Yujia Song

In this study, we used monitoring data on six representative pollutants, meteorological data, and socioeconomic data from January 2018 to December 2023 to clarify the spatiotemporal characteristics of air pollution in Changchun, Jilin Province, China, and to establish a short-term prediction model. First, correlation analysis (CA) was used to identify the key factors affecting pollution characteristics. Then, wavelet analysis (WA) was applied to capture the major periodic coupling characteristics of the time series, thereby analyzing the variation law of air quality. The results showed that the six air pollutants in Changchun exhibited significant seasonal differences. The peak concentration of O₃ occurred in summer, while the peaks of other pollutants were concentrated in winter and spring. The average air quality index (AQI) exhibited a downward, overall fluctuating trend, with PM₂.₅ and PM₁₀ as the major pollutants. Urbanization rate and green space coverage area were identified as key social driving factors, while temperature, relative humidity, and wind speed were identified as key meteorological driving factors. Furthermore, WA revealed a coupling phenomenon between the major periods of the AQI sequence and the PM₂.₅ and PM₁₀ sequences. Additionally, the low-frequency wavelet signals showed an overall downward trend, confirming that composite pollution is a typical feature of air pollution in Changchun, while the regional air quality is gradually improving. A short-term AQI forecasting equation based on ordinary least squares (OLS) was constructed. Unlike previous AQI prediction models that used only meteorological factors as independent variables, this model included "AQI data of the same period in the previous year" as a key independent variable. Verification showed that the model's fit outperformed that of traditional meteorologically driven models, yielding more accurate short-term AQI predictions for Changchun, driven by the following two major innovations. First, combined wavelet and CA comprehensively determined the periodic coupling characteristics between AQI and major pollutants, providing an efficient tool for analyzing the causes of composite pollution. Second, incorporating historical AQI data into the OLS prediction model mitigated the limitation of traditional models that rely solely on meteorological factors.

The total nitrogen (TN) increases and the water quality deteriorates when a large amount of nitrogen-containing water is discharged from farmlands into wetlands. This research on the relationship between the TN, ammonia nitrogen (NH₄-N), and nitrate nitrogen (NO₃-N) concentrations in water has a certain reference significance for understanding the spatial pattern of nitrogen removal in wetlands. Taking the Sanhuanpao wetland in northeast China as the research object, 24 sampling plots in the study area were sampled in the spring and summer of 2017 to test the concentrations of TN, NH₄-N, and NO₃-N. Based on the calculations of the change rates of the TN, NH₄-N, and NO₃-N in spring and summer, a step-by-step elimination analysis was carried out and the spatial pattern of the TN, NH₄-N, and NO₃-N removals were revealed by gradual buffer extrapolations, combined with stepwise fitting functions. The results show that the removal capacity of NH₄-N is strong within the range of 14.55 km–20 km and 26.93 km–35.96 km from the wetland inlet, and the removal capacity of NO₃-N is relatively strong within the range of 26.93 km–35.96 km. The strong NH₄-N and NO₃-N removal areas in the wetland are not in the geometric center of the wetland, but in separate narrow areas around the center. The TN removal along water channel direction is only 0.25 times higher than that direction perpendicular to the channel, indicating that regardless of whether wetlands are expanded along the water channel or perpendicular to the water channel, the difference to the TN removal is small. Effectively monitoring and managing the reception of agricultural drainage is extremely important for maintaining the water-purification function of wetlands. The aim of the research is to reveal a spatial law of nitrogen removal in wetland water, and provide a framework for studying the mechanism of spatial difference of nitrogen.

To determine the dynamic change characteristics of NO₃–N in a rural–urban ecotone channel, five tracer tests were conducted in the Dongda Channel in the suburbs of Changchuan city, Jilin province, China, from October 2016 to April 2017. NaBr was used as conservative tracer and KNO₃ served as an added nutritive salt. The kinetic features of NO₃–N were simulated via the addition of tracers and by employing the spiralling curve characterization approach and the Michaelis–Menten (M–M) equation. The average absorption length of NO₃⁻–N background concentration (S_w-amb) is 199 m, which is much less than the discharge channel length (2.5 km), thereby suggesting that the channel has a strong NO₃–N retention potential. Moreover, the M–M equation fits well the kinetic features of NO₃–N adsorption. The average maximum absorption rate and subsaturation constant are 631 μg (m² s)⁻¹ and 1.46 mg L⁻¹, respectively. The correlation analysis reveals that S_w-amb and NO₃⁻–N absorption rates (NO₃–N_amb) are significantly negatively correlated whereas the absorption rates of NO₃⁻–N background concentration (U_amb) and NO₃–N_amb are significantly positively correlated. The other spiralling indices show faint correlations with the background concentration of NO₃–N. Meanwhile, the hydrological factors slightly influence NO₃–N retention, but the geomorphic features of the channel, including (width residual) Ф_w and (cross-sectional area residual) Ф_A, have significant correlations with most spiralling indices, thereby highlighting the relatively important roles of geomorphic features in NO₃–N retention.

