spots and future development trend of sediment microplastics, taking the core collection of Web of Science and the literature of CNKI (China National Knowledge Network) as data sources, the visual analysis was carried out from the aspects of annual publication volume, author group, publication organization, keyword clustering and emergence using the citespace knowledge map analysis tool. The results showed that the researches on sediment microplastics were in a rapid development stage, and the main feature was the rapid growth of foreign literatures. China's researches in this field had important international influence, and the number of papers published ranks first. The number of papers published by the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences, and East China Normal University ranks in the top three. The author group analysis showed the characteristics of many and scattered, and the author with the highest number of papers was from the Chinese Academy of Sciences. The results of keyword cluster analysis and emergent word analysis indicated that the current researches on microplastics in sediments mainly focused on the quantitative methods, biological intake and enrichment of microplastics in marine sediments, while the unified quantitative analysis methods of microplastics in freshwater sediments, the toxic effect of microplastics on organisms and their combined toxic effect with the typical pollutants will be important directions and hotspots for future research.
2023, 41(1): 51-60.
doi: 10.13205/j.hjgc.202301007
Abstract:
Hanshiqiao Wetland Nature Reserve plays an essential role in water conservation, local climate regulation, and biodiversity protection of Beijing. In recent years, as the warming-drying trend and urbanization become remarkable in North China, Hanshiqiao Wetland faces severe water shortage problems, causing severe degradation of the ecology. Due to the implementation of water delivery projects such as the South-to-North Water Diversion Project, the shortage of water resources in Beijing has been effectively erased, making the supplement project of ecological water in the Hanshiqiao Wetland possible. However, formulating a scientific, efficient, and sustainable supplement plan is still an urgent problem, where the characteristics of the ecological water system network and needs of biodiversity in the Hanshiqiao Wetland should be considered. Based on observation data and field measurement results, this paper explored and determined the optimum water level of wetlands and the corresponding supplement project of ecological water from 3 perspectives:wetland water area, suitable habitat for reeds, and hydrological connectivity. The results showed that the water level must be at least 25.7 m to maintain the normal ecological function, and the optimum water level was 26.2 m. If the wetland water level exceeded the optimum water level, the effectiveness of the supplement project would gradually decrease and then become stable. Furtherly, we simulated the hydrodynamic process of the wetland by the MIKE21 model under four scenarios. Then, we explored the influence of different water supplement projects on the hydrodynamic process of the Hanshiqiao Wetland. We found that the hydrodynamic behavior of the north part got significantly improved, under the water replenishment scenario from the single route, however, the average velocity of the entire wetland did not markedly improve. The hydrodynamic behavior at the entrance of two replenishment routes and the entire wetland was improved. When the water replenishment was conducted by three divided routes, the hydrodynamic behavior was distributed more evenly. The research results provide necessary theoretical support for improving the efficiency of ecological water supplements and promoting the sustainable development of the wetland ecosystem in the Hanshiqiao Wetland Reserve.
Hanshiqiao Wetland Nature Reserve plays an essential role in water conservation, local climate regulation, and biodiversity protection of Beijing. In recent years, as the warming-drying trend and urbanization become remarkable in North China, Hanshiqiao Wetland faces severe water shortage problems, causing severe degradation of the ecology. Due to the implementation of water delivery projects such as the South-to-North Water Diversion Project, the shortage of water resources in Beijing has been effectively erased, making the supplement project of ecological water in the Hanshiqiao Wetland possible. However, formulating a scientific, efficient, and sustainable supplement plan is still an urgent problem, where the characteristics of the ecological water system network and needs of biodiversity in the Hanshiqiao Wetland should be considered. Based on observation data and field measurement results, this paper explored and determined the optimum water level of wetlands and the corresponding supplement project of ecological water from 3 perspectives:wetland water area, suitable habitat for reeds, and hydrological connectivity. The results showed that the water level must be at least 25.7 m to maintain the normal ecological function, and the optimum water level was 26.2 m. If the wetland water level exceeded the optimum water level, the effectiveness of the supplement project would gradually decrease and then become stable. Furtherly, we simulated the hydrodynamic process of the wetland by the MIKE21 model under four scenarios. Then, we explored the influence of different water supplement projects on the hydrodynamic process of the Hanshiqiao Wetland. We found that the hydrodynamic behavior of the north part got significantly improved, under the water replenishment scenario from the single route, however, the average velocity of the entire wetland did not markedly improve. The hydrodynamic behavior at the entrance of two replenishment routes and the entire wetland was improved. When the water replenishment was conducted by three divided routes, the hydrodynamic behavior was distributed more evenly. The research results provide necessary theoretical support for improving the efficiency of ecological water supplements and promoting the sustainable development of the wetland ecosystem in the Hanshiqiao Wetland Reserve.
2023, 41(1): 61-71.
doi: 10.13205/j.hjgc.202301008
Abstract:
Wetlands have important ecological service functions including water conservation, but they shrink and degenerate under the multiple stresses of human activities and climate change, and the insufficient water supply of wetlands is one of the main ecological problems. With the implementation and operation of trans-regional and trans-basin water transfer projects, ecological water replenishment has become a key technology component of wetland restoration and water resource allocation. Therefore, we should pay attention to the optimization of the water supply path of the wetland with multiple water sources, and propose the optimization scheme of the ecological water supply mode based on the hydrodynamic process of the wetland water supply. Under the background that the whole Chaobai River basin will be open to water in 2021, taking the only large reed marsh wetland in Beijing-Hanshiqiao Wetland as the case area, the SWAT model of the Chaobai River basin is constructed to simulate the runoff change rule, and the MIKE21 model is used to simulate the wetland water replenishment-hydrodynamic coupling process, and the hydrodynamic change characteristics of six wetland water replenishing scenarios are compared. The results show that the separation between the south and the north of the wetland caused by the blocked connection of the internal water system of the Hanshiqiao Wetland is the main bottleneck limiting the efficiency of ecological water replenishment. The simultaneous water replenishment of multiple flow paths in the north and south areas of the wetland, as well as the reconstruction of the wetland hydrological connection structure, are the optimal schemes to improve the hydrodynamic conditions of water replenishment and enhance the ecological water replenishment effect. The research conclusion can provide reference for long-term management and ecological restoration of wetlands, and is conducive to the construction of ecological water system in the capital city.
Wetlands have important ecological service functions including water conservation, but they shrink and degenerate under the multiple stresses of human activities and climate change, and the insufficient water supply of wetlands is one of the main ecological problems. With the implementation and operation of trans-regional and trans-basin water transfer projects, ecological water replenishment has become a key technology component of wetland restoration and water resource allocation. Therefore, we should pay attention to the optimization of the water supply path of the wetland with multiple water sources, and propose the optimization scheme of the ecological water supply mode based on the hydrodynamic process of the wetland water supply. Under the background that the whole Chaobai River basin will be open to water in 2021, taking the only large reed marsh wetland in Beijing-Hanshiqiao Wetland as the case area, the SWAT model of the Chaobai River basin is constructed to simulate the runoff change rule, and the MIKE21 model is used to simulate the wetland water replenishment-hydrodynamic coupling process, and the hydrodynamic change characteristics of six wetland water replenishing scenarios are compared. The results show that the separation between the south and the north of the wetland caused by the blocked connection of the internal water system of the Hanshiqiao Wetland is the main bottleneck limiting the efficiency of ecological water replenishment. The simultaneous water replenishment of multiple flow paths in the north and south areas of the wetland, as well as the reconstruction of the wetland hydrological connection structure, are the optimal schemes to improve the hydrodynamic conditions of water replenishment and enhance the ecological water replenishment effect. The research conclusion can provide reference for long-term management and ecological restoration of wetlands, and is conducive to the construction of ecological water system in the capital city.
