Watershed water quality target management has become the main mode of water environment management in developed countries. Beijing-Tianjin-Hebei Region, the core area of Haihe River, is the key area for national ecological and environmental protection. There existed several main problems, such as the shortage of water resources and the insufficient ability of overall allocation, the serious pollution of water environment and the weak level of collaborative governance, and the degradation and fragile stability of water ecology, in the overall planning and system management of the "three water", i.e. water resources, water environment and water ecology, in Beijing-Tianjin-Hebei Region. To solve these problems, key technologies were screened out and integrated from the projects related to the management technologies in Beijing-Tianjin-Hebei Region, based on the National Water Pollution and Treatment Science and Technology Water Major Project (briefly referred to as Water Major Project) during the 11th, 12th and 13th Five-year Plan periods. According to the technical characteristics, the integrated technologies were divided into three categories, including ecological water quantity guarantee management technology and policy, watershed pollutant discharge control based on water quality objectives, and ecological health and service function evaluation of river ecological corridor and spatial pattern construction and optimization technology. Therefore, the integration technology framework of watershed water quality target management was developed for the "three waters" overall planning and system management in Beijing-Tianjin-Hebei Region. The integrated technologies were applied to think about the construction of water quality objective management in key river basins of Beijing-Tianjin-Hebei Region, and work suggestions were proposed to support the coordinated development of economy, society and eco-environmental protection in Beijing-Tianjin-Hebei region and improve the fine management ability of water ecological environment in the new situation.

Taking Qingshui River Basin, the largest first-level tributary of the Yellow River in Ningxia, as an example, the water quality, water environmental capacity and the characteristics of pollution loads of each control unit in key sections were analyzed, and targeted pollution control strategies were proposed. The results showed that the water quality of Sanying national control section of the Qingshui River in 2015-2018 could not stably reach the Class Ⅳ water quality standard of Environmental Quality Standards for Surface Water (GB 3838-2002), and the chemical oxygen demand (COD) of Quanyanshan Section was at risk of exceeding the Class Ⅳ water quality standard. The water environmental capacity of the basin was 592.83-1 238.25 t/a for COD, 51.99-193.60 t/a for ammonia nitrogen (NH₃-N) and 5.02-12.85 t/a for total phosphorus (TP). The pollution load into the Qingshui River of the basin was 15 661.1 t/a for COD, 1 670.2 t/a for NH₃-N and 784.5 t/a for TP in normal water period, which was 16, 14 and 89 times of the water environmental capacity (COD 940.57 t/a, NH₃-N 114.64 t/a, TP 8.81 t/a). The pollution load per unit area in Guyuan City was the highest (COD 3.04 t/a, NH₃-N 0.22 t/a, TP 0.06 t/a), with outstanding problems of industrial pollution load and urban living pollution. The total pollution load in Zhongwei City control unit into the river was the highest (COD 6 738.45 t/a, NH₃-N 868.88 t/a, TP 218.12 t/a), with relatively serious urban living source pollution, while Wuzhong City control unit had relatively heavy poultry-farming pollution. Based on the water quality targets and the pollution characteristics of each unit, it was recommended that the wastewater recycling and utilization of industrial enterprises be strengthened and the urban wastewater treatment capacity be improved in Guyuan City control unit; the construction, transformation and upgrading of sewage collection and treatment facilities be focused on Zhongwei City control unit; and the centralized treatment and reuse of livestock manure in large-scale farms be implemented in Wuzhong City control unit.

Mastering the seawater quality variation trends and formulating scientific and reasonable water quality targets are helpful to the accurate implementation of the total amount control of pollutant discharge in key sea areas and formulate effective pollutant control policies. The water quality variation trends analysis model and the water quality target determination method were established by using the Generalized Additive Models (GAM), based on the nutrient concentration and precipitation data of Tianjin coastal waters for the 2007-2018 periods. The water quality targets of Tianjin coastal waters were put forward on the basis of evaluating the variation trend of inorganic nitrogen and reactive phosphate concentrations at 12 stations in Tianjin coastal waters, and the rationality and accessibility of the water quality targets were analyzed. The results showed that the concentration of inorganic nitrogen in the coastal waters of Tianjin generally showed a downward trend, with a decreasing ratio of 13.19% and a 95% confidence interval ranging from −30.37% to 3.96% in 2013-2018, compared with 2007-2012. The concentration of reactive phosphorus generally showed an upward trend, with an upward ratio of 7.01% and a 95% confidence interval ranging from −11.43% to 25.45%, which had not recovered to the average level from 2007 to 2012. It was proposed that the proportion of Grade Ⅰ-Ⅱ water quality of inorganic nitrogen and reactive phosphorus in Tianjin coastal waters would reach 75% in 2025. It was suggested to implement water quality zoning management, and the Tianjin coastal waters were divided into seven zones. Other measures such as further strengthening the prevention and control of agricultural non-point sources pollution, enhancing the upstream and downstream collaborative governance and inter provincial joint prevention and treatment of water pollution were also proposed to continually improve the water quality of the coastal waters of Tianjin.

In order to study the pollution level and distribution characteristics of parabens (PBs) in lakes, the pollution status of 14 PBs in typical lakes in Beijing was investigated and analyzed. The water samples of a lake in Beijing were collected in both winter and summer, and detected by solid-phase extraction and liquid chromatography-triple quadrupole tandem mass spectrometry. The results showed that ten kinds of PBs were detected with high level in the lake, among which methylparaben (MeP, 24.8 ng/L) and propylparaben (PrP, 44.8 ng/L) were the dominant compounds. The concentrations of the target compounds detected at the same sampling site changed seasonally, and the concentrations of chlorinated parabens in spring were lower than those in winter. However, in the winter near the outlet of the wastewater treatment plant, the concentrations of chlorinated parabens were higher than those at other sampling sites. The external sewage was the main source of PBs in the lake water, and the concentration of MeP at the sampling site of the outlet of the power plant in spring (24.8 ng/L) was higher than that in winter (1.30 ng/L). The survey results showed that the species and concentration level of PBs in the lake were medium comparing with those reported in the researches of other nations. The pollution of PBs in the lake mainly came from the surrounding sewage discharge, and the concentration of PBs varied greatly in different seasons.

