Huanjing Kexue/Environmental Science最新文献

Dissolved organic matter （DOM） plays an important role in indicating the pollution of the water environment, and sediment is the main source of endogenous pollution of the water environment. Research on the spectral characteristics of DOM in sediments was important for the interpretation of water environment pollution. In this study, UV-visible absorption spectroscopy and three-dimensional fluorescence spectroscopy combined with the parallel factor analysis （PARAFAC） were used to analyze the fluorescent components, sources, and influencing factors of DOM in sediments from the Yuanhe River Basin. The results showed that the average of ω（TN）, ω（TP）, and ω（OM） in sediments from the Yuanhe River Basin were 0.52, 0.66, and 21.22 g·kg^-1, respectively. The concentrations of total nitrogen and total phosphorus increased along the flow direction. In addition, the sediment DOM from the Yuanhe River Basin mainly originated from terrestrial sources. The chromophoric DOM concentration and aromaticity of DOM from the downstream reaches were significantly higher than those from the upstream and midstream reaches. Based on PARAFAC, four fluorescent components of DOM in sediments from the Yuanhe River Basin were identified, including three humus-like components （C1, C3, and C4） and one protein-like component （C2）. The sediment DOM was dominated by humus-like materials. Moreover, the fluorescent intensity of the fluorescent components was higher in the downstream reaches. Redundancy analysis revealed that the physicochemical properties of sediments in the mainstream and downstream reaches played a more significant role in the spectral properties of DOM. Phosphorus pollution and the terrestrial humus-like substance of sediment DOM were homologous. These results indicated that the spectral properties of DOM were the indicator of water environmental pollution in the region with strong anthropogenic influence.

Microbial communities play an important role in water quality regulation and biogeochemical cycles in lakes, and their community structure and function are affected by environmental factors. Therein, antibiotics affect the abundance, diversity, composition, and function of microbial communities. In this study, Baiyangdian Lake was selected as the study area. Sediment samples of 16 sites were collected in August 2018 and April 2019, respectively. Ultra-high performance liquid chromatography-mass spectrometry （HPLC-MS/MS） was used to determine the content of typical antibiotics-quinolones （QNs） in sediment. Through high-throughput sequencing technology, the structure and function of microbial communities was analyzed in the sediments to explore the spatiotemporal variation. Thereinto, redundancy analysis （RDA） was used to identify the key influencing factors of spatiotemporal variation of microbial communities. The results showed that： ① From August to April, the average ω（QNs） showed an increasing trend, and its mean value changed from 3.91 ng·g^-1 to 6.34 ng·g^-1, with significant seasonal differences in oxolinic acid （OXO） and total QNs content （P < 0.05）. ② In terms of temporal variation, the dominant bacteria were Proteobacteria and Chloroflexi. The relative abundance of Proteobacteria showed a decreasing trend, whereas Chloroflexi showed an increasing trend； at the genus level, the dominant bacteria genera in August were norank_ f__Anaerolineaceae and Thiobacilus, and the dominant bacteria genera in April were Acinetobacter and norank_ f_Anaerolineaceae, and the dominant bacteria genera had significant seasonal differences （P < 0.05）. ③ In terms of temporal variation, the index of Simpson, Chao, Ace, and OTU number all showed an increasing trend, and the seasonal differences were significant （P < 0.05）. ④ In terms of spatial variation, there were no significant spatial differences among functional genes of COG. In terms of temporal variation, there were significant seasonal differences in functional genes of energy production and conversion, carbohydrate transport and metabolism, transcription, cell wall/membrane/envelope biogenesis, and signal transduction mechanisms （P < 0.01 and P < 0.05）. ⑤ Microbial community structure and functional genes were significantly correlated with QNs （P < 0.01 and P < 0.05）, and QNs were the main influencing factors. Therefore, QNs were the main factor affecting the changes in microbial community structure and functional genes in sediments of Baiyangdian Lake. Thus, comprehensive control of antibiotic pollution in sediments should be further strengthened.

