Environmental impact assessment (EIA) system plays an important role in preventing environmental pollution and ecological damage from the source and is an important way for environmental protection to participate in comprehensive decision-making. The implementation of the Environmental Impact Assessment Law of the People's Republic of China in 2003 established the legal status of EIA as an environmental management system, which is a milestone in the development of China's EIA system. In the twenty years since the EIA Law was implemented, China's EIA system has achieved rapid development from project EIA to planning EIA, and then to large regional strategic EIA and policy EIA. Based on the research and practice progress of the EIA system, the identification of the existing deficiencies is helpful to provide a reference for the development of China's EIA system in the next stage. Firstly, the development of the EIA system was reviewed, and then the research progress of China's EIA system in the past 20 years was summarized and hot spots analyzed based on the method of bibliometrics and visual analysis. Combined with the analysis results, the practice progress of China's EIA system was summarized. Finally, some suggestions were provided including strengthening the cohesion between the EIA system and the pollutant discharge permit system, strengthening the supervision in process and afterwards, improving the legal position of planning EIA, strengthening the development of policy EIA and improving the effectiveness of public participation, to further improve the effectiveness of China's EIA system, and achieve sustainable improvement of ecological environment quality and high-quality economic development.

As an important system of environmental management, since its promulgation in 1969, environmental impact assessment (EIA) has undergone continuous revision and improvement globally. Especially in the past ten years, under different political and economic backgrounds, the development of EIA reforms in the three largest economies, the United States, China and the European Union, have all shown common trends of simplifying the administrative procedures and improving the quality of the EIA procedure and reports. The Multiple Stream Framework (MSF) was adopted to conduct a comparative study on the causes, dynamics and trends of EIA system reform in the selected countries/regions. The research showed that the main reason for the EIA reform lied in the practical feedback of policies under different national conditions, the awakening of public awareness of environmental protection as well as market pressure.

China first published the Environmental Impact Assessment Law of the People's Republic of China (Environmental Impact Assessment Law) and then the Administrative Licensing Law of the People's Republic of China (Administrative Licensing Law). After Administrative Licensing Law came into force in 2004, the approval of project EIA was explicitly included in the administrative licensing matters by State Council, and thus the EIA review and approval should be conducted in accordance with the requirements of the Administrative Licensing Law. Currently, the EIA approval work conducted by some local authorities is far from the requirements of the Administrative Licensing Law. In order to improve the quality of EIA approval, it is necessary to comprehensively implement the legal principles stipulated in the Administrative Licensing Law, including the principle of legitimacy, the principle of openness and fairness, the principle of public participation, the principle of reliance protection and the principle of supervision, etc. It was suggested that the Ministry of Ecology and Environment should actively bring the revision of the Environmental Impact Assessment Law to the agenda to organically link this law with the Administrative Licensing Law, so as to meet the practical needs of building a government under the rule of law, comprehensively administrating according to law and establishing a beautiful China under the new situation.

Environmental impact assessment (EIA) system of China has attracted considerable attention and controversy. When judging a system, it is important to consider its effectiveness objectively. The effectiveness of EIA is reflected in the entire process of system construction, system implementation, and taking effects, with multidimensional meaning. Aming at sustainable development of economy, society and environment, an evaluation framework of China's EIA system was explored and constructed based on the logic chain of "institutional basis→practical process→taking effects→social cognition", from four aspects of system effectiveness, procedural effectiveness, substantial effectiveness and cognitive effectiveness. Combined with the EIA system design and implementation mode of China, a set of scientific and applicable effectiveness evaluation indicators, with both practicality and flexibility, were proposed. These could provide ideas for objective and systematic assessment of China's EIA system, as well as reference for the establishment of a mechanism for tracking evaluation of the effectiveness of China's EIA system and for supporting its reform and optimization.

In order to explore the development and evolution characteristics of China's strategic environmental assessment (SEA) research in the past 20 years, the literature collected by Web of Science (WoS) and China National Knowledge Infrastructure (CNKI) databases in the past 20 years were taken as the research object. Using CiteSpace literature analysis tools, knowledge maps were created, and the research strengths, evolution characteristics, and other information concerning SEA were compared at home and abroad. Based on the foreign and domestic experience and empirical findings from cluster analysis, the research hotspots of SEA were analyzed. The prospect and assumption of SEA management were put forward based on comparing research results of SEA in foreign countries. In comparison with the main research areas of SEA at home and abroad, SEA was commonly recognized as a tool for participation in global environmental governance. It can be used to predict and evaluate complex dynamic giant systems, optimize land development patterns and ensure ecological security, and provide a platform for multi-stakeholder negotiation, consultation and decision-making. In spite of the remarkable and innovative research results of major regional SEA practices and eco-environmental zoning management in China in recent years, there were still some problems, such as insufficient publications and international collaboration. In order to enhance the prevention effect of SEA, on the one hand, it was necessary to actively integrate it into the ecological civilization construction, summarize the practical achievements of SEA systematically, continuously improve macro theory and methods suitable for China's situations by using a practice-theory-repractice approach, and to communicate research results worldwide. On the other hand, there is a need to continuously inject new vitality into research, accelerate the development of a multidisciplinary and multi-field expert pool, integrate various technical resources, and unite technical forces from all sides to provide countermeasures for improving "green content" in policies, strategies and planning.

Under the background of the reform of "Decentralization, Regulation and Service", the practice of linking planning EIA and project EIA focuses on simplifying the contents and procedures of the EIA of projects which are included in the planning, but too much attention on efficiency is not conducive to the realization of the risk precaution function of the EIA system. The relevant provisions in current laws, regulations and policies at the national level are relatively principled. In the local practice and exploration, there are major differences in the conditions and ranges of linkage, simplification of content and ways of approval, and the standardized and unified linkage mechanism has not yet been formed. Therefore, based on the construction mechanism of linkage between planning EIA and project EIA, aiming at the problems existing in the present practice, it was suggested that the opportunity should be taken to revise the EIA Law to make EIA return to the original precautionary essence, clarify the applicable conditions and scope of the linkage mechanism, determine the simplified or strengthened contents of the project EIA, respond to the legitimacy doubt about the reform practice of EIA, and establish a bottom-up feedback and supervision mechanism, which could provide a legal construction scheme for the linkage mechanism between planning EIA and project EIA.

Environmental Impact Assessment Law of the People's Republic of China (EIA Law for short) is an important basis for the safety supervision of nuclear facilities and plays an important role in nuclear safety supervision. By sorting out the specific clauses in the EIA Law, combined with the relevant requirements of EIA in the safety supervision of nuclear facilities, summarizing the review procedures and supervision requirements of EIA in the safety supervision of nuclear facilities, and using the research method combining analysis and descriptive statistics, the research on the effectiveness of the implementation of EIA Law in the supervision of nuclear facilities was carried out. The research was from three aspects, i.e. the construction of nuclear safety regulations and standards related to EIA Law, the changing trend of nuclear facility emissions under the supervision of EIA Law, and the implementation of "decentralization, regulation and service" to optimize EIA procedures. The results showed that, under the guidance of EIA Law, the nuclear facility safety regulation and the standard system had been continuously improved, the effluent and solid waste discharges and productions of nuclear facilities had been continuously optimized, the focus of supervision had become clearer, and the quality of EIA had been continuously improved. At the same time, from the perspectives of the inspection and random inspection mechanism, the implementation of post-evaluation and the specific supervision contents of EIA, the shortcomings of EIA Law in the supervision of nuclear facilities were put forward, with relevant suggestions given.

To meet current management requirements, the contents and environmental impact characteristics of spatial planning, regional planning and special planning were reviewed systematically based on clarifying the composition, types and interrelations of China's current planning system. Combined with the practice of planning environmental impact assessment (EIA) in the recent 20 years, some revising recommendations on the enforcement scope of planning EIA were proposed. For spatial planning, it was recommended that the national planning should not be included in the planning EIA system, the planning EIA at the provincial level should be carried out in the form of a chapter or explanation, and the planning EIA at the municipal level and below should be carried out in the form of reports. For regional planning, it was advised that the EIA of the directive large-scale regional planning should be in the form of chapters or explanations, and the that of the non-directive large-scale regional planning as well as the new district planning and the industrial park planning should be in the form of reports. For special planning, it was advised to include the planning of natural resources development, energy, transportation, water conservancy, agriculture (including animal husbandry and fishery) and industry into the planning EIA system, in which the EIA of the directive planning should be in the form of chapters or explanations, and that of the non-directive planning should be in the form of reports.