Based on MODIS NDVI data, the fractional vegetation cover (FVC) of Bayanbulak Grassland was measured from 2000 to 2020 by using a linear mixed spectral model, and the spatial-temporal variation patterns were analyzed by using the linear regression method. Besides, the influence of meteorological, terrain and land cover changes on regional FVC were analyzed. The results were as follows: 1) From 2000 to 2020, the average FVC of Bayanbulak Grassland was 46.19%, which showed a spatial distribution pattern of high in the west and low in the east. Areas with FVC greater than 60% were distributed in the northwest and south, accounting for 24.70% of the total area; areas with FVC lower than 15% were distributed at the edge of the study area. 2) FVC showed a trend of decreasing first and then increasing from 2000 to 2020, with an average annual decline rate of 0.093%; on the pixel scale, FVC remained basically unchanged in most areas, and the areas with a decreasing trend accounted for 24.86%, faceted in the central-east and north, and the areas with an increasing trend accounted for 10.54%, distributed in the edge of the middle and west of the study area. 3) FVC gradually decreased with elevation, and it was generally lower on the sunny slope than that on the shady slope. The effects of annual precipitation and annually average temperature on FVC showed significant spatial heterogeneity. About 10.70% and 13.99% of the regions had a positive correlation between FVC with the current year's precipitation and the last year's precipitation, and 8.23% and 11.11% of the regions had a positive correlation between FVC with the current year's average temperature and the last year's average temperature, and 8.23% and 5.35% of the regions had a negative correlation between FVC with the current year's average temperature and the last year's average temperature. The transformation of land cover types, especially the reduction of glaciers and permanent snow cover, contributed to the change of FVC.

China's Action Plan for Water Pollution Prevention and Control proposed to implement water ecological protection and water resource management in rivers and lakes. During the 14th Five-year Plan period, research on water ecological health evaluation methods of river basins, rivers and lakes should be carried out to support the transformation from water quality management to water ecological target in China, and provide basis for China's water ecological environment management needs. By combing the development process of water ecological health evaluation system abroad, several typical evaluation systems and methods such as prediction model method and biological integrity index method were mainly introduced and the limitations of the evaluation system through application cases were analyzed. The standards and norms related to water ecological health issued in China were combed, and the advantages and disadvantages of water ecological health evaluation methods in local watersheds in China were analyzed. Finally, some suggestions on China's water ecological health evaluation system, management criteria and policy system were put forward in order to provide reference for the research, development and practical application of water ecological health evaluation in China.

The index of biotic integrity (IBI) is an important and widely used indicator for the evaluation of river ecosystem health. However, there are few studies on the construction of IBI evaluation criteria based on the use of decomposer microbial communities in water. The evaluation of the ecosystem health of urban rivers in Beijing was carried out, and the evaluation process and criteria construction method of the microbial index of biotic integrity (M-IBI) were explored. Based on the high-throughput sequencing information of microbial Illumina in the sediments, the key environmental factors were screened (water quality indicators TN, TP, NH₃-N, NO₃-N and NO₂-N), and candidate biological parameters were determined. According to the results of discriminant analysis, six indexes were determined, including Shannon index, relative abundance of Bacteroidota, relative abundance of Chloroflexi, relative abundance of Cyanobacteria, relative abundances of COD_Cr tolerance genus and relative abundances of ammonia nitrogen clean genus. The standardized formula of parameters and the health evaluation standards were put forward. The evaluation results showed that each sampling point of the Yongding River supplied by natural water was evaluated as healthy state. Among the other three rivers, supplied by the effluent of the urban reclaimed water plant, four sampling points of the Qinghe River were evaluated as healthy to sub-healthy state, five sampling points of the Liangshui River were evaluated as healthy to general state, and four sampling points of the Dalong River were evaluated as sub-health to general state. M-IBI could effectively distinguish the damaged points of different degrees and give a reasonable evaluation of the health status of the urban river ecosystem.

Magnetic field is a field with special energies which is one of the physical factors affecting the physiological processes of living organisms. All organisms have their own magnetic fields, and the external magnetic field can have an impact on organism organization and metabolic processes. The magnetic field affects the whole process of organisms from growth to decay through the change of biological enzymes, an important substances in the body of life. The influence of magnetic field on microbes are more complex, and the magnetic field will produce different degrees of promotion or inhibition effect on microbes. Meanwhile, the application of magnetic field may have effects on cell structure, gene expression, cell membrane permeability, etc. In recent years, the role of magnetic field-induced biological magnetic effect in the treatment of environmental pollution such as water, soil and solid waste has attracted general attention. The effects of applied magnetic field on biological enzyme activity, microbial properties and biological cells were systematically reviewed. Based on this, the current researches of microbial magnetic effect in wastewater, soil environment and solid waste treatment were systematically summarized, and the application prospects of magnetic field biological effect in the environmental field were put forward, in order to provide a theoretical basis for biological magnetic effect to strengthen environmental remediation.

To explore the law of land use transformation and its ecological effects in the context of rapid urbanization in Suzhou, using the land use data of the city for 4 periods in 1980, 2000, 2010 and 2018, and according to the classification of the dominant functions of production-ecological-living (PEL), the methods of the land use transfer matrix, ecological environment quality index, and ecological contribution rate of land use transformation were used to quantitatively analyze the pattern of land use transformation and its ecological effects in Suzhou City, and the driving mechanism of ecological environment quality evolution was revealed through least square regression. The results showed that: from 1980 to 2018, the transformation of land use in Suzhou City displayed a decrease in productive land use, a small increase in ecological land use, and a rapid increase in living land use; the quality index of Suzhou ecological environment decreased from 0.431 2 in 1980 to 0.4139 in 2018, and the overall ecological environment quality decreased. There were both trends of ecological environment improvement and deterioration in Suzhou City. In 1980-2000, the conversion of agricultural production land into watershed ecological land and woodland ecological land was the main factor contributing to the improvement of ecological environment quality. The crowding of agricultural production land into watershed ecological land and the occupation of agricultural production land by towns and rural living land were the main reasons for the deterioration of ecological environment quality. In 2000-2018, the conversion of agricultural production land into watershed ecological land was the main factor for the improvement of ecological environment quality, and the crowding of agricultural production land by towns and rural living land was an important reason for the deterioration of ecological environment quality. The adjustment of industrial structure and energy structure was the main factor for the improvement of ecological environment quality in Suzhou City, while the increase of population, unreasonable economic development mode, the increase of social consumption level and other factors increased the pressure on ecological environment protection.

The theory of ecological security pattern provides theoretical basis and technical path for the ecological protection and restoration of landscape complex at regional scale. Taking the important ecological barrier in Southeast China, that is Huanggang Mountain area, the main peak of Wuyi Mountain, as an example, according to the research framework of "Identifying ecological sources - Constructing resistance surfaces - Extracting ecological corridors", a combination of qualitative and quantitative methods was adopted to evaluate and extract the areas with extremely important ecosystem service functions in the region, and superimpose the areas with natural reserves to generate ecological source areas. And the resistance surfaces were set for the study area with land type and terrain factors, then the minimum cumulative resistance model was used to extract the ecological corridors, the important ecological function areas were determined as the ecological buffer zones, and the ecological security pattern of Huanggang Mountain area was constructed. The results showed that the area of ecological sources in Huanggang Mountain area was high at 5 808.8 km², accounting for 34.16% of the regional land area, which were mainly distributed in the junction zones between the southern mountains in Jiangxi Province and northern mountains in Fujian Province. 21 ecological corridors in total were extracted, with a length of 455.1 km, connecting the central part of the study area with the source patches in the northeast and southwest in a group form. The ecological buffer zones covered an area of 1 574.13 km², accounting for 9.2%, and mainly distributed in the northern mountainous areas of the region. The study broke the boundaries of provinces, cities and river basins, regarded the study area as a complete community of life, fully considered the integrity of ecological structure, the connectivity of ecological process and the importance of ecological functions, and constructed a regional-scale point-line-plane ecological security pattern, which could provide spatial guidance for the local implementation of regional integrated conservation and restoration.

