Influence of Vehicular Emissions (NO, NO2, CO and NMHCs) on the Mixing Ratio of Atmospheric Ammonia (NH3) in Delhi, India

Mixing ratios of atmospheric ammonia (NH3), nitric oxide (NO), carbon monoxide (CO), nonmethane hydrocarbons (NMHCs), and methane (CH4) were measured to investigate the vehicular emissions, which are a dominant source of atmospheric NH3 in urban sites of Delhi, India from January 2013 to December 2014. The annual average mixing ratios of NH3, NO, CO, NMHCs, and CH4 were 21.2 +/- 2.1 ppb, 21.2 +/- 6.1 ppb, 1.89 +/- 0.18 ppm, 0.67 +/- 0.21 ppm and 3.11 +/- 0.53 ppm, respectively. Considering NO as a tracer of vehicular plume, ambient NH3 was correlated with NO during peak traffic hour in the morning (7:00-10:00 h) and evening (17:00-19:00 h) and observed significant positive correlation between them. Result reveals that the mixing ratio of atmospheric NH3 significantly positive correlated with traffic related pollutants (NO, CO, and NHHCs) during all the seasons (winter, summer, and monsoon). During winter, the average mixing ratio of atmospheric NH3 was increased by 1.2-3.5 ppb in the morning peak hour, whereas increased by 0.3-1.6 ppb in the evening peak hour. Similarly, an increase in NH3 mixing ratio was observed during summer (morning: 1.2-2.7 ppb and evening: 1.5-1.6 ppb) and monsoon (morning: 0.4-3.6 ppb and evening: 0.9-1.4 ppb) seasons. The results emphasized that the traffic could be one of the dominant source of ambient NH3 at the urban site of Delhi, as illustrated by positive relationships of NH3 with traffic related co-pollutants (NO, CO and NMHCs)

Barium ferrite nanoparticles: a highly effective EMI shielding material

Electromagnetic interference (EMI) is one of the main causes for the failure of electronic devices working in close vicinity of EM field induced by the neighboring electronic device. Therefore, we report a facile synthesis of barium ferrite (BaFe12O19) nanoparticles via sol-gel technique for efficient EMI shielding application. These nanoparticles were annealed at 400 degrees C, 700 degrees C, and 850 degrees C to investigate the effect of temperature on shielding efficiency and morphology of BaFe12O19 nanoparticles. The structure, morphology, phase purity, magnetism, and shielding effectiveness were analyzed using Fourier-transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD), electron microscopy (SEM and TEM), vibrating sample magnetometer (VSM) and vector network analyzer, respectively. These studies suggest that BaFe12O19 nanoparticles annealed at 850 degrees C exhibit crystalline pure phase hexagonal structure with the high magnetic moment (31.32 emu g(-1)) and coercivity (2.7 kOe). The total shielding effectiveness of the same was found to be -17.57 dB at 11.58 GHz, which is much higher than those of earlier reported studies

Long-Term Measurements of SO2 Over Delhi, India

Long-term measurements (2011-2018) of ambient sulphur dioxide (SO2) and meteorology were carried out at an urban site of Delhi, India, to study the seasonal and inter-annual variations of SO2 over Delhi. The average mixing ratio of SO2 was estimated as 2.26 +/- 0.48 ppb for the entire study period. Mixing ratio of ambient SO2 was estimated as 2.19 +/- 0.64 ppb, 2.07 +/- 0.89 ppb, 2.49 +/- 1.05 ppb and 2.27 +/- 0.71 ppb during winter, pre-monsoon, monsoon and post-monsoon seasons, respectively. SO2 mixing ratio was recorded maxima during monsoon (2.49 +/- 1.05 ppb) season, whereas minima during pre-monsoon season (2.07 +/- 0.89 ppb). The mixing ratio of SO2 showed slightly increase in the trend during observational period. Surface wind speed and wind directions analysis indicates the influence of local sources on the mixing ratio of SO2 at the study site. Backward trajectories and potential source contributing factor (PSCF) analysis also showed the local as well as the regional sources (industrial activities, coal burning and thermal power plants etc.,) influencing the mixing ratio of SO2 over Delhi