Analyzing the spatiotemporal evolution of urban land use and habitat quality can reveal the correlation between land use and habitat quality, aiding in rational urban land policies and high-quality ecological environment development. This study was based on land use transition matrices and an Intensity-Migration （IM） model to analyze the changes in land use in Harbin from 2000 to 2020. It combined the PLUS model to explore the driving factors of land use expansion for various land types and predicted land use scenarios for 2030 under natural development, ecological protection, farmland protection, and urban development scenarios. Finally, the InVEST model was used to complete the habitat quality analysis. The results indicated： ① The dominant land use types in Harbin were cropland, forest land, and grassland. From 2000 to 2020, there was a significant tendency of conversion into grassland, cropland, forest land, and artificial surfaces, with noticeable changes in land use intensity. Water bodies, bare land, and wetland types showed less conversion and tended to be restrictive. ② Elevation was the primary factor influencing the expansion of grassland, cropland, forest land, bare land, wetland, and water bodies. Socioeconomic factors were the main factor affecting the expansion of artificial surfaces. ③ Simulation of land use types in Harbin for 2030 under the four scenarios showed an increase in forest land area and a decrease in grassland area, with insignificant changes in wetland, water bodies, and bare land areas. Except for in the ecological protection scenario, the area of artificial surfaces increased, whereas cropland decreased. ④ Overall, habitat quality in Harbin improved from 2000 to 2020. ⑤ In 2030, the spatial pattern of habitat quality in Harbin remained consistent across all scenarios, showing an overall improvement in habitat quality. Under the ecological protection scenario, areas with low and medium habitat quality decreased, whereas areas with higher habitat quality increased, indicating a relatively significant improvement in habitat quality. The research results provide a scientific basis and insights for the development of ecological civilization and urban planning and construction in Harbin.

Based on the entropy weight TOPSIS method to measure the development level of "zero-waste cities" in China from 2004 to 2021, the social network analysis method and spatial Durbin model were used to explore the spatial correlation network structure and impact mechanism of the development level of "zero-waste cities." The results showed that： ① The development level of "zero-waste cities" was generally on the decline in the whole country and the eastern and central regions. However, it was on the rise in the western regions. ② The spatial correlation of the development level of "zero-waste cities" presented a core-edge structure, with an overall upward trend in network density and a stable state in the overall network. ③ Beijing, Shanghai, Jiangsu, Zhejiang, Fujian, and Guangdong were at the center and dominant position of the network. ④ Beijing, Tianjin, Shanghai, and Jiangsu belonged to the "net benefit" sector； Zhejiang, Fujian, and Guangdong belonged to the "broker" sector； and the other provinces belonged to the "net overflow" sectors. ⑤ The level of urbanization, economic development, technological innovation, foreign investment, environmental regulations, government intervention, and population size had a significant impact on the development level of "zero-waste cities" in local or neighboring provinces, respectively. The research results can provide a reference for the proposal of policies for constructing and coordinating the development of "zero-waste cities" in various regions.

Vegetation net primary productivity （NPP） represents the ability of plants to fix ecosystem carbon, which is a key indicator to determine the health status and sustainable development of ecosystems. Its spatial and temporal changes and driving factors play an important role in revealing the status of vegetation restoration and guiding ecological restoration. Based on MODIS17A3 NPP data, land use, and meteorological data from 2001 to 2020, the temporal and spatial variation characteristics and driving factors of vegetation NPP in the Ulansuhai Nur Basin of Inner Mongolia were explored by using the methods of coefficient of variation, Theil-Sen Median trend analysis, Mann-Kendall significance test, Hurst index, and Geodetector. The results showed that： ① From 2001 to 2020, the vegetation NPP in the Ulansuhai Nur Basin showed a fluctuating upward trend, with an average value （in terms of C） of 141.03 g·（m²·a）^-1 and an average increase rate of 2.33 g·（m²·a）^-1. The vegetation NPP had obvious spatial differentiation, which was characterized by high in the southwest and low in the northeast and high in Hetao Plain and low in sandy land and mountainous areas. ② NPP mainly showed an increasing trend, and the area proportions of increasing, decreasing, and unchanged areas were approximately 80%, 3%, and 17%, respectively. The average coefficient of variation of vegetation NPP was 0.149, which mainly showed low fluctuation change, and the area accounted for approximately 51%. The future change trend of NPP was mainly characterized by anti-persistence, with an area ratio of approximately 75%. ③ Land use, altitude, maximum temperature, and slope were the dominant driving factors of variation NPP change in the Ulansuhai Nur Basin, and the q values were all above 0.200. The interaction between altitude and relative humidity had the greatest explanatory power for the spatial differentiation of vegetation NPP in the Ulansuhai Nur Basin. There were significant differences in the explanatory power of land use and all factors except nighttime light to the spatial differentiation of vegetation NPP in the Ulansuhai Nur Basin. According to the research results, in the future, we should strengthen the ecosystem management of the Ulansuhai Nur Basin； continue to implement strict ecological protection and restoration policies； and comprehensively consider factors such as climate, topography, and human activities to carry out comprehensive ecological management according to local conditions to improve the quality of ecosystem services.

