Nitrogen fertilizers provide the nitrogen necessary for crop growth in modern agricultural production, but their excessive use in the long term leads to waste of resources, economic losses and profound negative environmental impacts. Microorganisms play a critical role in the nitrogen cycle; therefore, there is a significant need for further research in this field. Here, we summarize our findings on the mechanisms and processes by which microorganisms drive the soil nitrogen cycle, including nitrogen fixation, nitrification, denitrification, ammonification, and nitrogen assimilation/dissimilation. We further summarize microbial technologies and strategies for mitigating agricultural nitrogen loss and improving agricultural sustainability, such as nitrogen fixation, greenhouse gas emission reduction, nitrogen bioretention, and ammonia volatilization. These strategies illustrate the potential of microorganisms in reducing the dependence on nitrogen fertilizers and increasing crop yields, while also highlighting the challenges of research and effective field application of these technologies.

In this study, the hot water extraction method was utilized to extract polysaccharides from persimmon peel, and the persimmon peel polysaccharides were combined with trivalent chromium ions to prepare persimmon peel polysaccharide chromium. Considering the adsorption rate of chromium as the index, the adsorption process of persimmon peel polysaccharide chromium was optimized using single factor and response surface methodology. The results showed that the optimal preparation process of persimmon peel polysaccharide chromium consisted of the following steps, such as the mass ratio of persimmon peel polysaccharides to chromium chloride was set at 6.7∶1; the reaction time was 150 min; the temperature was set at 82 ℃; and the pH of the adsorption liquid was fixed at 5. Under these conditions, the maximum adsorption rate reached 92.81%. Therefore, this study has shown that persimmon peel polysaccharides can efficiently bind trivalent chromium ions, which can further provide technical support for the development of green pollution-free heavy-adsorption chromium adsorbents or animal nutritional supplements.

This study analyzed the climate change characteristics and causes of foggy days in Qingdao and Jinan using meteorological observation data from 1961 to 2020 in Qingdao and Jinan, as well as sea surface temperature data near Qingdao. Results showed that the average annual foggy days in Qingdao were 50.4 d, 3.1 times more than that in Jinan. The peak fog seasons were substantially different in the two cities; Qingdao experiences more foggy days in spring and summer, accounting for about 78.4% of the whole year, whereas Jinan experiences more foggy days in autumn and winter, accounting for about 70.7% of the whole year. Furthermore, remarkable differences in the annual and seasonal variations of foggy days were observed. Qingdao shows an increasing trend in annual foggy days, i.e., less foggy days in spring and summer, but significantly more in autumn and winter. Alternatively, Jinan exhibits a decreasing trend in annual foggy days, where the number of foggy days is lowest in autumn. Moreover, considerable climate variability and abrupt change in the number of annual foggy days between the two cities were noticed. The climate variability of Qingdao showed an increasing trend and remained at a high level, while Jinan witnessed a decreasing trend; this indicates a higher probability of extreme foggy weather in Qingdao than in Jinan. Qingdao witnessed an increase in the number of foggy days in 1969, while Jinan encountered a decrease in 1995. The increase in the number of foggy days in Qingdao during autumn and winter was closely related to the substantial increase in the sea surface temperature near the city. This increase promoted sea surface evaporation and subsequently increased the atmospheric water vapor content. However, the decrease in foggy days in Jinan during autumn and winter was closely associated with a substantial increase in the minimum temperature and the dew point temperature difference as well as reduced humidity.

A systematic review was conducted on the current status and causes of the ecological degradation of wetlands in the Yellow River Delta (YRD), and the ecological restoration technologies were summarized. The results revealed that the wetland areas in the YRD are currently in a serious state of degradation, with the total area of wetlands shrinking year by year. Along with the shrinking of the wetland area, the wetland composition has changed, natural wetlands are decreasing while artificial wetlands are gradually increasing, the pattern of the landscape shows a trend toward fragmentation, and the service function of the ecosystem has been seriously degraded. The main causes of wetland ecological degradation in the YRD include the reduction of water and sediment fluxes from the Yellow River, increased sea-land interactions, intensified salinization of the soil, climate change, invasive species, and human activities. Current ecological restoration techniques for wetland restoration include biocomponent restoration, water body restoration, soil improvement, and comprehensive habitat restoration. This study will utimately provide specific recommendations for wetland restoration in the YRD, which is of great significance for the national strategy of ecological protection and the high-quality development of the YRD.

The industrial production process produces large quantities of high-salinity wastewater comprising complex water-quality components, including a large amount of Na⁺, Cl^-, SO₄^2-, and other salts as well as toxic substances. Traditional high-salinity wastewater treatment technology has low efficiency and high operating cost. The freeze concentration method for high-salinity wastewater treatment has received widespread attention as a highly efficient and clean treatment technology without secondary pollution. However, the problem of impurities in the ice crystals prepared via freeze concentration should be solved urgently. This article summarizes the research progress of freeze concentration technology in high-salinity wastewater treatment in recent years. The key parameters such as freezing time, freezing temperature, and initial solution concentration were discussed, and various methods for removing impurities from ice crystals, including immersion, gravity, and water addition purification methods, were investigated. To accelerate the desalination process and improve the desalination effect, nucleating agent and ultrasonic-assisted freeze concentration methods were investigated. Furthermore, the energy consumption of the freeze concentration technology was economically analyzed. Moreover, the development of the technology is summarized and a prospect is proposed to provide specific references for the development and application of freeze concentration method in high-salinity wastewater treatment.

