环境科学最新文献

The air quality has significantly improved since the implementation of the Air Pollution Prevention and Control Action Plan in 2013. The effect of meteorological conditions on air quality improvement is complex, including affecting the emission, transport, diffusion, chemical transformation, and other processes of air pollutants. Based on the WRF-CMAQ model and process analysis （PA） tool, this study evaluates the impact of meteorological factor changes on the improvement of PM_2.5 concentration in the Beijing-Tianjin-Hebei Region from 2013 to 2020 and further analyzes the role of meteorological conditions on the diffusion, transport, and transformation of atmospheric pollutants. The results provided the technical support for improving air quality in China. The changed meteorological conditions resulted in the PM_2.5 concentration decreasing by 5.4 μg·m^-3 during the 2013-2017 period and increasing by 11.6 μg·m^-3 from 2017-2020. From 2013 to 2017, aerosol chemical processes, vertical transmission, and horizontal transmission processes were the main processes affecting the PM_2.5 improvement. Conversely, the change in meteorological conditions contributed little to the reduction of PM_2.5 level, which is mainly affected by aerosol chemical processes, horizontal transmission, and vertical transmission.

The composition and source information of the aquatic dissolved organic matter （DOM） in the Daihai Lake, a typical saline lake at the ecologically fragile agro-pastoral area, were explored with three-dimensional excitation and emission matrix fluorescence （3DEEM）, parallel factor analysis （PARAFAC）, and fluorescence peaks （B, T, A, M, C, D, and N）. Further, the relationship between aquatic DOM fluorescence characteristics and environmental factors were analyzed using correlation analysis in the Daihai Lake. The results showed that the water of Daihai was weakly alkaline, with high nutrient salt concentration and serious organic pollution. Two protein-like substances （C1 and C3） and one humic-like substance （C2） were identified using PARAFAC. The sum of C1 + C2 accounted for 80% of DOM. The results of fluorescence peaks showed that the total percentage of protein-like fluorescence absorption peaks （B, T, and N） was 49.67%. Aquatic DOM of Daihai demonstrated both terrigenous and endogenous characteristics. Terrestrial inputs were mainly from intensive agricultural activities and rapid ecological degradation of the watershed leading to large amounts of organic matter entering the lake. The environmental behavior of DOM was highly correlated with the metabolic activity of organisms and nutrient status of lakes. NH₄⁺-N, DOP, TP, DO, and permanganate index characterized the effect of the lake trophic state on DOM composition. DO, SAL, and Chla were mainly related to microbial metabolic processes （P<0.05）. This study provides basic data and insights for the improvement of inland lake environments in saline lakes.

HONO, or gaseous nitrous acid, has a significant impact on air quality and climate. An atmospheric gaseous nitrous acid （HONO） observation study was carried out in December 2021 （winter） and July 2022 （summer） in the Jiangbei New District of Nanjing City, respectively. Using the HONO concentration observation data, combined with the atmospheric NO_x and O₃ concentrations during the sampling period as well as the reaction rate of the HONO generation process and other parameters, we compared and analyzed the change rule of the atmospheric HONO concentration during winter and summer in the Nanjing area, quantitatively investigated the sources of diurnal atmospheric HONO and its generation mechanism, and explored the unknown sources of atmospheric HONO during the daytime. The results showed that the mean value of atmospheric ρ（HONO） in the Nanjing area during winter was （2.2±1.1） μg·m^-3, which was 3.0 times the average concentration [（0.72±0.45） μg·m^-3] during summer. The atmospheric HONO concentrations during winter and summer showed a significant daily pattern of low during the daytime and high at nighttime. Based on the reaction rates of different HONO generation pathways, it was calculated that the non-homogeneous reaction of NO₂ was the main pathway of atmospheric HONO generation at night in Nanjing. The analysis of the atmospheric HONO balance during the daytime showed that there existed an important unknown source of HONO during the daytime （P_unknown）, and its contribution to the daytime atmospheric HONO concentration was 69% during winter and 47% during summer, respectively. The results of correlation analysis showed that P_unknown was related to the light-catalyzed reaction of NO₂ during the daytime.