The follow-up assessment system is an important part of the planning environmental impact assessment (EIA) system. Improving the follow-up assessment system is of great significance to establishing a sound prevention system with the EIA system as the main body. On the basis of analyzing the progress of China's planning EIA follow-up assessment system and practice, the problems of the current system were systematically sorted out, including unclear circumstances of initiation, unspecific procedures, and insufficient binding forces. Countermeasures and suggestions were proposed in terms of initiating follow-up assessment according to the requirements of review opinions, guaranteeing the right to information and suggestion of ecology and environmental departments, and strengthening the legal consequences of violating the obligation of follow-up assessment system, so as to provide a reference for the revision of the Environmental Impact Assessment Law of the People's Republic of China.

As an important starting point to strengthen pollution prevention and control and environmental management in industrial parks, the planning environmental impact assessment (EIA) system provides the optimal solution to control pollution from the source, but it also faces the problem of a low implementation rate, which makes it difficult to effectively exert rigid constraints. Through the investigation of the planning EIA results of 586 national industrial parks, the achievements of the industrial park planning EIA system in improving the environmental management system, optimizing the scale and layout of the parks, and promoting the industrial upgrading, pollution prevention and ecological environment protection were systematically summarized. In addition, the practical problems faced in the process of planning EIA were comprehensively sorted out, and the fundamental reasons for the confusion in planning EIA review subjects and the lack of dynamic and effective management were deeply analyzed. According to the current situation and requirements of the planning EIA, countermeasures and suggestions were put forward, such as strengthening the top-level design to clarify the review subject, promoting the implementation of the planning EIA by classification, and using the numerical control platform to strengthen effective supervision, so as to improve the effectiveness of the industrial park planning EIA.

In order to develop a scientific, legitimate and effective environmental impact assessment (EIA) index system for industrial park planning, the establishment principles, basic procedures and methods of the EIA index system for high-pollution and energy-intensive industrial park planning were discussed based on relevant domestic and international researches, in combination with EIA objectives and the characteristics of the industrial park. One high-pollution and energy-intensive industrial park was taken as an example. On the basis of considering the constraining factors of regional resources and environment and analyzing the environmental impacts of the planning implementation, by using the methods of checklists, expert consultation, ArcGIS vector overlay, scenario analysis and pressure-state-response analysis, a set of EIA index system suitable for high-pollution and energy-intensive industrial park planning was proposed from the aspects of environmental quality, ecological protection, resource utilization, pollution discharge, risk prevention and control, carbon emissions, centralized governance, and environmental management. Through the determination of the indicator system, the industrial orientation, scale, layout and pollution prevention measures of the planning were optimized and adjusted from the perspective of the ecological environment, which could guide the green and high-quality development of industrial parks. Also, it had specific reference significance for other industrial parks to carry out planning environmental impact assessment.

To better improve the effectiveness of the planning environmental impact assessment (PEIA), twenty-six cases of industrial park PEIA were selected as examples to construct an indicator system to analyze the implementation achievements and inadequacies of industrial park PEIA. The indicator system included four dimensions and 14 indexes, with the four dimensions being promoting improvement of regional environmental quality, optimizing spatial layout, preventing and eliminating of environmental risks and promoting high-level development of the park. The results showed that PEIA of industrial parks had achieved remarkable substantive effectiveness results in implementation of total amount control and performance requirements, implementation of industrial admittance restrictions, protection and avoidance of environmental sensitive areas, and implementation of tracking and supervision plans. However, there still remained inadequacy in complete supporting sewage treatment facilities, coordination of residential environment and security risks, cleaner production and circular economy development. In terms of park levels, the implementation effects of PEIA of national industrial parks were better than that of industrial parks at provincial level and below, and as to time periods, the industrial parks passing examination during or after the 13th Five-year Plan period were better than before, with the strengthening of the guidance and reform promotion of industrial park planning EIA at the national level. In terms of regions, the eastern region had a strong economic foundation and early implementation of EIA, paid more attention to the role of PEIA as a preventive tool in promoting high-quality development, and thus was more capable than the other regions to implement and enforce the recommendations of PEIA. Based on problem orientation, some suggestions were proposed including enhancing industrial park environmental management, strengthening PEIA tracking and supervision, and promoting the joint participation of multi-departments in the preparation and implementation of PEIA. These proposals could provide references for the management departments to strengthen management of industrial park PEIA and promote the implementation of PEIA outcomes.

Industrial parks are not only important carriers of China's economy but also concentrated areas of pollutant emissions, which need effective eco-environmental management. Industrial parks of Guangdong Province were taken as a research object, and the achievements and shortcomings of eco-environmental management of industrial parks in recent years were systematically combed. The research showed that the planning EIA of industrial parks in Guangdong Province had been well carried out, the pollution control capacity of the parks had been effectively improved, and the energy conservation and emission reduction work of the parks had been steadily promoted. However, there were also some problems, such as the dynamic management of the planning EIA was not timely, the effectiveness of the planning EIA was not fully played, the working mechanism of the park management organization was not perfect, and the external environmental supervision was insufficient. Based on the existing problems, the countermeasures and suggestions, such as perfecting the planning EIA legal system, fulfilling the main responsibility of the park management organizations, and perfecting the supervision responsibility of the environmental agencies, were put forward, so as to provide support for strengthening the efficiency of eco-environment management in industrial parks.

Port planning environmental impact assessment (EIA) has played an important role in promoting port space resource intensive conservation and ecological protection. However, the existing port planning EIA index system lacks adaptability and relevance in responding to new policies and requirements for ecological environment protection. Based on the existing research results of EIA index system, the port planning EIA index system under the new situations was constructed using the basic index system model according to the environmental impact characteristics of the port master plans. The indicator system contained 4 categories, including ecological protection, environmental quality protection, resource utilization and environmental risk and emergency response, and a total of 50 indicators in 18 aspects, including ecological conservation redline, ecological environment subarea control, environmental sensitive area, shoreline zoning, ecological environment, fishery resources, biodiversity, water environment, atmospheric environment, carbon emission, sound environment, shoreline resources, land resources, water resources, resource recycling, berth specialization level, environmental risk, and emergency response. The relevant indicators generally reflected the environmental protection requirements, the degree of environmental impact and the level of resource utilization corresponding to the implementation of the plan, which could provide reference for port planning EIA practice.

There is no paradigm of policy strategic environmental assessment (SEA) commonly agreed in China. The relevant definitions of policies were sorted out into broad sense, narrow sense and policy instruments. Policies in a narrow sense should be the object of policy SEA. The practice of policy analysis should not only emphasize on policy coordination of policy instruments in the policy system consisting of policies in a broad sense, but also analyze the relationship between the policy and other policies from the perspective of relevant policy tools in the policy system to form a policy synergy. The paradigm of policy SEA, covering the levels of "value norm-disciplinary substrate and evaluation model- institutional arrangement", was proposed, and was preliminarily applied with a renewable energy policy of one province as an example. Suggestions included strengthening theoretical research on policy SEA, accumulating practical experience, promoting institutional construction, and finally establishing the paradigm of policy SEA.

In a broad sense, China's policies can be classified from the two aspects of level and form. Based on the policy classification, the objects of China's policy strategic environmental assessment (SEA) are mainly: 1) the economic policies which belong to the category of specific policy; 2) the policies formulated by the relevant departments of the State Council and the governments at or above the county level; 3) and the major policies that may result in significant environmental impacts. Considering the environmental impact assessment requirements of the existing laws and regulations in the formulation process of various policies, the normative documents in economic policies should be taken as the key objects of policy SEA, and the technical standards should be taken as the main type of technical policies and also be objects of policy SEA. In order to precisely identify the policy SEA objects, a normalized screening mechanism should be established.

