Ammonium (NH4+) is a significant component of fine aerosol particles (PM2.5), and its behavior in the atmosphere is crucial to air pollution. We present a novel study that analyzes the vertical distribution and temporal trends of NH4+ in the urban boundary layer of Beijing, tracking hourly concentrations throughout a complete haze episode. Our results unveil a surprising single-peak profile of NH4+ at heights of 300-700 m in the urban boundary layer with its hourly concentration reaching similar to 50 mu g m(-3), which is 3 times higher than that at the ground level, in contrast to the conventional patterns of decreasing concentrations with height. The vertical structure is closely related to the observed escape of ammonia (NH3) or NH4+ from upwind industrial sources via elevated chimneys. The NH4+ plumes emitted through these sources are prone to transport at an altitude of 270-750 m for approximately 6 h, covering >250 km to Beijing. This study reveals that non-agricultural point emissions of NH4+ impact the vertical patterns of aerosol NH4+ in the urban boundary layer, demonstrating potential opportunities for limiting such emission sources to curb PM2.5 pollution in the North China Plain.

>The influence of sintering temperatures on solution-processed cadmium telluride(CdTe) nanocrystal films is studied in order to maximize the performance of CdTe/Al Schottky nanocrystal solar cells.The best overall performance of 2.67%efficiency at air mass 1.5 was achieved from devices with CdTe films sintered at 350℃X-ray diffraction,scanning electron microscopy and UV-vis absorption measurements show that the CdTe nanocrystal grains began to grow remarkably well when sintering temperatures increased to 350℃.By analyzing the current-voltage characteristics,we find that the short-circuit current densities of devices increase with sintering temperatures ranging from 200 to 400℃,but,the over-sintered(450℃) treatment induces the shunting of devices.