Recently, circulating cooling water systems have been widely used to alleviate water shortage.However, cooling water usually contains various mineral ions,such as calcium and magnesium, which can easily form insoluble salts and scale on the surface of the equipment. The use of scale inhibitors in cooling water systems is one of the most effective methods to solve the scaling problem. In this paper, the recent research progress on green scale inhibitors at home and abroad was reviewed. The development and applications of green scale inhibitors were introduced here. The characteristics and scale inhibition performance of different types of scale inhibitors are also analyzed.Moreover,the scale inhibition mechanism was explained from different aspects,such as chelation and solubilization, coagulation and dispersion, and lattice distortion.Therefore,this review would provide an excellent reference for future research and development of green scale inhibitors.

Using the monitoring data of 34 air negative oxygenion stations and Moderate Resolution Imaging Spectroradiometer vegetation index product data of 13 counties in the western and southern mountainous areas of Henan Province, correlation analysis and random forest regression model were used to analyze the main meteorological and environmental factors affecting the concentration of negative oxygenion in these areas to establish a negative oxygenion concentration forecasting model. Results showed that temperature and relative humidity were the main meteorological factors affecting the diurnal variation of negative oxygenion concentration, concentration of PM_2.5, PM₁₀ and vegetation coverage were the main environmental factors.By establishing the negative oxygen ion concentration forecasting model, the quantification of negative oxygen ion prediction was realized. This study provides reference for regional air quality evaluation.

During oilfield workover, it is necessary to control the gel breaking speed of the temporary plugging agent, so that the gel is not broken during the workover to ensure the completion of the operation and is broken quickly after the workover to resume production. For traditional gel breakers, it is difficult to achieve a slow release at the initial stage and a fast release at the late of the workover. This paper describes a cellulose-based sustained-release encapsulated gel breaker with a double-layer film. This gel breaker is evenly mixed with molted Carnauba wax and the solid dispersion pellet is made using the extrusion-speronization method. In the Wurster fluidized bed, a double-layer film with different components is put on the pellet to prepare the sustained-release encapsulated gel breaker. The result of the orthogonal test shows that this method is reliable, the yield of the pellet is 93.2%. SEM result shows that the film on the surface of the pellet is smooth and uniform, and the sealing and unblocking of the film pores are crucial to sustained-release. The results of sustained-release test and simulation test of reservoir gel breaking exhibit that the sustained-release encapsulated gel breaker has an excellent controlled-release effect and reservoir permeability recovery effect. Herein, the preparation method is simple and efficient. The sustained-release of drugs is mainly controlled by the double-layer film.

To reveal the multiscale variation law of extreme precipitation events under climate warming, based on the daily precipitation data of the National Meteorological Station from 1961 to 2020, the spatiotemporal variation characteristics of extreme precipitation events on the monthly scale in Shandong Province were analyzed using the percentile relative threshold method. The results show that the monthly-scale extreme precipitation events in Shandong Province mainly occurred in July and August with the annual frequency bigger than 40%. The annual frequency showed a decreasing trend as one moves from southeast to northwest regions. The annual frequency and precipitation of extreme precipitation events increased in most areas for all seasons except autumn and considerably increased in winter. After the mid-1980s, extreme precipitation events have generally increased and intensified, and their interannual changes have increased significantly. The intensity of extreme precipitation in summer and winter increased significantly by 10 mm to 20 mm during 10 years in summer in the central, southwestern, and peninsular areas of Shandong and 20% to 50% in winter months in Shandong province. The precipitation instability generally increases under climate warming in Shandong, and it is necessary to strengthen early warning and defense services for disaster risks such as rainstorm, flood, and blizzard.

Using the datasets of major air pollutants and meteorological observations during the winter from 2016 to 2018 in Jinan, the characteristics of air pollution were analyzed to identify the major transport pathway of airmass. The results showed that during the winter from 2016 to 2018 in Jinan, about 63.8% and 34.7% of the major pollutants were PM_2.5 and PM₁₀, respectively. Of the total number of days, 58.6% had a pollution level worse than good polluted. The annual average concentration of PM_2.5 increased by 7.5 μg/m³ due to its high concentration in the winter. In terms of spatial distribution, the concentrations of PM₁₀ and PM_2.5 were high inTianqiao District, Huaiyin District, and Pingyin County; the concentration of SO₂ was high in Shanghe County and Jiyang District; and the concentrations of NO₂ and CO were high in Jiyang District, Tianqiao District and Huaiyin District. The results also showed that ρ(NO₂), ρ(CO), ρ(PM₁₀), and ρ(PM_2.5) had a positive correlation, with all r >0.7. It was inferred that traffic source, industrial combustion source, and burning coal were the major sources of particulate matter. The airmass in the winter of Jinan came from south, northwest, north, and east, and the airmass from south and east were the major transport pathway of air pollution. Further analyses of the potential source contribution and concentration weight showed that the air pollution in Jinan City was affected by the local and surrounding cities, and the current air pollution presents the characteristics of cross-contamination across regions. Therefore, a supervision and coordination mechanism for the joint prevention and control of air pollution in the region should be established to coordinate research and solve growing problems of air pollution.

