Particulate bound polycyclic aromatic hydrocarbons over Dhauladhar region of the north-western Himalayas

A systematic yearlong study was carried out in Dhauladhar region of the North-Western Himalayas to investigate dynamics in the composition and concentration of particulate bound polycyclic aromatic hydrocarbons (PAHs) and their source(s) activity. PM10 samples were collected for 24 h, once every week during January 2015-January 2016, at an urban mid-altitude site (Dharamshala) and a rural low-altitude site (Pohara). PAHs were identified and quantified using high performance liquid chromatography coupled with UV-detector. Seasonal average concentration of total PAHs followed a pattern: Summer > Winter > Autumn > Spring in the region. Seasonal average values of molecular diagnostic ratios indicated significant contribution from non-traffic (biomass burning and coal combustion) sources also during winter and spring season, whereas, traffic emissions (gasoline and diesel) were the dominant source at both the locations throughout the year in the region. The Principal Component Analysis deciphered a) emissions from gasoline driven vehicles b) diesel engine exhaust emissions c) biomass/wood burning source d) coal combustion and e) waste incineration and burning of oil/tar as major sources of PAHs in the region. Annual mean values of total Benzo(a)Pyrene Equivalent were much higher than 1 ng.m(-3) over both the locations indicating higher lung cancer risk to the people living in this part of the Himalayas. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study in the Dhauladhar region of the North-Western Himalayas revealed variations in the composition and concentration of particulate bound polycyclic aromatic hydrocarbons (PAHs) throughout the year, with traffic emissions being a dominant source. The analysis also identified contributions from biomass burning and coal combustion in winter and spring seasons. Overall, the concentration of PAHs showed a clear seasonal pattern in the region.