Ecological modern city is an important support for the construction of national ecological civilization, and the construction of ecological security pattern is an important basis for the realization of urban ecological priority and green development. Taking Wuhan City as an example, the importance of ecosystem services and ecological sensitivity were used to identify the ecological sources, the ecological corridor was extracted through the minimum cumulative resistance model, the ecological nodes were identified, and the ecological security pattern of Wuhan City was constructed. The results showed that there were 98 ecological sources in Wuhan City, covering an area of 2 214.7 km² and accounting for 25.82% of the total area of the city. The main type of ecological source was water, and it conformed to the ecological characteristics of water resources of rivers and lakes in Wuhan City with crisscross rivers and scattered lakes. 80 important ecological corridors were extracted, with a length of 928 km. The corridors were staggered to form a stable ecological network structure of "five horizontal and four vertical". 6 ecological nodes, or the key location of the ecological corridor to ensure the overall connectivity of ecological space, were identified. Finally, the network system of comprehensive ecological security pattern in Wuhan City was constructed. The construction of ecological patterns based on the model of "source - ecological corridor - ecological node" could identify important ecological functional areas, clarify regional ecological security risks, and provide a scientific basis for the protection of urban ecological security and regional sustainable development of Wuhan City.

In order to investigate the effects of land use change on ecosystem service value (ESV) in Guangxi Autonomous Region, the random forest algorithm was used to classify the land use of the 5 periods of Landsat series remote sensing images from 2000 to 2020, the land use dynamic degree and land use transfer matrix methods were used to reveal the land use change patterns, the ecosystem services value was calculated by using the equivalence factor method, with its spatiotemporal variation characteristics explored, and the intrinsic link between each land use type and changes in ecosystem service values was analyzed. The results showed that forest land and arable land were the main land use types in Guangxi, and the area of construction land had been increasing year by year, mainly by encroaching on arable land. The dynamic degree of single land use type was in the order of unutilized land > grassland > construction land > cropland > water > forest land. The overall ESV in Guangxi showed a fluctuating downward trend. The value of unidirectional ecosystem services was dominated by hydrological regulation and climate regulation. In terms of spatial distribution, the ESV was characterized by a low spatial distribution in the middle and high spatial distribution in the surrounding area. For the changes of ESV in Guangxi in the last 20 years, grassland, forest land and cropland were the main contributing factors and sensitive factors.

Rapid urbanization, agricultural activities and ecological restoration significantly altered land-use pattern and eco-environments of Qingshui River Basin. It is critical for assessing and projecting the future land-use patterns, ecosystem service and its values for ecologically sustainable areas. Based on the CA-Markov model and GIS software, the future ecosystem service and its values were simulated by using InVEST model in the way of prediction plus design. The results showed that: 1) In 2000, 2009 and 2018, the average values of carbon storage, soil conservation, and water yield in Qingshui River Basin approached approximately 100.68 t/hm², 800.62 t/hm², and 57.88 mm, respectively, exhibiting the increasing trends in water yield and soil conservation except for carbon storage which had a decreasing trend. 2) The total ecosystem service values in the study area reached approximately 2.44 billion yuan in 2018, with a 2.2% decrease compared with the level in 2000. This value was 2.31 times of the total output value of agriculture, forestry, fishery and animal husbandry, and 0.78 times of local gross domestic product (GDP). 3) As “Grain for Green” practices were implemented in the regions with >15° slopes, the ecosystem service values of carbon storage and soil conservation got pronouncedly improved, whereas water yield exhibited an obvious decreased trend. The research showed that under the condition of a homogeneous climate in Qingshui River Basin in the last 20 years, the ecosystem service and its values had not significantly increased or even declined. Specifically, the afforestation practices on steep slopes of >15° may help reverse the trend of ecological degradation in Qingshui River Basin.

In order to explore the response mechanism of plants and rhizosphere microorganisms in constructed wetlands under the stress of sulfamethoxazole (SMX), the removal efficiency of different concentrations of SMX in the combined remediation of five plants and rhizosphere microorganisms was characterized. According to the removal efficiency of SMX, the root activity, reactive oxygen species and antioxidant system of Gladiolus hybridus and Cyperus alternifolius were studied, and the response characteristics of their rhizosphere microbial community under SMX and temperature stress were analyzed simultaneously. The results showed that the removal rates of SMX by Gladiolus hybridus and Cyperus alternifolius were the highest in the five constructed wetland plants and rhizosphere microorganisms, with an average of 40.38% and 44.70%, respectively. When SMX concentration was higher than 30 mg/L, the root activity of Gladiolus hybridus and Cyperus alternifolius was inhibited, which was 69.77% and 67.26% lower than that of 0 mg/L, respectively. With the increase of SMX concentration, the reactive oxygen species (ROS) content of Gladiolus hybridus and Cyperus alternifolius increased by 69.08% and 72.67% compared with 0 mg/L, respectively, but the antioxidant enzyme activities decreased by 19.32% and 24.83%, respectively. Compared with normal temperature (20-25 ℃), the ROS content of Gladiolus hybridus and Cyperus alternifolius increased by 2.26% and 1.98%, and the antioxidant enzyme activity decreased by 47.72% and 44.42%, respectively, under low temperature (4-12 ℃). The measurement results of the rhizosphere microbial community by high-throughput sequencing technology showed that high concentrations of SMX inhibited the diversity and species richness of the plant rhizosphere microbial community. PICRUSt function prediction software was used to predict the microbial community function, and it was found that the relative abundance of microbes with amino acid and carbohydrate metabolism was higher.

The study on the amended bioretention systems was conducted in view of the instability and even the negative removal of N, P in rainwater by the bioretention tanks. By constructing two systems of straight-flow and fold-flow bioretention, traditional fillers and hydroxy-aluminium vermiculite sludge particle (HAVSP) were filled respectively. Three simulation test device columns were set up, of which 1^# was a traditional filling straight-flow bioretention column, 2^# was a modified filling straight-flow bioretention column, and 3^# was a modified filling fold-flow bioretention column. The removal effect of nitrogen and phosphorus in rainwater under three simulated experimental devices was compared, and the improvement effect of HAVSP on bioretention filler was discussed. The results showed that the reduction effect of nitrogen and phosphorus in HAVSP amended filler fold-flow bioretention system was more obvious than that in conventional filler and amended filler straight-flow bioretention system, and had the best effect on nitrogen and phosphorus reduction when the outflow height was 350 mm, with total nitrogen and nitrate-nitrogen removal rates up to 76% and 77%, respectively.

