Sources and atmospheric dynamics of organic aerosol in New Delhi, India:
Insights from receptor modeling
Abstract
Delhi, India, is the second most populated city in the world and
routinely experiences some of the highest particulate matter
concentrations of any megacity on the planet, posing acute challenges to
public health (World Health Organization, 2018). However, the current
understanding of the sources and dynamics of PM pollution in Delhi is
limited. Measurements at the Delhi Aerosol Supersite (DAS) provide a
long-term chemical characterization of ambient submicron aerosol in
Delhi, with near-continuous online measurements of aerosol composition.
Here we report on source apportionment based on positive matrix
factorization (PMF), conducted on 15 months of highly time-resolved
speciated submicron non-refractory PM1 (NRPM1) between January 2017 and
March 2018.We report on seasonal variability across four seasons of 2017
and interannual variability using data from the two winters and springs
of 2017 and 2018. We show that a modified tracer-based organic component
analysis provides an opportunity for a real-time source apportionment
approach for organics in Delhi. Thermodynamic modeling allows estimation
of the importance of ventilation coefficient (VC) and temperature in
controlling primary and secondary organic aerosol. We also find that
primary aerosol dominates severe air pollution episodes.