Policy environmental assessment is an institutional tool to analyze and predict the environmental impacts of proposed policies in advance and put forward necessary measures to optimize the environmental benefits of the policies. China already has provisions and requirements for policy environmental assessment in the Environmental Protection Law of the People's Republic of China and other relevant laws, regulations and documents, but some problems are still existing, such as non-uniform evaluation objects, unclear evaluation targets and inconsistent evaluation contents. By carrying out the eco-environmental impact assessment of economic and technological policies, economic assessment of environmental policies, review of policy legitimacy, post-legislative assessment and planning implementation assessment, China has accumulated some experience in policy environmental assessment, but there are still some factors that hinder the further promotion of policy environmental assessment. Therefore, it was proposed that policy-making and implementation departments should be policy environmental assessment subjects, the objects of policy environmental assessment could be defined through the combination of classifying + screening process, the policy environmental assessment and comprehensive assessment, pre-assessment and post-assessment should be integrated, and policy-making and implementation departments should be encouraged to take the initiative to carry out policy environmental assessment.

Policy-based strategic environmental assessment (policy-based SEA) is an important part of the environmental impact assessment system. It is very important to carry out the method research of policy-based SEA for its system improvement and practice. Difference-in-differences (DID) is one of the main methods used to evaluate policy effects in econometrics. Taking the policy of agricultural support and protection subsidy as an example, multi-period DID was used to evaluate the impact of the policy on agricultural non-point source pollution, and explore the applicability of DID in policy-based SEA. This study found that DID had good applicability in policy-based SEA. In addition to the environmental impact assessment of post-implementation policies, DID could also be used for the retrospective evaluation of the relevant policies of pre-implementation policies. In the future, the research on technical methods of policy-based SEA should be strengthened, and a unified technical method system should be formed to promote the construction and improvement of policy-based SEA system. In addition, it was found that although the policy for agricultural support and protection subsidy was a favorable policy for environment, its positive impact on agricultural non-point source pollution was not significant, and even stimulated farmers to use more pesticides, resulting in a negative environmental impact.

The stakeholders in policy environmental impact assessment were focused on, and the stakeholder theory, the collaborative governance theory and other relevant theories were adopted to establish a stakeholder analysis framework accessible for policy environmental impact assessment, including stakeholder identification, stakeholder participation, stakeholder analysis and stakeholder collaboration. The methodology was applied to the stakeholder analysis on the pilot policy environmental impact assessment, namely the plastic ban policy in Hainan Province. The results showed that the costs and benefits taken by the core stakeholders had been significantly changed because of the enforcement of the plastic ban policy. The government had strong motivation to promote the implementation of the policy, with great increase of the administration cost. Enterprises paid higher costs due to the increasement of the raw materials cost, while small merchants in farmer's markets were those who suffered the greatest loss, which may affect the implementation of the policy. The conflict of interests between the government and enterprises constituted a behavioral game relationship. On the one hand, the higher the punishment of the government for enterprises violations, the higher the probability of the enterprise compliance. On the other hand, the greater the cost of the enterprise compliance, the greater the government's supervision. The public, especially the price sensitive consumers, may adopt the behavior change strategies of changing living consumption, but the effect remained to be seen. Accordingly, countermeasures and suggestions were put forward to promote the coordination of stakeholders, from the perspectives of common interest prosperity, cost sharing, interest constraints and interest compensation. The stakeholder analysis methodology developed was helpful to identify key interest groups, clarify interest demands and policy relevance, and urge all parties to promote the implementation of the policy and maximize the environmental public interest with the acceptable cost.

The environmental impact assessment of nuclear power plants is the process of analyzing, predicting and evaluating the possible environmental impacts caused by the construction projects of nuclear power plants, and then putting forward measures to prevent and reduce the impacts. In the practice of environmental impact assessment of nuclear power plants, the assessment elements are very wide, not only focusing on the site characteristics, meteorology, hydrology and other aspects, but also paying great attention to biodiversity protection, which is mainly reflected in the standardization of assessment system, assessment factors and analysis and demonstration process. Based on this background, it was pointed out that the factors affecting biodiversity in nuclear power plant environmental assessment included entrainment effect, thermal discharge, residual chlorine, seasons and other factors. The problems of environmental impact assessment of nuclear power plants were analyzed, such as the lack of relevant regulations in practice and the limitations of temperature rise assessment methods. It was suggested that the environmental impact assessment of nuclear power plants should comprehensively consider the related factors affecting biodiversity, establish a sound legal and standard system, and clarify the discharge standards of residual chlorine and thermal drainage. Other suggestions such as making up for the limitations of evaluation methods by remote sensing monitoring and carrying out post-evaluation timely were also proposed.

The major canal projects proposed in the national strategic planning are characterized by complex construction contents, high development intensity, affecting diverse types of ecologically sensitive areas, and both positive and negative environmental benefits. However, there are few studies on environmental impact assessment of such canal projects, especially the identification of environmental impact pathways and index systems. The matrix method and system dynamics method were used to identify the main environmental impact pathways of major canal projects. The impact assessment should focus on five aspects: water resources allocation in the basin, river hydrodynamic conditions, water environment impact, ecological environment impact and regional environmental risk. According to the analysis of environmental impact characteristics of major canal projects and combined with the requirements of environmental protection objectives, an environmental impact assessment index system of major canal projects was proposed from seven aspects, including resource utilization, hydrodynamics and water environment, ambient air, acoustic environment, ecological environment, solid waste and environmental risks, with a total of 37 assessment indexes, which could provide reference for environmental impact assessment of major canal projects and the construction of green ecological canals.

In order to guide the environmental impact evaluation practice of aircraft noise in civil airports, by analyzing and summarizing the cases of airport aircraft noise impact assessment, it was figured out that there were some problems in aircraft noise environmental impact assessment, such as insufficient rationality in determining the assessment scope, the weak applicability of noise standard, the relative backwardness of the noise prediction model, and the non-comprehensive of noise prevention and control measures. In view of the above problems, the reasonable evaluation-scope delimiting method and noise evaluation standards were recommended, the development directions of the noise prediction model were proposed, and more comprehensive and advanced noise prevention measures were summarized. The suggestions were given on future aircraft noise impact assessment, such as establishing an aircraft noise source database, developing aircraft noise prediction software and speeding up the formulation of technical guidelines and standards with strong adaptability.

In order to study the vibration environmental impact of the unevenness of urban rail transit, by applying the vehicle-track space coupling dynamics model and the track-tunnel-soil three-dimensional finite element-infinite element coupling model, and verified with the measured data of vibration source intensity, the speed correction coefficients under the train speed of 100-120 km/h and different track irregularity spectrum conditions was obtained. When the track conditions were severe, the recommended value of correction coefficient of vibration environment influence speed was 36.2; when the track conditions were normal, the recommended value of correction coefficient of vibration environment influence speed was 31.0; when the track conditions were good, the recommended value of correction coefficient of vibration environment influence speed was 23.3. This research could provide a reference and basis for the evaluation of urban rail transit vibration environmental impact and vibration reduction design.

At the current stage, it is still in the exploration period for the collaborative governance of pollution and carbon reduction to be incorporated into the ecological environment management system. Under the existing institutional framework, the management mechanism and technical methods are relatively lagging. The main challenges in the process of incorporating the collaborative governance of pollution and carbon reduction into the ecological environment management system were analyzed. By clarifying the responsible subjects, boundary scope and functional positioning, etc., of each institution, the collaborative governance framework for pollution and carbon reduction based on the ecological environment management system was analyzed. Applying the management and technical elements in the main institutional links of the existing ecological environment management system and aiming at the problems, some countermeasures and suggestions were put forward. In terms of source prevention and control, combined with the relevant pilots of collaborative governance of pollution and carbon reduction, the boundary scope, work content and management mechanism of carbon assessment in Three Lines One Permit (TLOP), planning EIA and project EIA should be improved; in terms of process control, the further construction of integrated management of pollutant emission permit data should be considered; in terms of law enforcement and supervision, the ways such as establishing a national carbon monitoring system should be explored to improve the enforcement effectiveness of law supervision, strengthen the mechanism of supervision and accountability, and promote the construction of a cooperative system for reducing pollution and carbon emission.