In order to quantitatively evaluate the reduction rate of low impact development (LID) techniques on rainwater runoff pollution load, Liuan Hefeng Community in Jiaxing City was selected as the LID community, and Bay Community adjacent to it with similar underlying surface types was selected as the traditional community. The external discharge and TP concentration of the communities were monitored simultaneously. Then, the pollution load per unit area of the two communities was calculated according to the rainfall level differentiation under the same rainfall situation. Finally, the reduction rate of rainwater runoff pollution load of LID community was calculated based on the pollution load of unit area of traditional community. The results showed that: In light rain, LID facilities absorbed all the runoff and pollutants within their service range, and achieved a 100% reduction rate of pollution load. With the increase of rainfall, runoff and pollutants carried by it gradually exceeded the functional threshold of LID facilities, and the pollutant abatement rate began to decrease. In moderate rain the reduction rate dropped to 67% and in heavy rain it dropped to 46%. The average annual reduction rate of rainwater runoff pollution load was about 66%. On the whole, the reduction rate of rainwater runoff pollution load of LID facilities showed obvious differences in rainfall levels. The method of rainfall level differentiation could reduce the error caused by rainfall levels and ensure the accuracy of evaluation results, which provided a reliable decision-making basis for LID facility construction in communities.

The traditional process has a limited effect on the treatment of phenolic wastewater, and catalytic ozonation technology can effectively treat phenolic wastewater. α-Fe₂O₃ has exhibited high ozone catalytic activity in previous experiments. ·OH produced by catalysis can non-selectively mineralize phenol and intermediate products, which significantly enhances the removal of pollutants and the level of ozone utilization. In order to clarify the main influencing factors of the catalytic ozone oxidation process and optimize the process parameters, phenol was used to simulate phenolic wastewater, and L₁₆(4⁴) orthogonal experiment was designed. The results showed that ozone dosage, catalyst dosage, pH, and reaction time were the main influencing factors of COD removal rate and COD degradation per unit ozone. Among them, ozone dosage and reaction time had the most significant impact on the two indicators. Variance analysis and experimental verification showed that catalyst dosage had little effect on COD removal rate, and reaction pH had little effect on COD degradation per unit ozone. The optimized process parameters were calculated by weight matrix: ozone dosage was 5 mg/(L·min), catalyst dosage was 0.1 g/L, pH was 9, and reaction time was 45 min. Tert butyl alcohol shielding experiments showed that ·OH significantly promoted the catalytic ozone oxidation process.

Anaerobic ammonium oxidation (Anammox) is one of the most promising new nitrogen removal technologies for municipal wastewater in the future. Based on Anammox reaction mechanism, the operation control strategies of partial-nitrification coupled Anammox (PN/A) and partial-denitrification coupled Anammox (PD/A) under the condition of municipal wastewater were summarized, and the process modes of Anammox to strengthen the denitrification in municipal wastewater were elaborated. At the same time, the bottleneck problems hindering the realization of Anammox treatment from the perspective of engineering application were concluded. Finally, the nitrogen removal performance, effect of reducing consumption and emission, process characteristics and application scenarios of PN/A and PD/A in municipal wastewater were compared and analyzed, and the future research direction of Anammox was summarized and prospected, so as to provide reference for the transformation of urban sewage treatment to Anammox process.

As a novel biological nitrogen removal process, partial denitrification coupled with anammox (PD-A) process can save the cost of aeration and external carbon source, generate NO₂ ⁻ steadily and efficiently and have high removal efficiency of total nitrogen. Besides, PD-A process can reduce the emission of greenhouse gas N₂O. Existing researches on PD-A mostly focus on the simulated wastewater with single water quality conditions while the research on the real wastewater is still missing. The mechanism and characteristics of PD-A process were analyzed, the optimization strategy of PD-A process operation was proposed through comparing the optimal growth conditions of core functional bacteria, partial denitrification bacteria and anammox bacteria, in combination with the existing researches. Then the application cases of PD-A process in the real wastewater were analyzed. The results showed that optimizing COD/NO₃ ⁻, inoculating sludge with different structures and adding biofilm carriers were beneficial to the efficient and stable operation of the process. PD-A process could achieve higher nitrogen removal efficiency in the treatment of real domestic sewage, aquaculture wastewater and high nitrate wastewater, indicating that the treatment of real wastewater through PD-A process was feasible. Finally, the development trend of PD-A process was forecasted, the real wastewater should be treated, and the synergy mechanism of the core flora in the system and the mixed biological denitrification control method should be further studied to improve the stability of the process and the efficiency of synergistic removal of carbon and nitrogen.

In order to explore the minimum requirement of phosphorus for sulfur autotrophic denitrification, the sulfur autotrophic denitrification system was first treated with phosphorus starvation, and then the influents of different phosphorus concentrations were provided to investigate the influence of phosphorus concentration on the sulfur autotrophic denitrification performance and microbial community structure. The results showed that with the extension of the phosphorus starvation period, $ {\mathrm{N}\mathrm{O}}_{x}^{-} $-N removal efficiency declined gradually from 98.1%-99.6% before phosphorus starvation to 24.8%-49.6% after phosphorus starvation, accompanied by an accumulation of nitrite in the effluent. After phosphorus addition, $ {\mathrm{N}\mathrm{O}}_{x}^{-} $-N removal efficiency increased significantly with increasing influent phosphorus concentration. The higher the influent phosphorus concentration, the faster the $ {\mathrm{N}\mathrm{O}}_{x}^{-} $-N removal efficiency and effluent nitrite concentration recovered to the level before phosphorus starvation, with more than 98% and less than 0.05 mg/L, respectively. The efficiency of sulfur autotrophic denitrification was not limited by phosphorus concentration when the influent phosphorus concentration was not lower than 0.200 mg/L. The phosphorus concentration affected the microbial diversity of the sulfur autotrophic denitrification system, and the community diversity and richness of the sulfur autotrophic denitrification group recovered from phosphorus starvation were significantly higher than that of the group under phosphorus starvation. The functional genera related to sulfur autotrophic denitrification were the predominant genera in the sulfur autotrophic denitrification group recovered from phosphorus starvation, with the relative abundance accounting for 45.78%, while the relative abundance only accounted for 4.67% in the group under phosphorus starvation. The phosphorus concentration greatly affected the relative abundance of functional genera related to sulfur autotrophic denitrification in the sulfur autotrophic denitrification system.