2023, 41(1): 72-78.
doi: 10.13205/j.hjgc.202301009
Abstract:
To improve the accuracy of the water quality evaluation results, and reflect the quality status of the water environment more objectively, for the performance of support vector machines (SVM) is susceptible to the model parameters, this study presented an algorithm based on optimized SVM by krill clusters (krill herd, KH), and combined it with the surface water environmental quality standards. Five representative water quality indicators were selected as the input of the model, and five water quality standards were selected as the output. A water quality evaluation model based on KH-SVM as established, and the model was used to study the water quality status and change trend of the Poyang Lake in the high flow period, normal flow period and low flow period from 2013 to 2018. The results showed that the water quality of the Poyang Lake was basically maintained between category Ⅲ and Ⅳ Environment Quality Standard for Surface Water (GB 3838-2002), while it fluctuated greatly in each period, including mostly Ⅱ types and Ⅴ types in the wet season from 2013 to 2018, at the non-optimal level. The KH-SVM model performs well compared with the traditional evaluation method, and can reflect the water quality more accurately and objectively. The research results can provide a scientific basis for the scientific management of regional surface water resources and water environment protection. The results showed that the water quality in the North Lake area of the Poyang Lake was basically maintained between Class Ⅲ and Class Ⅳ, while the water quality in the South Lake area fluctuated greatly in different periods, with Class Ⅱ water in the high flow period and Class Ⅴ water in the normal and low flow periods. On the whole, the deterioration trend of the water quality in the Poyang Lake from 2013 to 2018 had not improved significantly, and the water quality level was still at the non-optimal level. The constructed KH-SVM model had a good performance. Compared with the traditional assessment methods, it could better realize the comprehensive assessment of water quality, and reflect the water quality status as a whole. The research can provide a scientific basis for the scientific management of regional surface water resources and water environment protection.
To improve the accuracy of the water quality evaluation results, and reflect the quality status of the water environment more objectively, for the performance of support vector machines (SVM) is susceptible to the model parameters, this study presented an algorithm based on optimized SVM by krill clusters (krill herd, KH), and combined it with the surface water environmental quality standards. Five representative water quality indicators were selected as the input of the model, and five water quality standards were selected as the output. A water quality evaluation model based on KH-SVM as established, and the model was used to study the water quality status and change trend of the Poyang Lake in the high flow period, normal flow period and low flow period from 2013 to 2018. The results showed that the water quality of the Poyang Lake was basically maintained between category Ⅲ and Ⅳ Environment Quality Standard for Surface Water (GB 3838-2002), while it fluctuated greatly in each period, including mostly Ⅱ types and Ⅴ types in the wet season from 2013 to 2018, at the non-optimal level. The KH-SVM model performs well compared with the traditional evaluation method, and can reflect the water quality more accurately and objectively. The research results can provide a scientific basis for the scientific management of regional surface water resources and water environment protection. The results showed that the water quality in the North Lake area of the Poyang Lake was basically maintained between Class Ⅲ and Class Ⅳ, while the water quality in the South Lake area fluctuated greatly in different periods, with Class Ⅱ water in the high flow period and Class Ⅴ water in the normal and low flow periods. On the whole, the deterioration trend of the water quality in the Poyang Lake from 2013 to 2018 had not improved significantly, and the water quality level was still at the non-optimal level. The constructed KH-SVM model had a good performance. Compared with the traditional assessment methods, it could better realize the comprehensive assessment of water quality, and reflect the water quality status as a whole. The research can provide a scientific basis for the scientific management of regional surface water resources and water environment protection.
2023, 41(1): 79-86.
doi: 10.13205/j.hjgc.202301010
Abstract:
To address the problem of flooding caused by the poor drainage capacity of the river network in the southern plain during the flood season, this study selected the river network of Shenzhuangyang polder in Nanxun district of Taihu Lake basin as the research object, and the storm intensity of the corresponding flood control standard for urban drainage, applied the multi-objective dynamic planning theory, took the water level and drainage time of the river network as the limiting target, combined the existing water conservancy engineering parameters and scheduling rules in the polder area, and set up three sluice gates based on the topographic and hydrological data of the river network. A MIKE21 river network hydrodynamic model was constructed to quantitatively simulate and analyze the drainage effect of the river network under the joint regulation and control of the gates and pumps. The results showed that:when facing a rainstorm with a returning period of 10 years or less, the river network could adopt the sluice gate drainage scheme, and all three schemes could reduce the water level to the lower limit of drainage within 24 h; when facing a rainstorm with a returning period of more than 20 years to one hundred years, the river network needed to adopt the pump drainage scheme of internal and external network linkage. Except in the case of 1 pump at the western gate, which does not meet the 100-year drainage requirement, at least 2 pumps at the western gate must be opened to ensure that the water level is lowered to the lower limit within 24h, The drainage effect is positively related to the number of pumps on The results of the study can provide a theoretical basis for the scheduling of flooding and the renovation of river networks in the southern plain. The results of the study can provide a theoretical basis for flood drainage scheduling and river network renovation in the southern plain river network.
To address the problem of flooding caused by the poor drainage capacity of the river network in the southern plain during the flood season, this study selected the river network of Shenzhuangyang polder in Nanxun district of Taihu Lake basin as the research object, and the storm intensity of the corresponding flood control standard for urban drainage, applied the multi-objective dynamic planning theory, took the water level and drainage time of the river network as the limiting target, combined the existing water conservancy engineering parameters and scheduling rules in the polder area, and set up three sluice gates based on the topographic and hydrological data of the river network. A MIKE21 river network hydrodynamic model was constructed to quantitatively simulate and analyze the drainage effect of the river network under the joint regulation and control of the gates and pumps. The results showed that:when facing a rainstorm with a returning period of 10 years or less, the river network could adopt the sluice gate drainage scheme, and all three schemes could reduce the water level to the lower limit of drainage within 24 h; when facing a rainstorm with a returning period of more than 20 years to one hundred years, the river network needed to adopt the pump drainage scheme of internal and external network linkage. Except in the case of 1 pump at the western gate, which does not meet the 100-year drainage requirement, at least 2 pumps at the western gate must be opened to ensure that the water level is lowered to the lower limit within 24h, The drainage effect is positively related to the number of pumps on The results of the study can provide a theoretical basis for the scheduling of flooding and the renovation of river networks in the southern plain. The results of the study can provide a theoretical basis for flood drainage scheduling and river network renovation in the southern plain river network.
2023, 41(1): 87-92,104.
doi: 10.13205/j.hjgc.202301011
Abstract:
To reveal the impact of reclaimed water supplement on the spatial distribution characteristics of nutrients in Hanshiqiao wetland sediments, 25 samples of surface sediments and 3 samples of core sediments were collected to explore the spatial and vertical distribution characteristics and stoichiometric characteristics of total organic matter (OM), total nitrogen (TN) and total phosphorus (TP). The results showed that:the average OM, TN and TP contents in the surface sediments in Hanshiqiao wetland were 70.65, 4.72, 0.96 g/kg, respectively, which were significantly higher than those in other wetlands. The contents of OM and TN were higher in the midstream and downstream than that in the upstream, while TP was evenly distributed in the whole wetland. In vertical direction, the content of OM, TN, and TP was the highest in the surface layer of sediment (0~10 cm), and showed a tendency of decreasing first and then gradually stabilizing with the increase of sediment profile depth, indicating the risk of C, N, P in surface sediment releasing to the overlying water. Stoichiometric characteristics indicated that there were significant positive correlations between OM, TN and TP in surface sediments (P<0.01). The comprehensive pollution evaluation and organic pollution evaluation showed that the whole wetland was in moderate to severe pollution level. The reclaimed water supplement intensified the accumulation of nutrients in the wetland sediments. The spatial distribution of nutrients in the wetland sediments was affected by the residual concentration of nutrients in the recharge water, hydrodynamic conditions and the wetland topographic features. In the areas with slow water flow and mostly stagnant water, the nutrient content in the sediments increased significantly. The replenishment of reclaimed water was an important driving force for wetland eutrophication.
To reveal the impact of reclaimed water supplement on the spatial distribution characteristics of nutrients in Hanshiqiao wetland sediments, 25 samples of surface sediments and 3 samples of core sediments were collected to explore the spatial and vertical distribution characteristics and stoichiometric characteristics of total organic matter (OM), total nitrogen (TN) and total phosphorus (TP). The results showed that:the average OM, TN and TP contents in the surface sediments in Hanshiqiao wetland were 70.65, 4.72, 0.96 g/kg, respectively, which were significantly higher than those in other wetlands. The contents of OM and TN were higher in the midstream and downstream than that in the upstream, while TP was evenly distributed in the whole wetland. In vertical direction, the content of OM, TN, and TP was the highest in the surface layer of sediment (0~10 cm), and showed a tendency of decreasing first and then gradually stabilizing with the increase of sediment profile depth, indicating the risk of C, N, P in surface sediment releasing to the overlying water. Stoichiometric characteristics indicated that there were significant positive correlations between OM, TN and TP in surface sediments (P<0.01). The comprehensive pollution evaluation and organic pollution evaluation showed that the whole wetland was in moderate to severe pollution level. The reclaimed water supplement intensified the accumulation of nutrients in the wetland sediments. The spatial distribution of nutrients in the wetland sediments was affected by the residual concentration of nutrients in the recharge water, hydrodynamic conditions and the wetland topographic features. In the areas with slow water flow and mostly stagnant water, the nutrient content in the sediments increased significantly. The replenishment of reclaimed water was an important driving force for wetland eutrophication.