Satellite-based formaldehyde（HCHO）columns and tropospheric nitrogen dioxide columns were observed using the Ozone Monitoring Instrument（OMI），and groundbased observations of ozone（O₃）for May-August from 2013 to 2022 were connected to calculate the threshold values of the HCHO to NO₂ ratio（FNR）in Shanxi Province. Then，the spatiotemporal distributions and variations in summertime ozone photochemical production regimes were analyzed. The results showed that：① The volatile organic compound（VOC） -sensitive regime area（FNR < 2.3）was obviously reduced，while the VOCs-NO_x transitional regime（FNR between 2.3-4.1）area increased in the early years and then decreased， and NO x -sensitive regime area expanded significantly in summer from 2013 to 2022 over Shanxi Province. ② The increased summertime FNR during 2013 to 2019 was associated with the co-effect of increased HCHO columns and decreased tropospheric NO₂ columns. The Shanxi Province was generally under an NO_x regime since 2016，which reflected the remarkable effect of NO x emission reductions；however，there was a shift from a VOC-sensitive regime to a VOCs-NO_x transitional regime，in which O₃ pollution aggravation was widespread under the background of decreased NO_x emissions. The decrease in O₃ concentration during 2020 to 2022 followed the synergistical declines in HCHO columns and tropospheric NO₂ columns. ③ The O₃ weekend effects were reversed in Linfen and Yuncheng but were persistent in the other nine cities. Satellite-based weekend HCHO and NO₂ levels were higher than those on weekdays in some cities of Shanxi Province，indicating that the O₃ weekend effect was not only dependent on the changes of precursors emissions but was also closely related to O₃ photochemical production sensitivity. The results indicated the necessity of simultaneous controls in NO_x emissions and VOCs emissions for ozone abatement plans over Shanxi Province. In addition，Taiyuan，Yangquan，Yuncheng，and Jincheng should continue to promote reduction in NO_x emissions.

Phytic acid-assisted sludge hydrothermal carbonization was employed to synthesize phytic acid-modified hydrochar via a one-step method. The surface morphology, pore structure, elemental composition, functional groups, and thermal stability of the phytic acid-modified hydrochar were characterized. Sorption kinetics and isotherm experiments were conducted to investigate the effects of humic acid, temperature, and pH on the sorption process of cadmium （Cd） onto the phytic acid-modified hydrochar. The Cd fixation ability was evaluated through soil passivation experiments. The results demonstrated that the surface of the phytic acid-modified hydrochar exhibited an abundance of phosphoric acid groups, enhanced electronegativity, and thermal stability. Furthermore, both the sorption rate and maximum sorption capacity for Cd increased by 1.88 times and 1.22 times compared to that in unmodified hydrochar, respectively, owing to the presence of phosphoric acid groups that enhanced complexation and electrostatic interaction with Cd. Elevated temperatures, higher pH values, and coexistence with humic acids were beneficial for enhancing Cd sorption onto phytic acid-modified hydrochar. When heavy metals such as Cu, Zn, and Pb coexisted, the sorption capacity of phytic acid-modified hydrochar for Cd was 0.77-6.88 times higher than that for other metals. Phyic acid-modified hydrochar exhibited excellent efficiency in fixing Cd （56.1%-81.l%）, mitigating the loss of available nutrients in soil and significantly increasing the AP content in the soil. In conclusion, the use of phytic acid-modified hydrochar could effectively remove Cd from water and serve as a promising soil amendment for stabilizing soil Cd content.

The concentrations of atmospheric pollutants PM_2.5, O₃, SO₂, NO₂, and CO together with the meteorological factors of temperature （T）, relative humidity （RH）, wind speed, and other relevant data in Tangshan from 2015 to 2021 were collected to study the variation characteristics of PM_2.5 and O₃ at different periods in Tangshan City in the past seven years and their influencing factors, to discuss the contributions of air mass transport to PM_2.5 and O₃ pollution, and to reveal the synergistic influence mechanism of PM_2.5 and O₃ on atmospheric compound pollution by using correlation analysis and backward trajectory cluster analysis techniques. The results showed that PM_2.5 concentrations in Tangshan decreased year by year from 2015 to 2021, whereas O₃ concentration showed a unimodal trend, with the peak appearing in 2017. Both PM_2.5 and O₃ concentrations showed obvious seasonal variation trends； PM_2.5 was characterized by the highest concentration in winter and the lowest concentration in summer, whereas O₃ was characterized by the highest concentration in summer and the lowest concentration in winter. In addition, the diurnal variation in PM_2.5 showed a bimodal distribution, with the peak occurring during the morning and evening on weekdays, and O₃ showed a unimodal distribution, with the peak value appearing during the period with strong ultraviolet radiation in the afternoon. PM_2.5 had a significant positive correlation with SO₂, NO₂, and CO, whereas O₃ had a significant positive correlation with radiation and temperature. Under the different pollution conditions, PM_2.5 and O₃ were affected by air mass transports from different directions. Being impacted by various factors, the synergistic effect of PM_2.5 and O₃ on atmospheric compound pollution showed an obvious negative effect in winter, whereas there was an obvious positive effect in spring, summer, and autumn. Under the backgrounds of different pollutions, when the concentration of PM_2.5 exceeded 150 μg·m^-3, the synergistic effect of PM_2.5 and O₃ showed an obvious negative effect.

