Aerosols behaviour: Northwestern Himalaya

Total suspended particulate (TSP) matter on fortnightly basis throughout the year and mass size distribution of aerosols as well as ultrafine aerosols on weekly basis in the months of May and June were monitored during 1996-2003 at different altitudinal locations of the Kullu-Manali tourist complex in the northwestern Himalaya. Concentration of TSP ranged from 35.8 (August 1996) to 207.3 µg m-3 (June 2003) at Mohal [1150 m from average sea level (ASL)] and from 31.7 (July 2003) to 239 µg m-3 (April 2001) at Manali (2050 m ASL). The mass size distribution of aerosols showed a bimodal distribution having one peak in the coarse size range (3.3-9 µm dia) and the other in the fine size range (0.08-2.1 µm dia) at both the locations. Ultrafine aerosol (UA) (0.001-0.1 µm radius) concentrations were found to be highest at the lowest experimental altitude site (Mohal) and vice versa. The diurnal variation of UA concentration for three years showed that the concentration ranges from 2640 (at 0500 hrs LT) to 5160 Number (N) cm-3 (at 1300 hrs LT) at Mohal and from 400 (at 0400 hrs LT) to 2190 N cm-3 (at 1300 hrs LT) at Kothi. On an average, TSP crossed its permissible limit set by National Ambient Air Quality Standard (NAAQS) level in the sensitive areas such as Kullu-Manali hill spots. Bimodal nature of mass size distribution indicates two important sources contributing in total aerosols—the fine mode, primarily due to anthropogenic activities and the coarse mode aerosols, mainly due to natural sources. Large number of concentration of ultrafine particles indicates the presence of air pollutants more at low altitudes as compared to high altitudes.

For Further reading please refer:

https://www.semanticscholar.org/paper/Aerosols-behaviour-in-sensitive-areas-of-the-A-case-Kuniyal-Momin/415fb9929621ed2dc350bbdbdc72443bdc2acaa9

Himalaya: Increasing Aerosols

Total suspended particulate (TSP), size-separated atmospheric aerosols and aitken nuclei (AN) were monitored at Mohal (Kullu) and Manali tourist complex, in the northwestern part of the Himalayas from 1996 and onwards. Long-term trend analysis for TSP indicated a significant increase since January 1996 to December 2003 at Mohal (P<0.05) and at Manali there is no increase in the TSP level (P=0.9). The results indicate that the eight years average concentration of TSP at Mohal is 78.4 μg m−3 and 66.9 μg m−3 at Manali. Seasonal average shows that the TSP is highest during summer (Mohal 90.3 μg m−3, P=0.2; and Manali 74.1 μg m−3, P=0.5) followed by winter season (Mohal 84.3 μg m−3, P<0.05; and Manali 71.0 μg m−3, P=0.7). The mass size distribution of aerosols showed bimodal distribution having one peak in fine mode (0.08–2.1 μm) and the other in coarse mode (3.3–10 μm) at both the locations. The highest value of fine size separated aerosol showed the maximum values at 0.43 μm mode. AN (0.001–0.1 μm) density shows fine particles of air pollutants more at low altitude as compared to high altitude. The diurnal variation of AN showed maximum values between 1100 and 1400 h. The daily average concentration of AN at Mohal, Manali and Kothi was found to be 3990, 3200 and 1350 N cm−3, respectively. The increasing trend of TSP, high value of size separated aerosols in the fine mode and the peaking of fine particles during noontime are the indication of rising air pollution due to anthropogenic activities in this region. 

For further reading: 

https://www.sciencedirect.com/science/article/abs/pii/S1352231005001202