2023, 41(1): 93-104.
doi: 10.13205/j.hjgc.202301012
Abstract:
The hydrodynamic process plays an important role in regulating the structure and functioning of the wetland ecosystem. Therefore, obtaining the hydrodynamic parameters accurately and efficiently is of great significance for wetland research and the protection and restoration of the wetland ecosystem. Given the advantage of high flexibility, strong adaptability to weather conditions, simplicity in operation, and ability to acquire data at a low flight height, the unmanned aerial vehicle (UAV) technology, has been widely used as an efficient and non-contact way to monitor wetland hydrodynamics in recent years. To provide references for hydrodynamic investigation and its application in future wetland protection management, the present study summarized the recent progress and limitation of UAV technology in wetland hydrodynamic research. Water level, bathymetry (water depth), and velocity (discharge), the three main parameters in the hydrodynamic investigation, were reviewed in this study. For the future requirements of wetland management, we proposed that high standardization and automatic monitoring are the key development direction for future UAV-based hydrodynamic investigation. In addition, to construct the digital twin wetland and enhance intelligent and information-based wetland protection and management, how to improve the detecting efficiency, data transmission efficiency of UAV and combine the UAV-based data with multi-platform data should receive more attention.
The hydrodynamic process plays an important role in regulating the structure and functioning of the wetland ecosystem. Therefore, obtaining the hydrodynamic parameters accurately and efficiently is of great significance for wetland research and the protection and restoration of the wetland ecosystem. Given the advantage of high flexibility, strong adaptability to weather conditions, simplicity in operation, and ability to acquire data at a low flight height, the unmanned aerial vehicle (UAV) technology, has been widely used as an efficient and non-contact way to monitor wetland hydrodynamics in recent years. To provide references for hydrodynamic investigation and its application in future wetland protection management, the present study summarized the recent progress and limitation of UAV technology in wetland hydrodynamic research. Water level, bathymetry (water depth), and velocity (discharge), the three main parameters in the hydrodynamic investigation, were reviewed in this study. For the future requirements of wetland management, we proposed that high standardization and automatic monitoring are the key development direction for future UAV-based hydrodynamic investigation. In addition, to construct the digital twin wetland and enhance intelligent and information-based wetland protection and management, how to improve the detecting efficiency, data transmission efficiency of UAV and combine the UAV-based data with multi-platform data should receive more attention.
2023, 41(1): 105-111.
doi: 10.13205/j.hjgc.202301013
Abstract:
This research aims at the demand for wetland ecology protection and restoration in Wuhan under the background of fast development of urbanization to reveal the spatio-temporal evolution law and key driving mechanism of wetlands. In this study, we first analyzed the spatiotemporal dynamics and driving processes trajectories of change of wetland landscape pattern in Wuhan from 1980 to 2020, and used the InVEST model to simulate the spatiotemporal changes in those key ecosystem services of the wetlands. The results showed that the ecosystem services of habitat quality, carbon storage, flood regulation, and landscape culture of Wuhan decreased by 17.75%, 2.28%, 0.49%, and 4.10% by 2020. Single human driving process trajectories of fishery breeding and reclamation led to damage to natural wetlands, while rehabilitation measures of returning farmland to wetlands contributed to the improvement of ecosystem services. Reclamation was the main driving process that decreased flood regulation and habitat quality services, and the core driving process that decreased carbon storage functions and landscape cultural functions was fishery breeding. The research identified the threats to wetland ecosystems to propose long-term wetland protection countermeasures and planning.
This research aims at the demand for wetland ecology protection and restoration in Wuhan under the background of fast development of urbanization to reveal the spatio-temporal evolution law and key driving mechanism of wetlands. In this study, we first analyzed the spatiotemporal dynamics and driving processes trajectories of change of wetland landscape pattern in Wuhan from 1980 to 2020, and used the InVEST model to simulate the spatiotemporal changes in those key ecosystem services of the wetlands. The results showed that the ecosystem services of habitat quality, carbon storage, flood regulation, and landscape culture of Wuhan decreased by 17.75%, 2.28%, 0.49%, and 4.10% by 2020. Single human driving process trajectories of fishery breeding and reclamation led to damage to natural wetlands, while rehabilitation measures of returning farmland to wetlands contributed to the improvement of ecosystem services. Reclamation was the main driving process that decreased flood regulation and habitat quality services, and the core driving process that decreased carbon storage functions and landscape cultural functions was fishery breeding. The research identified the threats to wetland ecosystems to propose long-term wetland protection countermeasures and planning.
2023, 41(1): 112-119.
doi: 10.13205/j.hjgc.202301014
Abstract:
In order to clarify the harmful degree of heavy metal pollution in the surface river water under the influence of pyrite, we took Chu River, a tributary of Han River, as the research object, and then selected the sections from the pyrite mining area to the entrance of Chu River into Ren River, to study the distribution characteristics of Fe, Mn, Cu, Zn, Cd and Cr in river water during different water periods. In addition, the health risk assessment model was used to evaluate the health risk of heavy metals in surface water in the two seasons. The results showed that:there were significant spatial and temporal differences in the distribution of heavy metals in rivers. In terms of time, excessive Fe and Cr existed in the dry season. Heavy metals were diluted in the river during the wet season, and the change in the river water environment led to the migration and transformation of heavy metals, so the overall water quality was improved. Spatially, affected by the distance from the mining area and rainy season, the concentration in the middle and upper reaches increased significantly when it was close to the mining area, and the influence of human activities downstream was also significant. The results of the health risk assessment showed that there was a non-carcinogenic risk in the middle reaches of the river in dry season. The order of non-carcinogenic risk of heavy metals was Cr>Cd>Fe>Cu>Mn>Zn. Heavy metal Cr had a significant carcinogenic risk to human body, and Cd had a significant carcinogenic risk to children in dry season. The study puts forward definite measures and suggestions to enhance the mine and river environment.
In order to clarify the harmful degree of heavy metal pollution in the surface river water under the influence of pyrite, we took Chu River, a tributary of Han River, as the research object, and then selected the sections from the pyrite mining area to the entrance of Chu River into Ren River, to study the distribution characteristics of Fe, Mn, Cu, Zn, Cd and Cr in river water during different water periods. In addition, the health risk assessment model was used to evaluate the health risk of heavy metals in surface water in the two seasons. The results showed that:there were significant spatial and temporal differences in the distribution of heavy metals in rivers. In terms of time, excessive Fe and Cr existed in the dry season. Heavy metals were diluted in the river during the wet season, and the change in the river water environment led to the migration and transformation of heavy metals, so the overall water quality was improved. Spatially, affected by the distance from the mining area and rainy season, the concentration in the middle and upper reaches increased significantly when it was close to the mining area, and the influence of human activities downstream was also significant. The results of the health risk assessment showed that there was a non-carcinogenic risk in the middle reaches of the river in dry season. The order of non-carcinogenic risk of heavy metals was Cr>Cd>Fe>Cu>Mn>Zn. Heavy metal Cr had a significant carcinogenic risk to human body, and Cd had a significant carcinogenic risk to children in dry season. The study puts forward definite measures and suggestions to enhance the mine and river environment.
