Soil health plays a vital role in global food security and ecological security. The decline of soil quality caused by human activities and other factors is widespread. How to improve soil health has been one of the most important hotspots and frontier issues on a global scale. The study systematically introduces the soil health evaluation system and its application status in domestic and foreign, summarizes the application of the existing soil health evaluation systems in agricultural management practice, and examines the development trend of the soil health evaluation system in China. The existing soil health assessment system needs to add some new indicators and new technologies, establish China's agricultural soil health network, use big data to understand the relationship between agricultural management practice and soil health, and develop an agricultural soil health assessment system which is suitable for China's climate environment and soil conditions. Finally, to provide theoretical support for improving China's agricultural soil health and realizing the goal of sustainable development, the solutions to maintain China's agricultural soil health are proposed based on the establishment of a soil health evaluation system and the cognition of social level on agricultural soil health.

Due to the rapid development of big data technology, the amount and type of data used to analyze and mine site pollution characteristics and formation mechanisms have also increased significantly. The traditional methods of acquiring, cleaning and mining site environmental data are difficult to meet the requirements of big data storage and processing. In recent years, it has become a research hotspot to use machine learning algorithms to mine multi-source heterogeneous site data to realize pollution identification at site and regional scales. The status and deficiencies of big data acquisition, processing and mining on intelligent identification of site pollution are systematically reviewed. Then, the application countermeasures to obtain site environmental data using 5G and the Internet, terminal information collection, web crawler, and natural language processing methods are proposed. Finally the key technologies of site multi-source site data integration and fusion and the future intelligent identification mode of site pollution in China are prospected.

Habitat quality is closely related to its suitability provided by land use/land cover type for biodiversity. In order to explore the characteristics of the changes of habitat quality caused by land use, reveal the fragility of the regional ecosystem, and provide a reference for the improvement of ecological service functions and regional ecological environmental protection, the urban agglomeration on the northern slope of the Tianshan Mountains was selected as the study area. Based on the land use data from 2000 to 2020, the InVEST model was adopted to measure the habitat quality from the spatial and temporal dimensions. Subsequently, the Moran index was used to analyze the spatial characteristics of habitat quality. The research results prove that:(1) The index of the overall habitat quality of the urban agglomeration on the northern slope of the Tianshan Mountains from 2000 to 2020 was above 0.8. Although the area with poor and worse habitat quality accounted for a higher proportion of the total study area, the overall trend is toward good and excellent development direction; (2) The habitat quality of the area of the urban agglomeration on the northern slope of Tianshan Mountains that has changed from excellent and good grades to poor and worse grades, accounted for 3.75% of the whole study area, while the area continued to deteriorate from poor to worse grades accounted of 10% of the whole study area; (3) Both the high-value Moran index areas and low-value Moran index areas of the urban agglomeration on the northern slope of the Tianshan Mountains have relatively high positive correlation characteristics in space, i.e. the habitat quality has high-high agglomeration and low-low agglomeration in space, and with time going by, this trend becomes more and more obvious. In general, the spatial change of habitat quality during the study period was not large. The main reason for the increase was that the implementation of ecological projects changed the type of land use/cover in the region, which increased the suitability of the habitat. However, the main reason for the decline was the expansion of construction land. Therefore, the ecological protection and ecological restoration measures in the study area should be further strengthened.

Chromium (Cr) is a typical toxic and hazardous heavy metal element. Its content in soil is closely related to natural conditions and human activities. Based on the data of Cr soil content, land use types, soil types, elevation and slope of Jiangning Economic and Technological Development Zone, the spatial correlation between Cr content in soil and various influencing factors is quantitatively studied using the principle of information entropy, and thus, the scaling effects are analyzed to identify the key factors for the distribution of Cr soil content at different spatial scales. The key factors affecting the distribution of Cr content in soil at different spatial scales are determined. The results show that at the large scale (over the Jiangning Economic and Technological Development Zone), the significance ranking of factors is land use type>soil type>elevation>slope; at the medium scale (the Niushoushan River basin scale), the order is elevation>slope>soil type>land use type; at the small scale (the tributary basin of Niushoushan River scale), elevation is most important, followed by soil type, slope, and land use type. This study can provide references for future decision-making on prevention and control of regional soil heavy metal pollution and for researches on the scaling effects of the key impact factors.