This study reviews the speciation analysis methods of antimony indifferent environmental media in recent years. Inductively-coupled plasma mass spectrometry is widely used in the antimony speciation analysis because of its advantages such as low detection limit, high sensitivity, and good stability. Before the speciation analysis, extracting different forms of antimony from a complex matrix and maintaining its valence stability are essential. This can be achieved by combining the sensitive detection technology, efficient sample pretreatment techniques, and separation methods. In recent years, the combined techniques have been widely used for the determination of antimony in various environmental samples. Moreover, the challenges in this field and the development prospect of antimony speciation analysis method are discussed.

In this study, common plant-fiber agricultural wastes (corn stalks, peanut shells, and straw) were mixed to storage sludge as bulking agents to study their biodrying performance. Four experimental groups were used, namely, corn stalks, peanut shells, straw, and a control group. Results showed that plant-fiber agricultural wastes could be used as bulking agents in the biodrying process of storage sludge, and the straw group performed best. The straw pile reached a maximum temperature of 57.5 ℃, and the moisture content decreased from 71.83% to 60.01%. The mass fraction of volatile solids (VS) decreased from 62.01% to 52.02%, and the mass ratio of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) showed a decreasing trend with the largest decrease. The w(DOC)/w(DON) gradually decreased during the biodrying process, and the ratio of the straw pile decreased from 4.29 to 2.53, indicating that biodrying could stabilize the materials.

Natural gas is an environmentally friendly energy source that can be used in various chemical raw materials. However, the presence of CO₂ in natural gas has a significant impact on the heat value and transportation performance of natural gas. Therefore, effective CO₂ removal from natural gas is critical. In this study, Mg-MOF-74 was selected as an adsorbent and its effect on CO₂/CH₄ adsorption and separation performance was investigated using a molecular dynamics simulation method. Based on the simulation results, at certain pressure and temperature settings, CO₂ is more likely to bind to the metal sites of Mg-MOF-74 than CH₄. Moreover, Mg-MOF-74 exhibits a stronger interaction force with CO₂ gas, indicating a higher capacity for CO₂ adsorption. To verify the accuracy of the simulation results, Mg-MOF-74 was prepared and its CO₂/CH₄ adsorption performance was tested.The experiment results is consistent with the simulation,that proved Mg-MOF-74 is more attractive to CO₂.

In order to ensure the rapid, timely, and effective treatment of water pollution, based on the excellent coagulation effect of poly-Si-Fe(PSF) and the rapid precipitation performance of flocculation, and with simulated domestic sewage as the experimental water sample, we studied the flocculation and precipitation time parameters of the shortened coagulation precipitation process (shortened process) and their impacts on filtration through beaker experiments, compared the removal effects of PSF and polyaluminum chloride (PAC) under the shortened and conventional processes of coagulation filtration, and analyzed the flocs by scanning electron microscopy (SEM). Finally, we observed the treatment effect of the shortened process on actual domestic sewage. The results show that in the coagulation sedimentation experiment, the PSF shortened process with 2 min of flocculation and 3 min of precipitation can reach the pollutant removal level close to that of the conventional process. With a dosage of 0.162 mmol/L, the turbidity and average COD_Cr removal rate are 0.59% and 11.5%, respectively. In the actual water treatment experiment, when the dosage reaches 0.162 mmol/L, the removal efficiencies of turbidity and COD_Cr by the PSF shortened process are 27.88% and 11.11% higher than that by PAC shortened process respectively. In the filtration experiment, the filtered water quality of the PSF shortened process was stable, and the average COD_Cr removal rate reached about 85%, 7% higher than the PAC shortened process. The SEM picture shows that the flocculation of PSF in the shortened process has a more compact structure and larger particle size than PAC catkins, thus better flocculation and precipitation effect.

Owing to the problems of drying high-humidity and high-viscosity sludge, this paper analyzes the water characteristics and drying characteristics of municipal sludge to optimize the design of the key components of ordinary rotary cylinder dryer and conduct industrial simulation test. The results show that the self-cleaning and dispersing rotary cylinder dryer with internal self-cleaning components such as chains, scraping plates, and dispersing shafts has better a antisticking and antiagglomeration effect as well as higher drying power and more ideal drying effect than the ordinary rotary drum dryers. It provides useful theoretical support for the development and application promotion of municipal sludge deep dewatering processes and devices.