The current greenhouse gas (GHG) emissions accounting method standards and guidelines were systematically sorted out, the differences of the current accounting methods were analyzed, the problems of the current accounting methods being incorporated into the environmental impact assessment (EIA) system were put forward, and the thermal power industry was taken as an example to put forward the carbon emission accounting boundary, calculation method and principles for selecting parameters in the EIA of thermal power construction projects. The results showed that the current GHG emissions accounting methods had certain discrepancies in accounting boundaries, scopes, factors and calculation methods. The current accounting methods could not be directly applied to the EIA of construction projects, and there were problems such as the inability to obtain the parameters accounting accurately, the inconformity of calculation boundaries with the requirements of EIA, and the difference in the recommended parameters among various guidelines. For the thermal power industry, from the perspective of the carbon emission sources considered, the fossil fuel combustion emissions accounted for 93.5%-99.8%. When carrying out the EIA, the fuel combustion emissions of generator sets could be mainly considered and other process emissions could be excluded. In terms of calculation methods, the calculation results of carbon dioxide based on elemental carbon content were relatively accurate, with an calculation error not exceeding 10%, while the error based on low-level calorific value was 18%-30%. It was recommended to carry out accounting based on elemental carbon content when conducting EIA. It was suggested to select the estimated value at the EIA stage for the fuel consumption of the coal-fired power plant, and select the measured value of the designed coal samples at the EIA stage for the elemental carbon content, avoiding using the default value of low-level calorific value and carbon content per unit calorific value. Also, it was recommended to directly select the default value for the carbon oxidation rate.

The carbon emissions of residents' water and energy use are related to their behaviour choice and technology level. The emissions also fluctuate greatly over time. Through intelligent monitoring, field research, questionnaires and other methods, a bottom-up carbon emission accounting method was developed, and its impact was assessed from the perspective of community infrastructure and residential water and energy consumption. A community in Haidian District, Beijing, was selected as a case in this study. The total carbon emission of this community was 18.2-20.8, 19.3-21.5, and 58.5-63.8 t/d in terms of CO₂ in summer, spring/autumn and winter, respectively. The average daily carbon emission of residential consumption on weekend was 1.0-1.2 times that of weekday.

The cement industry is one of the major energy-consuming industries and one of the major CO₂ emissions. It is very important to conduct carbon emission assessment and recommend appropriate low-carbon technologies in the environmental impact assessment (EIA) of the cement industry. The carbon production links of the cement production processes were analyzed, and the low-carbon technologies that appeared at home and abroad were sorted out. By establishing low-carbon technology evaluation index system in the cement industry, combined with actual investigation data, 15 low-carbon technologies of the cement representative enterprises in Hunan Province were evaluated, which provided a reference for the selection and application of carbon emission control technologies in the EIA of cement enterprises. The results showed that in terms of low carbon effect, the construction of energy management center, pure low-temperature waste heat power generation technology, high solid-gas ratio cement suspension pre-decomposition technology and the use of grinding aids had high scores, while in terms of technology maturity and technology universality, the scores of pure low-temperature waste heat power generation technology, roller mill grinding system, high voltage frequency conversion energy saving transformation and the use of grinding aids were high. From the perspective of economic evaluation index, the scores of pure low-temperature waste heat power generation technology, cement kiln cooperative disposal of municipal solid waste, high solid-gas ratio cement suspension pre-decomposition technology and the construction of energy management center were higher. The top technologies in the comprehensive ranking were mainly energy comprehensive utilization and energy-saving process control technologies, including pure low-temperature waste heat power generation technology, construction of energy management center, high solid-gas ratio cement suspension pre-decomposition technology, etc., which were the key recommended technologies in the environmental impact assessment.

The integrated ecological environment units are important basis for the implementation of the ecological environment zoning control. The scientific and reasonable delineation and updating of the integrated ecological environment units are the key technical difficulties in improving the ecological environment zoning control system of "Three Lines One Permit". On the basis of sorting out the overall application of the zoning methods for integrated ecological environmental units in all the provinces (autonomous regions and mulicipalities) of China, taking H Province and its three cities A, B, and C as examples, the differences in the results of two zoning methods of element merging method (merging method) and administrative boundary threshold fitting method (fitting method) of integrated ecological environment units were compared and analyzed, the applicability of two zoning methods were discussed under different geographical conditions and ecological environment function characteristics. It was suggested that the merging method should be preferred to delineate the integrated ecological environment units, and the scope and suggestions for the threshold standards in different terrain areas by fitting method were proposed, to provide technical support for optimizing the technical methods of delineating the integrated ecological environment units in "Three Lines One Permit", improving the zoning management and control system of ecological environment, and improving the fine management level and governance ability of ecological environment.

List of ecological environment permits originates from the integration of Three Lines delineation management and control results, which is a significant export for each environmental control unit to implement the bottom-line thinking and the hard constraints on ecological environment protection. It is worth pondering and discussing how the ecological environment permits list can be used, applicable and effective in the actual environmental management. With the characteristics of industrial park management control units, the ecological environment permits list system of Hunan Province is among the first to be issued and fully implemented in China. Taking the achievements of Hunan Province as an example, the compilation principles, technical ideas, characteristics of practice and application effect of the environmental permits list were systematically expounded. By summing up the problems, some thoughts and suggestions on optimizing the ecological environment permits list were put forward, including 1) to clarify the legal status and hierarchical positioning of Three Lines One Permit (TLOP), find out the functional positioning, and form a situation of multi-department coordinative promotion; 2) to strengthen the target support function of the ecological environment permits list and ensure its scientific application; 3) to standardize the form of ecological environmental permit list and coordinate multi-factor management control; and 4) to introduce supporting mechanism and guide the dynamic update of TLOP.

In the implementation of the Three Lines One Permit environmental management mechanism process, scientific delineation and effective management of ecological space is an essential part of planning environmental impact assessment (PEIA). Based on the four main stages of urban planning (i.e. outline formation, planning research, planning drafting, and planning approval), the main technical processes of ecological space optimization and management for PEIA were constructed, including the main tasks of spatial element analysis and basic scheme formation, analysis of the ecological environment and spatial coordination, evaluation of the impact of planning on spatial utilization, and recommendations for spatial optimization and management. The technical processes were also applied to the Environmental Impact Assessment of Shanghai Baoshan District Master Plan. The results showed that by incorporating ecological protection red lines and river networks as well as adding new ecological nodes and corridors, the total optimized ecological space in Baoshan District increased from 65.74 km² to 121.84 km², accounting for 40.4% of the regional land area, meeting the requirements of Shanghai Urban Master Plan (2016-2040), which proposed that by 2040, Baoshan District's ecological land would account for 40% of the land area. In conclusion, urban PEIA could further optimize the ecological spatial pattern in terms of major ecological environmental issues and regional environmental demands based on the ecological space of urban planning, and provide effective means to promote new urbanization and ecological civilization construction in China.

In order to explore the environmental classified management mode of the industrial land outside the industrial park under the situation of new industrial layout and development, the spatial overlay analysis and carrying capacity assessment method were used to evaluate the spatial layout constraints, environment carrying capacity and environmental risk control of the industrial land outside the industrial park in Shanghai based on the Three Lines One Permit requirements. Combination with the evaluation results, the new regulations and planning and the pilot experience of typical areas, three suggestions were put forward as follows: The relevant departments of environment, industry and planning should dynamically investigate the current situation of the industrial land outside the industrial park as well as the planning implementation of it; Based on the characteristics of resources and environment, planning and development intention and other factors, classified control should be implemented for different planning oriented plots; For the industrial land outside the industrial park reserved in the near and medium term, the environmental access will be strengthened by carrying out regional environmental impact assessment.