2023, 41(1): 120-131.
doi: 10.13205/j.hjgc.202301015
Abstract:
In order to solve the multi-attribute complex decision-making problems of water environmental carrying capacity in the Baiyangdian Lake Basin, a five-dimensional complex property decision-making index evaluation system based on population, economy, water ecology, water resources and water pollution was proposed in this study (includes 28 indicators). The ideal point method based on the new dominance relationship (TOPSIS), vlse kriterijumska optimizacija I kompromisno resenje method (VIKOR) and improved osculating value method was applied to the optimization of the multi-attribute decision-making method and scheme selection of the water environmental carrying capacity in the Baiyangdian Lake Basin. The results showed that:1) the variation coefficient attribute weighting method realized the quantification of multi-level and complex factors affecting water environmental carrying capacity, and we found that the main factors affecting the water environmental carrying capacity of the Baiyangdian Lake Basin were the amount of groundwater resources, the proportion of paper making and paper products industry, the proportion of textile industry, and the amount of water transferred into the lake. 2) Among the three multi-attribute decision-making methods, the improved osculating value method was simpler in calculation and theory, so it was the optimal decision method. It could not only deal with the multifaceted complex properties such as economic, social, environmental and technical standards involved in the decision-making of water environmental carrying capacity management, but also better realize the evaluation and optimization of multi-attribute decision-making scheme of water environmental carrying capacity. 3) The consistency of scheme ranking results of the three methods reached 83.3%, indicating that the optimal scheme was the ideal type scheme (F12), the sub-optimal scheme was the sustainable type scheme (F11), and the worst scheme was the low-speed economic development scheme (F2). Considering the actual situation of the Baiyangdian Lake Basin, the scale of the primary and secondary industries can be appropriately reduced in 2030. Tertiary industries such as high-end, high-tech industries and service industries should be vigorously developed, and the eco-tourism should be appropriately developed. In addition, it was essential to upgrade or close down industries with high water consumption and heavy pollution such as textiles, paper making and paper products within a specified period of time, increase the amount of water diverted from other regions, and implement stricter water environmental protection measures such as raising the standard of sewage treatment plant's effluent to level Ⅳ of GB 3838-2002 Environmental Quality Standards for Surface Water when necessary, in order to achieve the purpose of improving the environment, which can provide a basis for managers to make efficient decisions.
In order to solve the multi-attribute complex decision-making problems of water environmental carrying capacity in the Baiyangdian Lake Basin, a five-dimensional complex property decision-making index evaluation system based on population, economy, water ecology, water resources and water pollution was proposed in this study (includes 28 indicators). The ideal point method based on the new dominance relationship (TOPSIS), vlse kriterijumska optimizacija I kompromisno resenje method (VIKOR) and improved osculating value method was applied to the optimization of the multi-attribute decision-making method and scheme selection of the water environmental carrying capacity in the Baiyangdian Lake Basin. The results showed that:1) the variation coefficient attribute weighting method realized the quantification of multi-level and complex factors affecting water environmental carrying capacity, and we found that the main factors affecting the water environmental carrying capacity of the Baiyangdian Lake Basin were the amount of groundwater resources, the proportion of paper making and paper products industry, the proportion of textile industry, and the amount of water transferred into the lake. 2) Among the three multi-attribute decision-making methods, the improved osculating value method was simpler in calculation and theory, so it was the optimal decision method. It could not only deal with the multifaceted complex properties such as economic, social, environmental and technical standards involved in the decision-making of water environmental carrying capacity management, but also better realize the evaluation and optimization of multi-attribute decision-making scheme of water environmental carrying capacity. 3) The consistency of scheme ranking results of the three methods reached 83.3%, indicating that the optimal scheme was the ideal type scheme (F12), the sub-optimal scheme was the sustainable type scheme (F11), and the worst scheme was the low-speed economic development scheme (F2). Considering the actual situation of the Baiyangdian Lake Basin, the scale of the primary and secondary industries can be appropriately reduced in 2030. Tertiary industries such as high-end, high-tech industries and service industries should be vigorously developed, and the eco-tourism should be appropriately developed. In addition, it was essential to upgrade or close down industries with high water consumption and heavy pollution such as textiles, paper making and paper products within a specified period of time, increase the amount of water diverted from other regions, and implement stricter water environmental protection measures such as raising the standard of sewage treatment plant's effluent to level Ⅳ of GB 3838-2002 Environmental Quality Standards for Surface Water when necessary, in order to achieve the purpose of improving the environment, which can provide a basis for managers to make efficient decisions.
2023, 41(1): 132-140,163.
doi: 10.13205/j.hjgc.202301016
Abstract:
The development of tourism should pay attention to the coordination and order of ecology and social economy. Ecotourism takes into account regional economic development and ecological protection, conforms to the development strategy of efficient ecological economy, and is an important part of the industrial structure of the efficient ecological economic zone in the Yellow River Delta. However, tourism started late and developed slowly in the efficient ecological economic zone of the Yellow River Delta. At the same time, the fragile ecological environment and reclamation activities make the importance of ecological protection in tourism development and tourism activities of this region particularly prominent. This study evaluated the ecological, spatial, facility and social environmental carrying capacities by building a multi-level evaluation model of tourism environmental carrying capacity and relying on the minimum limiting factor method, in order to identify the major limiting factors of the tourism environmental carrying capacity of the study area and to diagnose the major issues affecting the carrying capacity of the area. The result showed that:1) the tourism carrying capacity between 1995 and 2020 was severely overloaded, and the tourism environmental capacity of the high-efficiency ecological economic zone in the Yellow River Delta increased from -2885700 people per day to 116000 people per day in 2020. 2) Sewage treatment was the minimum limiting factor in 1995, and transportation facilities was the minimum limiting factor in 2020. Only the two indicators were overloaded, other indicators were weak load; all other indications were either not loaded or only slightly loaded. 3) In 1995, the carrying capacity of tourism environment was mainly limited by the capacity of ecological environment, while in 2020, space>social>ecological>facilities were the secondary indicators of the Yellow River Delta's high-efficiency ecological economic zone's environmental capacity. 4) The overcrowding of tourism facilities in the Yellow Delta contradicted the underutilization of resources and the weak loading of the ecological and spatial environments, including wetland ecological indicators. However, there was still enough of potential for tourist expansion from appropriate loading. The carrying capacity of the biological environment had decreased during the past 25 years, despite a general increase in the capacity of the tourism environment due to a more rapid increase in visitor numbers. In this paper, we clarified the tourism development space that wetland ecology could support, identified the main limiting factors of tourism development, and analyzed the tourism development status of high-efficiency ecological economic zones in the Yellow River Delta from the perspective of tourism environmental carrying capacity. The research results also provided scientific basis and data support for solving the problem of environmental overload and weak load, realizing the rational use of resources and promoting the orderly and coordinated development of regional eco-economy.
The development of tourism should pay attention to the coordination and order of ecology and social economy. Ecotourism takes into account regional economic development and ecological protection, conforms to the development strategy of efficient ecological economy, and is an important part of the industrial structure of the efficient ecological economic zone in the Yellow River Delta. However, tourism started late and developed slowly in the efficient ecological economic zone of the Yellow River Delta. At the same time, the fragile ecological environment and reclamation activities make the importance of ecological protection in tourism development and tourism activities of this region particularly prominent. This study evaluated the ecological, spatial, facility and social environmental carrying capacities by building a multi-level evaluation model of tourism environmental carrying capacity and relying on the minimum limiting factor method, in order to identify the major limiting factors of the tourism environmental carrying capacity of the study area and to diagnose the major issues affecting the carrying capacity of the area. The result showed that:1) the tourism carrying capacity between 1995 and 2020 was severely overloaded, and the tourism environmental capacity of the high-efficiency ecological economic zone in the Yellow River Delta increased from -2885700 people per day to 116000 people per day in 2020. 2) Sewage treatment was the minimum limiting factor in 1995, and transportation facilities was the minimum limiting factor in 2020. Only the two indicators were overloaded, other indicators were weak load; all other indications were either not loaded or only slightly loaded. 3) In 1995, the carrying capacity of tourism environment was mainly limited by the capacity of ecological environment, while in 2020, space>social>ecological>facilities were the secondary indicators of the Yellow River Delta's high-efficiency ecological economic zone's environmental capacity. 4) The overcrowding of tourism facilities in the Yellow Delta contradicted the underutilization of resources and the weak loading of the ecological and spatial environments, including wetland ecological indicators. However, there was still enough of potential for tourist expansion from appropriate loading. The carrying capacity of the biological environment had decreased during the past 25 years, despite a general increase in the capacity of the tourism environment due to a more rapid increase in visitor numbers. In this paper, we clarified the tourism development space that wetland ecology could support, identified the main limiting factors of tourism development, and analyzed the tourism development status of high-efficiency ecological economic zones in the Yellow River Delta from the perspective of tourism environmental carrying capacity. The research results also provided scientific basis and data support for solving the problem of environmental overload and weak load, realizing the rational use of resources and promoting the orderly and coordinated development of regional eco-economy.
