环境科学最新文献

In order to investigate the influence of modified corn straw biochar on the hydraulic properties of water infiltration, evaporation, and water holding, corn straw biochar was prepared by pyrolysis at 500 ℃ for 2 hours in an N₂ environment. Three solvents （H₃PO₄, NaOH, and NH₄Cl） were selected, and different modified corn straw biochars were obtained by immersion modification at two concentrations （1 mol·L^-1 and 3 mol·L^-1）. The physical and chemical properties of all biochars, such as elemental composition, pore structure, functional groups, and surface morphology, were systematically characterized. Each type of corn straw biochar was selected to perform soil hydraulic properties tests under three different additions （1%, 2%, and 3%）. The influence of different corn straw biochar on the soil saturated hydraulic conductivity, water accumulation evaporation, and volume water content were analyzed by constant head method, soil evaporation test, and soil moisture characteristic curve. The results showed that the addition of modified corn straw biochar can significantly reduce the soil saturated hydraulic conductivity by 5.74%-46.69%, improve the soil volume water content by 0.74%-37.33%, and promote the soil water evaporation, while reduce the soil water accumulation evaporation by 0.63%-8.46% before the modification. With the increase in biochar addition, the saturated hydraulic conductivity of the soil decreased significantly, the cumulative evaporation gradually increased, and the volume water content showed a trend of first increasing and then decreasing. There was no correlation between the modified solution concentration and the soil saturated hydraulic conductivity, accumulated evaporation, and volume water content. This study can provide theoretical basis and technical support for improving the water retention performance of soil in the loess arid region of Shaanxi and Gansu.

Luohe City is an important node city in the Central Plains Urban Agglomeration in China, where the atmospheric ozone （O₃） pollution situation has been serious in recent years. In order to provide a scientific basis for O₃ pollution control, the online filed observation of O₃ precursor volatile organic compounds （VOCs） was carried out in Luohe City in July 2022 to understand their variation characteristics and sources. The mean ratio of φ（TVOCs） during the observation period was （16.49±5.73）×10^-9. Among them, alkane （33.7%）, oxygenated volatile organic compounds OVOC （24.0%）, and halohydrocarbon （21.9%） accounted for the top three. The results from source apportionment showed that the main VOCs sources （contributions） included the natural gas （NG） use （20.1%）, regional transport （14.8%）, solvent use （14.2%）, gasoline vehicle emissions （12.3%）, industrial emissions （11.6%）, diesel vehicle emissions （10.5%）, liquefied petroleum gas （LPG） use （9.8%）, and plant emissions （6.7%）. OVOC contributed the most to ozone formation potential （OFP） and free radical loss rate （L_·OH）. The results showed that the contribution of motor vehicle exhaust （>22.8%） was the primary source of VOCs in Luohe City. However, other sources were complex and with comparable contributions, requiring the development of targeted and comprehensive prevention and control measures.

Land use is one of the important factors causing the change in ecosystem carbon storage. Studying the spatio-temporal evolution characteristics of carbon storage driven by land use change is of great significance for enhancing the carbon sequestration capacity of terrestrial ecosystems, slowing down the effect of climate warming, and helping to achieve the goal of "dual carbon." Taking the Tarim River Basin as the research object, based on four periods of land use data from 1990 to 2020, the InVEST model carbon module was applied to estimate and analyze the temporal and spatial evolution characteristics of carbon storage in the basin, and the impact of land use change on the carbon sequestration capacity of the basin ecosystem and the spatial differentiation driving law of carbon storage were discussed. The results showed as follows： ① Grassland and unused land were the main land use types in the Tarim River Basin, accounting for more than 90% of the total land types, followed by cultivated land, forest land, water area, and construction land. From 1990 to 2020, the area of cultivated land, construction land, and unused land increased, while the area of grassland, forest land, and water area decreased. The total transfer area of land use type in the basin from 1990 to 2020 was 2.19×10⁵ km², and grassland was the main transfer type （accounting for 44.22% of the total transfer area）, which was mainly converted into unused land and cultivated land. ② The overall spatial distribution of carbon stocks in the Tarim River Basin was lower in the middle and higher in the surrounding areas. The high-to-high-cluster and high-to-low-cluster carbon stocks were mainly located in the distribution areas of woodland and grassland, and the low-value carbon stocks were mainly distributed in the unused land type areas in the middle of the Tarim River Basin. Over the past 30 years, an accumulative loss of 9×10⁷ Mg was observed. The center of gravity of carbon storage change shifted to the southeast, and most of the areas of carbon storage reduction were cultivated land and unused land expanding to the surrounding areas, encroaching on grassland and forest land with higher carbon density. ③ The contribution of different land use types to carbon storage was grassland, forest land, cultivated land, unused land, construction land, and water area. ④ The spatial differentiation of carbon stocks in the Tarim River Basin was influenced by various driving factors such as terrain, climate, environment, and population and their synergies.