As one of the three plains in China, the North China Plain is prone to large-scale and long-term pollution processes during the heating season due to its special geographical location, large number of heavy industry enterprises and higher pollution emissions in the season. The PM_2.5 concentration in the North China Plain is significantly higher than that in the surrounding areas during the heating season. To better understand the impact of weather system and meteorological elements on urban air quality in the North China Plain during the heating season, 50 cities in the North China Plain (32° to 40° N and 114° to 120° E) were selected as the research objects to analyze the impact of meteorological conditions on large-scale high pollution processes during the heating seasons from 2015 to 2021. Results show that when high pollution occurred in the North China Plain, the curvature of 500 hPa circulation decreases and is straighter. Due to the increased probability of temperature inversion, the horizontal and vertical directions were more stable, and the diffusion ability of pollutants was weakened. Near the surface, the abnormal southerly winds in Henan and central and southern Shandong led to regional warming and humidification, which was conducive to the growth of particle moisture absorption and secondary transformation. The abnormal easterly or northeasterly winds in central and western Hebei led to the accumulation of pollutants on the east side of Taihang Mountain, causing widespread pollution processes in the piedmont. They also formed wind convergence with the abnormal southerly winds in Henan and central and southern Shandong, diffusion conditions were unfavorable. The analysis of a pollution process from January 20, 2021 to January 28, 2021 shows that the upper air circulation in the North China Plain during the pollution was relatively straighter., the ground was mainly controlled by the pressure equalization field, and the main type was calm wind, and the humidity was continuously high. Unfavorable diffusion conditions were the main cause of this pollution process.

This paper proposes a field calibration method via standard weights accumulation to study the variation trend of the measurement error of the weighing precipitation sensor in an automatic meteorological station. Herein, the field calibration data of sensors from 2019 to 2021 are analyzed. Further, a calculation method is presented for measuring the error deviation degree and its variation trend with respect to the weighing precipitation sensor. The variation model of sensor deviation is obtained on the basis of the historical calibration data. The results show that the measurement error range and observation data quality are controllable. The overall deviation degree of the sensor is 2.1% of the standard value and its increase is 0.1% per year. This study can provide reference for predicting measurement errors and durability of meteorological sensors.

Based on the bibliometric analysis method, with the help of CiteSpace and VOSviewer visualization analysis software, this study, by combining quantitative and qualitative methods, systematically classifies the results of material stock research performed at home and abroad and analyzes the knowledge base, development context, and research progress of material stocks. Metals and buildings are found to be essential in material stock research and lay the basic foundation for this research. The research topics of material stocks include simple materials accounting to resource prediction, socioeconomic metabolism analysis, greenhouse gas emission reduction, and urban mineral development. The research methods are constantly enhanced, and life cycle assessment, decoupling analysis, and scenario analysis are introduced to expand the scope of this research. Furthermore, the research content of material stocks is enhanced, which involves greenhouse gas emission, circular economy, urban mineral resources, resource efficiency, and other sustainable development content. The existing problems in the development of material stock research are discussed, such as the difficulty in obtaining key data, data with different qualities, and practical guidance still need to be strengthened. The future development of material stock research should be actively integrated with other disciplines to improve the data accuracy and strengthen the ability of decision support services..

Based on the monitoring data of national geoinformation, this study analyzes the distribution pattern and change characteristics of natural ecosystems, including forest land, grassland, wetland, and bare land, from 2015 to 2019 in eight cities and one county along the Yellow River in Henan Province, China. Results show that the coverage rates of forest land, grassland, wetland, and bare land along the Yellow River are 36.12%, 2.61%, 2.01%, and 0.56%, respectively. Forest land was dominated by broad-leaved forests and broad-leaved shrub forests. The land coverage of coniferous forests, arbor-shrub-mixed forests, afforested land, and artificial young forests increased, and the land coverage of broad-leaved, coniferous, and broad-leaved shrub-mixed forests decreased during the study period. Grassland was dominated by high-coverage grassland, accounting for 81.47% of the grassland area. During the study period, the area of high-coverage grassland, artificial green grassland, and slope-protected shrub grassland increased and the area of medium-coverage grassland and herbage grassland decreased. The wetland was dominated by rivers, occupying 97.63% of the total wetland area. During the study period, the area of rivers and canals increased. The gravel surface was dominant, accounting for >60% of the total bare land. During the study period, the coverage area of all types of bare land showed a downtrend. Overall, in the Yellow River region of Henan Province, the distribution characteristics of different natural ecosystems differed; forest land was mainly distributed in the middle reaches, while the grassland was mainly distributed in the low reaches; the spatial distribution of the wetland area in the low reaches was higher than that in the middle reaches,while the area of bare land in the middle reaches was higher than that in the low reaches. During the study period, the coverage of forest land and bare land decreased, while that of grassland and wetland increased.

To handle inaccurate observations and errors in data analysis and assimilation, a single prediction is only one possible solution. To solve this problem, this study proposes an O₃ prediction model based on an artificial neural network ensemble prediction. To construct the artificial neural network forecast model, 8 types of meteorological factors and 2 types of pollutant factors are considered. Furthermore, the random disturbance method is used to create 15 sets of mutually independent random disturbance weather fields using data from May to September of each year, starting from 2013 and ending with 2019 as the training set and those from May to September 2020 as the test set. Results show that compared with a single artificial intelligence network prediction model, the proposed ensemble model clearly shows higher accuracy. The O₃ pollution hit rate is improved obviously, the nonresponse rate is remarkably reduced, and the empty rate is slightly higher than that of the single model. The O₃ pollution is predicted to happen more often using the proposed ensemble model, whereas that using the single model tends to be less. Considering a heavy O₃ pollution condition that occurred on July, 3 to 9, 2020 as an example, the proposed ensemble model can reflect the rapid cumulative increase and continuous process of O₃ pollution better than the single model. The proposed ensemble model can facilitate the probability of various occurrence, uncertainties and other more forecast information by providing quantitative probabilistic forecasts, which have certain practical application values.