2023, 41(1): 141-148.
doi: 10.13205/j.hjgc.202301017
Abstract:
This research is intended to study the effect of waves on the release of settling hydrophobic pollutants, which have been deposited on the riverbed surface after sudden water pollution accidents. Those contaminants will slowly diffuse from the riverbed into the overlying water body through hydrodynamic action, causing ongoing and serious water pollution. By taking dichloromethane as a typical contaminant, the response relationship between the release strength and wave elements (wave height, wave period) were analyzed through flume experiments. The mathematical regression model between the release flux and wave dynamics factors were established. The results suggested that wave disturbance caused the obvious release of settling hydrophobic pollutants. The TVC of suspended particles in DCM increased with the increase of wave height and decreases with the increase of wave period. For the same wave period, there was a significant exponential positive correlation between the release flux and wave height (R2>0.973). For the same wave height, there was a significant logarithmic negative correlation between the release flux and the wave period (R2>0.967). Besides, the mathematical relationships between the release flux and wave dynamic factors were established. Thus, this study offered a solution to solve the source term quantification problem of the differential equation of convective diffusion, which can provide the basis for further developing the mathematical models of these pollutants.
This research is intended to study the effect of waves on the release of settling hydrophobic pollutants, which have been deposited on the riverbed surface after sudden water pollution accidents. Those contaminants will slowly diffuse from the riverbed into the overlying water body through hydrodynamic action, causing ongoing and serious water pollution. By taking dichloromethane as a typical contaminant, the response relationship between the release strength and wave elements (wave height, wave period) were analyzed through flume experiments. The mathematical regression model between the release flux and wave dynamics factors were established. The results suggested that wave disturbance caused the obvious release of settling hydrophobic pollutants. The TVC of suspended particles in DCM increased with the increase of wave height and decreases with the increase of wave period. For the same wave period, there was a significant exponential positive correlation between the release flux and wave height (R2>0.973). For the same wave height, there was a significant logarithmic negative correlation between the release flux and the wave period (R2>0.967). Besides, the mathematical relationships between the release flux and wave dynamic factors were established. Thus, this study offered a solution to solve the source term quantification problem of the differential equation of convective diffusion, which can provide the basis for further developing the mathematical models of these pollutants.
2023, 41(1): 149-157.
doi: 10.13205/j.hjgc.202301018
Abstract:
Pudong river system is a typical urban black-odorous water body in Fuzhou, which has been facing with problems such as serious external pollution, accumulation of internal pollution, lack of instream flow, and ecosystem degradation. According to the characteristics of the drainage basin and overall consideration of "water environment, water ecology and water landscape", the technical route of "external pollution control, internal source treatment, improvement of water flow and quality, and ecological restoration" was adopted to solve the problem of Pudong river system. It was estimated that the overflow rate, COD and ammonia nitrogen pollution loads were reduced by 49.9%, 77.0% and 92.2%, respectively. According to the operation data, COD concentration in the Pudong river system was stable under 30 mg/L, and the ammonia nitrogen was stable under 4 mg/L, which showed good treatment results. This paper expounded the design experience and key points in the treatment measures and provided references for the similar urban black-odorous water treatment projects.
Pudong river system is a typical urban black-odorous water body in Fuzhou, which has been facing with problems such as serious external pollution, accumulation of internal pollution, lack of instream flow, and ecosystem degradation. According to the characteristics of the drainage basin and overall consideration of "water environment, water ecology and water landscape", the technical route of "external pollution control, internal source treatment, improvement of water flow and quality, and ecological restoration" was adopted to solve the problem of Pudong river system. It was estimated that the overflow rate, COD and ammonia nitrogen pollution loads were reduced by 49.9%, 77.0% and 92.2%, respectively. According to the operation data, COD concentration in the Pudong river system was stable under 30 mg/L, and the ammonia nitrogen was stable under 4 mg/L, which showed good treatment results. This paper expounded the design experience and key points in the treatment measures and provided references for the similar urban black-odorous water treatment projects.
2023, 41(1): 158-163.
doi: 10.13205/j.hjgc.202301019
Abstract:
In order to realize the dual functions of water purification and flood discharge and drainage in the micro-polluted river, this study constructed a kind of bypass wetland with a downward-upward compound flow process. The main parameters of the project were organic load, hydraulic load and hydraulic retention time, which were 21 kg BOD5/(hm2·d), 0.34 m3/(m2·d), 2.2 d, respectively. At the same time, the project was optimized by the structure of the wetland packing bed, the plant combination and the low-temperature operation measures in winter. The main conclusions were as follows:1) the downward/upward-flow composite functional wetland had a flexible spatial layout. The construction could save the land, and form a good Anaerobic/Anoxic/Aerobic microbial environment, which is conducive to the removal of nitrogen and phosphorus from the wetland system; 2) by adding the covering layer of thermal insulation filler, operating at low water level under low-temperature ice, and strengthening with low temperature-resistant plants/microorganisms, COD concentration, ammonia nitrogen concentration, and total phosphorus concentration of the effluent of the three bidding sections was 20.67 mg/L, 0.77 mg/L,0.17 mg/L, under their influent concentration of 30~40 mg/L, 1.5~2.0 mg/L and 0.3~0.4 mg/L in winter, basically meeting the water quality design goal under low-temperature conditions in winter.
In order to realize the dual functions of water purification and flood discharge and drainage in the micro-polluted river, this study constructed a kind of bypass wetland with a downward-upward compound flow process. The main parameters of the project were organic load, hydraulic load and hydraulic retention time, which were 21 kg BOD5/(hm2·d), 0.34 m3/(m2·d), 2.2 d, respectively. At the same time, the project was optimized by the structure of the wetland packing bed, the plant combination and the low-temperature operation measures in winter. The main conclusions were as follows:1) the downward/upward-flow composite functional wetland had a flexible spatial layout. The construction could save the land, and form a good Anaerobic/Anoxic/Aerobic microbial environment, which is conducive to the removal of nitrogen and phosphorus from the wetland system; 2) by adding the covering layer of thermal insulation filler, operating at low water level under low-temperature ice, and strengthening with low temperature-resistant plants/microorganisms, COD concentration, ammonia nitrogen concentration, and total phosphorus concentration of the effluent of the three bidding sections was 20.67 mg/L, 0.77 mg/L,0.17 mg/L, under their influent concentration of 30~40 mg/L, 1.5~2.0 mg/L and 0.3~0.4 mg/L in winter, basically meeting the water quality design goal under low-temperature conditions in winter.
2023, 41(1): 164-172.
doi: 10.13205/j.hjgc.202301020
Abstract:
In this project, four sectional IVCW column pilot systems with the column depth of 145 cm and 185cm were built for wastewater with a low C/N ratio, to examine the effects of substrate height, the addition of active biomass and nitrogen composition in influent on nitrogen removal efficiency of the system. Results showed when the hydraulic retention time was 1 d, the total nitrogen (TN) removal rate of the four systems was all above 30%, and when the half-way substrate layer was set at 95 cm, the HI group without active biomass added had the highest TN removal rate of 42%; the average removal rates of NH3-N and NO3-N ranged from 20% to 48% and 21% to 66% respectively, while NO2-N was found accumulated in different degrees in each system. With the increase of the proportion of NO3-N in the influent (from 1/7 to 6/7), the removal rate of NO3-N in the influent decreased as a whole, and the removal rate of HI group was more stable than that of the other groups. However, after the depth of the IVCW system was increased, adding active biomass will reduce its TN removal effect. The first stage of the IVCW system, i.e. the upper downflow unit, contributed the most to nitrogen removal, up to 80%; although the effect of enhanced nitrogen removal was not significant among different treatments, there were certain differences in the nitrogen removal pathway in the later stages of the system. Accordingly, the abundance and type of microbial fatty acids were the highest in the first segment, and their fatty acid composition was the most obvious difference from other segments; the anaerobic bacteria marked by cy19:0 gradually occupied the dominant position in the 3 to 4 segments of the upstream flow, and the deepened group was higher than the control; the aerobic bacteria characterized by monounsaturated fatty acids (MUFA) contributed more to the nitrogen removal efficiency of the IVCW system.
