Nighttime light (NTL) images obtained by the Visible Infrared Imaging Radiometer (VIIRS) mounted on the National Polar-orbiting Partnership (NPP) could objectively represent human activities and instantly identify urban shapes on a temporal and spatial scale. From 2013 to 2020, the built-up areas of eight provincial capital cities were extracted using NPP/VIIRS NTL data to examine the dynamic changes in city expansion and socioeconomic development in the Yellow River Basin during the urbanization process. The spatial characteristics of urban built-up area expansion were generated using the eight-quadrant analysis method and combined with the statistical data of population and (gross domestic product) GDP to analyze the correlations between the light intensity of built-up areas, population and GDP; this enables an understanding of the changes in population and economy in the development of urban built-up area expansion. The findings show that: (1) unbalanced city development existed in the Yellow River Basin’s upper, middle, and lower reaches, and the expansion and light intensity of cities in the upper reaches were slower than those in the middle and lower reaches; (2) the spatial differentiation of urban expansion was significant between each of the reaches in the Yellow River Basin, and greatly influenced by natural geographical elements; and (3) positive correlation exists between light intensity, population, and GDP in the built-up areas of the middle and lower reaches, while the correlations in the upper reaches were not stable. In conclusion, light data indirectly reflects urban development and could be used as a substitute variable for socioeconomic development indicators under certain conditions.
Aimed at improving the rational utilization of lignite which suffers not only lower efficiency,higher moisture content,but also greater greenhouse gas emissions,this paper introduces a research on the regularities of carbonization temperature and holding time on the product yield of dry distillation of lignite by using aluminium retort method and describes the characterization of the functional groups of semi-coke by FTIR in different carbonization temperatures.The result shows that the suitable carbonization condition of lignite is 450 ~ 510 ℃ and holding time is 30 min.The obvious decrease of 53.1% and 11.8% in the ratio of aliphatic and aromatic groups of 400 ℃ semi-coke compared with that of raw coal suggests the following changes,such as the gradually increased degree of aromatization of semi-coke,increased aromatic nucleus condensation degree,14.4% decrease in the oxygen content of semi-coke,decreases from 0.473 to 0.396,16.3% reduction in the decarbonylation ratio,the 21.5% increases in FCdaf,and 34.7% increase in the C/H ratio.The retort process of lignite proves a dehydrogenation,deoxidization and carbon-rich process.
Abstract. Carbon dioxide is considered an inert gas that rarely participates in atmospheric chemical reactions. However, we show here that CO2 is involved in some important photo-oxidation reactions in the atmosphere through the formation of carbonate radicals (CO3∙-). This potentially active intermediate CO3∙- is routinely overlooked in atmospheric chemistry regarding its effect on sulfate formation. Present work demonstrates that SO2 uptake coefficient is enhanced by 17 times on mineral dust particles driven by CO3∙-. It can be produced through two routes over mineral dust surfaces: i) hydroxyl radical + CO32-; ii) holes (h+) + CO32-. Employing a suite of laboratory investigations of sulfate formation in the presence of carbonate radical on the model and authentic dust particles, field measurements of sulfate and (bi)carbonate ions within ambient PM, together with density functional theory (DFT) calculations for single electron transfer processes in terms of CO3∙--initiated S(IV) oxidation, a new role of carbonate radical in atmospheric chemistry is elucidated.
CO2 of over 400 ppm is a universal greenhouse gas in the atmosphere. Our recent work emphasizes the important role of carbonate radicals produced on TiO2 surfaces in fast sulfate production under solar irradiation in the presence of CO2 at specifically low RH and light intensity (Atmospheric Chemistry and Physics, 22, 9175–9197, 2022). Yet so far how CO2 involves and affects secondary sulfate production under diverse meteorological conditions remains unknown, which essentially renders our comprehensive knowledge of CO3.-initiated SO2 oxidation scheme in the atmosphere. Following this, we extended that work to explore the heterogeneous SO2 oxidation at atmospherically relevant RH range of 30-70% and light intensity of 30-90 mW cm-2. Interestingly, we observe CO2 promotes sulfate yield at low RH and light intensity and in turn suppresses the SO2 uptake process at high RH and light intensity cases. This observation relates to the kinetic balance between SO2 oxidation triggered by CO3.- and self-quenching of these radical ions, where a proper meteorological condition minimizes the quenching process and eventually promotes sulfate production, and vice versa.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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