The corresponding Author of this paper transferred to another institution. The correct affiliation is shown in this paper.

With year-by-year rising social demand for applied talents, it’s imperative for environmental engineering specialty in applied universities to transit into application type, where the most important work is to cultivate undergraduates’ abilities in coordinated development of engineering theories and technology application. Taking undergraduate cultivation in applied environmental engineering as study object, this paper analyzes current situation of applied undergraduate cultivation in environmental engineering specialty and main existing problems. Based on special requirements for talent cultivation in this specialty, the cultivation idea depending on scientific and technological innovation team and university-enterprise collaborative innovation center is proposed, and applied engineering talent cultivation pattern and its security system are established on this basis.

Artificial bioretention system consisting of Ophiopogon japonicus infiltration medium was used to simulate an infiltration experiment of rainfall runoff. Continuous extraction method was used to detect contents of inorganic phosphorus (P) under exchangeable state (Ex-P) and aluminium phosphate (Al–P) and iron phosphate (Fe–P) at different depths (0, 5, 15 and 35 cm) of soil infiltration medium in bioretention system. Effluent total P (TP) concentration of the system was also monitored. Results indicated that the adsorption of inorganic P, Al–P and Fe–P by soil infiltration medium was implemented layer by layer from top to bottom and gradually weakened. Moreover, Ex-P was gradually transformed into Al–P and Fe–P, whereas Al–P was gradually transformed into Fe–P; thus, Ex-P content reduced layer by layer, whereas Al–P and Fe–P gradually accumulated. The TP removal rate in runoff rainwater by the system was more than 90%, where the TP that was not used by plants was under dynamic equilibrium in water–soil–root system/biological system.

In this work, microemulsion and hydrothermal methods were combined to synthesize hydroxyapatite nanomaterials. Competitive adsorption kinetics of aqueous Pb²⁺ and Cu²⁺ on nano-hydroxyapatite surfaces were investigated by performing adsorption kinetic experiments. Results showed that the adsorption quantity of Pb²⁺ on nano-hydroxyapatite was higher than that of Cu²⁺ in the single system. However, the competitive adsorption of Pb²⁺ and Cu²⁺ occurred in the coexistence system of Pb²⁺ and Cu²⁺. The adsorption quantity of Cu²⁺ on nano-hydroxyapatite increased, whereas that of Pb²⁺ decreased. The adsorption quantities of Pb²⁺ and Cu²⁺ on nano-hydroxyapatite presented a marked linear relationship with Ca²⁺ release from nano-hydroxyapatite (R² 0.861 to 0.954). The adsorption kinetics were fitted with the first-order, second-order, parabola, Elovich, double-constant, and Lennard–Jones function equations. Among these equations, the second-order equation and power function kinetics fitted the results optimally. Overall, the results indicate that the adsorption kinetics of Pb²⁺ and Cu²⁺ on nano-hydroxyapatite represent complex adsorption processes with both chemical reaction and physical adsorption.

The aim of this study was to examine the production of nanoscale ions via the liquid phase reduction method and the effectiveness of the removal of nitrate nitrogen (NO₃⁻–N) as well as measure the products and kinetics of the reactions. The nanoparticles obtained were approximately 50 nm in diameter and the main component was iron (Fe). This custom-made nanoscale Fe was highly positively charged, and reacted rapidly with NO₃⁻–N in oxygen-free and neutral conditions at room temperature. A 90% removal rate was achieved when the reaction occurred for 30 min in simulation sample water with vigorous shaking at 250 r/min at NO₃⁻–N concentrations of 30, 50, 80 or120 mg N/L. The nanometer Fe dosage was maintained throughout the experiment at 4 g/L. A first-order kinetics equation was applied to the obtained experimental data which followed a pseudo first-order reaction. Data demonstrated that the removal of nitrate nitrogen from polluted groundwater using a nanoscale Fe iron was effective and rapid.