After the special major explosion accident in Xiangshui, the central area of the explosion and the surrounding rivers were polluted by chemicals to different degrees, and the emergency treatment of the accidental wastewater was extremely difficult. How to scientifically and effectively carry out the emergency treatment of the accidental wastewater was the top priority of the on-site environmental emergency response. The emergency treatment decision-making processes, such as the environmental emergency water quality analysis, target setting, treatment and engineering implementation plan formulation of the explosion accident, were mainly introduced. The effectiveness, experience of the emergency treatment and disposal of wastewater in the explosion accident were also summarized and analyzed. In the process of on-site environmental emergency, the emergency technical chain of "quick plugging-safe transfer-proper disposal" in sudden environmental accidents in the chemical industry park was developed and practiced. The emergency wastewater treatment and engineering implementation plan was scientifically formulated, and the emergency treatment of all kinds of wastewater in the explosion area was successfully realized. Furthermore, the emergency treatment of wastewater achieved the emergency goals of "no secondary environmental disasters" and "not letting a drop of wastewater enter the Guan River", which verified the scientificity and correctness of on-site emergency decision-making. The successful experience accumulated in the environmental emergency response to the special major explosion accident in Xiangshui could provide a reference for the emergency response to similar sudden environmental pollution accidents in the future.

The wastewater generated by the sudden environmental pollution accidents in the chemical parks has the characteristics of high concentration and toxicity, complex pollutant composition, and difficulty in emergency treatment, which is seriously harmful to the ecological environment and has a great social impact. In response to the needs of emergency treatment of wastewater from the explosion pit of Xiangshui Chemical Industry Park explosion accident, research on wastewater quality analysis, treatment process screening, bench-scale test, and project implementation effect was carried out. The bench-scale test showed that by the pretreatment of activated carbon enhanced activated sludge (AC-AS), the pollutant concentration of the explosion pit wastewater was greatly reduced, the removal efficiency of total organic carbon and ammonia nitrogen reached 96.9% and 65.7%, respectively, and the pretreated effluent met the influent requirements of the follow-up Chenjiagang Wastewater Treatment Plant (WTP). The project operation showed that after the pretreatment of AC-AS, and the treatment of WTP, all indicators of the effluent (COD, ammonia nitrogen and other pollutants) met the discharge standards of Discharge Standard of Main Water Pollutants for Chemical Industry of Jiangsu Province (DB 32/939-2006) and Emission Standard of Pollutants for Petrochemical Industry (GB 31571-2015). The emergency treatment project reduced chemical oxygen demand by 33319.6 kg, ammonia nitrogen by 209.4 kg, and aniline by 6.2 kg. After the wastewater was treated up to the discharge standard by Chenjiagang WTP, the water quality of the downstream receiving water body kept normal and the water environment was not significantly adversely affected. This wastewater treatment case showed that AC-AS had a good treatment effect on this kind of accidental wastewater.

Luming mining tailings pond leakage incident resulted in a large amount of molybdenum-containing tailings water leaking into the river, causing serious pollution of the downstream river and threatening the safety of drinking water source. Scientifically and effectively carrying out environmental emergency disposal was a difficulty of the on-site emergency response work. The emergency disposal decision-making, the emergency plan formulation and the project implementation results were systematically expounded, mainly including emergency goal formulation, water quality monitoring and analysis, emergency disposal ideas and engineering measures, etc. In the process of on-site environmental emergency response, through the implementation of measures such as plugging leakage points, dam blocking and interception, coagulation and precipitation, two major projects for pollution control and for pollutant concentration peak reduction and water purification were implemented to achieve the emergency goal of "not to allow standard-limits-exceeding water entering Songhua River". The successful experiences of emergency disposal of this accident was summarized, and suggestions for the prevention, control and disposal of environmental risks of tailings pond were put forward, so as to provide reference for scientific prevention of environmental risks of tailings pond and proper response to such sudden environmental emergencies.

At present, the probability of environmental emergencies in China is still high, which include a high proportion of water-related incidents, bringing about a great risk to the ecological environment. By analyzing the characteristics of some typical cases of water pollution emergencies in China in recent years and the national management policies of environmental emergencies, combined with some thoughts in environmental emergency support work such as participating in emergency response and investigation for many times, the development needs and future research directions of emergency response technologies for water pollution emergencies in China were analyzed from four aspects: emergency standard formulation, emergency platform construction, emergency technology research and intelligent emergency response. These could provide a reference for establishing and improving the emergency response technology system for water pollution emergencies and improving the national environmental emergency response capacity.

The artificial liner system is an important protective barrier for disposal of solid waste in landfill, but the breakage of liner will cause leachate leakage, which will seriously endanger the environment and human health. Therefore, it is necessary to detect the leakage of artificial lining in a timely and effective manner. The current commonly used leakage detection technologies, such as tracer method and dipole method, cannot be applied to the leakage detection of landfill during operation, which are difficult to meet the requirements of emergency detection in case of sudden leakage. Aiming at the problem of emergency detection of landfill leakage, a novel emergency leakage detection method of geomembrane named boundary location method was proposed, which had the advantages of nondestructive detection, convenient operation and rapid and efficient data processing. The detection range of boundary location method was extended by placing electrodes around the landfill, then the obtained signals were calculated by integrated developed boundary location detection system. Finally, GPS coordinates of leakage sources and data visualization results were given at the terminal. A municipal solid waste landfill and a hazardous waste landfill in East China were taken as research cases to analyze the application effect of leakage emergency detection technology based on boundary location method in practical projects. The results showed that the boundary location method could achieve rapid localization of leakage source in practical engineering, and the error between the predicted and actual locations of leakage sources was within 2 m, and it could be corrected by tracking and measuring the on-site excavation process. In addition, the signal errors made the boundary location detection system calculate them as one if the distances among leakage sources were less than 1 m, and multiple leakage points with a distance of more than 2 m could be effectively detected when there were multiple leakage points in the landfill.

To reveal the effects of dredging on the temporal and spatial distribution and the release process of nutrients in surface sediments, the contents of organic matter (OM), total nitrogen (TN) and total phosphorus (TP) of the surface sediments as well as the concentrations of ammonia nitrogen (NH₄ ⁺-N), TN and TP of the interstitial water and the overlying water at 10 points from Xiashan Daxi Basin of Lianjiang River were analyzed before and after dredging, and the pollution status of surface sediments after dredging was also evaluated. The results showed that TP, TN, and NH₄ ⁺-N concentrations in interstitial water and overlying water decreased significantly after dredging. The average concentrations of OM and TN of surface sediments decreased by 53.3% and 54.5%, respectively, compared with those before dredging. TP concentration of surface sediment was higher than that before dredging at nearly half of the points, and the ability of dredging to remove nutrients in surface sediments was TN>OM>TP. The pollution of OM, TN and TP in surface sediments after dredging improved compared with that before dredging, but the pollution level was still high. After dredging, the nitrogen in the sediments displayed as "source", and phosphorus changed from "source" to "sink", indicating that this dredging promoted the internal release of nitrogen in the interstitial water of surface sediment and inhibited the internal release of phosphorus. This was related to the dredging depth, the changes in the physicochemical characteristics of the sediments and the occurrence environment.

Zooplankton plays an important role in regulating the structural balance of marine ecosystem. In order to study the distribution of zooplankton in Tianjin coastal waters and its relationship with the environmental factors, a survey was carried out at 16 monitoring sites in Tianjin coastal waters in September 2020. The biodiversity index was used to evaluate the zooplankton diversity, redundancy analysis (RDA) and principal components analysis (PCA) were used to analyze the relationship between zooplankton diversity and water environment factors as well as the main water environment impact factors in Tianjin coastal waters, respectively. The results showed that 18 species of zooplankton were identified and Copepods were the main group, which accounting for 50% of the total zooplankton, and the dominant species were Copepodite larva, Corycaeus affinis and Nauplius larva (Copepoda). Margalef richness index (D), Pielou evenness index (J), Simpson dominance index(C) and Shannon-Wiener diversity index (H') were 1.37, 0.71, 0.36 and 1.31, respectively. RDA showed that suspended solids (SS) was negatively correlated with total biomass, D, J and H', respectively. The concentration of active phosphate was positively correlated with J and H', while pH and salinity were negatively correlated with the C. The concentrations of chlorophyll a and ammonia were positively correlated with C and J. The content of dissolved oxygen was negatively correlated with C and total biomass, while that of petroleum was negatively correlated with C. PCA showed that the main water environment factors affecting zooplankton diversity distribution in Tianjin coastal waters were suspended matter, chlorophyll a and ammonia.ll a and ammonia.