Numerical model simulation has irreplaceable advantages in the design, operation, and optimization of the secondary sedimentation tank of the sewage treatment plant. It is very important to summarize existing numerical models for the selection and establishment of models in practical applications. The principles of multiphase models such as Euler-Lagrange model, Euler-Euler model, and Mixture model for numerical simulation of secondary sedimentation tank were introduced. The applicability of each model was described, the advantages and disadvantages of each model put forward, and the application principles of the single-phase model in sludge sedimentation explained. The single-phase model described the movement law of sludge sedimentation by coupling a single solid-phase transport equation, which was better than multiphase model in predicting the distribution of sludge mass concentration in the secondary sedimentation tank. The research status of the sludge sedimentation velocity model was discussed, including the model of intermittent sludge settlement using batch settlement test and the model of continuous flow sludge settlement describing the secondary sedimentation tank of the sewage treatment plant. The influence of sludge load, geometry structure, and temperature on water quality simulation of the secondary sedimentation tank was systematically reviewed. Finally, the selection of mathematical models for secondary sedimentation tank of the sewage treatment plant and future research on sedimentation models were prospected, to provide a theoretical basis and technical reference for the operation and design optimization of the secondary sedimentation tank of the sewage treatment plant.

The implementation of cleaner production technologies in the pharmaceutical industry can reduce the generation of pollutants from the source, which is conducive to promoting the healthy and sustainable development of the pharmaceutical industry. In order to correctly select the appropriate cleaner production technologies in the pharmaceutical industry, the evaluation index system of cleaner production technologies in the pharmaceutical industry including technical, economic and environmental indexes was established, and the analytic hierarchy process-fuzzy comprehensive evaluation (AHP-FCE) model was constructed. The evaluation standard of cleaner production technologies in the pharmaceutical industry was determined, and the comprehensive evaluation of four cleaner production technologies in the pharmaceutical industry was carried out based on the AHP-FCE model. The results showed that cephalexin enzymatic synthesis technology was better in technical performance, large-scale preparation technology of immobilized enzyme for antibiotic synthesis was better in economic performance, and penicillin fermentation and emission reduction technology based on medium substitution was better in environmental performance. The comprehensive evaluation results showed that cephalexin enzymatic synthesis technology was the best technology in four cleaner production technologies in pharmaceutical industry.

To clarify the research status and future development trend of arsenic removal from groundwater, the bibliometric method was used to analyze the literature on arsenic removal from groundwater published in the Web of Science (WoS) database from 2008 to 2020, and the comprehensive analysis was conducted from the aspects of the annual number of articles published, publishing organizations, journals, authors, and keywords. The results indicated that: in WoS database, there were 1 501 research papers on arsenic removal from groundwater, and the annual number of publications was on an overall upward trend; the top three countries in terms of publication volume were China, the United States and India; a total of 1 503 research institutions and 4 875 authors participated in the research of arsenic removal from groundwater, in which universities were the main research bases, and university teachers, postgraduate students werethe main force of the research. Keywords analysis showed that the adsorption and electrocoagulation technology were the mainstream methods for arsenic removal from groundwater, the zero-valent iron materials were popular adsorbents applied in the research from 2008 to 2020. At the same time, the emergence analysis showed that the preparation of binary or even multiple oxides and nanocomposites would become the frontier hotspot in the research of arsenic removal from groundwater.

Taking a decommissioned chemical site as the research object, in view of the organically polluted groundwater aquifer in it, the groundwater pollution characteristics were investigated. The risk assessment model and DRASTIC model were applied to evaluate the human health risk and groundwater vulnerability in the study area, respectively, and the groundwater migration and diffusion model of typical pollutants was constructed to further analyze the influencing factors and dynamic modes of the migration and diffusion of typical pollutants. The results showed that the groundwater in the study area was polluted by 1,2-dichloroethane, benzene and trichloromethane. The total carcinogenic risk of 1,2-dichloroethane was 4.00×10⁻⁶, exceeding the acceptable level of human health risk, which was mainly caused by inhaling gaseous pollutants from groundwater in indoor air. The groundwater vulnerability index of the study area ranged from 4.912 to 5.305, which was at the medium vulnerability level as a whole. The groundwater system had a strong ability to resist pollution. The groundwater depth, net recharge and aquifer thickness were the main factors affecting groundwater vulnerability. The migration and diffusion of 1,2-dichloroethane were jointly affected by the convection of groundwater, the adsorption and retardation of aqueous media, and biochemical effects. Groundwater convection was the main driving force for its migration and diffusion. Moreover, the adsorption and retardation of aqueous media and biochemical effects had significant effects on the distribution range of 1,2-dichloroethane.

Taking an industrial site in the intertidal zone of the river estuary as the research object, the total petroleum hydrocarbons (TPHs) of soil and groundwater samples were collected and investigated, and the migration law of TPHs in the soil and groundwater of the industrial site in the intertidal zone and the influence of tide on it were analyzed and discussed. The results showed that the groundwater level in the area along the river of the site fluctuated obviously by tide, the average permeability coefficient of the aquifer was 1.40 m/d, and the permeability of aquifer near the river was better. The maximum exceeding multiple of TPHs in the soil of the site was 1.39 times. The pollution was mainly distributed in the core production area, mainly neared the junction between the first two different lithological layers. The vertical distribution of TPHs in soil was significantly influenced by stratum structure and tidal effect. When the water level decreased, TPHs migrated downward and part of TPHs remained in vadose zone, while when the water level rose, it led to the opposite process. The maximum exceeding multiple of TPHs in the groundwater of the site was 95.23 times, the pollution plume center was consistent with the main areas of soil TPHs pollution, and the groundwater flow field had a significant impact on the migration and distribution of pollutants. The tidal effect expanded the range of TPH pollution plume. The fluctuation of groundwater level with no long-term stable flow direction made TPHs redistribute countless times between soil and groundwater, so that its migration law was not obvious. This study revealed to a certain extent that the long-term fluctuation of the intertidal groundwater level caused by the tidal effect had a significant impact on the migration law of pollutants in the soil and groundwater, which could provide a scientific guidance for the effective control and restoration of similar contaminated sites

Screening scientific and reasonable groundwater remediation technologies for operating enterprises is of great significance for effectively remediating contaminated groundwater bodies, saving corporate environmental investment, and achieving green and sustainable development. For the groundwater contaminated by iron and manganese of an operating enterprise, four technical schemes were put forward: extraction treatment, in-situ chemical oxidation, permeable reactive barrier, and monitoring natural attenuation, and the analytic hierarchy process (AHP) method and the technique for order preference by similarity to an ideal solution (TOPSIS) were used to select the best remediation scheme. 14 indicators in technical, economic, environmental and social terms were selected to establish the AHP model. The indicator weights were first determined by AHP, and then the four remediation schemes were ranked by TOPSIS in order of merit. The results showed that the technical scheme of monitoring natural attenuation was most suitable for groundwater treatment and remediation of the operating enterprise, due to its advantages in resource and energy consumption, waste generation and discharge, and pre-construction investment.

Accelerating the green and low-carbon transformation and development of coal-based industry is very important for China to achieve the goal of carbon peak and carbon neutrality. The basic situation of product outputs and greenhouse gas emissions in coal, coal power and coal chemical industry was mainly analyzed, and the risks and challenges faced by coal-based industry in terms of industrial distribution, ecological environment protection pressure, energy utilization efficiency and low-carbon technology innovation were identified. The green and low-carbon development paths of coal-based industry were put forward, from the aspects of scientifically planning industrial layouts, strengthening ecological environment protection, strengthening energy-saving transformation and improving efficiency, focusing on the application of technological innovation and deepening the coupling development of multiple industries, so as to provide policy support for the green and low-carbon development of coal-based industry.