To study the characteristics of heavy-air pollution process of Jinan in winter, a typical heavy-air pollution process that occurred during December 8 to 13 in 2020 was taken as an example to comprehensively analyze the characteristics and causes from the perspectives of pollution process, meteorological conditions, and chemical composition of fine particles. The results were shown as follows: During the heavy pollution process, the primary pollutant was PM_2.5, with an average mass concentration of 137 μg/m³. The pollution peak was reached at 21:00 on the December 11, and the mass concentration of PM_2.5 was as high as 235 μg/m³. During heavy pollution, the high-altitude circulation was relatively straight; the low 850 hPa was affected by the southwest airflow, which was conducive to the formation of temperature inversion stratification; the ground pressure field was controlled, and advection and radiation fogs occurred alternately. The static and stable meteorological conditions worsened the accumulation of PM_2.5 concentration and the secondary conversion of particulate matter under high-humidity conditions. During the observation period, the mass concentration of SNA was 85.4 μg/m³, accounting for 52.0% of the PM_2.5 concentration. The average values of R_S and R_N were 0.44 and 0.33 respectively, the secondary oxidation of SO₂ and NO₂ in the atmosphere was relatively high. R_S was higher than R_N, indicating that the secondary conversion efficiency of $SO^{2-}_{4}$ is higher than $NO^{-}_{3}$. The average value of $\rho_{NO^{-}_{3}}$ / $\rho_{SO^{2-}_{4}}$ was 2.1, indicating that the contribution of mobile sources to PM_2.5 pollution is dominant. The average ratio of OC/EC was 6.5, which indicated that there was SOC pollution in the atmosphere of Jinan during the heavy pollution period. Using the ρ_OC/ρ_EC minimum ratio method, the mass concentrations of POC and SOC during the heavy pollution period were estimated to be 11.9 μg/m³ and 4.3 μg/m³, respectively. The mass concentration of POC was higher than SOC, and it indicated that the primary combustion source has a greater contribution to the pollution process.

To explore the salt tolerance ability of different varieties of willow species, three new varieties of willow species were used to study the change characteristics of their growth and related physiological indicators under different concentrations of NaCl(20, 40, 60, and 80 mmol/L).We measured 15 parameters associated with growth physical and chemical characteristics, and the salt tolerance of three varieties of willow seedlings was evaluated comprehensively by four objective analysis methods: equal weight grey correlation analysis, entropy weight grey correlation analysis, principal component analysis and principal component-grey correlation analysis. The results showed that combining with cluster analysis the contents of soluble protein, free proline, soluble sugar, H₂O₂ and relative water content of leaves could be considered as the main indexes for the identification of salt tolerance of willow seedlings. According to four analysis methods, Salix matsudana 'Wuxu1' (cultivated code A34), Salix matsudana 'Shidi1' (cultivated code A42) present the better performance in resisting salt stress. It can be used as alternative germplasm material for exploitation and utilization of saline soil. As a scientific and reasonable evaluation method, principal component-grey correlation analysis can be one more useful appraisement method to provide theoretical support for screening and breeding of salt tolerance of willow seedlings.

High-concentration brine exists in the northern part of the Bailang River catchment aquifer.In recent years,the brine has flowed southward and potentially impacts the water supply in the southern plain area.Correct understanding of its hydrochemical characteristics and the evolution of Bailang River catchment is important for the reasonable management of groundwater resources and safety of water supply.Based on the previous research results,through groundwater sampling and a variety of hydrochemical analysis,including Piper Diagram,Gibbs Diagram,and inorganic ion tracer,groundwater hydrochemistry characteristics and its controlling factors in both freshwater area and brine area were studied.The total dissolved solids of groundwater in freshwater area and brine area are 1 098.1 and 115 669.3 mg/L,respectively,which indicates that the formation of groundwater chemical composition in the two areas is controlled by different factors.The chemical composition of groundwater in freshwater area is mainly decided by the water-rock interaction.The salt in the brine area comes from three seawater intrudings,but the groundwater in brine area is no longer the original seawater; it has been replaced by new water from precipitation in the southern mountain area under the driving force of the natural hydraulic gradient.The distribution of hydrochemical field is the result of water-salt interaction during the groundwater recharge,runoff,and discharge processes.The main minerals dissolved in the water-salt interaction process are NaCl,MgCl₂,Na₂SO₄,and MgSO₄.

The concentrated liquid behind a landfill leachate membrane is a type of high-concentration organic wastewater generated during the leachate membrane treatment of landfills. It has a complex composition and is difficult to process via biodegradation. Because of its high chemical oxygen demand (COD), high ammonia nitrogen, high salt content, and other characteristics, the salt cannot crystallize and precipitate smoothly after reaching the saturated state, making it difficult to execute the follow-up mechanical vapor recompression process. To execute the follow-up treatment process smoothly, ferric chloride, aluminum chloride hexahydrate, polyaluminum chloride, and polyaluminum ferric chloride were used as coagulants; polyacrylamide was used as a coagulant aid; and the removal rate of COD was used as an evaluation parameter to coagulate the post-membrane concentrated liquid of a waste treatment plant in Jinan, and the optimal operating conditions were obtained. Results show that ferric chloride is the best coagulant. When FeCl₃ dosage was 0.64 g/L, polyacrylamide dosage was 4 mg/L, and pH was 6, the removal rate of COD was the highest (80.6%).

