The discharge loads of COD, NH₃-N, TN and TP from typical cities at the mainstream, tributary streams and around the lakes connected with the Yangtze River Basin were evaluated. The characteristics of urban water environment quality, water ecology, water resources and water security of the typical cities were analyzed. The results showed that 1937800, 155700, 310100 and 21800 tons of COD, NH₃-N, TN and TP, respectively, were discharged from 56 cities in the Yangtze River Basin for each year. The domestic source was the main pollution source for most cities in the Yangtze River Basin, and the pollution from industry and non-point sources was also nonnegligible. In recent years, the increasing non-point source proportion, the general damage of the urban water ecosystem, the shortage of water due to water quality and resources in some cities, the rough use of water and low utilization of unconventional water sources led to the prominent water ecological risk in these cities in the Yangtze River Basin. Finally, comprehensive countermeasures were proposed to improve the urban water eco-environment quality in the Yangtze River Basin in the 14th Five-Year Plan period.

Taking 18 cities in Sichuan region of the Yangtze River Basin as research objects, the water environment quality change trend and the main pollution indexes of the urban built-up areas at the main stream of the Yangtze River as well as the Minjiang-Tuojiang River and Jialing River tributary streams in Sichuan region of the Yangtze River Basin from 2016 to 2020 were investigated. The pollution discharge load of chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), total nitrogen (TN) and total phosphorus (TP) from the urban domestic sources, industrial sources and urban non-point sources of the typical cities were also estimated, to analyze the problems and causes of urban water eco-environmental problems. The results showed that water quality of urban water bodies in Sichuan region of the Yangtze River Basin had improved year by year in the recent five years, and TP, NH₃-N, TN and COD were the main pollution indexes of water bodies in the region. In addition, the domestic source was the main pollution source of the cities in the region. The insufficient urban infrastructure construction , the prominent industrial pollution problems of some cities, large urban non-point source load in wet season and the coexistence of water resources and water quality shortage were the main reasons which led to the water eco-environmental problems in the cities. On this basis, countermeasures and suggestions on further improving the quality of urban water ecological environment in Sichuan region of the Yangtze River Basin were put forward, including strengthening the construction of urban sewage collection and treatment facilities, treating typical industrial wastewater specially, strengthening the construction of rainwater and wastewater diversion pipelines and rainwater collection devices, and repairing polluted surface water with ecological methods.

Six cities were taken as the research object to analyze the water environment pollution problems of Dongting Lake and the Yangtze River Basin caused by cities in Dongting Lake region, and put forward the corresponding countermeasures. The water quality variation of the state-controlled sections, characteristics of water resources and heavy metal pollution of the six cities in the region were summarized, and the pollution load of industrial sources, urban domestic sources, and urban non-point sources were calculated. The results showed that the loading of COD, ammonia nitrogen, TN and TP discharged by the 6 cities in this region were 140 700, 12 100, 24 500 and 1 400 t/a, respectively. The main pollution sources were urban domestic sources, followed by industrial sources and urban non-point sources. The main factors affecting urban water quality in this region were ammonia nitrogen and total phosphorus. Through analyzing the urban water environment problems in this region, it was found that the imperfect construction of the pipe network was one of the important reasons for the deterioration of urban water quality, and the expansion of industrial scale and the problems left over from industrial history led to the discharge of industrial wastewater and heavy metal pollution. Based on the above analysis, the corresponding governance suggestions for urban water environment problems were put forward.

In order to improve the urban water ecological environment in Hubei region of the Yangtze River Basin, the characteristics and problems of the urban water eco-environment in the region were investigated from the aspects of water environment, water resources, water ecology and water security. The discharge load of the main pollution sources were analyzed and estimated. The results showed that the domestic sewage was the main pollution source in the region, and COD, NH₃-N, TN and TP from the domestic wastewater accounted for 68.75%, 76.58%, 75.82% and 80.46%, respectively, of the total pollutant discharge from these cities. The main reasons for the urban water eco-environmental problems included the lagging of pipe network construction, overloaded operation of sewage treatment plants, prominent problems of industrial phosphorus chemical industry, phosphate rock and phosphogypsum (briefly called "three phosphorus"), significant contradiction between supply and demand of water resources, serious eutrophication of water bodies and insufficient water safety assurance capacity. In view of the above problems, combined with the actual situation of the cities in the region, the comprehensive improvement countermeasures for water eco-environment were put forward from various aspects. For living sources, the construction of pipe networks should be increased, and the quality and efficiency of sewage treatment plants be improved. For industrial sources, solving the "three phosphorus" problems should be focused on. For water resources, it should adhere to the principle of determining the city by water, developing by the amount of water, and building a water-saving city. In terms of water ecology, the construction of river and lake buffer zone and the biodiversity restoration should be strengthened. And for water security, risk control should be enhanced and emergency warning mechanisms should be established and improved.

In recent years, the urbanization rate in Jiangxi and Anhui region of the Yangtze River Basin has been increasing, but due to the lag in the construction of urban sewage collection and treatment facilities, a large number of pollutants have been discharged into the urban water bodies, and the urban water eco-environment has been damaged. Taking 19 cities in the region as the study object, the characteristics of regional urban water eco-environment were summarized from the aspects of water environment quality, water resources, water ecology and water security, and the intrinsic factors causing water eco-environmental problems were analyzed by means of literature survey and calculation of pollution load of relevant pollution sources. The results showed that: urban domestic sources were the largest source of pollution in most cities; low water use efficiency had aggravated urban water shortage; the construction of urbanization had made the lake eutrophication risk prominent, and water ecosystem seriously damaged; the development of non-ferrous metal mining and shipping had caused prominent risk of heavy metal and shipping pollution in rivers and lakes. In view of the above problems, comprehensive treatment countermeasures and suggestions for water eco-environment, including urban point source, non-point source pollution prevention, water-saving city construction, eutrophication risk control and non-ferrous metal and shipping terminal pollution control, were proposed.

Taking the main environmental sensitive targets in the Yangtze River Estuary in Shanghai as the research object, the Oilmap visited probability model was used to calculate the oil spill risk probability of the main eco-environmental sensitive targets in the Yangtze River Estuary, such as Qingcaosha centralized drinking water source, Dongtan Wetland National Nature Reserve, urban coastline tourism area and fishery fishing area. The oil spill risk index system was established based on the probability of oil spill occurrence, impact factors, meteorological and hydrological conditions and the sensitivity coefficients of sensitive target, to form a secondary zoning of oil spill risk in the Yangtze Estuary. According to the calculation results of oil spill risk index, the oil spill risk zoning of the Yangtze River Estuary in Shanghai was divided into four levels: >5 (highest risk area), 3-5 (higher risk area), 1-3 (medium risk area) and <1 (low risk area). The area of each risk level was 335, 2375, 5695 and 3068 km², respectively. For four key prevention and control areas, such as the oil spill risk prevention and control area in the water source area of the Yangtze River Estuary, some suggestions on zoning and classification requirements for prevention and control were put forward, the primary protection objectives of different zones were defined, and early warning, prevention and control levels in different regions were put forward according to the hierarchical control requirements, so as to provide basic decision-making basis for oil spill risk prevention and control management in the Yangtze River Estuary.

Carbon emission reduction has become an urgent problem to be solved in the construction of ecological civilization in the new era. Carbon emission is closely related to regional spatial location. In order to better promote carbon peak and carbon emission reduction, regional differences and trend analysis of carbon emission influencing factors have become the focus of carbon emission reduction analysis. Through the geographically weighted regression method, the impact of population factors, energy consumption and urbanization construction and development on the carbon emission in 30 provinces of China from 2007 to 2017 were studied, and then the correlation between carbon emission and regional socioeconomic development was revealed. The results showed that the spatial aggregation of carbon emissions was strong, and the spatial distribution patterns of various influencing factors were quite different. Among them, the increase of total power consumption and total fossil energy consumption had the greatest positive impact on carbon emissions, and population size also had a certain positive role in promoting carbon emissions. The total consumption of urban public vehicles and main building materials had no significant impact on carbon emissions, showing an unstable positive and negative correlation. Some suggestions were provided for China's carbon emission reduction, including adjusting the energy consumption structure, further improving clean energy technology innovation, integrating urbanization and carbon emission reduction in stages, and increasing the support for green consumption, green building, and green travel.