China is in a period of economic transformation and rapid development. Coordinated emission reduction of carbon dioxide and air pollutants is a challenge for economic and social development on the one side, and on the other side it is also an important opportunity to promote the green transformation of economic structure, accelerate the formation of green production mode and lifestyle, and boost high-quality development. Thus a comprehensive understanding of the air pollution and carbon dioxide reduction and economic development levels in various regions of China will be helpful for national and local governments to formulate policies related to "air pollution and carbon dioxide reduction" according to local conditions. Therefore, an "air pollution reduction-carbon dioxide reduction-economic development" comprehensive evaluation index system was constructed, and energy economy, pollutants and carbon dioxide emission data of 30 provinces/municipalities/autonomous regions in 2016 and 2018 were selected to make the comprehensive evaluation of the pollution reduction, carbon dioxide reduction and economic indicators of various regions using the grey correlation degree method, and the development status of various indicators was analyzed. In addition, the coordination of the three indicators in each region was analyzed, through the calculation of the binary coupling coordination degree and ternary coupling coordination degree of indicators. Based on the evaluation index scores and the coordination degree data of various regions, suggestions on air pollution and carbon dioxide reduction and regional economic development were put forward according to local conditions.

Based on HYSPLIT backward trajectory model and NCEP's GDAS data (from March 2019 to February 2020), the seasonal clustering of air mass backward trajectory in Linfen City for 24 hours in winter was simulated, the main pollution sources and pollution transmission channels of PM_2.5 from different source areas were studied, and the seasonal characteristics of different trajectory transmission of PM_2.5 were clarified. Combined with the potential source contribution factor (PSCF) analysis method and the concentration weighted trajectory (CWT) analysis method, the pollution contribution intensity of different pollution source areas to Linfen City was analyzed. The results showed that PM_2.5 pollution in Linfen City was mainly concentrated in winter, followed by spring and autumn, and the lowest in summer. Through the cluster analysis of the backward trajectory of the air mass, it was found that the southwest and northwest directions along Fenhe River Basin were the main pollution transmission channels of air pollution. Through the analysis of potential source contribution and concentration weight trajectory, it was found that the pollution contribution intensity in Hongtong County, Yaodu District, and Xiangfen County of Linfen City was relatively strong, and the surrounding cities of Yulin, Yuncheng, and Jiaozuo had a certain impact on Linfen City.

To study the change of the concentrations of NO₂ emitted by motor vehicles on the urban road, 4 roads in Dadukou District, Chongqing Municipality were selected for one-week automatic online monitoring. Combined with the information of traffic flow and vehicles collected by RFID Base Stations on the road, the change features of NO₂ concentration and traffic flow, as well as their correlation were analyzed. The results showed that the daily averaged concentration of NO₂ on 4 roads was 29-57 μg/m³, all lower than Level 2 standard threshold of Ambient Air Quality Standard (GB 3095-2012). The hourly concentration of NO₂ peak value at about 20:00 was significantly higher than that at 08:00, with the minimum value appearing at around 14:00. The traffic flow of 4 roads had the obvious trend of morning and evening rush hours. The traffic flow at weekends was 20%-40% lower than the average traffic flow on workdays. The vehicle models with a high proportion included minibus, taxi, bus, and light truck. The change of the hourly concentration of NO₂ was consistent with that of traffic flow. Both of them had the obvious trend of morning and evening rush hours, but during the evening rush hours, the peak concentration of NO₂ appeared slightly later than the peak value of traffic flow.

In order to strengthen the comprehensive regulation of industrial volatile organic compounds (VOCs), Shenzhen City, a developed industrial and economic area, was selected as the research area. Through field investigation and field testing, the VOCs emission characteristics and end-of-pipe (EOP) treatment status of typical solvent sources such as rubber and plastic products industry, printing industry, surface coating industry and electronic components manufacturing industry were discussed. At the same time, some specific measures of emission reduction for source substitution and terminal management were made. The results showed that: The average emission of VOCs from typical solvent sources in Shenzhen City was in the order of surface coating (51.8 t/a) > electronic components (36.5 t/a) > printing (21.0 t/a) > rubber and plastic (17.4 t/a). Rubber enterprises and printing enterprises of different emission scales contributed more evenly to their respective industries, while painting enterprises and electronic enterprises with emissions higher than 300 t/a contributed 63.9% and 44.9% to their respective industries, respectively. Under the influence of control policies such as the substitution of water-based raw materials and the promotion of EOP treatment facilities, OVOCs were the main VOCs components of the four industries' fixed emission sources, with a mass proportion ranging from 76.8% to 97.0%. Besides, the characteristic pollutants were formaldehyde and acetaldehyde. The EOP process types of the four industries were mainly the inefficient combination of UV photolysis, water spraying and activated carbon adsorption, accounting for about 51.4%-69.6%. The evaluation results showed that 78% of the tested typical combined processes had an average treatment efficiency of lower than 35%. The lack of pertinence of treatment schemes and the lack of standardization of operation management were the main factors causing the low EOP reduction rate of VOCs from the sources of solvent use. Therefore, in order to control the emission of VOCs from the sources of solvent use in the future, the source control should be promoted from "baseline constraint" to "advanced driven". The EOP treatment should comprehensively consider the technical feasibility and management effectiveness to ensure the efficient reduction of the total amount of VOCs emissions in the industries.

Taking the cultivated soil in Bailang County and Jiangzi County of Nianchu River basin in Tibet as the research objects, the contents of 9 kinds of heavy metals, Hg, As, Pb, Cd, Cr, Cu, Mn, Zn and Ni, were investigated and analyzed. The single factor index method, Nemerow comprehensive pollution index method and other methods, combined with the spatial interpolation method were used to evaluate the heavy metal pollution of agricultural land in Nianchu River basin. Meanwhile, correlation analysis and principal component analysis were used to explore the sources of soil heavy metals. The results showed that: 1) The content of Hg, Cu, Mn and Ni in the soil of agricultural land showed different degrees of accumulation, compared with the background values of the soil environment in Tibet. Compared with Soil Environmental Quality: Risk Control Standard for Soil Contamination of Agricultural Land (GB 15618-2018), As had the highest rate exceeding the standard. From Jiangzi County to Bailang County, the comprehensive ecological risk index of soil heavy metals in agricultural land gradually increased. 2) The regional pollution load index of the study area was 1.45, which was a low pollution level. Severe pollution was concentrated in Bailang County. 3) Principal component analysis showed that the sources of 9 kinds of heavy metals could be divided into natural and anthropogenic complex factors, mining factors, agricultural factors, soil parent material factors and atmospheric transmission factors.