Numerical simulation of a flue gas desulfurization (FGD) system using rapid preparation amorphous powder activated coke (RAC) as the desulfurizer was conducted using ASPEN Plus. The existing coking model for RAC and the desulfurization model were used in the simulation. For the design conditions, the components of three key gas flows were collected, and the mass conservation and element balance of the proposed system were calculated and confirmed. The mass enthalpy and heat flow distribution were also described in detail to verify the energy conservation. For the ultra-low emission conditions, the effects of key parameters on the C-coal consumption, the recovered sulfur, and coke deposit amount in the fluidized desulfurization bed were calculated and discussed in detail.

An experimental equipment, which included a reflux reaction device, a drying device, a lye absorption device, and a vacuum inert gas replacement protection device, was set up to synthesize chlorinated paraffins (CPs) with different chlorination degrees. CPs with a carbon chain length of 10 (C₁₀-CPs) were synthesized through radical substitution reaction by refluxing decane with sulfuryl chloride (SO₂Cl₂) in the presence of a mercury lamp (10 W, 254 nm). Purification of reaction products was achieved via adsorption chromatography on silica gel and Florisil composite column to remove the unreacted decane. The products′ purity and their congener profiles were characterized via gas chromatography/mass spectrometry (GC/MS) operated in electron ionization (EI) and in the electron capture negative ionization (ECNI) modes. The results showed that the purified product does not contain decane and other impurities. The C₁₀-CPs with seven and eight chlorine atoms were the most abundant congeners. It was found that the light intensity, reaction temperature, and reaction time influence the chlorination degree of the product. The calculated purity of the synthesized product was above 98%, and the chlorination degree was between 55.6% and 66.9%. The results showed that this method can be used to produce CPs with different chlorination degrees.

The gas production process in sludge-municipal solid waste (MSW) mixture under different sludge addition conditions was studied through laboratory experiments, and a kinetic model of gas production process in the mixture degradation was established. Results show that the gas production process can be divided into three stages: adjustment stage, acceleration stage, and attenuation stage. With the increase in sludge amount, the cumulative gas production gradually increased, but when the sludge amount exceeded 30%, the cumulative gas production gradually decreased. With the addition of sludge, the methane production stage of the gas production process was significantly advanced, and the CH₄ content in the degradation gas production increased, which shortened the time required for the landfill to stabilize. However, there is a certain range for the amount of sludge that can be added. In the experiments, the mixture with 30% sludge amount exhibited the fastest degradation rate.

Red mud is an alkaline solid waste produced during aluminum production，and can be recycled by converting acidified red mud into Fenton-like catalyst. In this study, red mud was acidified using hydrochloric acid and then loaded on cobalt oxides via impregnation method to prepare a heterogeneous catalyst. Peroxymonosulfate (PMS) was activated by the as-prepared catalyst to remove Rhodamine B. The effects of catalyst dosage, PMS concentration, initial Rhodamine B concentration, and reaction temperature on the removal efficiency were investigated. Results show that the removal efficiency of Rhodamine B was 95.9% at the catalyst dosage of 0.05 g/L, PMS concentration of 0.1 mmol/L, initial solution pH of 4.8, temperature of 65℃, Rhodamine B concentration of 10 mg/L, and reaction time of 50 min. Free radical scavenging experiment confirmed the presence of SO₄^-· ,·OH, and singlet oxygen (¹O₂)in the reaction system, where ¹O₂played a major role in the oxidation of Rhodamine B. Even in the third reuse of the catalyst, the removal efficiency of Rhodamine B remained above 80%.

In this study, the presence of five phenolic compounds-bisphenol F, bisphenol S, bisphenol A, octyl phenol, and nonyl phenol-in environmental water was determined using solid-phase extraction coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The compounds were enriched using the hydrophile-lipophile balance column and then eluted using dichloromethane/acetonitrile. The samples were separated using C18 chromatographic column with methanol-water as mobile phase and then detected via HPLC-MS/MS under the multiple-reactions-monitoring mode with the negative-ion mode and quantified using an external standard method. Under optimal conditions, the method exhibits a wide linear response to the five phenolic compounds, ranging 1~500 ng/mL, with a low detection limit of 0.05~0.15 ng/L. The correlation coefficients were between 0.998 7 and 0.999 7. Satisfactory precision (relative standard deviation: 2.54%~7.88%, n=5) and excellent recoveries of 89.40%~104.2% for analytes determination in spiked water samples were observed. The method was successfully applied to four types of environmental water， results show that the proposed method can simultaneously determinate five phenolic compounds in environmental water with high accuracy and sensitivity.