By sorting out changes in Tianjin's carbon emissions from 2000 to 2019, the carbon emission models were constructed based on LMDI method and STIRPAT model, respectively. The influencing factors of carbon emissions were compared and analyzed, and the carbon peak and carbon neutrality situation in Tianjin under three scenarios, including baseline scenario, low-carbon scenario, and ultra-low-carbon scenario, were predicted. The results showed that the continuous optimization of Tianjin's energy structure and the continuous reduction of energy intensity were the main factors leading to the reduction of Tianjin's carbon emissions, but the increase in Tianjin's wealth and the increase in urbanization rate had promoted the increase in Tianjin's carbon emissions. Under the baseline scenario, it was difficult for Tianjin to achieve carbon peak in 2025 and carbon neutrality before 2060. In the low-carbon scenario, Tianjin could achieve carbon peak before 2025, but it was more difficult to achieve carbon neutrality before 2060. Under the ultra-low-carbon scenario, Tianjin was more likely to achieve carbon peak before 2025, and under the implementation of the carbon sink project, it could achieve carbon neutrality before 2060.

In view of China's action plan for peak carbon dioxide emission before 2030 and the current rapid development of economic and energy demand, based on the time series data from 2000 to 2020, the Tapio decoupling model was used to quantitatively analyze the decoupling status between CO₂ emission of energy consumption and economic growth in China. The expanded STIRPAT model was established, the influencing factors on CO₂ emission of energy consumption were analyzed, and the scenario analysis was used to predict CO₂ emission of China's energy consumption in the future under four different scenarios: baseline scenario (S0), industrial structure optimization scenario (S1), energy structure optimization scenario (S2) and multi-factor optimization scenario (S3). The results showed that: The decoupling between CO₂ emission of energy consumption and economic growth was generally dominated by weak decoupling. It was found that for 1% change in population, energy consumption structure, proportion of the secondary industry, urbanization level, per-capita GDP, proportion of the tertiary industry, and carbon emissions intensity, there was 2.857%, 0.879%, 0.836%, 0.623%, (0.221+0.011ln A₁)%, 0.241%, and 0.132% change in CO₂ emission, respectively. Under the baseline scenario, the carbon dioxide peak could not be achieved before 2030. Under the industrial structure optimization scenario and the energy structure optimization scenario, China would achieve the peak carbon dioxide emission in 2030, with peaks of 11.090 billion tons and 10.918 billion tons, respectively. Under the multi-factor optimization scenario, the carbon dioxide peak could be achieved before 2030, and the peak would be 10.503 billion tons.

The catalytic conversion of CO₂ to valuable chemical materials such as methane, methanol, carbon monoxide, methanoic acid, light olefins, arene, and so on is an important way for the carbon peak and carbon neutrality. Catalyst is one of the decisive factors in the conversion process, so the development of new catalysts with high conversion rate and selectivity is still the focus of CO₂ catalytic conversion research. The catalysts currently used are mainly noble metal catalysts, with some parts being transition metal catalysts. Moreover, some nonmetal catalysts, new catalysts and bulk catalysts are also proven to have good catalytic performance. With the complexity and heterogeneity of converted products increasing, the conversion rate and selectivity of CO₂ catalytic conversion turns lower. The catalytic reaction mainly contains thermocatalytic and photocatalytic, and the differences of catalytic conditions lead to the poor comparability of the performance of different kinds of catalysts. As a result, establishing standardized evaluation methods for CO₂ catalytic conversion will also be the key research area besides developing high-performance catalysts.

Collaborative reduction of pollution and carbon dioxide is the key way to promote ecological civilization construction in China. Therefore, the analysis of domestic and foreign research hotspots and trends provides a reference for the theoretical research and practical paths of China's collaborative emission reduction governance. CiteSpace was used to sort out and analyze Chinese and English literature of WoS and CNKI, respectively, and the development trend of research in this field was explored. The results showed that the number of papers in this field was on the rise and had specific periodical differences. The United States and China had the largest number of publications, while other publications were mainly from developed countries in Europe and East Asia. In addition to more articles published in environmental science journals, foreign energy journals are more influential, while domestic economic and management journals are more influential. Foreign and domestic studies focus on strategies and policies in this field and their effect evaluation, in addition to foreign studies focusing on emission simulation and domestic studies focusing on mechanism construction in specific industries and regions. The focus of future research should be to comprehensively consider the background of regional collaborative development and the impact mechanism of multiple environmental policies, and to study the paths and policy system of collaborative reduction of pollution and carbon dioxide.

In order to study the pollution characteristics, ecological risks and pollution sources of metal elements in PM_2.5 in Jiaxing, the 24-hour online monitoring data of Shanxi (SX) site in Jiaxing City from March 1, 2019 to February 29, 2020 were collected to investigate PM_2.5 and 12 metal elements (K, Ca, Fe, Zn, Mn, Cd, Pb, Cr, Ni, Ba, Cu and V) in PM_2.5 samples. The results indicated that the average concentration of PM_2.5 was 30.94 μg/m³ during the sampling period, which was better than the secondary concentration standard of Ambient Air Quality Standard (GB 3095-2012) (PM_2.5, 35 μg/m³). PM_2.5 concentrations in the samples were in the following order: winter > spring > autumn > summer. Meanwhile, the concentrations of metal elements were ranked as follows: K > Fe > Zn > Ca > Mn > Pb > Ba > Cu > Cr > Ni > Cd > V (the total concentration being 1.36 μg/m³), in which concentrations of Fe and Zn were affected by the COVID-19 outbreak and the Spring Festival. It was found that both the total metal concentration and each metal element concentration in PM_2.5 increased with the pollution increasing, while the proportion of most metal elements in PM_2.5 decreased. The enrichment factor (EF) method results indicated that K, Ca, Fe, Ba and V were considered almost with no elements enrichment, while Zn and Cd showed extremely heavy enrichment. The geoaccumulation index (I_geo) results implied that Cu, Pb, Zn and Cd were strongly influenced by anthropogenic activities. In addition, the ecological risk index (E_i) results of mental elements indicated that Mn, Cr and Ni showed slight ecological risk, and Zn, Cu, Pb and Cd showed high ecological risk. In addition, the principal component analysis indicated that industrial processes, coal combustion, vehicle traffic and crustal sources were the main sources of these metal elements in PM_2.5 in Jiaxing City.

To investigate mass concentrations, molecular compositions and sources of n-alkanes in PM_2.5 in Qingdao during the winter, PM_2.5 samples were collected from Laoshan District, Qingdao from January 10 to 23, 2020. Twenty-six kinds of n-alkanes (C₁₁-C₃₆) were determined through quantitative analysis by gas chromatography-mass spectrometry (GC-MS), and the pollution characteristics and sources of n-alkanes were analyzed in detail. The results showed that the concentration of total n-alkanes was （230.9±111.7）ng/m³, with the average concentration ranging from 59.2-429.2 ng/m³. C₂₄ was the monomer species with the highest concentration, which concentration was 49.63 ng/m³. According to the secondary concentration limit of PM_2.5 of the National Ambient Air Quality Standards of China (NAAQS), the sampling period was divided into 8 polluted days and 6 clean days. The concentrations of n-alkanes on polluted and clean days were (283.7±93.6) ng/m³ and (160.5±82.1) ng/m³, respectively. The carbon number distribution of n-alkanes on polluted days and clean days was similar. The main peak carbon (C_max) was C₂₂ and the secondary peak carbon was C₂₄. CPI, CPI1 and CPI2 values of n-alkanes on polluted and clean days were 0.91, 0.81, 1.19 and 0.98, 0.84, 1.38, respectively, and %WaxC_n was 6.67% and 19.31%, respectively, indicating that anthropogenic emissions were the main source of n-alkanes in Qingdao during the winter. Principal component analysis (PCA) results showed that the n-alkanes in Qingdao during the winter mainly came from anthropogenic emission sources (coal combustion, vehicle exhaust emissions), and the contribution of plant emission sources was small. The potential source analysis results showed that the potential source distributions of low carbon number n-alkanes and high carbon number n-alkanes were basically the same, mainly from the long-distance transmission in the northwest direction.