Clarifying the carbon sink of cropland ecosystem not only plays a significant role in the realization of the carbon neutralization plan for Henan Province, but also provides the helps for low-carbon and sustainable agriculture development. However, current studies on the carbon sink accounting are mainly based on only one single calculation method, lacking of multiple methods comparison. Based on the data of the Third National Land Survey, Statistical Yearbook of Henan Province, and the parameter data in the assessment report of the United Nations Intergovernmental Panel on Climate Change, the net carbon sink method and the carbon sequestration rate method were used to assess the carbon sink of cropland ecosystem in Henan Province. The net carbon sink method estimated the net carbon sink from the perspective of carbon absorption and carbon emission, while the carbon sequestration rate method mainly considered the net carbon sink of cropland soil. The results show that the net carbon sink method is more suitable for calculating the carbon sink of cropland ecosystem in Henan Province, and its value was 3.54 million t C; Meanwhile, the calculation results of the two methods all show that the cropland ecosystem in Henan Province is a carbon sink. Spatially, the distribution of carbon sinks estimated by the two methods presented a generally consistent law, that is, it gradually increased from the northwest to the southeast. On the whole, the carbon sinks of cropland ecosystem in Henan Province estimated in this study are far lower than the results of the previous studies, but it is more reasonable compared with the corresponding carbon sink of the proportion of Henan Province to the national cropland area.

Chengde City is an important ecological barrier in the Jing-Jin-Ji region and a key water retention area. Quantitative assessment of the water retention function of this region has important ecological and research implications. InVEST model and center of gravity migration model were used to quantify temporal and spatial changes in the water retention function of Chengde City from 1990 to 2017; scenario analysis method was used to evaluate the effects of the changes of climate and land use/cover on water retention function. The results show as follows:The annual average water retention was 33.12×10⁸ m³·a^-1, and the average water retention depth was 83.9 mm. Over the past 28 years, the water retention function in Chengde City first decreased and then increased. The center of gravity of the water retention function migrated from the northwestern to the southeastern part of the city over a distance of 14.28 km. The water retention function was significantly and positively correlated with precipitation and the normalized difference vegetation index (NDVI) and significantly and negatively correlated with the comprehensive land-use index. The relative contributions of climate and land-use changes to the migration of the water retention function in Chengde City were 94.49% and 5.51%, respectively. Climate change was the most important factor affecting the migration of the water retention function, and the effect of land-use change on the migration of the water retention function gradually increased over the study period. Our findings provide new insights that could aid future researches on ecosystem services in Chengde City.

The China-Pakistan Economic Corridor is a flagship project of the Belt and Road Initiative, the change of the normalized differential vegetation index (NDVI) along the Corridor has a profound impact on the improvement of the local ecological environment. Based on the 1995-2015 AVHRR GIMMS NDVI data set, and in combination with data on the climate and land use types during the same period, the spatiotemporal shifts and trends of the vegetation NDVI of the Corridor, as well as the relationship between climate changes and land uses have been analyzed by using maximum value synthesis methods, the Sen+MK trend analysis and the partial correlation analysis. The results show that:(1) There is relatively poor vegetation coverage along the China-Pakistan Economic Corridor. Over the 20 years period, its overall vegetation NDVI had shown an upward trend, despite some fluctuations; however, the spatial difference is remarkable, showcasing a decreasing trend from the center to the north and south; (2) The vegetation NDVI along the Corridor has been generally improved and kept basically stable. The improved areas are mainly distributed in the northeastern part of Pakistan and the western part of Kashgar of Xinjiang, China, while the basically stable ones are located in the southwestern part of Pakistan and the eastern part of Xinjiang; (3) The average annual temperature and precipitation in the China-Pakistan Economic Corridor area demonstrated a fluctuating upward trend from 1995 to 2015, indicating a significant positive correlation with the changes in the vegetation NDVI. The temperature in the research area inhibits the growth of vegetation, whereas the precipitation promotes it. Among all the climate zones of the Corridor, the tropical monsoon climate delivers the highest vegetation NDVI, and with the fastest annual growth rate; precipitation and vegetation NDVI are positively correlated in all climate zones of the Corridor, but vegetation and temperature are negatively correlated in the tropical desert climate; (4) From 1995 to 2015, there was an increasing trend in the average NDVI of cultivated land, woodland and grassland in the Corridor. Specifically, the NDVI of cultivated land grew at the fastest speed (0.002 4 a-1), contributing the most to the total increase in NDVI across the entire region. The results of this study can provide a scientific basis and reference for vegetation enhancement and regional ecological environment protection in the China-Pakistan Economic Corridor.