In recent years, ground-level-ozone（O₃） pollution in urban areas in the Bohai Rim has attracted wide attention. Based on the analysis of the spatiotemporal distribution characteristics of O₃ concentration in Dongying, a representative city in the Bohai Rim from 2017 to 2022, the effects of meteorological factors and sea-land breeze circulation on O₃ concentration were evaluated. The results showed that： ① From 2017 to 2022, the annual assessment value of O₃ concentration in Dongying showed a fluctuating upward trend, and the pollution days with O₃ as the primary pollutant increased. O₃ pollution mainly occurred in spring, summer, and autumn, with the most severe O₃ pollution episodes typically occurring in May and June, and the duration of O₃ pollution season tended to be longer. The monthly variation in the daily maximum 8-h average ozone （MDA8 O₃） presented a bimodal distribution, with significant increases in the 5th and 25th percentiles, and the spatial distribution was "high in the north and south, low in the middle." In addition, the nocturnal O₃ concentration in recent years in Dongying also showed a significant increase trend. ② Meteorological factors greatly influenced O₃ concentration in Dongying. When the temperature was greater than 30℃, the relative humidity was less than 50%, and the wind direction was south-southwest or east-northeast, a high O₃ value was more likely to occur. Meteorological factors contributed 30% of the MDA8 O₃ variation in Dongying during the study period. In the case of moderate and severe O₃ pollution, the contribution of meteorological factors to the change in MDA8 O₃ could be as high as 40%. ③ To some extent, sea-land breeze contributed to the occurrence of MDA8 O₃ exceeding the secondary standard limit value of the National Ambient Air Quality Standard. In the afternoon, the hourly concentration of O₃ during the sea-land breeze days was approximately 20 μg·m^-3 higher than that during the non-sea-land breeze days. On the days of moderate and severe O₃ pollution, the O₃ concentration during the sea-land breeze days from 10：00 to 16：00 was higher than that during non-sea-land breeze days, and the O₃ concentration was also at a high level from 20：00 to 23：00 on sea-land breeze days. In the O₃ pollution season, the sea-land breeze could significantly affect the O₃ level in coastal cities, which could bring significant challenges for O₃ pollution prevention and control in this region. In the future, cities in the Bohai Rim need to further strengthen regional joint prevention and control of O₃ pollution and increase emission reduction efforts of nitrogen oxides and volatile organic compounds. This strategy could effectively lower pollutan

Owing to the influence of human activities, the issue of heavy metal pollution in farmland soil at the urban-rural fringe has become increasingly prominent. An accurate understanding of the characteristics of soil-crop heavy metal pollution in these areas is of great significance for ensuring food safety and promoting social sustainable development. Most of the existing studies rely on small-scale field monitoring, but research at the national level has not effectively captured the unique pollution dynamics of this urban-rural interface. Based on the published literature, the present study investigated the status of heavy metal pollution in the soil-crop system within China's urban-rural fringe through Meta-analysis. On this basis, the study evaluated the risks to human health associated with heavy metals in major crops in a given region. The results showed that heavy metals were accumulated in farmland soil in the urban-rural fringe of China, especially in Cd （I_geo = 0.89） pollution, and its distinct spatial heterogeneity patterns emerged. When considering different types of cultivated land, paddy fields and irrigated land exhibited a higher tendency of heavy metal accumulation. From the varying urbanization levels, the accumulation of heavy metals in soils of small and medium-sized cities was more obvious. For crops in the urban-rural fringe, Cd and Pb had the highest exceedance rate in rice （28.25% and 39.64%） and wheat （27.72% and 42.72%）. The health risk assessment results of heavy metals in crops showed that Cd was the main element that posed human health risks, which had some degree of non-carcinogenic risk and unacceptable carcinogenic risk to both children and adults.