Taking a typical textile industrial park in Changzhou City, Jiangsu Province as an example, PM_2.5 and PM₁₀ samples were collected in the surrounding areas. Through the microwave pretreatment method, the contents of Sb, Co, V, Pb, Cd, As, Cu, Ni, and Cr in PM_2.5 and PM₁₀ were obtained using the inductively coupled plasma mass spectrometer (ICP-MS). The characteristics and seasonal variation of heavy metal concentrations in summer and winter were analyzed, and the sources and health risks of heavy metals were evaluated using the positive definite matrix factor model (PMF) and the US EPA health risk assessment model. The results showed that the mean values of PM_2.5 around the textile industrial park in summer and winter were 64.41 and 109.29 μg/m³, respectively, and the mean values of PM₁₀ were 89.08 and 146.65 μg/m³, respectively. Both PM_2.5 and PM₁₀ concentrations were higher in winter than in summer. PM_2.5 content in winter was about 1.70 times that in summer, and PM₁₀ content in winter was about 1.65 times that in summer. Particulate matter around the textile industrial park exceeded the standard, with the maximum over-standard multiple being 33.3 times of the reference concentration limit of the Ambient Air Quality Standard (GB 3095-2012), and the levels of metal elements in winter were greater than in summer. PMF model analysis showed that the main sources of heavy metals in PM_2.5 and PM₁₀ in the surrounding areas of the textile industrial park were road dust and industrial emissions, contributing 59.7% and 64.2% in summer and winter, respectively. The health risk model showed that in winter, exposure to the PM_2.5 and PM₁₀ had a non-carcinogenic risk to children, and the total non-carcinogenic risk value were 1.13 and 1.20, respectively. The carcinogenic risk indexes of Cr and As were not within the threshold range (10⁻⁶-10⁻⁴), which was at an unacceptable level.

Fine particulate matter (PM_2.5) has been paid more and more attention because of its negative effect on human health. Previous studies have shown that green space has an effect on PM_2.5 concentration, but it is not clear whether this effect correlates with the spatial distribution of PM_2.5 concentration. In addition, most of these studies focus on the change of PM_2.5 concentration in the interior of green space, and there is little research on the spillover effect of green space. Based on the 2018 remote sensing images and PM_2.5 raster data of urban districts in Hefei, the study area was divided into three regions, namely HH (High-High) effect area, LL (Low-Low) effect area and insignificant effect area through autocorrelation analysis of the spatial distribution of PM_2.5 concentration. According to the interpretation and selection of the green space, the research green spaces were obtained, PM_2.5 raster data were statistically analyzed by ArcGIS, and the correlation analysis and regression analysis were carried out by SPSS. The results showed that the spillover effect of green spaces in different regions had different effects on PM_2.5 concentration. In HH effect area, the average concentration of PM_2.5 decreased with the increase of the distance from the green spaces, but it increased in LL effect area. The effect of green space index on the variation of PM_2.5 concentration was different in different regions, NDVI_g had the greatest effect on PM_2.5 concentration in LL effect area, while S_g had the greatest effect on PM_2.5 concentration in HH effect area and insignificant effect area.

There is a big gap between the motor vehicle emission laboratory test and the actual road test, and the actual road test generally uses portable emission measurement system (PEMS) technology, but PEMS test has the disadvantages of complicated operation and heavy test equipment, and there is an urgent need for simple and easy actual road emission test technology. Smart Emission Measurement System (SEMS), based on sensor technology for motor vehicles emission test, has a simple system structure and convenient operation, and it is very necessary to introduce it into the actual driving emission testing of motor vehicles. There was a lack of SEMS technology testing and application research in China. By studying the current research status of SEMS technology, and carrying out comparative test experiments, the feasibility of introducing SEMS technology into motor vehicle emission testing and the problems were studied. The results showed that the difference between the particle number (PN) tested by SEMS and PEMS technologies was in the range of 10%-30%. The actual road comparison test results of nitrogen oxides (NO_x) emission had a large deviation, especially in the case of intense driving, and the maximum deviation was as high as 369%. The instantaneous distribution and cumulative distribution trends of PN and NO_x emission test results were relatively agreeable. Based on the test experiments and result analysis, the feasibility of introducing SEMS technology into vehicle emission testing was explored, which had certain feasibility and could be used for NO_x and PN high-emission vehicle screening.

Based on the fuzzy analytic hierarchy process (FAHP), 14 evaluation indicators in four levels, including project establishment, on-site inspection, leak repair and retesting, and account management, were selected from the existing LDAR-related standards and technical guidelines in China, and a hierarchical structure model for LDAR implementation effect evaluation was constructed. By distributing more than 30 questionnaires to representatives of 3 types of groups: experts, enterprises, and third-party service providers, and then calculating the index weights, in order to solve the problem of how to scientifically assess the quality of LDAR implementation under the situation that the country pays more attention to the control of volatile organic compounds (VOCs).The results showed that the primary indicators in the assessment of LDAR implementation effectiveness were leak repair and retesting (0.305), project establishment (0.281), site inspection (0.245) and account management (0.169), and the 14 secondary indicators were ranked with the highest weight of leak repair timeliness and the lowest weight of compliance with exemption from inspection. The study established a systematic LDAR implementation effect assessment system based on the weight values and applied it to 10 enterprises in pharmaceutical, plastic products, synthetic resin and coating ink manufacturing, and concluded that the overall implementation effect of the pharmaceutical industry is preferred, the synthetic resin and coating ink industries have comparable implementation levels, and the compliance of plastic products enterprises in implementing LDAR work is slightly lower.

In order to study the dynamic change law of landscape pattern in the basin with the cascade flow characteristics of plateau-mountain-plain-coastal ecological elements, 7 Landsat remote sensing images of Yongding River Basin from 1980 to 2020 were taken as the main data source, and the evolution characteristics of landscape pattern in Yongding River Basin in recent 40 years were analyzed by comprehensively using the methods of landscape area dynamic analysis, landscape pattern index and mathematical statistics, and its driving factors were revealed. The results showed that: 1) From 1980 to 2020, Yongding River Basin was dominated by cultivated, forest and grass land, accounting for about 90%. The area of cultivated land and grassland had decreased by 1376.38 and 463.42 km² respectively in the recent 40 years, the area of construction land and forest land had increased, and the dynamic degree of comprehensive land use had changed the most from 2015 to 2020. 2) At the type level, the fragmentation degree of construction land patches had decreased significantly, while the changes of other land types were not obvious. At the landscape level, Shannon Diversity Index (SHDI) and Shannon Evenness Index (SHEI) had increased from 1.29 to 1.35 and 0.67 to 0.75, respectively; the overall landscape structure tended to be complex, the heterogeneity had increased, the degree of agglomeration had decreased, and the landscape fragmentation had been intensified. 3) The change of watershed landscape pattern was affected by socio-economic factors, natural factors and policy factors, in which socio-economic development was the main driving force, and economic development and the change of urban and rural population structure were the main driving factors of landscape pattern change.

The microorganism of lake sediments plays an important role in the transformation of organic matter and nutrients, and the microbial community structure is also affected by various environmental factors. In order to explore the differences of the microbial community structure and the influencing factors in the sediments of Hengshui Lake in winter, based on 16S rRNA gene high-throughput sequencing, the microbial community structure composition, diversity and response relationship with environmental factors in various lake areas were analyzed. The results showed that the microbial community diversity in the sediments of various lake areas was in the order of the north area of lake>the center area of lake>the south area of lake. There were extremely significant differences (P<0.01) in the microbial community structure of sediments in the north area of lake and the center area of lake. At the phylum level, the relative abundance of Chloroflexi in the sediment samples in the center area of lake was significantly higher than that in other lake areas, which was related to the serious organic pollution in the center area of lake. At the genus level, the relative abundance of P9X2b3D02 in sediment samples of the north area was significantly higher than that in other areas, indicating that this genus was more suitable for growth and reproduction in an environment with rich aquatic plants. The total organic carbon (TOC) content of the sediments was the key influencing factor of microbial community structure in lake sediments. The high correlation between TOC concentration and the relative abundance of microbial species was related to the heavy organic pollution of the sediments.

Aquatic macrophyte plays an important role in radiant belt toward lake of lake-terrestrial ecotone. Based on the survey data of aquatic macrophyte in radiant belt toward lake of lake-terrestrial ecotone in Lake Taihu during spring and summer in 2021, by means of correlation analysis and canonical correspondence analysis (CCA), the analysis on the distribution of aquatic macrophyte and environmental factors were carried out and their evolution characteristics were explored. The results showed that: 1) A total of 12 species of aquatic macrophyte were collected in radiant belt toward lake of lake-terrestrial ecotone of Taihu Lake in the two surveys, which belonged to 7 families and 9 genera respectively and included 3 species of floating-leaved macrophyte and 9 species of submerged macrophyte. 2) The results of correlation analysis showed that there was no significant correlation between Alpha diversity index of aquatic macrophyte community and environmental factors in spring, while there was an obvious significant positive correlation between Alpha diversity index and dissolved oxygen (DO) concentration in summer, and also a significant positive correlation with transparency and the ratio of transparency to water depth. Shannon Wiener index and Margelef index had a significant negative correlation with total nitrogen concentration. 3) The CCA results showed that the DO concentration in the water body had the largest interpretation value for the survey results, followed by the ratio of transparency to water depth and water depth. The total interpretation value of 10 environmental factors of distribution of aquatic macrophyte was relatively low. 4) In contrast with prior research, the aquatic macrophyte diversity obtained was low and the dominant species were homogeneous, indicating that the structure and diversity level of the aquatic macrophyte community in radiant belt toward lake were strongly influenced by human activities and environmental factors. For the long natural recovery process, anthropogenic control in community structure and diversity was urgently needed as a key to promote the recovery of aquatic macrophytes in Lake Taihu.