Gymnodiptychus dybowskii, an ecologically sensitive local economic species, was chosen to assess the environmental risks caused by the introducing of rainbow trout (Oncorhynchus mykiss) into the Tianchi Scenic Area. Niche breadth index, trophic level assignment (TLA), intestine emptying rate, similarity index, Spearman's ρ, and selectivity index were used to assess the trophic niche of the two species. Furthermore, the dangerous level of invasive rainbow trout was assessed by using an invasive species evaluation index. Results reflect that the occurrence frequency of entomic food between young rainbow trout and G. dybowskii was substantially overlapped, with Spearman's rank correlation coefficient to be 0.600 (P<0.01). Chironomidae, Copepods, Caddisfly, Ephemeroptera, Amphipod, Clams, and Coleoptera were shown to be competing diets between the two fish species. Unlike earlier articles "ate Algae sometimes (Chlorophyta, 15.6%)" that were reported in other papers, G. dybowskii primarily foraged Algae (Chlorophyta, 81.82%). Rainbow trout was a top consumer in the food web and its trophic level was higher than that of G. dybowskii (TLA, 2.30 > 2.06). On the other hand, the higher diversity index in G. dybowskii than in rainbow trout (Simpson index, Shannon-Wiener index, P<0.05) might indicate that G. dybowskii was compelled to expand content species items, particularly hunting more algae. After reviewing articles and conducting field research, it is concluded that rainbow trout is a harmful introduced species with a risk score of 0.995 5. The finding demonstrates that rainbow trout encroaches the trophic niches of local species, forcing native species to adjust their diet composition to a certain degree. As a result, activities such as importing and releasing alien species (such as rainbow trout) into Tianchi nature reserve are not recommended and this study also offers protective measures for the protection of endemic biodiversity.

Biochar was prepared by pyrolysis using sludge from secondary sedimentation tank of sewage treatment plant as raw material. The physicochemical properties of biochar were characterized by scanning electron microscope, specific surface area and pore size analyzer, X-ray diffractometer and X-ray photoelectron spectroscopy. A sludge biochar/persulfate system was constructed and used for the degradation of sulfadiazine. The effects of the dosage, temperature, pH value and other reaction conditions on the removal of sulfadiazine were explored, and the removal mechanism of sulfadiazine in the system was analyzed. The results show that the pyrolysis process caused certain changes in the pore structure and surface composition of the sludge. The sludge biochar prepared at high temperature (700℃) performed better persulfate activation efficiency and the increase of temperature favored the degradation of sulfadiazine. In the range of pH value (3.8-8.8), chloride ion concentration (0-10 mmol·L^-1) and sulfate ion concentration (0-10 mmol·L^-1), the system could maintain high removal efficiency of sulfadiazine. High concentrations (10 mmol·L^-1) of carbonate, bicarbonate and hydrogen phosphate ions had certain inhibition function on the system. High concentration (10-100 mg·L^-1) of humic acid could obviously inhibit the degradation of sulfadiazine, but the actual water environment showed little effect on the system. The active species quenching test and electron paramagnetic resonance (EPR) detection proves that free radicals could play a major role in the degradation of sulfadiazine in the system.

Several problems such as poor treatment performance and easy to return to black and odor in autumn and winter are existing in the traditional technologies for the purification of urban polluted river water. By coupling rotating biological contactors (RBCs) and surface flow constructed wetlands (FWSCWs) technology, a bio-ecological combined process was constructed to explore the treatment effects on polluted river water in autumn and winter. The characteristics of microbial population are analyzed, and reveal the relationship between microbial community structure and pollutant enhanced treatment efficiency are revealed. The results show that the removal rates of ammonium (NH₄⁺-N), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) were 83.83%, 3.32%, 11.09% and 20.52%, respectively. The effluent concentrations of NH₄⁺-N and COD met with the Ⅲ class and Ⅴ class of the national Environmental Quality Standards for Surface Water (GB 3838-2002), respectively. Nitrospira, Nitrosomonas, Rhodobacter, Lactobacillus, Bacillius, Dechloromonas, Sphingomonas, Comamonas and Acinetobacter were dominant bacteria in the combined process. The abundance of Nitrosomonas and Nitrospira in RBCs was 2.69% and 22.16%, respectively, which ensured the normal nitrosation and nitrification processes in RBCs. The Dechloromonas and Comamonas, as the main denitrifying functional bacteria genus, accounted for 0.73% and 0.48% in FWSCWs, respectively, significantly higher than 0.04% and 0.21% in RBCs, which indicates that denitrification was mainly carried out in FWSCWs in autumn and winter.