The groundwater in the northern region of China is an important source for water supplement. In recent years, with the acceleration of urbanization and the impact of human activities, the hydrochemical characteristics of groundwater have become increasingly complex. It is important to identify the hydrochemical characteristics of groundwater in the water source areas and the cause mechanisms for the rational development and utilization of groundwater resources and for the insurance of local socio-economic sustainable development and ecological security. Based on the collection of groundwater samples, the mathematical statistics, correlation analysis, Piper three-line diagram, Gibbs diagram, and the ratio of groundwater main ions were applied to analyze the chemical characteristics and genetic mechanism of the groundwater in Jiuxian County, Tai'an City. The results showed that the chemical types of groundwater in the research area were diverse. The pore water was mainly HCO₃-Ca, HCO₃+SO₄-Ca type, and the karst water was HCO₃-Ca, HCO₃-Ca+Mg, HCO₃+SO₄-Ca, and HCO₃+SO₄-Ca+Mg type. The chemical composition of pore water and karst water in the area was mainly controlled by both of the natural and human factors. The main ionic components of groundwater were affected by the interaction of water and rock. The ions mainly came from the dissolution of carbonate rock, calcite, and dolomite, and the cation exchange effect was weak. Moreover, the increase of the concentration of Cl⁻ and NO₃ ⁻ in groundwater was due to human activities.

In order to explore the main reasons for water quality fluctuation in the Yixun River in the spring flood season, Yixun River Basin was sampled and investigated in December 2020 and March 2021, respectively. Based on an analysis of the spatial and temporal characteristics of water environment factors, the excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC), fluorescence characteristic analysis and Spearman rank correlation analysis were used in fluorescence characteristics studies and source characteristics studies. The results showed that the water quality of the Yixun River in the spring flood season deteriorated significantly, which was mainly reflected in the increase in the proportion of Class V and worse water bodies of the national standard from 14.29% to 88.24%. The main over-standard factors were COD_Cr, TP and COD_Mn. Three fluorescence components, including UVC humic-like substances (C1), UVA humic-like substances (C2), and tryptophan-like substances (C3) were detected in the dissolved organic matter (DOM) in the water body, of which the total contribution of humic-like substances accounted for nearly 80%. The fluorescence index (FI) of DOM during the freezing and spring flood seasons were 1.65-1.88 and 1.49-1.75, the biological source index (BIX) was 0.76-1.31 and 0.65-0.99, and the humification index (HIX) was 0.10-7.00 and 0.40-6.00, respectively. During the spring flood season, the DOM of the Yixun River body showed stronger humility and weaker recent autochthonous characteristics, and the proportion of land source contribution significantly increased. The fluorescence parameters of FI and BIX were significantly negatively correlated (R>0.6, P<0.01) with the water quality parameters such as DOC, TP, COD_Cr and COD_Mn. The increase of the concentration of DOC, TP and other pollutants in water bodies during the spring flood season was mainly affected by three factors, including high humus background, soil erosion and agricultural non-point source pollution.

At present groundwater quality assessment method is numerous, and the selection of the appropriate assessment method is of great significance to the management and utilization of groundwater. Based on the detection results of groundwater samples collected in Chaoyang District, Beijing during the dry season in 2020, the improved analytic hierarchy process (AHP), single factor index method and comprehensive pollution index method were used to assess the groundwater quality, and the accuracy and irrationality of the assessment results of different water quality methods were compared. The results showed that: 1) The results of different water quality assessment methods varied greatly, the improved AHP was the best, the single factor index method was the worst, and the comprehensive pollution index method had the highest consistency with other methods. 2) In water quality assessment, the comprehensive pollution index method could be preferred. The single factor index method was suitable for water with high water quality requirements or few pollutants exceeding the standard. The improved AHP was suitable for water with multiple pollutants exceeding the standard. 3) In order to further determine the accuracy of groundwater assessment by different methods, the reliability analysis of different water quality assessment methods was carried out. The improved AHP, single factor index method and comprehensive pollution index method accounted for 90.48%, 42.86% and 47.62%, respectively, of the water quality assessment results that were the same as those in the reliability analysis. Therefore, in the comprehensive assessment of groundwater quality, the improved AHP could be used.

As China has planned for carbon peak and carbon neutralization, the country's ecological environment governance has entered a new stage of comprehensive integration and collaborative governance of pollution reduction and carbon reduction. Carbon reduction is the key to achieving carbon peaking and carbon neutrality goals. Therefore, to synergize the reduction of pollution and carbon emissions, the service mode of environmental stewardship needs to be comprehensively upgraded to provide carbon management services. Based on the analysis of the current situation and problems of environmental stewardship, it was proposed that upgrading environmental stewardship was a policy requirement for synergizing the reduction of pollution and carbon emissions, a practical request for achieving the goals of peaking carbon emissions and subsequent carbon neutrality and reducing enterprise performance costs, and also a future development trend of improving energy conservation and environmental protection technology. Finally, it was suggested that the upgrading of environmental stewardship service mode under the dual carbon target could be promoted from six aspects, including improving the relevant policy system, expanding the financing channels, promoting independent research and development of green and low-carbon technologies, building a scientific management platform for pollution reduction and carbon reduction, cultivating professional carbon asset managers and setting up innovative demonstrations.

Since the 21st century, China's carbon dioxide emissions have continued to rise. The country has determined the goal of carbon dioxide peaking before 2030 and carbon neutrality before 2060. There are many challenges in how to achieve it on schedule. By 2020, about 50 countries in the world had reached the target of carbon dioxide peaking, of which the total amount of carbon dioxide emissions accounted for about 36% of global emissions. The progress of carbon dioxide peaking in developed countries and regions was compared and analyzed, from the perspectives of economic level, industrial structure, industrialization and urbanization level, energy consumption, policy support and so on. The results showed that: at the peak of carbon dioxide emissions, the per capita GDP of major countries and regions was more than 10 000 US dollars, and that of the United States and Japan was more than 30 000 US dollars. In most countries and regions, the proportion of the secondary industry decreased steadily, and the proportion of the tertiary industry increased gradually during the period of carbon dioxide peaking. When the major countries and regions achieved the goals of carbon dioxide peaking, the urbanization rate was more than 53%, and more than half of the countries and regions reached more than 75%. When the major countries and regions achieved the goals of carbon dioxide peaking, the consumption intensity of energy was mostly between 1.0 to 4.7 tons of standard coal per 10 000 US dollars. From the perspective of the released medium and long-term carbon dioxide emission development strategy and carbon neutralization goal, the experience of developed countries and regions achieving deep decarbonization and carbon neutralization was expounded in depth. It was pointed out that the vast majority of countries and regions had put the control of the total amount of energy consumption and the transformation of low-carbon energy as their strategic focus, taken the development of the circular economy and the improvement of the energy efficiency as specific measures, and taken the S&T innovation as an important field and continuous motivation. According to the consumption of energy in China, the period from carbon dioxide peaking to carbon neutrality was only 30 years, which meant that after reaching the goal of carbon dioxide peaking, the task of carbon neutrality would be very heavy. This required that China's carbon dioxide peaking should not be simply climbing the peak, but a rational low peak. China needed to make greater efforts to promote the adjustment of economic and industrial structure, build a clean, low-carbon, safe and efficient energy system, strengthen the R&D and innovation of clean and low-carbon technologies, and orderly promote the construction of carbon emission trading market.