In order to better understand the characteristics and sources of pollutants in Daliao River Basin, the spatial topological relationship of "Watershed-Control unit-Administrative district" was established, the water quality of the state-controlled sections of Daliao River Basin, the amount of pollutants into the river in every control unit, and the spatial distribution characteristics in 2019 were analyzed. The results indicated that: 1) Among 28 water quality monitoring sections in Daliao River Basin, 29% of the monthly water quality could reach the targets of the Action Plan for Prevention and Control of Water Pollution. COD and NH₃-N were the main pollutants that exceeded the standard. In the section exceeding the standard, the main sources of COD and NH₃-N were urban life sources, rural life sources and decentralized livestock and poultry breeding, while TP mainly came from pollution sources of different land use types and urban life sources. 2) The amount of COD, NH₃-N, TN, and TP pollutants into the river was 59 195.5, 3115.5, 18 229.7, and 538.3 t/a, respectively. The contribution rate in descending order was urban living source, rural living source, decentralized livestock and poultry breeding source, source of various landuse types (including woodland, grassland, farmland, urban land), industrial source, large-scale livestock and poultry breeding source. 3) The spatial distribution of the inflowing amount of pollutants into the river in descending order was central, southwest, and northeast, with C3, C6, C8, C11, C13, C15, C17 being the key control units. In the above key control units, the contribution rates of COD, NH₃-N, TN, and TP into the river were 68%, 73%, 77%, and 72%, respectively. 4) The error between the estimation result of the inflowing amount of pollutant into the river and the flux simulation value were all less than 20%. The methods should be suitable for the estimation of pollution load in the study area.

Permanganate index (COD_Mn) is one of the most important parameters to measure water quality and could reflect the degree of water pollution by reducing substances. A novel COD_Mn forecast model (EWT-BLSTM) by combining empirical wavelet transform (EWT) and bidirectional long short-term memory (BLSTM) neural network was proposed. First, the original COD_Mn time series was decomposed into several components by EWT. Next, BLSTM neural network was employed to predict each decomposed component. Finally, the predictions of all components were reconstructed to obtain the new hybrid model EWT-BLSTM for the final COD_Mn predictions. COD_Mn data of Poyang Lake was used to evaluate the proposed forecast model. The results showed that EWT-BLSTM model had a powerful forecast capacity. For 1, 7-day ahead forecasting, the mean absolute percentage error (MAPE) of the forecast by EWT-BLSTM was 2.25% and 8.36%, respectively. The MAPE reduced by EWT-BLSTM over BLSTM was 10.53% for 1-day ahead forecasting and 16.16% for 7-day ahead forecasting. Furthermore, the proposed model showed highly stable forecasting performance for COD_Mn peak points, indicating that the proposed method was still applicable in the case of relatively complex data with extreme points.

Influenced by human activities and climate change, the salinization of shallow lake wetlands in semi-arid regions is becoming worse, which threatens the health of riparian ecosystems. Daihai Lake, a typical salinized lake, was selected to analyze the distribution of four nutrients such as organic matter (OM), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP) and available potassium (AK), as well as soil calcium ion (Ca²⁺), magnesium ion (Mg²⁺), exchangeable potassium ion (K⁺), exchangeable sodium ion (Na⁺), carbonate ion (CO₃ ²⁻), bicarbonate ion (HCO₃ ⁻), chloride ion (Cl⁻) and sulfate ion (SO₄ ²⁻) concentrations in three types of soil profile, including riparian grassland, shoal and saline-alkali land. By statistical methods such as principal component analysis (PCA) and redundancy analysis, the salinization characteristics and influencing factors were investigated. The results showed that the difference in the spatial distribution of salts in different types of soil profile in Daihai lakeside zone was large, and there was obvious salt accumulation in grassland and shoals, with the total salt average of 1.99 g/kg and 15.27 g/kg, respectively, on the soil surface; however, the total salt content was the highest at 10-20 cm in the saline-alkali soil, with a total salt content of 17.30 g/kg. pH in the lakeside zone soil was 8.24-8.86, which was higher in the deep soil of shoal and saline-alkali land, as well as the shallow soil of grassland. According to the classification of alkalization, saline-alkali land and shoal soil belonged to alkali soil, and the surface soil of grassland was mainly moderate alkali soil, with a decline of alkalization as the soil went deeper. The major salinization factors in the three land types of Daihai Lake were Cl⁻, Mg²⁺, SO₄ ²⁻, Na⁺, total salt, HCO₃ ⁻, pH, and CO₃ ²⁻. The concentrations of the four nutrients showed a trend of decline with the increase of depth in the 3 types of soil. Besides, the nutrients were the most abundant in the shoal. According to redundancy analysis, a strong correlation existed between most ions in the 3 types of soil. AP and Mg²⁺ were negatively correlated with pH, but other salts and nutrients showed a disparity in different types of soil.

The Dan'ao River is the one with the largest flow and the worst water quality in Daya Bay's rivers flowing into the Southern Ocean. Exploring the hydrodynamic water quality changes of the Dan'ao River is of great significance for coastal environmental risk control and coastal zone remediation. The hydrodynamic water quality model of the tidal reach and the whole estuary area of the Dan'ao River were established based on the EFDC model. The hydrodynamic process in the downstream and estuarine area under the action of runoff and current was mainly researched, and the response relationship between saltwater intrusion and water quality in different water periods was estimated quantitatively. The results showed that the tidal characteristics of Daya Bay were mainly irregular semi-diurnal mixed tide, which was diurnal tide about 8-10 days a month, and semi-diurnal tide about 20-22 days a month. Under the diurnal tide and semi-diurnal tide, the bottom water could invade the upstream of Huzhao section (the national section) about 700-1 100 m, but the surface water could not reach the section. The salt water intrusion in different water periods showed that the salt content was the highest in the low water period, up to 16‰. Based on the hydrologic data of 2019, the boundary of river and sea water mass was preliminarily divided, which could provide the basis for the classification and regulation of fresh water and sea water in the estuary and coastal zone. According to the interaction between salt water and fresh water, the concentration of pollutants in the high water period increased significantly, about 10% higher compared with that in the average water period, and the change of upstream flow directly affected the water quality, especially during the neap tide. It was suggested to optimize the project scheduling to reduce the discharge during the neap tide.

Constructed wetland-microbial fuel cell (CW-MFC) coupling system is a combination of constructed wetland and bioelectrochemical technology, in which the anode is the key factor to limit the output power and pollutant purification performance of the coupling system. Two coupling systems, CW-MFC1 (without granular activated carbon) and CW-MFC2 (with granular activated carbon), were constructed to investigate the effects of the addition of granular activated carbon at the anode on the power generation and nitrogen removal performance of the coupling system. The compositions of microbial communities at the anode and cathode of the two systems were analyzed by high-throughput sequencing technology. The results showed that the output voltage and maximum power density (430 mV, 8.39 mW/m²) of the CW-MFC2 reactor were higher than those of CW-MFC1 (379 mV, 7.77 mW/m²). The ammonia nitrogen removal rate of the CW-MFC2 reactor was 65.72%±3.06% in the early stage of the experimental operation (days 0 to 29), which was significantly higher than that of CW-MFC1 (56.06%±3.71%), and the total nitrogen removal rates of the two were relatively close. On days 30 to 105, the ammonia nitrogen and total nitrogen removal rate of the CW-MFC1 reactor were gradually higher than that of CW-MFC2, especially the total nitrogen removal was more significant (CW-MFC1 42.69%±4.19%, CW-MFC2 32.50%±11.51%). Besides, the high-throughput sequencing results showed that the high abundance of Acinetobacter at the anode and plentiful denitrifying bacteria (Gemmobacter, Geobacter, Flavobacterium, Acinetobacter, and Dechloromonas, etc.) in CW-MFC1 might be the main reasons for the better denitrification performance of CW-MFC1 than CW-MFC2. Overall, adding granular activated carbon to the anode could improve the power generation performance of the CW-MFC coupling system, but it was not conducive to the biological nitrogen removal process.