Reclaimed water is the primary source of urban landscape rivers in northern China, but its high nitrogen content can lead to river eutrophication and groundwater contamination. However, river sediment is the medium between river water and groundwater, which can help to purify water through physical, chemical and biological reactions, and the acid-base conditions of river water environment have a certain impact on the purification effect of sediment NO₃^--N. Using a river channel simulator, the aim of this experiment is to determine how well sediment in the trough system can remove NO₃^--N from inlet water with pH levels of 4, 7, and 10, respectively. The results indicated that sediment in the trough system had a significant impact on the removal of NO₃^--N under all the three pH conditions, with the overall removal efficiency being 51.3%, 57.5% and 69.9%, respectively. The impact is more pronounced at the depths of 10, 20 and 30 cm of trough sediment, where the removal efficiency of NO₃^--N was higher than 89.0%. The removal efficiency differed considerably across the three pH treatments at 50 and 70 cm, with the best removal efficiency occurring at pH=4. In the vertical variation, ρ(NO₃^--N) in the sediment was relatively lower at 10, 20 and 30 cm, and relatively higher at 50 and 70 cm under all three conditions. It was also observed that ρ(NH₄⁺-N) of bottom water at pH values of 4 and 10, was higher than that with pH values of 7, indicating that the removal ability of sediment to ammonia nitrogen was poor under acid-base conditions. NO₂^--N accumulated in the initial phase of pH=7 and 10 and the intermediate phase of pH=4, but it was finally eliminated. When pH=7 and 10, there was a significant negative correlation between bottom water pH and NO₂^--N concentration (P< 0.05). When the pH of the influent was 4, 7 and 10, the pH of the sediment remained between 7 and 9, indicating that the water environment provided a certain buffer against external acid-base changes, i. e. it has the ability to resist acid and alkali. The study demonstrates the purification effects of riverbed sediment on reclaimed water under different acid-base conditions, the sediment under alkaline conditions has a better purification effect on NO₃^--N, whereas the sediment under neutral conditions has a greater purification effect on NH₄⁺-N. This information can be used as a reference for the safe recharge of reclaimed water to rivers and lakes.

The photolytic properties of pinoxaden under different conditions were investigated under the irradiation of a xenon lamp. The results show that the photodegradation of pinoxaden in various organic solvents conformed to the first-order kinetics. The photolysis rates descended in the order of acetonitrile, n-hexane, methanol and acetone, in which the half-lives of pinoxaden in these solvents were 9.76, 15.1, 31.5 and 138 h, respectively. The addition of NH₄⁺ and NO₃^- at 1 mg·L^-1 significantly increased the photodegradation rate of pinoxaden in aqueous solution, with the shortest half-life of pinoxaden as 3.17 h. The sensitization effect induced by these ions reduced as the concentrations further increased. Both Fe³⁺ and Cu²⁺ had a photoquenching effect on the photodegradation of pinoxaden, with a quenching rate up to 16.7%. The photolysis rates of pinoxaden in water were accelerated with increasing concentrations of H₂O₂ and TiO₂. PNDA was used as a hydroxyl radical indicator to confirm that H₂O₂ and TiO₂ both promoted the generation of hydroxyl radicals to accelerate the photodegradation of pinoxaden.

In order to study the effect of earthworm-vetiver combination on the total and available heavy metals (Cr, Cu, Pb, Zn) in reclaimed soils. The soil column simulation experiment was set up for two groups of overburden soil thickness (50 and 70 cm). Each group was set up with four treatments:no vetiver plant without earthworm addition (CK), vetiver plant alone (V), earthworm alone (E) and the combined earthworm-vetiver (VE). The total and available Cr, Cu, Pb and Zn contents and the physicochemical properties of the overburden soil were analyzed for different treatments. The results show that treatments of V, E and VE significantly reduced the total Cr, total Cu, total Pb and total Zn contents of the soil compared to the control (P<0.05). The VE was more effectively in reducing the total amounts of heavy metals than other treatments. The reduction rate of total Cr, total Cu, total Pb and total Zn in VE was 4.90%, 13.12%, 10.36% and 6.91% in the 50 cm group and 5.47%, 11.20%, 10.34% and 6.96% in the 70 cm group, as compared with the CK, respectively. In comparison with CK, treatment E increased the available heavy metals contents, treatment V reduced the available contents of Cu, Pb and Zn, treatment VE showed a weaker reduction for available Pb, but a stronger reduction for available Cu and Zn. At the same thickness, treatments of V, E and VE all reduced pH and increased OM, TN and TP compared to CK. In addition, inoculation with earthworm increased the biomass of vetiver grass, and the root biomass was increased more than shoot biomass. Correlation and redundancy analysis for inoculation with earthworms revealed that, soil pH was significantly and negatively correlated with available Cr and Pb (P<0.05); OM was significantly and negatively correlated with available Cr and Pb and positively correlated with available Zn (P<0.05); TN and TP were significantly negatively correlated with total Cu and total Pb (P<0.05). Soil pH and OM are the key factors affecting soil heavy metal content. Therefore, the combination of earthworm-vetiver can improve physicochemical properties and reduce heavy metal concentration in the reclaimed soil, which provides an important method for the remediation of reclaimed soils.