The selection of rich plants with high growth, high biomass, and high economic value is a new breakthrough in the bioremediation of heavy metals. To study the accumulation characteristic of cadmium (Cd) by Pueraria thomsonii in farmland soil, field experiments were conducted to investigate Cd contents in tuber (radix pueraria and arrowroot), basal part of stem, main vine, lateral branch, and leaf of Pueraria thomsonii under three pollution levels. The results showed that Cd contents in different parts of Pueraria thomsonii were lateral branch (8.96 mg/kg) > main vine (6.85 mg/kg) > leaf (5.22 mg/kg) > basal part of stem (2.80 mg/kg) > radix pueraria (1.36 mg/kg)> tuber (1.21 mg/kg)> arrowroot (0.16 mg/kg). Cd contents increased with the increase of soil pollution, showing that Cd contents in medium and high pollution were significantly higher than in low pollution (P < 0.05). Except for tuber, the accumulation coefficient of Cd in other parts of the plant was higher than 1 (1.09-8.65), and the transport coefficient was 2.59-8.98. The distribution rates of Cd content in various parts of Pueraria thomsonii were as follows: lateral branch (35.64%-43.81%) > main vine (21.55%-25.49%) > leaf (15.40%-23.63%) > tuber (7.03%-9.94%) > basal part of stem (5.99%-9.57%). The biomass in various parts of Pueraria thomsonii was tuber > lateral branch > leaf > main vine > basal part of stem. The removal amount of Cd increased with the pollution level, which was high pollution (45.39 g/hm²) > medium pollution (39.96 g/hm²) > low pollution (16.56 g/hm²). In general, Cd contents in various parts of Pueraria thomsonii were significantly positively correlated with soil organic matter, available Cd, and total Cd, but negatively correlated with soil pH. In the treatment of Cd contaminated farmland soil, Pueraria thomsonii (used as arrowroot) has application value for Cd contaminated farmland soil remediation.

The sludge of sewage treatment plants is rich in phosphorus and recycling phosphorus from sludge can alleviate phosphorus depletion to a certain extent. Sludge was treated by incineration, with rice husk as an additive, and the variation of phosphorus fraction and extraction efficiency in sludge-rice husk incineration ash were investigated by using Hedley's stepwise extraction method and acid extraction method. The effect of rice husk dose on phosphorus fraction in incineration ash was explored. The results showed that the phosphorus bioavailability was the best when the dose of rice husk was 50% of the total mass. Based on the optimization by response surface method, the optimal condition was found that HCl concentration, extraction time, and the ratio of liquid and solid were 0.33 mol/L, 6.4 h, and 50 mL/g, respectively. The phosphorus extraction efficiency at the optimal experimental condition was as high as 93%, which was 20% higher than that of sludge incineration ash. Through comparing the physical and chemical properties of sludge ash, rice husk ash and ash of co-incineration, it was found that the co-incineration of sludge and rice husk did not change the main components of sludge ash and rice husk ash, but the new phase was generated and the morphology changed. The results illustrated that the co-incineration of sludge and rice husk could improve the phosphorus extraction efficiency of incineration ashes, which was beneficial to the recovery of phosphorus resources from sludge.

Different kinds of active biochar were prepared from cyanobacteria in Taihu Lake and put into the cathode of bioelectrochemical system (BES) to promote hydrogen autotrophic denitrification. Three groups of cyanobacterial biochar of Unmodified (ABC-800), modified by nitric acid (ABC-800N) and modified by KOH (ABC-800K) were observed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR), and were compared with the control group without the addition of cyanobacteria biochar, to investigate the electron transfer mechanism in denitrification process of biochar promotes BES biocathode. The results showed that the contents of nitrogen and oxygen on ABC-800N surface were the highest, and the abundance of conjugated quinone and ketone structures related to electron transport capacity and biocompatibility was also the highest. Adding cyanobacteria biochar to the abiotic cathode of BES could improve the nitrogen removal efficiency of the cathode. After adding 0.5 g ABC-800N into the BES abiotic cathode, the nitrogen removal efficiency reached the highest within 7 days, which was 96.0%, while the control group was only 29.6%. High-throughput sequencing showed that the dominant bacteria in ABC-800N group were Thauera, JGI_0001001_H03, Thiobacillus, and Denitratisoma, etc.

High-density polyethylene (HDPE) membrane is the core component of landfill anti-seepage system, and the leakage of leachate caused by its breakage can seriously contaminate the soil and groundwater environment, so the repair of landfill HDPE membrane leaks is crucial. The impermeable structures of domestic waste, general industrial waste and hazardous waste landfills were systematically summarized, and the advantages, disadvantages and conditions of present landfill HDPE membrane leak repair technologies at different stages of the landfill operation were discussed, according to the causes and characteristics of HDPE membrane leaks. The analysis showed that the self-sealing/self-healing technology could automatically repair the leaks after they were generated, being the design direction for future landfill liners, while the electrokinetic repair technology could achieve targeted and precise repair of landfill HDPE membrane leaks after operation and closure, which should have broader application prospects.

To recover and reutilize phosphorus from wastewater, a methodological framework for phosphorous removal and recovery using Fe-Al-Zr modified anthracite materials was proposed. The adsorbent presented a total adsorption capacity of 13.022 mg/g and the adsorption mechanism mainly included electrostatic forces, ligands exchange and surface deposition and so on. Micropores provided the major adsorption sites for phosphorous, and determined the adsorption capacity of phosphorous. The modified adsorbents could be repeatedly used in four operation cycles until the adsorption rate decreased below 50%. The phosphorous could be desorbed and recovered in the form of hydroxyapatite (HAP) by adding a certain amount of CaCl₂ (n(Ca)∶n(P)=2∶1) under alkaline conditions.

A series of porous silicon aluminate materials is defined as zeolite, which is widely used in sewage purification, catalytic chemical synthesis and other fields due to its higher cation exchangeability. Coal ash, gasification ash, casting ash, and other industrial ashes may be used as the main raw materials for the synthesis of zeolite because they contained a large number of Si and Al elements, to achieve the purpose of resource utilization of these solid wastes. The formation and sources of coal ash, gasification ash and casting ash were analyzed. By comparing their chemical composition contents, it was found that the chemical composition contents of coal ash followed the order of SiO₂>Al₂O₃>Fe₂O₃>CaO. The ignition loss of gasification ash was 36.1%, which was relatively higher, and the ratio of Si to Al was significantly higher in casting ash than those in gasification ash and coal ash. At present, among the three kinds of ashes, more research and utilization work had been done for coal ash, while less had been done for casting ash and gasification ash. The total content of Al₂O₃ and SiO₂ in casting ash was relatively high, and its loss on ignition and metal oxide content was low. Casting ash was a high-quality raw material, which could be used to prepare high-quality zeolite. In addition to considering the recovery and utilization of Si and Al of gasification ash, its residual carbon should be fully utilized because the residual carbon content of gasification ash was relatively high.