To address the problem of insufficient removal of total nitrogen (TN) from low C/N ratio effluent, fibrous bamboo shavings were used as a solid carbon source and elemental iron powder as an iron source, and the coupling of the two materials was used for nitrogen removal. Static denitrification experiments were conducted to investigate the effect of different Fe/C mass ratios on nitrate-nitrogen (NO₃ ⁻-N) removal and to determine the appropriate Fe/C ratio for the coupled system. On this basis, the dynamic denitrification test was divided into a control group of simple bamboo shavings (1^#) and a test group of coupled fillers (2^#) to study their denitrification performance. The results of static tests showed that the NO₃ ⁻-N removal rate of the coupled system with the addition of iron powder was higher than that of the simple bamboo shavings system, but when Fe/C was greater than 0.125: 1, the improvement of NO₃ ⁻-N removal was not significant. Taking into account the denitrification effect and cost, Fe/C ratio of the coupled fillers in the dynamic test was determined to be 0.125∶1. The dynamic test results showed that, when the influent TOC was <2 mg/L , TN was (40.93±2.04) mg/L, and hydraulic retention time of 18 h, the denitrification efficiency of 1^# and 2^# stabilized after running about 10 d. 12-81 d, the effluent TOC of both groups were low, and the average TN removal rates of 1^# and 2^# were 32.99% and 75.58%, respectively, and TN removal rate of 2^# increased by 129% higher than that of 1^#; both groups had some nitrite nitrogen (NO₂ ⁻-N) accumulation, but the NO₂ ⁻-N concentration of 2^# was about 47% lower than that of 1^#; the average concentration of total iron in the effluent of 2^# was lower than the limit value of Surface Water Environmental Quality Standard (GB 3838-2002), and there was no excessive iron release and obvious ammonia nitrogen (NH₃-N) accumulation. In conclusion, the bamboo shavings-iron coupled system has significant denitrification efficiency and low secondary effects. China is rich in bamboo resources and has a wide source of iron, and the bamboo shavings-iron coupled system can be used for TN removal of low C/N ratio domestic wastewater.

Solid carbon source is one of key factors affecting the antibiotics' simultaneous removal during the advanced nitrogen removal process in a denitrifying biofilter. The typical antibiotic ciprofloxacin (CIP) was selected as the research object, and a solid phase carbon source, poly(hydroxybutyrate-co-valerate) (PHBV) supported denitrifying biofilter, was built, focusing on the variation of effluent quality and microbial community structure characteristics of the system under the conditions of different concentrations of CIP. The results showed that the nitrate and CIP removal efficiency were both more than 95% when the influent CIP concentration was lower than 300 μg/L under the suitable temperature (3 to 27 ℃) in autumn. However, under lower temperature (−8 to 12 ℃) in winter, the nitrate and CIP removal efficiency decreased to 60% and 49%, respectively, with influent CIP of 1 000 μg/L. Microbial community structure characteristics analysis revealed that Proteobacteria and Gammaproteobacteria were the most dominant phylum and class, respectively. Gammaproteobacteria was resistant to antibiotics due to their good secretion of extracellular polymeric substances. Meanwhile, the relative abundance of denitrifying bacteria in this system still kept high under a long-term exposure to CIP. The relative abundance of Dechloromonas, the most dominant denitrifying bacteria, was all more than 5% along the longitudinal profile of the system with the highest of 10%. The study confirmed that PHBV supported denitrifying biofilter is an efficient technology to fulfill the simultaneous removal of nitrate and antibiotics. And it also provided data support for denitrifying biological filter under low temperature in practical engineering.

Catalytic ozonation is an effective method for the treatment of phenolic wastewater. In order to study the degradation efficiency of phenolic wastewater by α-Fe₂O₃ catalytic oxidation and effectively recover the catalyst, micron-sized α-Fe₂O₃ catalytic ozonation was applied to the simulated phenol wastewater, and the catalyst dispersed in the reaction system was intercepted and recovered by the ceramic membrane to realize the continuous operation of the process. The results showed that: Under the condition of intermittent operation, COD removal rate of wastewater reached more than 97% after catalytic oxidation reaction for 30 min. The main reason for the high COD removal rate was that α-Fe₂O₃ had strong catalytic activity for ozone and strong oxidizing product ·OH was produced during catalytic oxidation.Under the condition of constant pressure, R_r accounted for more than 50% of the total resistance, which was verified by membrane fouling model fitting and series resistance model. However, when the operating pressure exceeded 30 kPa, some reversible fouling gradually transformed into irreversible fouling, and R_ir increased significantly. The formation mechanism of membrane fouling was explored by kinetic fitting. The ceramic membrane fouling model during operation was intermediate blockage or filter cake blockage. Membrane fouling mainly occurred on the membrane surface. The membrane could effectively intercept α-Fe₂O₃ and recover the flux through backwashing. During the six-cycle operation of continuous influent, COD removal rate of simulated wastewater remained above 85%, the irreversible resistance of ceramic membrane was controlled below 13% of the total resistance, and the reaction system maintained stable operation.

Ozone-powdered activated carbon (O₃-PAC) wastewater treatment technology has good development potential, but the inability to effectively separate wastewater from PAC has become the technology bottleneck. A coupled O₃-PAC-ceramic membrane technology system was constructed with phenol as the target pollutant. The technology was investigated in terms of the performance of COD removal and membrane separation of PAC by reaction kinetics, the tandem resistance model and the Hermans-Bredee model, respectively. The results showed that O₃-PAC was able to achieve 100% COD removal within 40 min, and the reaction rate was 2.5 times that of O₃-GAC. PAC and wastewater were separated by the ceramic membrane, and when the operating pressure exceeded 0.06 MPa, the reversible contamination was converted to irreversible contamination. Membrane contamination was a process of conversion from complete blockage to filter cake blockage, and increasing the wastewater flow rate on the membrane surface could destroy the formation of the filter cake layer. After six consecutive cycles of the experiment, COD removal rate of the simulated wastewater at 40 min remained above 95%, but the irreversible contamination of the ceramic membrane tended to increase.

The stocked sludge has the characteristics of high moisture content and potential heavy metal pollution, which may pose potential ecological risks to the landfill site and the surrounding environment. Three solid waste materials, straw powder (SP), fly ash (FA) and phosphogypsum (PG), combined with two common dehydrators, quick lime (CaO) and polyaluminium chloride (PAC), were used to dehydrate the stocked sludge and study the stabilization effect of heavy metals. In addition, the microstructure and composition of the dehydrated sludge cake were studied by SEM-EDS. The results showed that the combined conditioner with solid waste materials had significant effects on sludge dewatering and heavy metal stabilization, and the group with PG was the best. When the addition of CaO, PAC and PG (dry basis ratio) were 20%, 25% and 23% respectively, the capillary water absorption time was 42.1 s and the moisture content of mud cake was 49.00%. The rich pore structure and phosphate impurities in PG had good adsorption and precipitation effects on heavy metals. The microstructure analysis showed that CaSO₄ or Al₂(SO₄)₃ formed the skeleton structure of treated sludge.

A five-compartment purification tank reactor (FcPTR) with the same volume as three-compartment septic tank (TcST) was constructed to address the problem of substandard effluent from TcST, and a study of the start-up characteristics of FcPTR and TcST for treating actual domestic wastewater was conducted. The results showed that the removal rates of FcPTR and TcST of COD_Cr decreased to 44% and 31%, respectively, on the 13th day (HRT is 80 h). On the 46th day (HRT is 36 h), the removal rates of FcPTR and TcST of COD_Cr increased to 86% and 61%, respectively, by reducing HRT. On the 46th day, pH of FcPTR anaerobic fold 1 zone was generally larger than that of anaerobic fold 2 zone, and the acid to basic ratio of FcPTR anaerobic zone was 0.12-0.20, which had better acidification and methanation separation characteristics. On the 46th day, the filler and sludge in FcPTR were observed by sweeping electron microscopy, the morphology of biofilm on the fillers was successful, and the microorganisms in the sludge were mainly short bacilli and spherical bacteria. Research shows FcPTR had a better treatment effect than TcST, and COD_Cr effluent reached the Class Ⅰ A of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB 18918-2002).

Agricultural non-point source (AGNPS) pollution has become one of the main factor affecting the continuous improvement of water environment quality in China. Nitrogen and phosphorus pollutants from agricultural planting account for about a quarter of the total amount of water pollutants. Agricultural planting pollutants migrate to receiving water bodies mainly through runoff, lateral infiltration and infiltration. As one of the important components of the farmland environment, the ridge is the first treatment facility for pollutants in the field to enter the receiving water body. Field ridge can effectively reduce runoff, lateral seepage and soil erosion, and ultimately reduce the amount of planting pollutants directly discharged to the water body. As an economical and simple AGNPS control technology, it also has the basic conditions for widespread use. Based on extensive literature review, the existing research results of field ridges at home and abroad were systematically combed from the perspective of AGNPS pollution control, the research status of field ridges were summarized, the main ways of pollutant removal by field ridges were expounded, the possible mechanisms of pollutant removal by field ridges were analyzed, and finally discussed the problems that need to be paid attention to when it is widely used, in order to promote the in-depth study and standardized application of field ridge technology, and to provide technical support for AGNPS pollution control in China.