Over recent years, ozone pollution has become a prominent issue in China. To perpetuate the improvement of environmental quality in Beijing-Tianjin-Hebei (BTH) Region and its surrounding areas and Fen-Wei Plain, the Ministry of Ecology and Environment launched the Thousand Miles Eye Program to build a grid-based air pollution monitoring system. In 2020, to address the ozone pollution problem during the summer months, a study was conducted to identify high ozone production area and pushed anomaly environmental information to the environmental authorities in key regions and the onsite inspection and assistance teams, thus providing important support for winning the blue sky defense war. Based on the data from Sentinel-5P satellite, and combined with the enterprise data inventories, electricity consumption data, pollution source inspection records, and so on, high ozone production areas were identified and located through the RFM model. The findings of the study showed that most urban areas and industrial clusters in the BTH region and Fen-Wei Plain were located within VOC-control areas or VOC-NO_x-cooperative control areas. The problem rate of high ozone production areas pushed by the method was 65.3%, 21.5 percentage points higher than the overall problem rate. The problem rate among enterprises in high ozone production areas was 27.1%, 3.7 percentage points higher than those in non-high ozone production areas. This methodology improved the efficacy of inspection and assistance in ozone pollution inspection and control during the summer of 2020. The problem rate of high ozone production areas and the problem rate of enterprises in high ozone production areas were correlated with the times of push notifications of high ozone production areas; and the practice results showed that after repeated pushes of such notifications, the rate of problematic enterprises in high ozone production areas showed a pattern of rising first before falling, and the inflection point of the problem rate of enterprises was correlational to their cycle of rectification. This methodology proves more effective with industrial clusters dominated by packaging printing and industrial painting businesses.

Nitrogen oxides (NO_x), the precursors of PM_2.5 and O₃, are important air pollution control indices. Selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) are mature technologies for NO_x removal from coal-fired industrial boiler flue gas. However, the application of the two technologies in small-and-medium denitrification engineering is limited because of their high investment costs, harsh operating conditions and other factors. In recent years, biological denitrification technologies have been used increasingly in small-and-medium flue-gas denitration projects. Many scholars have carried out extensive research on them. The advances of bioprocesses for NO_x removal from flue gas were critically reviewed, and the denitrification principles and technical characteristics of related processes were summarized. The latest research directions of chemical absorption-biological denitrification (BioDeNO_x) were reviewed, and the operational principles, reduction mechanism, reactor developments, operational parameters and influencing factors of complexation absorption-biological reduction (CABR) were emphatically elucidated. The obstacles of the CABR system and its solutions were systematically discussed, and the future trends of bioprocesses for NO_x removal were prospected.

Artificial intelligence (AI) technologies have great potential in the field of environmental engineering because of the unique performance of self-learning, self-adaptation and self-organization. At present, they have been widely used in the environmental fields such as water pollution, air pollution, solid waste treatment, climate change, which indicate that AI technologies are good assistants for environmental monitoring and governance. In the current situation of serious water resources shoutage, water pollution prevention and control is of great importance. Traditional water pollution control and supervision technologies have problems such as serious lag effect of water pollution monitoring, high cost of sewage optimization control, and low prediction accuracy of pollutant removal efficiency. The introduction of artificial intelligence technology can effectively overcome the above problems. It is of great significance to develop the application of AI in water pollution control. The characteristics and classification of various AI technologies were discussed, the research status and application progress of AI technologies in the field of water pollution control were summarized, in order to provide scientific reference for comprehensively strengthening water pollution control.

Using cyanobacteria as raw material to prepare biochar, the adsorption efficiency of cyanobacteria biochar on tetracycline at different temperatures was investigated and the optimal preparation temperature of cyanobacteria biochar was screened. Cyanobacteria biochar modified with different Fe/C mass ratios was prepared by the liquid phase reduction method. The removing efficiency, influencing factors and removing mechanism of the iron-modified cyanobacteria biochar for tetracycline were studied. The results showed that the iron-modified cyanobacteria biochar had a high removing capacity for tetracycline at 700 ℃ and an iron-carbon mass ratio of 1∶1, and the removing rate reached 87.2% in 60 min, which was 1.2 times of that before modification. The adsorption type was in accordance with the pseudo-second-order kinetic equation (R²>0.99). The relationship between the iron-modified cyanobacteria biochar tetracycline removal performance and its structure was discussed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was proved that the main removal effects of tetracycline were adsorption and chemical degradation, the zero-valent iron as the electron donor promoted the redox reaction, and the oxygen-containing functional groups as the bridge of electron transfer played an important role in the adsorption and degradation process. The test results of influencing factors showed that the influence degree of anions was in the order of SO₄ ²⁻ > Cl⁻, the influence degree of cations was Ca²⁺ > Na⁺, and the influence degree of organic fulvic acid (FA) was weak relative to ionic strength. The iron-modified cyanobacteria biochar had good removal efficiency on tetracycline antibiotics, which could provide a new idea for cyanobacteria resource utilization.

As a kind of high concentration organic wastewater, the wet stacking wastewater from the edible mushroom breeding is hard to be degraded with dense COD and ammonia nitrogen. It poses a challenge to make the discharge reach the standard just using conventional treatment processes.The combined process of Air Floatation-Baffled A/O Biofilm Reactor (HAOBR)-O₃/H₂O₂ was adopted to study the treatment effect of Air Floatation-HAOBR on COD and ammonia nitrogen in mushroom breeding wastewater, to discuss the treatment effect and optimal control parameters of O₃/H₂O₂ catalytic oxidation section under different combination modes. Three-dimensional fluorescence spectroscopy was employed to analyze the variation of dissolved organic matter (DOM) in the wastewater in this combined process. The results showed that the concentration of COD and ammonia nitrogen in the mushroom wastewater decreased to (485±25) and (1.32±0.11) mg/L respectively after the treatment of Air Flotation-HAOBR; when the dosage of O₃ and H₂O₂ was 0.88 and 333 mg/L respectively; the final effluent COD and ammonia nitrogen concentrations were (22.50±1.50) and (1.30±0.15) mg/L respectively, and the average removal rates were 99.40% and 98.70% respectively. It was assayed that fulvic acid-like substances, soluble microbial metabolites and humic acid-like substances were the dominant DOMs in mushroom breeding wastewater. After the treatment, the fluorescence intensity of DOM was greatly reduced, but the major components remained unchanged. The combined process could effectively remove COD, ammonia nitrogen and DOM in mushroom breeding wastewater, and the effluent could meet the first level discharge standard of Integrated Wastewater Discharge Standard (GB 8978-1996), with a good prospect for the treatment of mushroom breeding wastewater.

The extensive application of tetracycline antibiotics in stock farming has brought potential hazards to people and animals. A well-functioning chlortetracycline-degrading pure bacteria strain was isolated from the sludge of the chlortetracycline pharmaceutical factory. The strain was named ZL-1 and identified to belong to gram-negative bacteria and Acinetobacter sp. based on the morphological observation, gram staining and 16S rDNA sequencing identification. Furthermore, the effects of carbon source, temperature, pH, initial chlortetracycline concentration and inoculation amount on the chlortetracycline degradation performance of ZL-1 were analyzed by the orthogonal test. The results showed that the temperature, inoculation amount, and initial chlortetracycline concentration had a greater impact on the chlortetracycline degradation efficiency. Based on the results of the orthogonal test, the chlortetracycline degradation conditions of the bacteria were optimized by the response surface method, and the optimal conditions for degrading chlortetracycline were determined. The optimal conditions were the initial chlortetracycline concentration 134.864 mg/L, the temperature 34.409 ℃, and the inoculation concentration 5.223%. Under the optimal conditions, the actual degradation efficiency of chlortetracycline was 93.70%, whereas the predictive value was 93.723%, indicating that the proposed model had high accuracy.

In recent years, fitting with the actual situation of rural areas and low cost are becoming the development requirements of rural sewage treatment technology. Adapting measures to local conditions and utilizing local resources are the best choice of rural sewage treatment. However, due to the lack of early standards and imperfect treatment system, resource utilization of rural sewage is still a weak point. The reasons for the low utilization rate of rural sewage were deeply analyzed, and it was pointed out that the best way to recycle rural sewage was to recycle it into agricultural production. Based on years of engineering practice and research results, four resource utilization modes in combination with rural sewage treatment and agricultural production were put forward. These four modes included pollutant reduction and cash crop planting coupling mode, tail water irrigation mode, water quality control type on-demand discharge mode, and black water and grey water graded resource utilization mode. Detailed analysis of the characteristics, application scope, treatment effect, construction investment, operation cost and occupation area of each mode were carried out.