The rapid development of economy in China has resulted in the mass production of industrial solid wastes. Especially in the chemical, pharmaceutical, printing and dyeing industries, the large amount of hazardous industrial waste salts has caused a serious threat to human health and the safety of the natural environment and restricted the rapid development of enterprises as well. On the basis of summarizing the treatment and disposal methods of industrial waste salts in China in recent years, the output, characteristics and hazards of industrial waste salts were introduced, and the common methods for the treatment of industrial waste salt were reviewed. Current thermal treatment technologies used in disposal of industrial waste salts in China were analyzed, including both traditional and new-type thermal treatment technologies. The traditional thermal treatment technologies such as incineration in a rotary kiln, incineration in a fluidized bed, and liquid jet incineration and new-type thermal treatment technologies such as incineration in a suspended furnace, graded carbonization, molten salt oxidation, high-temperature thermal pipe technology and microwave absorption technology were investigated. The treatment effects, advantages and disadvantages of different thermal treatment technologies were compared and analyzed, and the latest development progress of industrial waste salt thermal treatment technologies in China was systematically combed. In addition, the elimination mechanisms of organic pollutants in the process of these technologies were discussed, including the generation mechanism of reactive oxygen and the change of organic pollutant elimination with temperature. Finally, the migration and transformation law of non-metal elements (mainly N and S, etc.) and heavy metal elements contained in waste salts in process of thermal treatment, and the possible secondary pollution caused by dioxins were summarized.

Improving the level of green development is an important way to promote the construction of ecological civilization and realize beautiful China. The driving force-pressure-state-impact-response (DPSIR) model was used in the evaluation of green development performance to build a provincial green development performance evaluation index system under the vision of building a beautiful China. The analytic hierarchy process was used to calculate the index weights, and the objective asymptotic method was used for data standardization. On this basis, the provincial green development performance comprehensive index was constructed. The green development level from 2009 to 2019 of Guizhou Province was evaluated. The results showed that the green development performance comprehensive index of Guizhou Province from 2009 to 2019 had been increasing yearly, with the trend from Level Ⅰ (low) to Level Ⅲ (general). The indexes of social pressure, resource consumption, and pollutant emissions of the pressure layer had the greatest impact on the green development of Guizhou Province in the DPSIR model. At present, the green development of Guizhou Province was at a general level (Level Ⅲ). Improving the level of economic development, implementing ecological environment remediation, promoting pollution reduction and carbon reduction, and increasing people′s livelihood security should be paid more attention to improve the level of green development in Guizhou Province, and ultimately complete the construction of the Beautiful Guizhou.

It is urgent for the law enforcement of the air pollutants emissions from stationary sources to rely on an intelligent law enforcement system to accurately locate the illegal emission behavior of enterprises, and quickly monitor and obtain the pollutant emission concentrations as the evidence. Aiming at the common functional defects of the current air environment law enforcement system, known as "paying more attention to the management than the evidence", a new-generation intelligent law enforcement and supervision system with integrated hardware and software was put forward. The concept of IoT was adopted in the new system, combined with multi-scale air monitoring technologies. The ability of real-time data transmission between airborne, on-board, portable monitoring equipment and the law enforcement system was achieved, which relied on multiple data transmission and integration technology. Through a database with embedded analysis and calculation models, intelligent law enforcement functions were realized, such as identification of areas with air pollutants emission anomalies, rapid monitoring and evidence collection of on-site air pollutant concentrations, covert inspection and evidence collection, law enforcement process guidance, recognition of law and standard violations, remote command of the law enforcement, etc. Air environment law enforcement demonstration was carried out in iron and steel, heavy metals and other industries. Through IoT monitoring sensor sampling, multiple on-site violations were discovered, such as the exceeding of emission standards from outlets, excessive air pollutant concentrations at the factory boundary, and the inconsistency of approval and construction of exhaust outlets. Penalty opinions were put forward and filed for the record provided. This process significantly improved the efficiency and accuracy of environmental law enforcement.

In order to effectively improve the regional atmospheric environmental quality, China has launched large-scale rural clean heating renovation projects in the northern region, mainly from coal to electricity and coal to gas. How to choose a technically feasible and economically acceptable clean heating technology path is a key issue for the sustainability of clean heating renovation. Based on field survey data in rural areas of Beijing, the applicability of four rural clean heating technologies was evaluated from two dimensions of economy and comfort, the applicable conditions of various technologies were summarized and the suggestions on the choice of rural clean heating technologies were proposed. The results showed that: The air source heat pump had low operating cost and good comfort, which was suitable for various areas where the temperature was not lower than −20 ℃ in winter. The gas wall-hung boiler operation cost was slightly higher than the air source heat pump and had good comfort, which was suitable for plain and semi-mountainous areas close to gas pipelines or gas stations, and it was applicable to various climate and temperature ranges. Energy storage heater had high operating costs and poor comfort, which was suitable for rural areas where the winter temperature was close to urban areas, or areas of urban-rural junctions and small farm houses. The ground-source heat pump was best implemented in conjunction with government-funded projects, with lower operating costs, better comfort, and was suitable for areas where the geological structure was suitable for well construction and there was enough space for underground pipes. It was suggested that the rural clean heating work should be based on the long-term perspective, select clean heating technologies according to local conditions, and strive to reduce the operation cost of clean heating for farmers, while improving the reliability of rural clean heating power and natural gas supply.

Tetracycline is a tetracycline antibiotic. Tetracycline residues in the environment have chronic effects on aquatic organisms. However, there were no aquatic life criteria for tetracycline in fresh water in China. The acute and chronic toxicity data of tetracycline on freshwater aquatic organisms in China were collected and screened. A total of twelve acute toxicity data from seven phyla and twelve families and nine chronic toxicity data from seven phyla and nine families were obtained. The aquatic life criteria of tetracycline were derived by toxicity percentile rank and species sensitivity distribution methods. Finally, the short-term and long-term water quality criteria of tetracycline were 61.650 and 9.439 μg/L, respectively, derived by the species sensitivity distribution method. The ecological risk of tetracycline in some water bodies in China was assessed by the entropy method and the safety threshold method, finally the entropy method was used to evaluate the ecological risk level of tetracycline in freshwater environment in China. The results of the assessment suggested that the areas surveyed with ecological risk exposed to tetracycline mainly located in the Nanming River of Guiyang Province, and most other areas were basically risk-free. The research conclusions could provide scientific basis for formulating the water quality standards in terms of tetracycline, protecting freshwater aquatic life and managing water eco-environment.

Copper is one of the main pollutants in Fen River watershed. In order to accurately evaluate the ecological risk of copper exposure in the watershed, the toxicity data for native aquatic species in the Fen River watershed were investigated. The short-term and long-term water quality criteria of copper for the protection of aquatic organisms in the Fen River were obtained by using the biological ligand model method, which were 98.62 and 29.71 μg/L, respectively. According to the water quality criteria of copper, the risk assessment results showed that copper in Fen River water had no risk to aquatic organisms.