In order to reveal the high efficiency, timeliness and sustainability of alfalfa (Medicago sativa) on soil improvement in extremely harsh mining environment, the soil microbial community structure and soil nutrient accumulation characteristics of alfalfa land with different restoration years (3, 6, 10 and 15 years) in Yanshan mining area were studied by using high-throughput sequencing technology. The results showed that alfalfa could effectively improve the concentration of nutrients such as soil available nitrogen, available potassium, organic matter and the relative abundance of some dominant microbial groups, including Proteobacteria, Acidobacteria, Ascomycota, Basidiomycota, Sphingomonadaceae, Burkholderiaceae, Rhizobiaceae, Bacillaceae, Chaetomiaceae and Entolomataceae. The effect of alfalfa on soil nutrient improvement was the best in the 6th year. The relative abundance of dominant soil microbial groups increased significantly in the 6th or 10th year, and the restoration rate of bacteria by alfalfa was faster, while that of fungi was slower.

Gas thermal remediation technology (GTR) is an efficient technology to clean up organic contaminants from soil. A case study using GTR in a decommissioned oil-to-gas facility site was introduced. The changes of remediation target temperature, and concentrations of contaminants (COC) in soil, waste water and waste gas with the heating time of in-situ GTR were discussed. The results showed that the temperature of different soil layers finally reached or approached the target temperature at the end of thermal remediation. The COC in soil in the same or similar target areas was at a low level at different time periods and temperatures, and the removal rate reached above 96%. The removal rate of contaminants in waste water and waste gas reached 98.5%-99.8% and the above treatment processes were highly effective. The case study had proved that in-situ GTR could be applied on a large scale.

In order to investigate the impact of mineral mining on soil ecology, soil samples were collected from the southeastern part of Dayi Mountain rock mass to analyze the concentrations of heavy metals Cu, Pb, Zn, Cr, Ni, Cd, As and Hg. The single-factor index, pollution load index and potential ecological hazard index methods were used to evaluate the pollution status and ecological risk of soil in mining areas. The results showed that the average concentrations of As, Cd, Pb, Zn and Cu exceeded the standard limits of GB 15618-2018 (Soil Environmental Quality Standard for Soil Pollution Risk Control of Agricultural Land (Trial)) (pH>7.5) by 119.70, 47.33, 6.18, 4.67 and 4.43 times, respectively. The single factor index was As>Cd>Pb>Zn>Cu>Cr>Ni>Hg in descending order, and As, Cd, Pb, Zn and Cu were heavily polluted. The individual potential risk indices were Cd>As>Pb>Cu>Zn>Hg>Ni>Cr in descending order, and the average soil RI was 2 680.40, which was a very strong ecological risk level. The statistics showed that the enrichment centers of Cu, Zn, Cd and As were located in mining areas, Cr, Pb and Ni were enriched in villages, mining production areas and other population activity areas, and there was no obvious distribution pattern of Hg element. The correlation and principal component analysis showed that the abnormal enrichment of Cu, Zn, Cd, As, Pb, Cr and Ni in soils was related to mining and human activities, respectively, while the abnormal enrichment of Hg mainly originated from parent material weathering and soil formation.

Taking a relocated electroplating plant as an example and based on the sampling data in the survey report of the polluted site, the categories of polluting heavy metals were screened according to the Soil Environmental Quality-Risk Control Standard for Soil Contamination of Agricultural Land (Trial) (GB 15618-2018). The inverse distance weighting (IDW) method was used to analyze the distribution characteristics of heavy metals in the study area, Moran index was used for spatial correlation analysis, and the semivariogram was used to analyze the overall spatial structure and trend of heavy metal pollution, so as to explore the spatial characteristics of heavy metal pollution in the polluted site. The results showed that the concentrations of Ni, Cr, Zn and Cu in the soil in the study area exceeded the soil background value, and the risk screening value multiples of the sampling points with the highest concentration were 9.55, 1.35, 5.94 and 10.67, respectively. The concentrations of Cu and Zn showed an inverted U-shaped trend in the east-west and north-south directions within the site, high in the middle and low around. The spatial distribution characteristics of Ni and Cr concentrations are similar, and the high value area is located at the northeast boundary of the site. The spatial characteristics of the four over-standard heavy metals were quite different, but they all showed aggregation characteristics.

Based on the database of Web of Science (WoS) Core Collection and China National Knowledge Infrastructure (CNKI), the literature in the past 20 years was searched by using literature metrology and visual analysis software to reveal the development context, research hotspots and development direction of the research field of heavy metal contaminated soil remediation materials at home and abroad. The results showed that compared with 2001-2004, the number of articles published in the field of heavy metal contaminated soil remediation materials in 2013-2016 and 2017-2020 increased significantly by 1302% and 2201% respectively, showing rapid growth. Compared with foreign research, although China started late in this field, it had developed rapidly. Keywords hot spot analysis showed current pollution remediation research focused on remediation of farmland soil, remediation of heavy metals cadmium and lead, and application of immobilized materials. Through keywords cluster analysis, screening and application of immobilized materials was a hot topic of current research, especially the repair mechanism and effect evaluation of immobilized materials were the focus and difficulty of this topic. At present, research on remediation materials for heavy metal pollution in farmland is developing rapidly and functional modification of immobilized materials and their application in farmland are expected to achieve good results in remediation. Moreover, the research and development and application of "green pollution-free" and "safe and sustainable" remediation materials are becoming a research hotspot at present and in the future.

Soil heavy metal pollution in China is still relatively serious, and inappropriate disposal of heavy metal contaminated soil can lead to a serious damage to both the ecological environment and human health. However, soil normally contains a significant amount of SiO₂, Al₂O₃ and Fe₂O₃, which makes it applicable to prepare sintered bricks. In order to ascertain the feasibility and environmental safety of making sintered bricks by using heavy metal contained soil, an industrialization experiment was carried out in a brick kiln, with a blending ratio of 70% soil to replace shale, to investigate the heavy metal emission in flue gas, and the leaching and distribution properties in fired brick. The results revealed that soil had a similar content of SiO₂, Al₂O₃ and Fe₂O₃ compared to shale, and therefore, it could be used as a substitute for shale raw materials. The mechanical properties of the fired bricks met the product quality standards. During the sintering process with heavy metal soil as raw material, the emission of conventional flue gas pollutants and heavy metal pollutants met the relevant standards, and the environmental risk was controllable. The concentration of leachable heavy metals in sintered bricks was significantly lower than the leaching limit of Technical Specification for Cooperative Disposal of Solid Waste in Cement Kilns （GB 30760-2014 ）, and therefore, the leaching risk was low during using bricks. As, Cd, Cr, Mn, Ni, Pb and Cu basically stayed in fired bricks under sintering, and the contents of heavy metals remained in the desulfurization filter cake after flue gas volatilization and wet desulfurization filter pressing were extremely low. The research showed that using heavy metal-contained soil to make sintered brick could meet the existing standards from both mechanical and environmental safety aspects and had certain resource benefits.

A large amount of sewage sludge is produced during the municipal wastewater treatment process with complex composition, and improper disposal would cause secondary pollution to the environment. Heavy metals in the sludge cannot be degraded in the sludge treatment and disposal process with only solid-liquid phase migration and chemical speciation transformation, and they will accumulate and migrate in the environment and finally enter the food chain and endanger human health. Not only the environmental risk of heavy metals is determined by their types and contents, but the chemical speciation distributions of the heavy metals are also the key factors affecting their bioavailability, migratability and ecological toxicity. Focusing on common treatment methods used in the harmlessness, stabilization, reduction and recycling of municipal sludge, including physical methods (thermal hydrolysis, ultrasonic, microwave) and chemical methods (pyrolysis, acid treatment, oxidation, electrochemistry), the impacts of these methods on interphase migration and chemical speciation transformation of heavy metals were described briefly. The reasons for the migration and transformation of the heavy metals were analyzed, and the relevant mechanisms were summarized and discussed. On this basis, recommendations were put forward for risk control of heavy metals in the sewage sludge, including total amount reduction and stabilization of heavy metals in the sewage sludge, as well as the control of heavy metal content in the wastewater.