An indoor cultivation system was used to study the environmental impact of nano silver on various soil characteristics, such as soil respiration, carbon-conversion-related enzyme activities, and functional diversity of microbial community. The experimental sample was set as blank control boil (untreated,CK), wheat-straw-returned soil(SW), nano silver amended soil (AgSW). The results showed that when compared with blank control soil, wheat-straw-returned soil had increased the soil respiration rate, cumulative release of CO₂ was increased by 9.9%. Further, nano-silver amendment inhibited soil respiration in comparison with wheat straw treatment, and cumulative release of CO₂ was reduced by 36.8%, the activities of peroxidase, polyphenol oxidase, and cellulase were considerably reduced highest by 25.1%, 27.1%, and 14.3%, respectively. The results of microbial community level physiological characteristics revealed that nano silver significantly reduced the average well color development（AWCD） (reduced by 73.8% compared with SW) as well as microbial diversity and richness. The results show that nano silver alters the ecological process of soil organic matter decomposition by inhibiting soil microbial activity and reduces the functional diversity of microbial communities.

To study the influence of atmospheric circulation background and meteorological conditions on PM2.5 pollution in Midwest of Shandong Province, this paper uses meteorological and PM2.5 concentration data and selects Jinan as a typical representative city to diagnose and analyze the effect of atmospheric circulation background and meteorological evolution process on PM2.5 concentration in Jinan for the month of January 2014. The stable weather index formula of Jinan is established. Analysis shows that from the north of East China to the south of North China in January 2014, wind speed from the ground to the middle troposphere was a negative anomaly; thus, the ability of horizontal diffusion was very weak. Water vapor transportation enhanced by abnormal southerly winds helps gaseous pollutant to transform into aerosol and results in higher PM2.5 concentration. The East Asian winter monsoon is considerably weaker, with increased inversion temperature and poor vertical pollution diffusion ability. An abnormally high pressure of 500 hPa has inhibited the development of the East Asian trough and is more conducive to the accumulation of pollutants in the lower troposphere. Analysis of the weather evolution process shows that the meteorological conditions in both the horizontal direction at the ground and the vertical direction at high altitude can affect PM2.5 concentration. Results indicate that light wind, high humidity, and surface wind convergence can increase PM2.5 concentration; moreover, low depth of the planetary boundary layer, vertical airflow sinking, and increasing instability of atmospheric stratification in the middle and lower atmosphere can increase PM2.5 concentration and vice versa. A stable index can better predict air quality and heavy pollution process.

The spectral model of soil phosphorous (P) has relatively poor stability, mainly owing to the insufficient understanding of its visible and near-infrared spectral characteristics. To this end, we propose a new method to explore the reflectance spectrum of total P using soil residues by sequentially extracting different P fractions. In particular, the reflectance spectra of different P fractions were measured indirectly using the standard whiteboard as the reference spectrum and measured directly using the soil residues as the reference spectrum. The spectral characteristics of these P fractions and their spectral models were analyzed.Both indirect and direct results showed that each P fraction had a specific reflectance spectrum with different spectral characteristics, spectral shapes, reflectance rates, and peak/valley positions. Therefore, they could be qualitatively and quantitatively analyzed by visible and near-infrared spectroscopy (200~1000 nm). Results suggesteed that 250~750 nm is the sensitive band of soil P. This study can provide an important theoretical basis for understanding the reflectance spectrum and predicting the concentrations of total P.

Wind environment has a considerable influence on urban residents′ comfort,which is the focus of urban climate research. Taking Dongcheng District of Daqing City as an example, a wind environment assessment method based on CFD computational fluid dynamics） and urban morphology parameters was studied. First, the wind environment in the central area of the city was simulated by CFD software to obtain the wind speed nephogram. Then, the wind speed nephogram was divided into grids, and the regression equation between grid wind speed ratio and urban shape parameters was obtained by SPSS. Finally, the wind speed ratio of Dongcheng District was calculated by the regression fitting equation, and the wind environment was evaluated. Results show that sky openness and windward area density are the most important urban morphological parameters affecting the wind speed ratio, and the combination of multiple urban morphology parameters can explain the change in wind speed ratio better. Thus, by combining the wind speed ratio calculation equation and wind environment evaluation standard, the bad wind environment areas in a city can be found and relevant optimization suggestions can be proposed.

Material sorting at the pretreatment stage of food waste greatly influences the overall treatment process. If the sorting accomplished inappropriately and there are a lot of impurities in the slurry, there will be problems such as serious pipeline wear and high equipment failure rate. Therefore, the better-operating parameter range of the large material sorting machine is explored herein by adjusting the feeding and operating frequencies, making the sorting work more effective. The better operating parameter range can be obtained from the experiment results, that operating frequency of the large material sorting machine is 70 Hz, and the feeding frequency is below 17 Hz. Under this working condition, the current value of the equipment is low and the fluctuation curve is relatively stable. The proportion of organic matter in the sorting material is between 33% and 37%. Compared with other working conditions, the proportion of organic matter is at least 3% lower. Changes in operating conditions have no effect on the composition of the slurry, the sum of organic matter, peel, and bone accounts for more than 98%, and other impurities account for less than 2%.