Pollution source emission inventories are the basis for analyzing the causes of pollution, identifying the contribution of pollution sources, and scientifically formulating air pollution prevention strategies. The current inventory construction methods mainly focus on improving the accuracy and spatial and temporal resolution of the inventory, and there is an urgent need to look into dynamic updating methods to address the problem of lagging source emission inventories. In order to develop an effective and versatile method for the dynamic updating of source emission inventories, a meteorological normalization method based on random forests was chosen to capture the response relationship between pollutants and anthropogenic emissions. Based on the response relationship and the base emission inventory, the method for updating emission inventories based on the relationship between emissions and air quality （REQEI） was developed. Taking MEIC as the example, the REQEI_MEIC inventory was constructed using this method. The applicability and reasonableness of the REQEI_MEIC inventory was examined through the horizontal comparison method and the model validation method, so as to prove the feasibility of the inventory construction method. The results showed that the differences in pollutant emissions between the REQEI_MEIC and MEIC inventories were small, and the model validation effects of the two inventories were generally consistent. In some areas, the emissions of the REQEI_MEIC were closer to the actual emissions, and the pollutant modeling effect was more favorable. The inventory dynamic updating method can construct a relatively accurate pollutant emission inventory on the basis of greatly reducing the workload. The method quickly extrapolates the inventory through the relationship between anthropogenic source emissions and air quality response, accelerates the speed of inventory updating, is suitable for realizing the rapid dynamic updating of existing inventories, and can to a certain extent reduce the limitations imposed by the spatial and temporal limitations of emission inventories on the analysis of the causes of pollution.

Based on PM_2.5 and O₃ remote sensing concentration data in Beijing-Tianjin-Hebei and its surrounding areas from 2015 to 2020, we used trend analysis, geographic detectors, and a geographically and temporally weighted regression model to explore the spatiotemporal characteristics and key driving socio-economic factors of multi-scale PM_2.5 and O₃ concentrations. The results indicated that： ① The changing slope of PM_2.5 concentration ranged from -12.93 to 0.43 μg·（m³·a）^-1, and the changing slope of O₃ concentration ranged from 0.70 to 14.90 μg·（m³·a）^-1. The decreasing slope of PM_2.5 concentration was the largest in winter, and the increasing slope of O₃ concentration was the largest in summer. ② The concentrations of PM_2.5 and O₃ were spatially correlated, and the H-H concentrations of PM_2.5 were located in the southern Hebei Province and the northern Henan Province. The spatial clustering pattern of O₃ changed greatly. ③ From the perspective of urban agglomeration, the GDP, population density, and civilian car ownership had a strong explanatory power for PM_2.5, while GDP, urbanization rate, and civilian car ownership had a strong explanatory power for O₃. The dominant interaction factors of 2016 and 2020 were the population density∩the proportion of the secondary industry and urbanization rate∩road network density, respectively. ④ From the perspective of single city, population density, industrial nitrogen oxide emissions, and electricity consumption had mainly positive effects on PM_2.5 and O₃ pollution and became the socio-economic driving factors that need to be focused on to control PM_2.5 and O₃ co-pollution.

With the extensive use of electric vehicles, it is of great significance to measure traffic carbon emissions and analyze its evolution law under the mixed traffic environment in order to effectively achieve traffic carbon reduction. Utilizing taxi GPS data from 2016, 2018, 2020, and 2022, we assessed the carbon emission levels of taxis in Xi'an and matched the results to a grid using map matching. The K-means algorithm was used to analyze the spatial clustering and spatial-temporal distribution of carbon emissions, and the gradient boosting iterative decision tree model （GBDT） was used to explore the influence of built environments on carbon emissions. The results showed that： Weekend carbon emissions were greater than weekday emissions in all years, and the difference between weekend and weekday carbon emissions decreased year by year with the increase in the proportion of electric cabs. The overall weekend carbon emissions in 2022 decreased by approximately 56%, and the overall weekday carbon emissions decreased by approximately 40% compared to those in 2016. The carbon emission region in Xi'an had experienced an evolution from a region-wide ring-shaped distribution in 2016 to 2022. The evolution process of the ring-shaped distribution of peripheral low-carbon emission regions, partial reticulation of medium-carbon emission regions, and reticulation of high-carbon emission regions. From the importance analysis of built environmental factors, it could be seen that residential land and population density had relatively high importance for carbon emissions in each year. The importance of public facilities land was higher on weekdays than that on weekends, while the importance of leisure and entertainment land was higher on weekends than that on weekdays. This work reveals the spatial and temporal distribution evolution of carbon emissions, which can provide a reference for the control and management of transportation carbon emissions under the mixed traffic state.