Given the frequent occurrence of the sludge bulking phenomena caused by Microthrix parvicella （M. parvicella） overgrowth during the low-temperature period in the full-scale municipal wastewater treatment plant, the filamentous bacteria dynamics of the M. parvicella population were systematically investigated during the completed bulking period using the multi-dimensional integrated filamentous monitoring method combined with the molecular quantitative method. A lab-scale reactor was constructed and successfully simulated bulking phenomena under the low-temperature condition. The trend of dominant filamentous bacterial shift and the main influencing parameters were estimated during the bulking period, to verify the key factors for filament growth and extinction of the sludge bulking phenomenon in the full-scale plant. The results showed that the bulking-caused M. parvicella was characterized by significant changes in the diversity of filamentous bacteria, and the dominant filamentous bacterial succession was reflected in the competition between the skeleton filamentous bacteria Type 0092 and Type 0041 and M. parvicella. At lower temperatures, sludge loading was an important controlling factor for the competitive growth advantage of M. parvicella： when the temperature was lower （approximately 15°C）, low sludge loading [0.05 kg·（kg·d）^-1] could lead to the stabilized elevation of M. parvicella, and with the loading increased to 0.1 kg·（kg·d）^-1 or more, M. parvicella populations showed a targeted decline despite the presence of the low temperature factor.

In the process of ecological restoration, vegetation plays a crucial role in restoring ecosystem functions. Soil microorganisms are essential components of soil ecosystems, driving material cycling processes and enhancing plant productivity and resilience. This study aimed to investigate the community structure characteristics of rhizosphere soil and root-endophytic bacteria in different shrubs. Specifically, the composition of rhizosphere soil and root-endophytic bacteria in Cotoneaster acutifolius Turcz., Lonicera japonica Thunb., and Cornus alba L. in the loess hilly area of northwest Shanxi was determined using Illumina high-throughput sequencing technology. The results revealed that the dominant phyla of rhizosphere soil bacteria and root-endophytic bacteria in different shrubs were Proteobacteria and Actinobacteria. Additionally, the genera of rhizosphere soil and root-endophytic bacteria differed. Furthermore, the species richness and diversity index of rhizosphere soil bacteria were significantly higher than those of root-endophytic bacteria （P < 0.05）. It was also observed that approximately 64% of the root-endophytic bacteria in the shrubs were present in the rhizosphere soil bacteria, indicating similarity in the bacterial community compositions of different niches. Redundancy analysis （RDA） and Pearson correlation analysis revealed that soil dehydrogenase, soil N-acetyl-β-D glucosidase, alkaline protease, pH, and total phosphorus were the main influencing factors on the bacterial community structures in root-endophytic bacteria （P < 0.05）, while alkaline protease, pH, total carbon, and total nitrogen significantly impacted rhizosphere soil community structures （P < 0.05）. Additionally, the partial least squares path model （PLS-PM） indicated that vegetation could directly affect bacterial communities and indirectly affect them by influencing soil physicochemical properties and soil enzyme activity. In conclusion, the findings of this study provide a theoretical foundation for further research on the relationship between endophytic bacteria and resistance in shrubs.