River ecological restoration is an important step for improving water quality and maintaining the stability of the river ecosystem, as well as a key measure for fulfilling overall requirements of water-ecological environment protection in key basins in the 14th Five-year Plan. Taking Shengjiawan River course, a tributary of Yuhuitang, in Jiashan County as the research area, riverine buffer zone and water ecological restoration projects were implemented and carried out. In the light of seriously occupied ecological space, damaged habitat in some river sections, reduced biodiversity, unstable river water quality and so on in the region, the overall scheme of ecological restoration project for Shengjiawan River course was presented as following innovative idea of "protection-restoration-development". With comprehensively improving the water-ecological environment quality and building a healthy and stable water ecosystem as the targets, the measures like non-point source pollution control, ecological space restoration and water ecological restoration were taken, including the construction of artificial wetland (17 700 m²) and ecological grass planting ditch (2 200 m), riverine vegetation buffer zone (30 m×1 480 m), ecological transformation of riverbank (1 210 m) and underwater forest ecological restoration project (20 400 m²). By ecological restoration of Shengjiawan River course, the ecological environment in this area was comprehensively improved, "clear water and green banks" were observed and the biodiversity of the water body was restored.

As an important drinking water source in Taizhou City, Changtan Reservoir is of great significance to regional development and social stability. Taking Changtan Reservoir as the research object, the delimitation and ecological restoration of the lake littoral zone and lake buffer zone were carried out in Changtan Reservoir under the guidance of Technical Guide for Delimitation and Ecological Restoration of Ecological Buffer Zone of Lakes and Reservoirs in Zhejiang Province (Trial). The results showed that the total length of the lake littoral zone of Changtan Reservoir was about 97 km. The lake littoral zone was divided into six types, including mountain type, natural beach type, farmland type, road type, estuary type and reservoir dam type, accounting for 42.6%, 25.3%, 3.4%, 20.6%, 7.6% and 0.5% of the total length, respectively. The lake buffer zone of Changtan Reservoir was divided into three types, including mountain type, farmland type and reservoir dam type. The area of these three types of buffer zones was 46.73, 2.89 and 0.168 km², respectively. Based on the delimitation of the lake littoral zone and lake buffer zone of Changtan Reservoir, the main environmental problems were identified and key ecological restoration areas were selected. From the aspects of disturbance removal, pollution prevention and ecological restoration, targeted ecological restoration countermeasures were proposed to create a reservoir ecological buffer system with strong capabilities of protection and adjustment, and harmonious coexistence between man and nature.

Water ecological function zoning is a zoning method based on the regional differences of the water ecosystem in a basin, which is an inevitable requirement for the fine-grained water quality management of "classification, zoning, grading and staging" in the basin. By analyzing the progress and the present situation of water ecological zoning at home and abroad, the regional partitioning index selection basis and system characteristics were compared, the problems existing in the current water ecological function zoning in China, such as imperfect partitioning system and less consideration of zoning water ecological elementsin zoning were analyzed. Adopting the idea of "combining land and water, determining land by water", the water ecological function zoning method based on the dual drive of "nature-society" was put forward. By analyzing the natural elements and water ecological characteristics of the basin, exploring the driving-response mechanism of the water ecosystem, combining the management needs, proposing a water ecological function zoning index system for the Miyun Reservoir basin, and conducting a study on the primary, secondary and tertiary water ecological function zoning of the reservoir basin. The results showed that the water ecological function zones in Miyun Reservoir Basin can be divided into 3 primary zones, 14 secondary zones and 22 tertiary zones. On this basis, according to the water ecological situation and function of each region, the traceability and propose appropriate management solutions in the context of current ecological problems were carried out.

Human activities have an important impact on the ecosystem and its service value. Taking Changzhou City, Jiangsu Province as an example, using six periods of land use data from 1995 to 2018 and based on 2 km×2 km grid, the ecosystem service value and human activity intensity were calculated, and the temporal and spatial variation characteristics and their correlation were analyzed. The results showed that from 1995 to 2018, the cultivated land area in Changzhou City decreased by 19.5%, while the water area and construction land area increased by 11.6% and 93.7%, respectively. The value of ecosystem service experienced a process of first increasing, then decreasing and overall increasing, with an increase of 2.955 billion yuan. The increase of value mainly came from the transformation of cultivated land into water, while the decrease of value mainly from the transformation of cultivated land into construction land. The intensity of human activities had increased significantly, especially in the urban area of Changzhou City. There was a significant negative correlation between human activity intensity and ecosystem service value, and this negative correlation was increasing.

In order to analyze the effectiveness of the ecological protection compensation of drinking water sources in Kunming in recent years, taking Songhuaba Reservoir as the research area, the Analytic Hierarchy Process, entropy weighting method and the model of coupling coordination degree were used to analyze the comprehensive benefits of ecological protection compensation of drinking water sources, and the evolution process of coupling and coordination between ecological environment and socio-economic development. The results were as follows: the comprehensive benefits of ecological protection compensation of drinking water source of Songhuaba Reservoir in Kunming showed a volatility uptrend in 2008-2020, and the average annual growth rate of the comprehensive benefits evaluation index was 23.6%. The degree of coupling and coordination between the two sub-systems of ecological environment construction and socio-economic development showed a continuous upward trend and gradually changed from the stage of imbalance and decline to the stages of transition and coordination and coordinated development. The research results showed that Kunming City had attached great importance to and continued to increase the protection and management of drinking water sources in recent years, the degree of regional ecological environment construction had been continuously improved, and the degree of coupling and coordination between ecological environment construction and socio-economic development had increased. It was suggested that in the future, while the regional socio-economic development was stable, the ecological environment construction should be continuously strengthened in order to reach the coordinated and sustainable development of the ecological environment and socio-economy of drinking water source areas.

Environmental regulation is an inevitable requirement to improve environmental quality and an important means to enhance the coordination between environmental protection and economic development. The calculation of the intensity of environmental regulation is the basis for subsequent related research. Nine environmental regulation intensity measurement indicators were selected to construct the environmental regulation index system. The environmental regulation intensity was calculated by the factor analysis method. The analysis was carried out from two aspects of time trend and spatial pattern. In terms of time dimension, the intensity of environmental regulation at the national level from 2011 to 2019 was measured, and three public factors were extracted, including regulation effect, formal environmental regulation and environmental awareness. There were cross changes between formal environmental regulation factors and regulation effect factors. The change of environmental awareness factors needed a large time span, and China's environmental regulation was stable and slightly fluctuated as a whole. In terms of spatial dimension, the environmental regulation intensity of 30 provinces (autonomous regions and cities) in China was measured, and the level of environmental regulation intensity was obtained by cluster analysis. The environmental regulation intensity in China showed a spatial pattern of high in the east and low in the west, but the regional difference was narrowing. Finally, the lag between formal environmental regulation and environmental regulation effect, such as emission-reduction investment and control, the imbalance between eastern and western regions, and the importance of informal environmental regulation were analyzed. Some suggestions were proposed, including increasing investment and implementation of environmental governance, optimizing industrial structure and paying attention to the cultivation of public environmental awareness, to improve the intensity of environmental regulation and promote balanced regional development.

In order to promote the construction of life cycle impact assessment (LCIA) methods in China, the current situation and future development direction of LCIA methods and their localization research were analyzed by the literature review. Firstly, the origin and development of life cycle assessment (LCA) were reviewed, and the progress and shortcomings of LCA in China were discussed. Secondly, the theories and methods of LCIA were introduced, and the impact assessment methods used by Chinese scholars in LCA were analyzed using the bibliometric method. The results showed that 77% of the studies adopted foreign impact assessment methods. Finally, the localization research progress of LCIA methods in China were combed, and three deficiencies of LCIA methods at this stage were found, namely, the need to update the selected indicators and benchmark values, the need to strengthen the systematicness and integrity of the model, and the need to carry out the in-depth research of the model. It was proposed that complete and comprehensive LCIA methods and corresponding parameter benchmark values suitable for China's national conditions should be explored and built, so as to improve the authenticity and accuracy of China's LCA results and provide decision support for China's environmental policy-making and related industrial development.