In this project, four sectional IVCW column pilot systems with the column depth of 145 cm and 185cm were built for wastewater with a low C/N ratio, to examine the effects of substrate height, the addition of active biomass and nitrogen composition in influent on nitrogen removal efficiency of the system. Results showed when the hydraulic retention time was 1 d, the total nitrogen (TN) removal rate of the four systems was all above 30%, and when the half-way substrate layer was set at 95 cm, the HI group without active biomass added had the highest TN removal rate of 42%; the average removal rates of NH3-N and NO3-N ranged from 20% to 48% and 21% to 66% respectively, while NO2-N was found accumulated in different degrees in each system. With the increase of the proportion of NO3-N in the influent (from 1/7 to 6/7), the removal rate of NO3-N in the influent decreased as a whole, and the removal rate of HI group was more stable than that of the other groups. However, after the depth of the IVCW system was increased, adding active biomass will reduce its TN removal effect. The first stage of the IVCW system, i.e. the upper downflow unit, contributed the most to nitrogen removal, up to 80%; although the effect of enhanced nitrogen removal was not significant among different treatments, there were certain differences in the nitrogen removal pathway in the later stages of the system. Accordingly, the abundance and type of microbial fatty acids were the highest in the first segment, and their fatty acid composition was the most obvious difference from other segments; the anaerobic bacteria marked by cy19:0 gradually occupied the dominant position in the 3 to 4 segments of the upstream flow, and the deepened group was higher than the control; the aerobic bacteria characterized by monounsaturated fatty acids (MUFA) contributed more to the nitrogen removal efficiency of the IVCW system.
2023, 41(1): 173-180.
doi: 10.13205/j.hjgc.202301021
Abstract:
As one of the important ecological restoration measures, sediment dredging has been widely used for the comprehensive restoration of the polluted water system in the Taihu Lake basin. In order to solve the regional environmental problems of the water system and further improve the quality of human settlements, we selected the north lake area of Jiuli Estuary in the Wanshan Lake in Xishan District in Wuxi and studied sediment pollution and ecological dredging. Our study determined the range and quantity of the dredging by analyzing the basic and present situation of sediment pollution in the Wanshan Lake with a full consideration of several limiting factors such as navigation, water demand and constructional depth. The results showed that the whole project achieved 568200 m3 of dredging with an area of 0.75 square kilometers and depth of 0.3 to 1.3 m, including 348200 m3 of sediment dredging, and 220,000 m3 of channel dredging. Several key aspects of techniques were considered for the deeper dredging in northern Wanshan Lake, including desilting requirement, dredging depth, dredging equipment selection and dredging process. As a whole, this study highlighted that ecological dredging effectively reduced the sediment pollution level and water quality of the Wanshan Lake, which laid a solid foundation for the restoration of the polluted water bodies.
As one of the important ecological restoration measures, sediment dredging has been widely used for the comprehensive restoration of the polluted water system in the Taihu Lake basin. In order to solve the regional environmental problems of the water system and further improve the quality of human settlements, we selected the north lake area of Jiuli Estuary in the Wanshan Lake in Xishan District in Wuxi and studied sediment pollution and ecological dredging. Our study determined the range and quantity of the dredging by analyzing the basic and present situation of sediment pollution in the Wanshan Lake with a full consideration of several limiting factors such as navigation, water demand and constructional depth. The results showed that the whole project achieved 568200 m3 of dredging with an area of 0.75 square kilometers and depth of 0.3 to 1.3 m, including 348200 m3 of sediment dredging, and 220,000 m3 of channel dredging. Several key aspects of techniques were considered for the deeper dredging in northern Wanshan Lake, including desilting requirement, dredging depth, dredging equipment selection and dredging process. As a whole, this study highlighted that ecological dredging effectively reduced the sediment pollution level and water quality of the Wanshan Lake, which laid a solid foundation for the restoration of the polluted water bodies.
2023, 41(1): 181-188.
doi: 10.13205/j.hjgc.202301022
Abstract:
In order to evaluate the operation effect of the tailwater constructed wetland in the Great Protection of Yangtze River and to put forward operation and maintenance management suggestions, the effluent water quality, pollutants removal paths and influence factors of different functional units in the Wuhu Jiangdong Water Ecological Park were monitored and analyzed from July 2021 to January 2022. The results showed that Jiangdong water ecological park still had a good removal effect of various pollutants under the premise of good tailwater quality (The concentration indexes of COD, ammonia nitrogen, total nitrogen, total phosphorus were much lower than the Class A standard in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant) in terms of purification effect. The average removal rates of ammonia nitrogen, total nitrogen and total phosphorus in the enhanced surface flow constructed wetland were 85.53%, 17.6% and 33.71% respectively. The ecological conservation pond connected to the end of the enhanced surface flow constructed wetland had the ability to further reduce the pollutants in the effluent of the enhanced surface flow constructed wetland. The average removal rates of ammonia nitrogen and total phosphorus in summer and autumn (August to October) were 27.04% and 22.51% respectively. In terms of impact factors, temperature and dissolved oxygen concentration had a great impact on the denitrification effect of constructed wetland, therefore it was recommended to take thermal insulation and oxygen-enhancing measures in winter. According to the actual operation, addition of small doses of plant carbon sources in batches, optimization of subsurface flow constructed wetland fillers, and design of multi-stage constructed wetland system can be taken to further ensure the sustainability of the operation effect of the tailwater constructed wetland in the Great Protection of the Yangtze River.
In order to evaluate the operation effect of the tailwater constructed wetland in the Great Protection of Yangtze River and to put forward operation and maintenance management suggestions, the effluent water quality, pollutants removal paths and influence factors of different functional units in the Wuhu Jiangdong Water Ecological Park were monitored and analyzed from July 2021 to January 2022. The results showed that Jiangdong water ecological park still had a good removal effect of various pollutants under the premise of good tailwater quality (The concentration indexes of COD, ammonia nitrogen, total nitrogen, total phosphorus were much lower than the Class A standard in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant) in terms of purification effect. The average removal rates of ammonia nitrogen, total nitrogen and total phosphorus in the enhanced surface flow constructed wetland were 85.53%, 17.6% and 33.71% respectively. The ecological conservation pond connected to the end of the enhanced surface flow constructed wetland had the ability to further reduce the pollutants in the effluent of the enhanced surface flow constructed wetland. The average removal rates of ammonia nitrogen and total phosphorus in summer and autumn (August to October) were 27.04% and 22.51% respectively. In terms of impact factors, temperature and dissolved oxygen concentration had a great impact on the denitrification effect of constructed wetland, therefore it was recommended to take thermal insulation and oxygen-enhancing measures in winter. According to the actual operation, addition of small doses of plant carbon sources in batches, optimization of subsurface flow constructed wetland fillers, and design of multi-stage constructed wetland system can be taken to further ensure the sustainability of the operation effect of the tailwater constructed wetland in the Great Protection of the Yangtze River.
2023, 41(1): 189-194.
doi: 10.13205/j.hjgc.202301023
Abstract:
Utilization of reclaimed water landscape is one of the effective ways to solve the shortage of urban landscape water. However, reclaimed water with a high concentration of nitrogen and phosphorus enters the landscape water with poor mobility, which is prone to water bloom. Under the existing reclaimed water discharge standard, the regulation of hydraulic retention time is an effective means to control microalgae biomass in landscape water. In this study, based on the microalgae growth model and the water quality dynamical model, a method for controlling the water bloom of landscape water and its threshold determination based on regulation of hydraulic retention time were proposed. Through calculation, the threshold value of hydraulic retention time corresponding to the national standard GB 18918-2002 (TN=15 mg/L, TP=0.5 mg/L) was 2.477 d; corresponding to the discharge standard (DB11/800-2012) level A (TN=10 mg/L, TP=0.2 mg/L) of water pollutants for urban sewage treatment plants in Beijing was 5.033 d; corresponding to the discharge standard (DB5301/T43-2020) level A of Kunming sewage treatment plants (TN=5 mg/L, TP=0.05 mg/L) was 21.655 d; corresponding to the discharge standard (DB5301/T43-2020) level B of Kunming sewage treatment plants (TN=10 mg/L, TP=0.3 mg/L) was 3.783 d; corresponding to the discharge standard (DB5301/T43-2020) level C of Kunming sewage treatment plants (TN=15 mg/L, TP=0.4 mg/L) was 2.811 d; corresponding to the standard of EU urban sewage treatment (91/271/ZEC) (TN=15 mg/L, TP=2 mg/L) was 1.475 d. If the hydraulic retention time of the landscape water body is less than the corresponding threshold, the water blooms in the landscape water body can be effectively controlled.