The water level of leachate will affect the stability of landfill and have the risk of leakage and pollution. When the leachate is stored on the HDPE impermeable membrane, the extreme differentiation characteristics of the resistivity characteristics of the two and the boundary effect and other factors make the least squares and other traditional geophysical inversion methods unable to accurately invert the actual resistivity distribution, and then according to the resistivity the difference feature locates the height of the leachate water level above the HDPE membrane. In order to accurately describe the fine distribution of the local resistivity of the leachate-HDPE membrane inside the garbage dump, The traditional high density electrical method (ERT) device is improved, and a detection device (C-ERT) is proposed, and the resistivity inversion model algorithm of BP neural network is adopted. The method is verified by COMSOL theoretical model and field data collected from a domestic waste landfill in Jiangxi Province, and compared with the least square algorithm (LS). The results show that the BP algorithm based on C-ERT can effectively identify the leachate area above HDPE membrane, and the recognition accuracy is about 83.2%, while LS inversion algorithm can not identify the leachate area.

A novel mass-energy coupling treatment system for blast furnace slag was proposed, which realized efficient recovery of waste heat in slag and high value-added utilization of slag components. The methods of life cycle assessment and life cycle cost were adopted to calculate the environmental impact and economic cost of the system. The resource and energy consumption included were also calculated. Main sources in terms of environmental impact, economic cost and resource and energy consumption of the system were traced through the identification of main contributors. The key elements to system optimization were determined through the comprehensive performance evaluation and sensitivity analysis. Besides, the environmental, energy and economic benefits of the system were analyzed based on its characteristics. The results showed that: 1) The environmental impact of the system was mainly global warming (with a contribution rate of 47.68%), the economic cost was mainly internal cost (with a contribution rate of 91.89%), and the resource consumption was mainly non-energy resources (with a contribution rate of 98.57%). 2) The key unit to system optimization was pretreatment and the key input was HCl. 3) For each ton of slag treated, the net CO₂ emission was −6 098.68 kg, the net energy consumption was −682.68 MJ and the economic cost was 2 078.24 yuan after a full consideration of system characteristics.

A kitchen waste enterprise adopting bio-chemical processor treatment in Shanghai was selected as the research object. The odor pollution characteristics and key influencing factors of kitchen waste enterprises adopting aerobic biochemical processor treatment were deeply analyzed by screening the key test substances of the kitchen wastes, monitoring VOCs and odorous substances from the exhaust outlets of all treatment processes and the fugitive emission of factory area and boundary, and identifying typical odorous substances based on the evaluation of their odor activity value (OAV). The results showed that the concentration of VOCs and odorous substances was sorted as pretreatment workshop, biochemical workshop, and deep processing workshop from high to low, and the emission components were mainly organic substances such as alcohols, carbonyls, sulfides and aromatic hydrocarbons. The major odorous substances were sulfides such as ethyl mercaptan, butyl mercaptan, methyl mercaptan and ethyl sulfide. The wastewater treatment facilities were the main potential sources of odor, including the leakage of biogas in the anaerobic wastewater tank and the escape of fugitive odor from wastewater treatment facilities, etc. The surrounding odor pollution of the kitchen waste enterprise adopting aerobic biochemical treatment had a significant relationship with their production processes. It was suggested that enterprises of the same type could alleviate the odor pollution problem by reducing fugitive odor emission links, establishing regular biogas leakage detection and emergency management system, and improving the operation effect of deodorization devices.

With the rapid development of urbanization, the contradiction between construction land and ecological land has become increasingly prominent. Controlling the expansion of urban construction land from the perspective of ecological security is the embodiment of ecological priority and green development in land and space planning in the new era. Changzhutan metropolitan area was selected as the research object, and the changes in construction land from 2000 to 2020 were identified through remote sensing data. The comprehensive ecological importance assessment model and the minimal cumulative resistance (MCR) model were used to construct the ecological security pattern of the metropolitan area. Based on the future land use change scenario simulation (FLUS) model, three construction land simulation scenarios of natural development (ND), core ecological block protection (CEP), and ecological security pattern restriction (ESPR) were set up. And the urban development boundary of Changzhutan metropolitan area was delineated on the basis of the simulation results. The results showed that from 2000 to 2020, the construction land in Changzhutan metropolitan area expanded very rapidly, and gradually changed from rapid and disorderly expansion to slow and concentrated expansion. By using the comprehensive ecological importance evaluation, it was concluded that the extremely important ecological land was 2 649.54 km², the ecological source area was 1 204.38 km², accounting for 13.97% of the total area of the study area, and the comprehensive ecological security pattern of Changzhutan metropolitan area was constructed. Under the three scenarios of ND, CEP and ESPR, the scale of construction land reached 1 345.88 km², 1 345.79 km² and 1 284.94 km², respectively. The delineation of urban development boundaries based on ESPR scenarios could effectively maximize land economy and ecological benefits, and provide references for ecological protection and land use planning in the region.

In 2014, Nujiang Lisu Autonomous Prefecture (Nujiang Prefecture for short) in Yunnan Province officially launched a new round of converting cropland to forest project. In order to explore the impact of the round of conversion of cropland to forest project on the quality of the ecological environment in Lanping Bai Pumi Autonomous County (Lanping County for short) in Nujiang Prefecture, three periods of time were selected: before the implementation of the project (2013), during the implementation of the project (2017), and at the end of the project (2020). Based on remote sensing ecological index (RSEI) model, four indexes, including greenness, dryness, wetness and heat, were selected and principal component analysis method adopted to study the dynamic changes of the ecological environment quality in Lanping County from 2013 to 2020. The results showed that: 1) The ecological environment quality of Lanping County had been on the rise from 2013 to 2020, and the ecological environment quality of Zhongpai Township, Shideng Township and Hexi Township improved significantly. 2) From 2013 to 2020, the ecological environment quality level of more than 75% of the regions had remained unchanged, and the ecological environment quality levels of other regions changed slightly. The area of better ecological environment was larger than the area of worse ecological environment. 3) The improvement degree of the ecological environment quality of the converting cropland to forest patches was higher than that of 2 km buffer zone of the converting cropland to forest project and the whole study area. The conversion of cropland to forest project had a significant impact on the improvement of the ecological environment quality. The ecological environment of Lanping County could be improved by further promoting the project of converting cropland to forest. 4) The potential abandoned farmlands in the study area were mainly distributed in the four townships of Zhongpai Township, Shideng Township, Yingpan Township and Tu'e Township, which could be used as key areas for further conversion of farmland to forests.armland to forests.

The study of land use change and the evolution of ecosystem service value (ESV) is of great significance for optimizing the allocation of land resources in fragile karst mountainous areas and realizing ecological restoration. Taking Weng'an County in Guizhou Province as an example, the remote sensing image data from 2001, 2011, and 2019 were used to predict the land use pattern in 2027 through CA-Markov model, and quantitatively analyze the spatio-temporal evolution trend of land use and ESV in the study area from 2001 to 2027. The results showed that the land use types in Weng'an County were mainly forest land and arable land. The transfer of arable land to forest land was relatively intense. The area of forest land and construction land continued to increase, and the dynamic degree of construction land and water body was the largest; ESV was generally increasing, and the transfer of arable land to forest land was the main contributor to the increase of ESV. The increase of ESV mainly occurred in the western and northeastern regions. In the future, low ESV areas would still be distributed in the central urban areas; ESV generated by the service type was mainly based on soil formation and protection services, followed by water sources conservation service and biodiversity protection; forest land and cultivated land were sensitive factors that caused ESV changes in the study area, and ESV of the study area was inelastic to improve the value coefficient. During the study period, the land use structure of Weng'an County had changed significantly, and the ESV increased significantly.

Assessing the evolution of habitat quality under land use changes in the process of urbanization is of great significance for building a comprehensive ecological planning system and responding to major challenges in global sustainable development. Based on the land use data and socio-economic data interpreted by remote sensing images of Suzhou in 2010 and 2018, this paper selects driving factors such as elevation, slope, distance to highway, and population density, and uses the CLUE-S model to simulate land use changes in 2030 under multiple scenarios, and the InVEST model is used to assess and predict the spatial and temporal evolution of habitat quality in the past and future to explore the impact of land use change on habitat. The results showed that the optimal fitting scale was 400 m × 400 m, the Kappa coefficient reached 0.854 5, and the model was able to simulate the future land use cover pattern of the study area well. In terms of temporal distribution, the habitat quality under the ecological protection scenario in Suzhou in 2030 was the best, while the habitat quality under the natural growth scenario in 2030 was lower than that in 2010 and 2018. In terms of spatial distribution, the habitat quality in the central city of Suzhou, areas with higher concentration of industries and high intensity of population activities are poor, while the habitat quality in the areas with developed water systems such as around Taihu Lake is better. Therefore, the future research area should pay more attention to ecological protection and achieve high-quality development while developing the economy.