Airborne pollen is considered to be one of the air pollutants that can cause allergic reactions in humans, leading to the occurrence or aggravation of a series of allergic diseases. The latest study showed that the positive rate of pollen allergens in allergic rhinitis patients in urban areas of Beijing exceeded 80%. Accurate prediction of pollen content could provide more effective assistance to susceptible populations. Based on the measured data from multiple stations in the urban area of Beijing during the pollen season from 2021 to 2022, the spatiotemporal distribution characteristics of pollen content were analyzed. The results showed that the main meteorological factors affecting spring pollen content in the urban area of Beijing were daily average wind speed, 3-day average temperature, water vapor pressure, daily average, temperature, and accumulated temperature. The main meteorological factors affecting autumn pollen content were 3-day average temperature, water vapor pressure, minimum surface temperature, and daily average temperature. In addition, it was found that there was a consistent spatial correlation between the current air pollen content and meteorological elements in the urban area of Beijing, but this correlation had significant seasonal differences. Furthermore, the Granger causality test method was applied to select the main meteorological factors that affected airborne pollen content in the urban area of Beijing, and two prediction models for air pollen content in the Beijing urban area for different seasons were established based on the support vector machine method （SVM） and multiple linear regression theory. The test of the prediction results for 2023 showed that both the SVM model considering seasonal differences and the multiple linear regression model could predict the daily distribution trend of pollen content well. The overall correlation coefficients between the predicted pollen content and the measured values were 0.693 and 0.636 （P <0.01）, respectively. Additionally, both models had good predictive ability for several severe content pollen pollution events within the year. In the spring of 2023, the prediction accuracy of the SVM model and linear model were 61.2% and 60.1%, respectively. During autumn, the prediction accuracy was 68.1% and 66.7%, respectively. The performance was better than that of existing business models, especially in the cross-level error improvement of heavy pollution event prediction. The research results provide reference value for further improving the prediction technology of airborne pollen content in the Beijing area.

In order to investigate the effects of polystyrene （PS） microplastics with different particle sizes on the growth, development, and quality of Brassica campestris L. （Chinese cabbage） in consecutive seasons, we studied the effects of PS plastics with different particle sizes （<25, 25-48, 48-150, and 150-850 μm） on the growth and development of B. campestris L. and on the supply of nutrients to the soil in a potting experiment in three consecutive seasons. The results showed that PS microplastics had a significant inhibitory effect on the growth of Chinese cabbage in three consecutive seasons, and the fresh weight, chlorophyll b, and total chlorophyll content of Chinese cabbage were reduced by 9.22%-30.4%, 51.5%-88.9%, and 25.3%-67.1%, respectively. PS microplastics also affected the quality of Chinese cabbage in three seasons and significantly reduced cabbage starch （20.6%-73.2%）, Mn （23.9%-56.3%）, Zn （18.8%-23.2%）, and Cu （18.9%-35.1%） and increased its soluble sugar content （18.9%-220%）. Soil quick-acting phosphorus and quick-acting potassium content under the influence of PS microplastics showed the largest decreases of 26.0% and 55.8%, respectively, but had no significant effect on the effective Cu, Fe, Zn, and Mn contents. Overall, the effect of PS microplastics on the growth and quality of Chinese cabbage increased with the decrease in particle size and decreased with the increase in consecutive planting seasons； however, there was no obvious pattern of change in the effect of PS microplastic particle size on the soil fast-acting nutrient content.

