[Optimization Method and Case Study of Air Pollution Emission Spatial Pattern].

Few of the current methods of improving air quality, including end-pipe treatment, industrial, energy and transportation structure adjustments, are from the viewpoint of the spatial pattern optimization of pollutant emissions. Therefore, based on factors such as natural environment, human health, pollutant transmission capability, and meteorological diffusion conditions, our research group used the threshold approach, natural breaks, spatial erasure, and other methods to define the layout area suitable for atmospheric pollution sources. Based on these results, the emissions pattern was optimized to achieve air quality improvement. Taking Guangdong Province as an example, we examined the application of the emissions pattern optimization of air quality improvement and atmospheric environment zoning. The results indicate that the first class area of environmental air quality accounts for 9% of total province area, the densely populated area accounts for 3%, the sensitive area of the national air quality monitor stations accounts for 15%, the pollutant accumulation area accounts for 22%, and the layout area suitable for atmospheric pollution sources primarily distributed in the west part of the province accounts for 60%. By shifting the non-thermal power industrial sources into those area, the concentration level of PM2.5 will decrease by 4% at the provincial scale and 10% at the city scale. Emissions pattern optimization has become an innovative aided support technology for the continuous improvement of air quality. In practical applications, it can be combined with energy and industrial structure adjustments, pollution control technology enhancements, and cross-regional prevention and control to formulate the most feasible air quality improvement plan.

[Source Apportionment of Air Pollutants for a Typical Pollution Event in Zhaoqing].

Based on observational data for pollutants and meteorology, this study analyzed the pollution episode that occurred during Dec 17th to 23th in 2018 in Zhaoqing, Guangdong Province, China. Using the source apportionment model CMAQ-ISAM and the hybrid receptor model, the regional contributions to air pollution were examined. The results showed that low-pressure conditions had an adverse effect on the diffusion of pollutants during this pollution episode in Zhaoqing. Prior to the pollution episode, pollutants were mainly derived from Zhaoqing and Qingyuan, accounting for 19.2% and 10.7% of pollutants, respectively. As well as pollutants from Guangdong Province, long-distance transport of pollutants from Jiangxi, Hunan, Hubei, and Shaanxi accounted for approximately 64.5% of the total during the non-pollution period. During the polluted episode, major cities in Pearl River Delta and the eastern part of Guangdong Province contributed more pollutants as a surface high-pressure field moved southward. Zhaoqing, Foshan, Dongguan, Guangzhou, and Huizhou contributed 25.5%, 14.8%, 9.8%, 9.5%, and 5.3% of the pollutants, respectively. Cities in the eastern part of Guangdong Province including Heyuan, Meizhou, Shanwei, Jieyang, Shantou, and Chaozhou contributed 13.7% of the total pollutants. In addition, pollutants from Fujian, Jiangxi, and the Yangtze River Delta accounted for approximately 32.9%. Furthermore, pollutants transported under marine influences were one of the main causes of this pollution episode in Zhaoqing.

On the thermal annealing conditions for self-synthesis of tungsten carbide nanowires from WC(x) films.

The thermal annealing conditions in nitrogen ambient for the self-synthesis of tungsten carbide nanowires from sputter-deposited WC(x) films were investigated. Experimental results show that the temperature window for the growth of nanowires lies in the range of 500-750 °C with the corresponding annealing time interval ranging from 2.5 to 0.25 h. The diameter, length, and density of the grown nanowires are in the range of 10-15 nm, 0.1-0.3 µm, and 210-410 µm(-2), respectively. The degree of carbon depletion in the annealed WC(x) films plays a crucial role in determining both the shape and density of the self-synthesized nanowires. Nanowires synthesized at lower temperatures were seen to be smaller in dimension but higher in density. Material analysis reveals that the phase transition from WC to W(2)C arising from decarburization of the WC(x) film during thermal annealing should be responsible for the self-synthesis of nanowires.