Optimizing the spatial development pattern of land is the primary measure to promote the construction of ecological civilization. Based on the analysis of the spatial and temporal evolution law of the ecological-production-living spaces in Jiaodong Peninsula, an ecological-production-living spaces conflict measurement model was constructed based on "risk source-risk receptor-risk effect" to identify the region and intensity of the ecological-production-living spaces conflict. The results showed that: From 2000 to 2015, the area change of ecological-production-living spaces in Jiaodong Peninsula had the characteristics of "one decline, one rise and one stability". The proportion of production space in Jiaodong Peninsula was the highest, followed by living space, the sum of which was about 85%. From 2000 to 2015, the average conflict index of Jiaodong Peninsula showed an increasing trend. The stable and controllable areas were mainly distributed in the nature reserves within the ecological space, and the seriously out-of-control areas were mainly distributed in the ecotone between the ecological space and production space, and that between ecological space and living space. The order of space conflict degree was production space > living space > ecological space. There were also great differences in spatial types and counties that changed with time.

With the increasing recognition of the importance of wetlands, the demand for wetland ecological restoration techniques is increasing in China, among which near-natural wetland restoration method has attracted more and more attention. The history of the development of near-natural method was reviewed. The definition of near-natural wetland was put forward, and the main differences between near-natural wetland and constructed wetland were analyzed. The ecological restoration of Zhushanhu wetland in Taihu Lake was used as an example to illustrate the design process, main technical measures and restoration effects of near-natural ecological restoration. In the near-natural ecological restoration of Zhushanhu wetland, measures such as the improvement of hydrological and hydrodynamic conditions, the construction of basement forms, plant restoration, aquatic animal restoration, and biomass and species management were successively implemented. The connectivity and mobility of water bodies were improved, the habitat diversity and suitability were enhanced. The wave style basal morphology was constructed based on five types of basement morphology. According to the principles of suitable habitat, priority of water purification and consideration of landscape, 35 species of indigenous wetland plants from 21 genera were selected, and two plant configuration models were designed and used in Zhushanhu wetland restoration process. Based on the analysis results of Ecopath with Ecosim (EwE) model on the structure of wetland food web, some suggestions were put forward on regulating the harvest of aquatic plants and the population number of shrimps, crabs and fishes. After ecological restoration, the water quality of Zhushanhu wetland was improved from below Class Ⅴ to Class Ⅱ of Environmental Quality Standards for Surface Water (GB 3838-2002), and the diversity of large aquatic plants increased significantly. The ecological restoration effect of Zhushanhu wetland has proved the effectiveness of near-natural ecological restoration methods. In the future, it is necessary to continuously enrich the theory and technology of near-natural ecological restoration in practice and carry out large-scale practical applications.

Taking the main urban area of Kunming as the research object, based on LandsatTM/OLI remote sensing images of three periods in 2000, 2010 and 2020, the surface temperatures in three periods were inversed. The temporal and spatial evolution of the thermal environment effect was analyzed with the standard deviation ellipse, and the influencing factors of thermal environment effect were discussed by the geographic detector. The results showed that in the recent 20 years, the heat island areas in the main urban area of Kunming had been concentrated in those with intensive urban construction, and the main axis of the thermal environment direction had changed from northeast-southwest to northwest-southeast. In the early stage, the center of the thermal environment deflected 57.5° to the northwest and shifted by 2.47 km, and in the later stage, deflected 24.25° to the northwest and shifted by 0.86 km. There was a trend of transition from extremely low-temperature zone to low-temperature zone and relatively low-temperature zone, and from relatively high-temperature zone and high-temperature zone to extremely high-temperature zone. Among them, the enhancement trend of the thermal environment effect in Guandu District was the most significant. The building lot and fractional vegetation cover (FVC) had the greatest influence on the surface temperature. The influence on the surface temperature would be increased when the interaction between building lot and elevation. And the interaction between water and building lot or impermeable surface would weaken the mitigation effect of water on the thermal environment effect.

Taking the model organism zebrafish (Danio Rerio) as the research object, the toxic effects and molecular mechanism of chronic exposure of decabromodiphenyl ether (BDE-209) on intestinal tissue were explored. Zebrafish were exposed to different concentrations of BDE-209 (6, 60, and 600 μg/L, dimethyl sulfoxide solvent control) for 28 d. The intestinal tissue of zebrafish was pathologically examined by hematoxylin-eosin (H & E) staining. The contents of biomarkers related to oxidative stress and inflammatory response in the intestine were analyzed by biochemical indicators and ELISA experiments. The relative expression of genes related to the intestinal barrier, inflammatory response, and apoptosis was analyzed by real-time qPCR. The results showed that BDE-209 exposure resulted in thinning of the intestinal wall, increase of vacuolation in intestinal villi and external longitudinal muscle, damage of intestinal wall and cilia, and down-regulation of intestinal ZO-1, Claudin-2, and Tjp2a mRNA relative expression to affect intestinal physical barrier function. BDE-209 exposure increased the contents of reactive oxygen species (ROS), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD) in the intestine, indicating that BDE-209 exposure caused intestinal oxidative stress. In addition, BDE-209 exposure up-regulated the contents of pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) and the content of lipopolysaccharide (LPS) in the intestine, leading to increased intestinal inflammatory response, and increased the expression of p53, Bax, Caspase3 gene and down-regulated Bcl2 gene expression, promoting the apoptosis of zebrafish intestine.

In order to enrich the research on the distribution characteristics of the root system of Sedum plants in green roofs in China, and to explore the relationship between the root characteristic parameters and the saturated hydraulic conductivity of the green roof matrix layer, Sedum sarmentosum and Sedum lineare were planted in perlite substrate with a depth of 6, 10, and 14 cm. The plants were cultivated in a uniform watering system in accordance with the characteristics of rainfall in Wuhan. The root length density, root surface area density, root volume density were selected to describe the root morphology, and the saturated hydraulic conductivity of each group was measured. The group without plants was used as a control to quantitatively compare the root distribution characteristics of Sedum plants and the variation of saturated hydraulic conductivity under different substrate depths. The results showed that: 1) The root length density, root surface area density, and root volume density of Sedum plants were significantly affected by the depth of the perlite substrate. Under the same conditions, the root diameter of plants in the 6 cm substrate ranged from 0 to 0.8 mm, and the total root length density was the highest, which was mainly related to the roots with a diameter of 0.2 to 0.4 mm. The root diameter of plants in the 14 cm substrate ranged from 0 to 2 mm. The total root surface area density and root volume density were the largest, and their values were mainly related to the roots with a diameter of 1 to 2 mm. 2) Compared with the group without plants, the addition of Sedum roots changed the saturated hydraulic conductivity of the perlite substrate by −98.95% to −95.15%, and the saturated hydraulic conductivity of the plant group was much lower than that of the non-plant group. For the plant group, the saturated hydraulic conductivity had a significant positive correlation with the root length density (P=0.050, R²=0.786), root surface area density (P=0.047, R²=0.818), and root volume density (P=0.044, R²=0.824) of Sedum plants with a diameter of 0.2-0.4 mm. 3) The roots of Sedum plants significantly changed the saturated hydraulic conductivity of perlite substrate.

Pollutant discharge permit system is widely used in water environment management, which has played an important role in water pollution control and water environment quality improvement. By comparing the allowable discharges based on the water environmental capacity constraints and the discharge standards for the watershed, the management mode of total discharge permit limit of control units and the optimization method of total discharge permit limit of polluting sources were constructed. The empirical study based on the typical control units of Yongding River watershed showed that the typical control unit of Beijing section could meet the needs of water environment quality improvement when implementing the watershed discharge standard, but the typical control unit of Zhangjiakou section still needed to reduce 210.388 t/a of COD_Cr. In the typical control unit of Zhangjiakou section, 0.002 and 32.039 t/a of COD_Cr should be reduced respectively in the two fixed sources whose wastewater was discharged into the sewage treatment plants.

The existing laws, administrative regulations, department rules and documents, and relevant standards on the management of fly ash in China were introduced systematically. It showed that there was no specific technical standard for environmental pollution prevention and control of fly ash in the current ecological environment standards, and the standards related to general industrial solid waste were applicable in the environmental management of fly ash, with a small number of standards and incomplete coverage. There was also a lack of technical standards for environmental pollution prevention and control in the production, collection and transportation of fly ash, as well as in various comprehensive utilization modes of fly ash, which was not convenient for the comprehensive utilization and pollution prevention and control of fly ash. The current standard system of ecology and environment of fly ash needs to be further improved from the aspects of the whole process management and promotion of comprehensive utilization and pollution prevention, risk prevention and control, information construction, and so on.