To explore the distribution and sources characteristics of soil heavy metals As, Cr, Cu, Ni, Pb, V and Zn in Lujiang County, surface soil samples were collected by using grid point method. The spatial distribution data of heavy metals and the Unmix model were jointly adopted to explain the sources of heavy metals. The results show that the As and Cu contents of a few soil samples in the study area exceeded the standard values. In addition, the contents of other heavy metals only exceeded the standard at individual sites. The spatial distribution of soil heavy metal content in Lujiang County generally showed a decreasing trend from southeast to northwest. Among them, in the southeast, the enrichment of As, Cu, Pb and V in the soil was higher than that in other areas. Parent material sources, industrial sources and mining sources were the main sources of heavy metals in local soils, and their contribution to soil heavy metals accounted for 47%, 28%, and 25%, respectively. Among them, the parent material source was the main source of local soil heavy metals. As, V and Zn in soil were affected by all the three sources. Cr and Ni were mainly derived from parent materials, Cu was mainly derived from mining activities, and Pb was mainly derived from industrial activities. The study can provide theoretical support for the control and governance of local soil heavy metal pollution.

A structure-improved biological filter tower (BFT) was designed to improve its NH₃ and H₂S removal efficiency, so as to avoid the secondary contaminant accumulation due to insufficient oxygen in the circulating liquid. The improved BFT can increase mass transfer efficiency and provide aeration for the circulating liquid. The results of the comparing study of the improved BFT and ordinary BFT show that the improved BFT has the following advantages:It brings high treatment efficiency under the condition of short residence time and low intake gas concentrations. Under short residence time (i. e. 10 s), the average efficiency of the improved BFT in removing NH₃ and H₂S was 86.90% and 80.79%, respectively, 10.52 and 10.68 percentage point higher than that of the ordinary one, respectively. Compared with the ordinary BFT, the improved BFT can achieve efficient treatment under the condition of lower residence time, resulting in smaller device size and lower construction and operation costs. Under low intake gas concentrations (i. e. NH₃, 5×10^-6; H₂S, 1×10^-6), the average efficiency of the improved BFT in removing NH₃ and H₂S was 93.98% and 87.73%, respectively, 10.74 and 17.47 percentage point higher than that of the ordinary one, respectively. Compared with the ordinary BFT, the improved BFT can realize the efficient treatment of a wider range of applicable concentration, and can be applied to different emission levels of chicken house. It brings high efficiency in removing the accumulated pollutants in circulating liquid. In the last period of the experiment, the concentration of NH₄⁺ and NO₂^- in circulating liquid from the improved BFT was 5.77 and 1.99 mg·L^-1, respectively, 70.81% and 76.49% lower than that in the circulating liquid from ordinary BFT. The concentration of the stable end-products, NO₃^- and SO₄^2-(both not being indicators in the current national wastewater discharge standards for livestock farms), from the improved BFT, was 70.69 and 13.78 mg·L^-1, respectively, 56.29% and 29.21% higher than that in the circulating liquid from the ordinary BFT.

Rapid urbanization in the Taihu Lake Basin has led to the increasing ecological fragmentation, and is facing a series of ecological degradation and environmental problems. This study divided the Basin into 1 613 basic units at 5 km spatial resolution. The evaluation matrix of ecosystem service supply and demand based on land use types was used to assess the trend of ecosystem service supply and demand balance in the Taihu Lake Basin from 1995 to 2018. The matching level of ecosystem service supply and demand, and its spatio-temporal change pattern in the Basin were analyzed. The results show that:(1) The supply of ecosystem services has decreased while the demand of ecosystem services has increased in recent 20 years in this Basin, and the overall trend of the demand exceeded the supply; (2) The matching level of ecosystem service supply and demand has generally shifted from matching to mismatching, and the proportion with the downgrading matching levels was far higher than that with the upgrading matching levels; (3) The area with ecosystem service deficit increased by 2 times, and the rapid urbanization was the main factor to accelerate ecosystem service deficit in the Basin. Future study needs to improve the regional correction on the evaluation matrix of ecosystem services supply and demand, and explore the matching level of ecosystem service supply and demand at the long-term scale with higher resolution, so as to support watershed ecological protection and territorial space planning.