HOSTED BY Contents lists available at ScienceDirect Atmospheric Pollution Research journal homepage: www.elsevier.com/locate/apr Characteristics of Black Carbon aerosols over Patiala Northwestern part of the IGP: Source apportionment using cluster and CWT analysis Onam Bansal * , Atinderpal Singh, Darshan Singh Department of Physics, Punjabi University, Patiala, 147002 Punjab, India ARTICLE INFO Keywords: Atmospheric boundary layer (ABL) Black Carbon (BC) Concentration Weighted Trajectory (CWT) Biomass burning Indo-Gangetic Plain (IGP) ABSTRACT The present study represents the variation in characteristics of Black Carbon aerosols over Patiala (Punjab), northwest region of the IGP, India during two separate periods i.e. October 2013–September 2014 and October 2015–September 2016. Averaged BC mass concentration were found to be 9.9 μgm -3 , 6.6 μgm -3 ,3.4 μgm -3 and 2.8 μgm -3 during Autumn (Oct–Nov), Winter(Dec–March), Summer(Apr–June) and Monsoon (July–Aug) seasons respectively. During the entire study period, spectral dependence of aerosol mass absorption coefficient reveals that dominant source of BC is biomass burning during autumn season while there is mixed contribution from biomass, bio-fuel burning and fossil fuel combustion in rest of the seasons. These results are further sup- ported by seasonal variations in Angstrom coefficient and Delta -C values. Averaged values of mass absorption efficiency of BC were found to be 3.8 m 2 g -1 , 5.0 m 2 g -1 , 5.6 m 2 g -1 and 7.1 m 2 g -1 during autumn, winter, summer and monsoon seasons respectively. Cluster & Concentration weighted trajectory (CWT) analysis suggests that potential sources of BC aerosol over the study region are local as well as transported from distant places mostly situated in the northwest, south-west and south-east side of the observation site depending upon the meteor- ological conditions and regional anthropogenic activities that varies with season. BC concentration derived from online MERRA-2 model for Patiala region and from global inventory EDGARHTAP site for agriculture waste burning further supports our findings. 1. Introduction Black carbon (BC) is one of the crucial components of ambient particulate matter released in to the atmosphere due to incomplete combustion of fossil fuels, bio-fuels and biomass burning. Due to its strong absorption over a wide range of wavelengths (UV to IR), BC is considered to be prime contributor of radiative warming of the atmo- sphere (Marinoni et al., 2010). During last decade, BC has attracted special attention as in IPCC report its global mean clear sky forcing was estimated to be 0.23 ± 0.25 Wm -2 which amounts to almost half of warming by green house gas methane (Solomon et al., 2007). Strong light absorbing nature of BC coupled with its longer atmospheric life- time makes BC an important aerosol constituent affecting the regional climate. Increasing incidences of flooding and drought conditions over India and China are attributed to high mass concentration of BC (Bond et al., 2013; Menon et al., 2002). Similarly, increased mass concentra- tion of BC when got deposited on plants suppresses the agricultural and plant productivity as reported by Chameides et al., (1999) and Bergin et al., 2001. Apart from climate impact, BC aerosols, being ultrafine particles (< 100 nm in diameter) impact the human health and some epidemiological evidences also link exposure to BC with increased cardiopulmonary hospital admissions and mortality cases (Janssen et al., 2012). BC aerosols being mostly in the sub-micron range have mean residence time of few days to weeks in the atmosphere and thus can be carried over to long distances from their sources depending upon the prevailing meteorological conditions. Thus observed BC aerosols over a specific location can have mixed contribution from local emis- sions as well as transported part from distant sources. Indo-Gangetic Plains (IGP) is the most densely populated region constituting almost 40% population of Indian sub-continent and a potential source region of aerosols due to which it always remained hot spot for aerosol research. Western and central part of IGP has high atmospheric aerosol loading constituting mixture of both anthropogenic and natural origin with varying contribution depending upon the season and meteorological conditions. Major anthropogenic emissions are due to industries, au- tomobile and vehicles, brick kilns, thermal plants, large-scale post- harvest agricultural residue burning, bio-fuel burning etc. and natural source is the dust storms. (Ramanathan and Ramana, 2005; Srivastava https://doi.org/10.1016/j.apr.2018.08.001 Received 17 April 2018; Received in revised form 1 August 2018; Accepted 1 August 2018 Peer review under responsibility of Turkish National Committee for Air Pollution Research and Control. * Corresponding author. E-mail address: onubansal@gmail.com (O. Bansal). Atmospheric Pollution Research xxx (xxxx) xxx–xxx 1309-1042/ © 2018 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved. Please cite this article as: Bansal, O., Atmospheric Pollution Research (2018), https://doi.org/10.1016/j.apr.2018.08.001