We tested the bacterial diversity of filter membrane samples in freshair purification systems in Licheng，Jinan，at different times, and analyzed the potential risk of secondary microbial contamination in indoor fresh-air purification systems.The bacterial diversity of three air-filtration membrane samples obtained from the fresh-air purification system used in Licheng at different times was analyzed using the 16S rDNA amplicon sequencing technology.The dominant bacterial phyla were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. The dominant genera in three samples were Paracoccus, Sphingomonas, Bacillus, Methylobacterium,and Bifidobacterium. With the extension of the usage time of the fresh-air purification system, the relative abundance ratio among the dominant fungi did not change significantly, but the total abundance showed an increasing trend, indicating that the microorganism in indoor air was abundant in this area and the community structure did not change much in the long term. For the air-filtration membrane used in the area for 12 months, Rheinheimer, Lactobacillus, and Acinetobacter were also the dominant genera. Moreover, the relative abundance of opportunistic pathogen Moraxella osloensis was high, which indicatesthe indoor fresh-air purification system has a certain risk of microbial secondary pollution when it is used for 12 months. The results of this study can guide residents to prevent and control indoor-air secondary pollution.

Bioremediation is the most promising and viable technology to ameliorate the pollution status of petroleum contaminated soil, which seriously endangers human health. Herein, we reviewed the research progress of microbial remediation, phytoremediation, and the joint remediation technologies. We concluded that the current applications of bioremediation around the world were associated with problems such as lack of highly efficient degradation bacterial strains and low efficient degradation. Further development should aim to screen highly efficient degradation strains and improve the efficiency of degradation.

To solve the problem of turbidity removal from highly turbid water, this study uses composite materials prepared by acid-modified fly ash and chitosan with different mass ratios to treat highly turbid water. The effects of amount of fly ash and chitosan composite materials, stirring time, pH, and initial turbidity on the turbidity removal performance and the combined effects of various other factors were studied through single-factor experiments and orthogonal experiments. The single-factor experiment results show that when the mass ratio of fly ash to chitosan is 6:1, the turbidity removal rate can reach 93.78%; when the composite material CWF3 dosage is 0.6 g, the turbidity removal rate can reach 73.52 %; when the stirring time is 30 min, the turbidity removal rate can reach 90.28%; when pH = 6, the turbidity removal rate can reach 84.50%; when the initial turbidity is 300 NTU, the turbidity removal rate can reach 95.67%. The orthogonal experiment results show that when the mass ratio of fly ash to chitosan is 6:1 and the optimal combination includes a dosage of 0.7 g, stirring time of 35 min, initial wastewater pH of 7, and initial wastewater turbidity of 350 NTU. Adding chitosan to acidmodified fly ash will strengthen the affinity and lower the cost. It can compensate for the shortcomings of using fly ash or chitosan alone and benefit large-scale wastewater treatment.

Corncob was selected as an adsorbent to study its adsorption of Cr⁶⁺ in wastewater. Corncob was modified due to its poor adsorption effect. Subsequent to being modified with H₃PO₄, NaOH, and NaNO₂ solutions, corncob had expanded pores and increased specific surface area so that it could efficiently eliminate Cr⁶⁺ in wastewater. The experimental results show that when the initial concentration of Cr⁶⁺ in the simulated wastewater is 20 mg/L and its volume is 50.00 mL, modified corncob dosage of 0.040 g, pH of 5.00, and adsorption time of 20 min, corncob modified using NaOH solution exhibit best adsorption effect. The highest Cr⁶⁺ removal in wastewater is 96.83%. At this time, the Cr⁶⁺ adsorption process by modified corncobs is fairly consistent with the Freundlich adsorption isotherm model and the pseudo-second-order kinetic model.

Based on DMSP/OLS night-time light remote sensing imagery, the authors selected four years from the fourteen-year period of 2000 to 2013 to perform image acquisition and correction and extract data including the total amount of the light and the area of the light. Based on the annual growth of the light data, the differences among regions in the country were analyzed, and the correlation analysis was performed with regard to air pollutants. Experimental results show that：(1) As a whole, the amount of night-time light has increased nationwide, and the range of increase was affected by the policies of the relevant year. (2) There is a positive correlation between the total amount of night-time light and the air pollutants, and the correlation coefficient between the two is high. The correlation between industrial air pollutants and night light is decreasing, whereas the correlation between domestic air pollutants and night light is increasing. (3) The consistency between the total amount of night-time light and air pollution high/high concentration area has steadily enhanced. In this paper, we combine the night-time light imagery data and air pollution data to explore the temporal and spatial evolution of air pollutants through the comparison of the variations of night-time light data and provide a novel perspective for the comprehensive treatment of air pollution in China.

Polyferric titanium water purification agent (I-PTF) was prepared from ilmenite and its microscopic properties were analyzed using scanning electron microscopy and X-ray diffraction. The water purification effect and sludge settling performance of I-PTF were studied through beaker and sludge settling experiment. The morphology of sludge was observed using a fluorescence microscope. Results showed that the removal rate of CODCr by I-PTF was better than polyaluminium chloride (PAC). When the dosage was 168 mg/L, the removal rate of COD_Cr by I-PTF was 22%,and it was higher than that of PAC. Compared with PAC, the sludge volume reduction rate by I-PTF was more than 80%, and its settling speed was faster. The settling could be completed in approximately 11 minutes. The flocs formed using I-PTF were more compact and the boundary was clearer.