AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Source Apportionment of High Temporal Resolution PM1 Data for Delhi, India
Sahil Bhandari, DONGYU S. WANG, Shahzad Gani, Sarah Seraj, Zainab Arub, Gazala Habib, Joshua Apte, Lea Hildebrandt Ruiz, University of Texas at Austin
Abstract Number: 620 Working Group: Source Apportionment
Abstract Exposure to fine particulate matter (PM) poses significant health risks, especially to residents in heavily populated areas. The current understanding of the sources and dynamics of PM pollution in developing countries like India is limited. Delhi, India is the second most populated city in the world that has year-round high PM concentrations and frequent severe pollution episodes. This study reports on composition measurements of non-refractory submicron aerosol at 1-minute time resolution in the winter and spring of 2017, collected at the Indian Institute of Technology Delhi using an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and refractory submicron aerosol black carbon (BC) measurements using an Aethalometer. Source apportionment was conducted on organic and inorganic mass spectra measured by the ACSM using Positive Matrix Factorization (PMF).
High concentrations of particulate matter were observed with total PM1 at times exceeding 200 µg m-3 in winter. A significant drop in PM1 concentrations was observed in the winter-spring transition. Along with diurnal variation in total PM1 mass loadings, particulate chloride levels also exhibited a strong diurnal cycle with concentrations as high as 50 µg m-3 observed in the early morning. As observed elsewhere, organic species dominated the submicron mass, contributing 60% of the total mass over the duration of the campaign. However, this fractional contribution varied substantially over the day: from 48% early in the morning to 73% late at night. PMF receptor modeling identified several factors with distinct diurnal patterns. Interestingly, hydrocarbon-like organic aerosol (HOA) factor has the largest mass fraction contribution in PMF results. These results point to substantial differences in aerosol composition in Indian cities in comparison to cities around the world, especially with regards to the abundance of particulate chloride, and provide insights into the sources of PM1 measured in Delhi.