Utilization of reclaimed water landscape is one of the effective ways to solve the shortage of urban landscape water. However, reclaimed water with a high concentration of nitrogen and phosphorus enters the landscape water with poor mobility, which is prone to water bloom. Under the existing reclaimed water discharge standard, the regulation of hydraulic retention time is an effective means to control microalgae biomass in landscape water. In this study, based on the microalgae growth model and the water quality dynamical model, a method for controlling the water bloom of landscape water and its threshold determination based on regulation of hydraulic retention time were proposed. Through calculation, the threshold value of hydraulic retention time corresponding to the national standard GB 18918-2002 (TN=15 mg/L, TP=0.5 mg/L) was 2.477 d; corresponding to the discharge standard (DB11/800-2012) level A (TN=10 mg/L, TP=0.2 mg/L) of water pollutants for urban sewage treatment plants in Beijing was 5.033 d; corresponding to the discharge standard (DB5301/T43-2020) level A of Kunming sewage treatment plants (TN=5 mg/L, TP=0.05 mg/L) was 21.655 d; corresponding to the discharge standard (DB5301/T43-2020) level B of Kunming sewage treatment plants (TN=10 mg/L, TP=0.3 mg/L) was 3.783 d; corresponding to the discharge standard (DB5301/T43-2020) level C of Kunming sewage treatment plants (TN=15 mg/L, TP=0.4 mg/L) was 2.811 d; corresponding to the standard of EU urban sewage treatment (91/271/ZEC) (TN=15 mg/L, TP=2 mg/L) was 1.475 d. If the hydraulic retention time of the landscape water body is less than the corresponding threshold, the water blooms in the landscape water body can be effectively controlled.
2023, 41(1): 195-203.
doi: 10.13205/j.hjgc.202301024
Abstract:
The control of water bloom and the improvement of hydraulic conditions have become the key problems of ecological health restoration of urban lakes and rivers. The ecological water replenishment measures of Yongding River can alleviate the prone problem of water bloom in landscape slow-moving water bodies, including Lianshi No. 8 lake. However, the effect of the water replenishment process on water bloom control of landscape water bodies is not clear. Based on the data of water quality, hydrology and algae from 2019 to 2021, the two-dimensional coupling numerical model of hydrodynamic water quality of Lianshi Lake No.8 Lake was constructed to study the variation characteristics of chlorophyll-a content and slow flow area of Lianshi No. 8 Lake under different replenishment conditions. When the external water refill flow was within the range of 0.23 to 0.96 m3/s, the concentration of chlorophyll-a in the surface water of Lianshi Lake No.8 Lake was lower, and the slow flow area was small. This study can provide data support for the research of urban landscape water bloom control and formulation of water replenishment optimization schemes.
The control of water bloom and the improvement of hydraulic conditions have become the key problems of ecological health restoration of urban lakes and rivers. The ecological water replenishment measures of Yongding River can alleviate the prone problem of water bloom in landscape slow-moving water bodies, including Lianshi No. 8 lake. However, the effect of the water replenishment process on water bloom control of landscape water bodies is not clear. Based on the data of water quality, hydrology and algae from 2019 to 2021, the two-dimensional coupling numerical model of hydrodynamic water quality of Lianshi Lake No.8 Lake was constructed to study the variation characteristics of chlorophyll-a content and slow flow area of Lianshi No. 8 Lake under different replenishment conditions. When the external water refill flow was within the range of 0.23 to 0.96 m3/s, the concentration of chlorophyll-a in the surface water of Lianshi Lake No.8 Lake was lower, and the slow flow area was small. This study can provide data support for the research of urban landscape water bloom control and formulation of water replenishment optimization schemes.
2023, 41(1): 204-212.
doi: 10.13205/j.hjgc.202301025
Abstract:
The growth and reproduction of submerged plants are affected by the process of lake water level. However, it is still unclear how the changes of different hydrological processes and the duration of flooding affect the individual adaptability of submerged plants. In this study, we selected typical submerged plant Vallisneria spinulosa Yan of Poyang Lake as the target plant, and explored its individual adaptability characteristic under the six different flooding conditions by a mesocosm experiment. The results showed that prolonged high flooding level stresses could significantly affect the individual functional traits:plant height, leaf number, leaf length, root length, stolon length, vegetative propagation ability and total biomass. When the flooding level was more than 3.5 m, the prolonged flooding stress (over 21 days) would lead to large number of leaves apoptosis. However, when the water level exceeded 3.5 m for a short period of time (no more than 14 days), with the high flooding level stress reducing, and the normal growth of V. spinulosa could be restored. The results indicated that high water level stress and adverse flooding duration in summer were the main stress factors affecting the reduction of individual adaptability of submerged plants. This study could provide scientific theoretical support for submerged plant degradation as well as restoration of submerged vegetation.
The growth and reproduction of submerged plants are affected by the process of lake water level. However, it is still unclear how the changes of different hydrological processes and the duration of flooding affect the individual adaptability of submerged plants. In this study, we selected typical submerged plant Vallisneria spinulosa Yan of Poyang Lake as the target plant, and explored its individual adaptability characteristic under the six different flooding conditions by a mesocosm experiment. The results showed that prolonged high flooding level stresses could significantly affect the individual functional traits:plant height, leaf number, leaf length, root length, stolon length, vegetative propagation ability and total biomass. When the flooding level was more than 3.5 m, the prolonged flooding stress (over 21 days) would lead to large number of leaves apoptosis. However, when the water level exceeded 3.5 m for a short period of time (no more than 14 days), with the high flooding level stress reducing, and the normal growth of V. spinulosa could be restored. The results indicated that high water level stress and adverse flooding duration in summer were the main stress factors affecting the reduction of individual adaptability of submerged plants. This study could provide scientific theoretical support for submerged plant degradation as well as restoration of submerged vegetation.
2023, 41(1): 213-221.
doi: 10.13205/j.hjgc.202301026
Abstract:
Follow-up monitoring and evaluation of restoration effects are important aspects of wetland ecological restoration. Follow-up monitoring can observe the state and process of wetland restoration, identify potential problems in the restoration process and adjust the application of restoration techniques in time to improve the restoration efficiency, and also provide data for evaluating the restoration effects of wetlands. In this study, the effect of vegetation restoration in the Yellow River Delta wetland biodiversity conservation project was evaluated through field ecological monitoring and remote sensing inversion. The results showed that the soil moisture content in the south and north restoration areas was increased by 45.86% and 25.17% respectively, and the soil salinity decreased by 70.51% and 64.71% respectively; the vegetation coverage in the south and north restoration areas was increased by 5% and 54% respectively; NDVI was increased by 48.4% and 44.1% respectively. The vegetation species in the restoration area tended to be diversified and the vegetation community structure was improved. Different restoration methods were effective for vegetation restoration, but the differences in effects were not significant. Reed was the dominant species of vegetation in the restoration area, with a dominance of 0.748, while the dominance of other vegetation was low. The overall vegetation cover, reed density and plant height in the restored area were not significantly different from those of the unrestored area. As a whole, the vegetations situation in the north restored area had not yet recovered to a high level, while vegetation in the south restored area had been recovered well. The damage to native species should be mitigated when the ecological restoration project is implemented, the lag of vegetation recovery should be paid attention to after the implementation, and the wetland management as well as the invasion prevention of alien species should be strengthened. This study can provide data and technical references for the ecological restoration of coastal wetlands in China.
Follow-up monitoring and evaluation of restoration effects are important aspects of wetland ecological restoration. Follow-up monitoring can observe the state and process of wetland restoration, identify potential problems in the restoration process and adjust the application of restoration techniques in time to improve the restoration efficiency, and also provide data for evaluating the restoration effects of wetlands. In this study, the effect of vegetation restoration in the Yellow River Delta wetland biodiversity conservation project was evaluated through field ecological monitoring and remote sensing inversion. The results showed that the soil moisture content in the south and north restoration areas was increased by 45.86% and 25.17% respectively, and the soil salinity decreased by 70.51% and 64.71% respectively; the vegetation coverage in the south and north restoration areas was increased by 5% and 54% respectively; NDVI was increased by 48.4% and 44.1% respectively. The vegetation species in the restoration area tended to be diversified and the vegetation community structure was improved. Different restoration methods were effective for vegetation restoration, but the differences in effects were not significant. Reed was the dominant species of vegetation in the restoration area, with a dominance of 0.748, while the dominance of other vegetation was low. The overall vegetation cover, reed density and plant height in the restored area were not significantly different from those of the unrestored area. As a whole, the vegetations situation in the north restored area had not yet recovered to a high level, while vegetation in the south restored area had been recovered well. The damage to native species should be mitigated when the ecological restoration project is implemented, the lag of vegetation recovery should be paid attention to after the implementation, and the wetland management as well as the invasion prevention of alien species should be strengthened. This study can provide data and technical references for the ecological restoration of coastal wetlands in China.
