The effluent total nitrogen (TN) is one of the key indicators for assessing the biological denitrification performance of wastewater treatment plants(WWTPs). To mitigate the prevalent issue of excessive TN discharges from WTTPs, we proposed a real-time prediction model based on long short-term memory (LSTM) networks. We performed Pearson correlation analysis to determine model inputs and used grid search algorithm to optimize model hyperparameters. Then, we used the proposed model to predict the actual effluent TN in a WWTP in Chongqing and compared its predictive performance with that of traditional time-series models. Results indicate that the proposed model can effectively predict effluent TN with an average absolute error of 0.911 mg/L, an average root mean square error of 1.074 mg/L, and an average absolute percentage error of 11.28%. All of these performance indicators surpass those of the recurrent neural network and ARIMA models. The proposed model can serve as the foundation for effective monitoring of effluent TN.

Based on the monthly average global precipitation data from January 1982 to April 2022, this study discusses the spatial distribution and time series of mode one and mode two using the cyclostationary empirical orthogonal function (CSEOF) method; analyzes the spatial distribution, seasonal variation characteristics, and interannual variation characteristics of global marine precipitation at low and middle latitudes; and discusses the possible causes of these variations. Results show that the interannual variation of precipitation exhibits periodic characteristics, with the main areas experiencing variations being distributed in the tropical Pacific region; additionally, the spatial field of mode one demonstrates an east-west inverse phase distribution, which is stronger in winter than in summer. The seasonal variation of the spatial field of mode two is more complex than that of mode one, with the high-value positive and negative variability regions demonstrating an east-west inverse phase distribution in winter and negative variability regions dominating in summer with weaker intensity. ENSO has an important impact on the interannual variations of precipitation. The spatiotemporal variation characteristics of mode one are primarily affected by the ENSO phenomenon, while those of mode two are mainly affected by the El Niño Modoki phenomenon. The main precipitation variation characteristics are affected by the superposition of these two phenomena.

To ascertain the current status of plant resources and biodiversity in the Yellow River, Yishu River, Nansi Lake Basin and Weifang in Shandong Province, a comprehensive and detailed investigation was conducted by combining field investigation, specimen collection, indoor classification, and anatomical identification. The results identified 1 194 species of vascular plants belonging to 587 genera and 155 families. Among these, 6 species, namely Teucrium japonicum, Euphorbia heyneana, Echinochloa colona, Commelina diffusa, Braya humilis, and Bidens maximowicziana, were newly recorded in Shandong Province. The key identification characteristics of these species are described in this study, and the distribution status and application value are also discussed. The discovery of these plants not only enriches the background data of plant resources and plant diversity in Shandong, but also is significancant to the study of the systematic classification, floristic plant geography, and distribution patterns of related families and genera.

As the second most abundant element on earth, silicon plays an important role in soil biogeochemical processes. However, the geochemical characteristics of soil silicon in different forms in coastal wetlands still need further investigation. In this study, we selected four typical coastal wetlands (nonflooding Phragmites australis, tidal P. australis, freshwater P. australis, and tidal Suaeda salsa wetlands) as sampling sites and collected soils from 0 to 20 cm depth. Furthermore, we determined oxalate-extractable silicon, dithionite-citrate-extractable silicon, pyrophosphate-extractable silicon and analyzed their soil physical and chemical properties, distribution patterns, and influencing factors in typical coastal wetlands. Results showed that dithionite-citrate-extractable silicon and pyrophosphate-extractable silicon showed no significant differences among four wetlands (p>0.05), while oxalate-extractable silicon in nonflooding P. australis wetlands was significantly lower than tidal P. australis wetlands (p<0.05). As for the profile distribution, the three types of extractable silicon in soils from 0 to 10 cm were generally higher than in soils from 10 cm to 20 cm. Additionally, the correlation analysis revealed that soil organic matter, total nitrogen, bulk density, pH, silt and moisture were important factors influencing these three types of extractable silicon.

Based on MOD17A3 product data for Shandong Province from 2010 to 2022, this study uses univariate regression trend analysis, the coefficient of variation method, partial correlation analysis, and the Hurst index method to investigate the spatiotemporal distribution of vegetation net primary productivity (NPP) for the ecosystem of Shandong Province and analyze the impact of climate factors. Results demonstrate the fluctuating upward trend of vegetation NPP for Shandong Province in recent years, with an annual average of (398.03±150.20) g/(m²·a), higher than the national average and comparable with that of the Beijing-Tianjin-Hebei region. Vegetation NPP varies considerably across different areas. The vegetation NPP in the eastern coastal hilly area is higher than that in the inland plain area. With respect to interannual variation, the overall vegetation NPP in Shandong Province is relatively stable. With regard to the variation trend of vegetation NPP, the areas of positive and negative trends are equivalent. The trend analysis shows that 27.86% of the areas show an increasing trend, whereas 33.49% show a decreasing trend. However, the areas that have shifted from the increasing trend to the decreasing trend are mostly in woodland areas with high vegetation NPP levels, and further research is needed. In general, a positive correlation exists between vegetation NPP and climate factors. Temperature has a wider and more considerable impact on vegetation NPP than precipitation; moreover, the correlation between vegetation NPP and climate factors is poor in plain agricultural areas.

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.