Due to the aggravation of atmospheric nitrogen and sulfur deposition and the unreasonable application of fertilizer, soil acidification is becoming increasingly serious. In heavy metal-contaminated soils, acidification not only seriously affects fertility but also the effectiveness and sustainability of conventional passivation remediation materials such as biochar. The application of calcium fertilizer may improve soil acidification, alleviate the aging of biochar materials in soil, and improve its remediation ability to composite polluted soil. However, the mechanism of its effect is still unclear. Based on this, this study selected iron-manganese oxide （FM） and hickory cattails biochar （BC） to prepare biochar-ferromanganese composites （BFM） and conducted simulated acidification on it. Through characterization and an aqueous adsorption test, the changes in physicochemical properties and adsorption properties of the material after acidification were explored. Then, orthogonal tests were carried out to explore the effects of the combination of BFM and calcium fertilizer on soil pH and the availability of Cd and As under acidification conditions and to obtain the best combination scheme. The results showed that the optimal ratio of BC and FM in BFM was 7∶3 （quality ratio）, the removal rates of Cd（Ⅱ） and As（Ⅲ） were as high as 94.58% and 97.14%, respectively, and the adsorption capacities were 120.74 mg·g^-1 and 129.29 mg·g^-1 （solid-liquid ratio 1∶500）. After acidification treatment, the pore structure of BFM surface decreased, and the types and quantities of functional groups changed, resulting in the removal rates of Cd（Ⅱ） and As（Ⅲ） in aqueous solution decreasing by 73.97%-92.84% and 73.56%-93.61%, respectively. The combined application of calcium fertilizer and BFM could significantly increase soil pH, with an increase range of 3.06%-37.84%. The effect of increasing pH decreased with the increase in culture time and acidification degree. Compared with that in the blank control, the content of available Cd in soil was significantly reduced by 22.67%-97.78%. The content of available As in soil was generally stable. According to the effect curve analysis of the orthogonal test results, under the condition of weak acidification degree （pH=5.6）, the application of 2% supplemental amount with 2% silica-calcium fertilizer and 2% calcium-magnesium phosphate fertilizer had a good passivation effect on soil Cd. Under the condition of strong acidification degree （pH=4.0）, the application of 2% supplemental amount and 2% silica-calcium fertilizer had a good passivation effect on soil As. In summary, simulated acidification will affect the adsorption performance of BFM, and calcium fertilizer combined with it can increase soil pH, improve soil acidification, alleviate the aging of BFM in acidified soil, and improve its repair ability to heavy metal-polluted soil.

To evaluate the effectiveness of air pollution prevention and control measures in Beijing, this study measured the content of 13 metal elements, including seven heavy metal elements [As, Cd, Co, Cr（Ⅵ）, Ni, Pb, and V], through daily PM_2.5 sampling （n = 934） in the urban area of Beijing for four years. We analyzed the interannual changes in the concentration levels of various metals and the differences between heating and non-heating seasons, used a positive definite matrix factorization （PMF） model for quantitative source analysis, and used health risk assessment methods to evaluate the health risks of six metals. The results showed that, except for a few metal elements such as Cr（Ⅵ） and Ni, which showed an increase in concentration in individual years, the overall concentration of each element showed a downward trend. The concentrations of ten metals, including V, Co, Pb, and Mn, during the heating season were significantly higher than those during the non-heating season （P<0.05）. There were five main types of atmospheric heavy metal pollution sources in Beijing： dust sources, transportation sources, coal sources, industrial sources, and fuel oil combustion sources. Among them, the proportion of coal sources was generally decreasing. The HQ values of each metal were all less than 1, indicating no non-carcinogenic health risk. The carcinogenic risk of Ni and Cd could be ignored, while the R values of As, Co, and Cr（Ⅵ） in each year were between 10^-6 and 10^-4, indicating a certain carcinogenic risk. The interannual trends in atmospheric concentration, sources, and health risks indicate that the relevant measures for air pollution prevention and control in Beijing have achieved positive results.

Farm manure is one of the largest sources of antibiotics in environmental media. At present, there are limited studies on antibiotic residues and microbial diversity in different environmental media. The residual characteristics of five typical veterinary antibiotics （sulfadiazine, SDZ； doxycycline, DOX； oxytetracycline, OTC； tetracycline, TC； and chlortetracycline, CTC） in different environmental media and their effects on environmental microbial diversity were preliminarily discussed by taking an ecological farm and a seven-year long-term experimental field in Bishan District of Chongqing as the research object. The results showed that the content of oxytetracycline in chicken manure was the highest （17.75-18.80 μg·kg^-1）, the content of doxycycline in soil was the highest （2.00-2.55 μg·kg^-1）, and the concentration of chlortetracycline in water was the highest （13.77-21.10 μg·L^-1）. During the sampling time, the total antibiotics in soil and chicken manure changed little. The five antibiotics in the water had high ecological risks. The five antibiotics significantly affected the microbial diversity in the environmental media. The dominant bacteria in the soil were Proteobacteria and Actinobacteria, and the dominant bacteria in water were Proteobacteria and Bacteroidetes.