Achieving effective treatment and resource reuse of municipal sludge is a worthwhile research issue. Currently, anaerobic digestion treatment is an effective way to achieve the resource utilization of municipal sludge. However, due to the slow start-up, poor stability and low gas production efficiency of anaerobic digestion systems, sludge anaerobic digestion faces many challenges in practical engineering applications. Iron-based material has been proven to be a good conductive material for promoting anaerobic digestion of municipal sludge. On the basis of previous studies, this article summarized the effects of different iron-based materials on anaerobic digestion of municipal sludge. Simultaneously, from the perspectives of alleviating toxic substance inhibition, enhancing microbial metabolism, and promoting electron transfer between symbiotic microorganisms, the mechanism of iron-based materials enhancing anaerobic digestion of municipal sludge was summarized. The mechanism of direct interspecific electron transfer mediated by iron-based materials in enhancing anaerobic digestion of municipal sludge was described, and the research direction of iron-based materials enhancing anaerobic digestion of municipal sludge was prospected.

Carbon budget accounting and identification of carbon imbalance risks contribute to revealing the impact mechanism and extent of human activity on the regional carbon budget. It is of great significance to conduct regional differentiated carbon governance and promote regional collaborative emission reduction. As a result, this study first constructed a research framework for regional carbon imbalance risk assessment based on carbon budget. Then, the carbon budget was calculated at a grid and county scale taking Henan Province as an example, and its spatio-temporal pattern was discussed. Finally, the regional carbon imbalance risk index was constructed to reveal the temporal and spatial evolution characteristics of carbon imbalance risk in Henan Province. The results showed： ① From 2001 to 2020, the carbon emissions in Henan Province increased from 232 million tons to 586 million tons. Spatially, it exhibited a gradually decreasing distribution pattern from the central areas to the periphery of each city. Carbon absorption showed a slight fluctuating increase trend （117 million-153 million） with a distribution feature of "higher in the west, lower in the east； higher in the south, lower in the north." ② The carbon source/sink ratio in Henan Province showed a characteristic of rapid growth followed by a gradual decline, reaching a peak of 5.14 in 2013. The carbon source/sink value in economically developed areas was significantly higher than that in economically underdeveloped areas. The regional differences in carbon balance transformation were evident, showing an overall "imbalance-neutralization-imbalance" trend. ③ During the study period, carbon imbalance risks in Henan Province gradually stabilized, and the number of districts and counties with a carbon imbalance risk index higher than 0.6 was 107 （68.2%） during 2016-2020. The high-risk areas of carbon imbalance mainly expanded from the Zhengzhou metropolitan area to the periphery along major transportation routes. ④ Future efforts should focus on establishing land spatial optimization and differentiated governance strategies, considering varying carbon imbalance risks across regions. This includes enhancing county-level cross-compensation mechanisms based on carbon imbalance risk assessments； mitigating regional carbon imbalances； and advancing regional collaborative emission reductions, carbon sequestration, and carbon neutrality goals.

The Net Primary Productivity （NPP） of vegetation plays a crucial role in terrestrial ecosystems, and a detailed investigation into the annual average NPP and its driving factors is of significant importance for promoting regional ecological construction and sustainable development. This research utilized MOD17A3 annual average NPP data from 2000 to 2020 and employed methods such as trend analysis, Hurst index, random forest model, partial dependence model, geographic weighted regression, and partial least squares-structural equation model （PLS-SEM） to analyze the annual variation characteristics of NPP and its relationship with driving factors in the upper and middle reaches of the Yellow River. The results showed： ① During the period from 2000 to 2020, the annual average NPP in the upper and middle reaches of the Yellow River generally exhibited a year-on-year increasing trend, with 79.25% of the region showing a significant improvement in annual average NPP, while 0.25% of the region exhibited a severe degradation trend. ② The dominant influencing factors of the annual average NPP in the upper and middle reaches of the Yellow River included precipitation, NDVI, drought, and relative humidity. The suitable range for increasing annual average NPP was 400 mm to 650 mm for precipitation and 40% to 70% for relative humidity, and NDVI showed a significantly linear positive correlation with annual average NPP. Drought index was negatively correlated with annual average NPP. The annual average NPP tended to stabilize and did not decline further when the drought index exceeded the threshold of 8. ③ Extreme rainfall indirectly affected the variation in annual average NPP in the basin by influencing the vegetation growth condition. The impact degree of extreme rainfall indices on the annual average NPP in the basin was in the following order： R10>R95P>PRCPTOT>SDII>Rx5day>R99P. ④ The next steps in ecological construction in the upper and middle reaches of the Yellow River should focus on the arid and severely arid regions in the northern part of the Yellow River, adapting measures to local conditions and enhancing the regional ecological environment.