10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Investigation of Concentration Variability, Sources and Atmospheric Transformations of Short-lived Climate Pollutants (SLCPs) at the Rural-site of Indo-Gangetic Plain (IGP), India
Jai Prakash, Harsh Raj Mishra, Atul Kumar, Bhilok Chand, Mattias Hallquist, Gazala Habib, Geetam Tiwari, Jan B. C. Pettersson, Johan Boman, Håkan Pleijel, RAVI KANT PATHAK, University of Gothenburg, Sweden
Abstract Number: 1370 Working Group: Aerosol Chemistry
Abstract Short-lived climate pollutants (SLCPs) such as light absorbing (at 375 nm) organic aerosol referred as ultra-violet particulate matter (UVPM), black carbon (BC), ozone (O3), carbon monoxide (CO), and nitrogen oxides (NOX) are thought to have significantly contributed to climate change both regionally and globally and adverse human health. However, the quantification of climatic effects of SLCPs such as BC and O3 remain poorly understood. The increasing importance of SLCPs compared to previous studies are attributed to new emission estimates and their sources especially for the people living low-and-middle-income (LMI) rural areas in the Western Pacific and South East Asia including India. Therefore, it is of critical importance to assess the characteristics of SLCPs in India, specifically in the Indo Gangetic Plains, which is a major hub of biomass burning led pollution and atmospheric brown clouds. Further, understanding the aerosol transformation and inter-linked atmospheric processes in the IGP region becomes imperative for developing robust modeling tools to predict their impacts on global climate, human health, and ecosystem. For the first time in India, this study investigated the variability of short-lived climate pollutants (SLCPs) at a long-term measurement rural site in IGP region called “Indo-Gangetic Plains Centre for Air Research and Education (IGP-CARE). The IGP-CARE site is situated in agricultural fields adjacent to a forest by the River Burma (a tributary of the River Betwa) surrounded by six villages in the Hamirpur district, Uttar Pradesh, India. In the present work, the SLCPS (UVPM, BC, O3, CO, and NOX) were continuously measured real time during the period of January 2017 to December 2017 at the IGP-CARE and also recorded parallel meteorological data such as temperature, relative humidity, wind speed, wind direction. During the study period, the annual average UVPM, BC, O3, CO, and NOX were observed 4.0 ± 2.8 µg m−3, 2.8 ± 1.8 µg m−3, 30.4 ± 20.9 ppbv, 497 ± 376 ppbv, and 6.4 ± 2.9 ppbv, respectively. Seasonally, highest concentrations were observed in summer time followed by winter and autumn for O3 and highest concentration was found in winter and autumn for UVPM, BC, CO, and NOX. O3 showed highest diurnal variation (38 ppbv) during daytime and lowest (10 ppbv) during late evening as well as early morning hours. Interestingly, in diurnal pattern of winter season, BC concentration was observed 4.0 µg m−3 almost constant during day and night time, while UVPM showed highest (8.0 µg m−3) during late evening as well as early morning hour. Also for the other seasons, UVPM/BC ratio showed a significant diurnal variability. These indicate that UVPM and BC although co-emitted from the biomass burning, undergo different atmospheric transformation and their ratio is likely to be influenced by temperature or light intensity as the ratio of UVPM/BC was lowest at the noon time. The UVPM represents the fraction of brown carbon (BrC) in aerosol and suggests that light absorbing aerosol compounds are sensitive to either light or temperature or both. Interesting chemistry of UVPM from the biomass burning is yet to be explored. For the source investigation and contribution of local or regional sources and UVPM/BC, O3/BC, O3/CO, BC/CO, UVPM/NOX, O3/CO ratio will be characterized and presented using air mass back-trajectories during the sampling period. Furthermore, the loss of BC and O3 during transport with temperature and RH will be also discussed for the coatings of aged particles by water-soluble compound from this region would be the most likely chemistry of atmospheric processes.