EFFECT OF WETLAND ECOLOGICAL RESTORATION PROJECT ON MACROBENTHOS COMMUNITY IN THE YELLOW RIVER DELTA
2023, 41(1): 222-231.
doi: 10.13205/j.hjgc.202301027
Abstract:
To explore the impact of the Yellow River Delta restoration project on the macrobenthos community and the key impact factors, in 2019, 2020 and 2021, six sampling batches of macrobenthos and soil/sediment samples were conducted in the restoration area and unrecovered area of the Yellow River Delta International Important Wetland Biodiversity Conservation Project. In the survey, 78 species of macrobenthos were found, belonging to 4 phyla, 8 classes and 61 families. The results showed that the dominance of Insecta was increasing with time, while the dominance of molluscs and annelids with strong pollution resistance was decreasing. In the comparison of the two growth seasons in May 2020 and June 2021, it was found that the density of Insecta species showed an upward trend in the south bank area against the background of the decline of the overall density of benthos. The change in dominant species and species density indicated that the ecological restoration project had improved the environmental conditions of the restoration area. At the initial stage of the completion of the ecological restoration project, the living environment and community structure of macrobenthos were seriously disturbed by the project construction, and it took time to restore biodiversity. The analysis of environmental factors showed that the macrobenthos community had a positive correlation with salinity and total carbon content of soil/sediment, indicating the impact of estuarine environmental factors on distribution of benthos. This study contrastively analyzed the characteristics and change process of benthos communities in the ecological restoration area and natural wetlands in the Yellow River Delta, provided important data and support for the implementation effect evaluation of the Yellow River Delta Estuary Wetland Restoration Project, and provided guidance and reference for the implementation and management of the subsequent wetland restoration project.
To explore the impact of the Yellow River Delta restoration project on the macrobenthos community and the key impact factors, in 2019, 2020 and 2021, six sampling batches of macrobenthos and soil/sediment samples were conducted in the restoration area and unrecovered area of the Yellow River Delta International Important Wetland Biodiversity Conservation Project. In the survey, 78 species of macrobenthos were found, belonging to 4 phyla, 8 classes and 61 families. The results showed that the dominance of Insecta was increasing with time, while the dominance of molluscs and annelids with strong pollution resistance was decreasing. In the comparison of the two growth seasons in May 2020 and June 2021, it was found that the density of Insecta species showed an upward trend in the south bank area against the background of the decline of the overall density of benthos. The change in dominant species and species density indicated that the ecological restoration project had improved the environmental conditions of the restoration area. At the initial stage of the completion of the ecological restoration project, the living environment and community structure of macrobenthos were seriously disturbed by the project construction, and it took time to restore biodiversity. The analysis of environmental factors showed that the macrobenthos community had a positive correlation with salinity and total carbon content of soil/sediment, indicating the impact of estuarine environmental factors on distribution of benthos. This study contrastively analyzed the characteristics and change process of benthos communities in the ecological restoration area and natural wetlands in the Yellow River Delta, provided important data and support for the implementation effect evaluation of the Yellow River Delta Estuary Wetland Restoration Project, and provided guidance and reference for the implementation and management of the subsequent wetland restoration project.
2023, 41(1): 232-239.
doi: 10.13205/j.hjgc.202301028
Abstract:
To evaluate the ecological restoration effect of heavy metals in the wetland freshwater restoration project of the Yellow River Delta National Nature Reserve, the heavy metals (As, Cd, Cr, Cu, Pb and Hg) in the surface sediments of the study area were monitored, and the spatial distribution characteristics, ecological risks and potential sources were analyzed. The results showed that the average contents of As, Cd, Cr, Cu and Pb in surface sediments of the restored area were 10.22, 0.17, 40.78, 17.75, 18.12 mg/kg, and Hg was not detected. The RI value of heavy metals in the restored area was lower than 60, indicating low ecological risk; and the Er value of Cd was mainly between 30 and 60, which was the main potential ecological risk factor. The potential risk of each type of restored wetland habitat varied significantly, with the lowest risk in the southern cassis and the highest in the northern ecological island. Compared with the unrestored area, the spatial variability and aggregation effect of heavy metal content in the restoration area was reduced, and the environmental risk was significantly lower, indicating that after the implementation of the restoration project, the improvement of wetland hydrological function would help reduce the ecological risks of heavy metals. In addition, As, Cd, Cr, Cu, and Pb were highly homologous in the sediments, and their potential sources were mainly pollutants discharged from oilfield exploitation and industrial and agricultural activities. The study results could provide a scientific basis for ecological restoration and heavy metal risk prevention and control in the Yellow River Delta.
To evaluate the ecological restoration effect of heavy metals in the wetland freshwater restoration project of the Yellow River Delta National Nature Reserve, the heavy metals (As, Cd, Cr, Cu, Pb and Hg) in the surface sediments of the study area were monitored, and the spatial distribution characteristics, ecological risks and potential sources were analyzed. The results showed that the average contents of As, Cd, Cr, Cu and Pb in surface sediments of the restored area were 10.22, 0.17, 40.78, 17.75, 18.12 mg/kg, and Hg was not detected. The RI value of heavy metals in the restored area was lower than 60, indicating low ecological risk; and the Er value of Cd was mainly between 30 and 60, which was the main potential ecological risk factor. The potential risk of each type of restored wetland habitat varied significantly, with the lowest risk in the southern cassis and the highest in the northern ecological island. Compared with the unrestored area, the spatial variability and aggregation effect of heavy metal content in the restoration area was reduced, and the environmental risk was significantly lower, indicating that after the implementation of the restoration project, the improvement of wetland hydrological function would help reduce the ecological risks of heavy metals. In addition, As, Cd, Cr, Cu, and Pb were highly homologous in the sediments, and their potential sources were mainly pollutants discharged from oilfield exploitation and industrial and agricultural activities. The study results could provide a scientific basis for ecological restoration and heavy metal risk prevention and control in the Yellow River Delta.
2023, 41(1): 240-247.
doi: 10.13205/j.hjgc.202301029
Abstract:
To investigate the application of combined in-situ ecological restoration technology for the treatment of urban black and odorous river water bodies, based on the restoration concept of in situ ecological restoration, pollution interception and source control, landscape creation, hydrodynamic improvement, and biodiversity. The bioremediation method was mainly used, and the source analysis and water quality tests were conducted. A combined ecological restoration system of microbial carrier slow release+aeration and reoxygenation+aquatic plants+circulation pumping equipment was constructed to conduct an engineering trial study on a black and odorous river in Shanghai. The engineering practice showed that the average removal rates of COD, NH3-N and TP in the upper, middle, and lower reaches of the river reached 71.25%, 84.10% and 89.94%, respectively, after the test was carried out for 56 days, and the black odor phenomenon was eliminated. The dissolved oxygen content in water increased from 1.1 mg/L to 4.5 mg/L. The water quality restoration of the river was significantly improved and upgraded to Class Ⅳ of China's Surface Water Environmental Quality Standard (GB 3838-2002). The combined ecological restoration system could effectively eliminate the black and odorous phenomenon, increase the dissolved oxygen content, and degrade the organic pollutants in the water body, and has good purification and landscape effect on black and odorous water bodies in cities and towns. This case can provide practical references for the similar projects.
To investigate the application of combined in-situ ecological restoration technology for the treatment of urban black and odorous river water bodies, based on the restoration concept of in situ ecological restoration, pollution interception and source control, landscape creation, hydrodynamic improvement, and biodiversity. The bioremediation method was mainly used, and the source analysis and water quality tests were conducted. A combined ecological restoration system of microbial carrier slow release+aeration and reoxygenation+aquatic plants+circulation pumping equipment was constructed to conduct an engineering trial study on a black and odorous river in Shanghai. The engineering practice showed that the average removal rates of COD, NH3-N and TP in the upper, middle, and lower reaches of the river reached 71.25%, 84.10% and 89.94%, respectively, after the test was carried out for 56 days, and the black odor phenomenon was eliminated. The dissolved oxygen content in water increased from 1.1 mg/L to 4.5 mg/L. The water quality restoration of the river was significantly improved and upgraded to Class Ⅳ of China's Surface Water Environmental Quality Standard (GB 3838-2002). The combined ecological restoration system could effectively eliminate the black and odorous phenomenon, increase the dissolved oxygen content, and degrade the organic pollutants in the water body, and has good purification and landscape effect on black and odorous water bodies in cities and towns. This case can provide practical references for the similar projects.
