Emissions of Climate-Affecting Substances from Incomplete Combustion in South Asia: Multiple Isotope-Based Source Apportionment

Vast emissions from incomplete combustion practices affects the health of millions in South Asia.

In addition to affecting air quality, components like black carbon aerosols (BC) and carbon monoxide (CO) also contribute to the regional climate warming, however, with highly uncertain radiative forcings.

A major uncertainty regarding the environmental impact of these two central components is the poorly constrained emissions from different sources, limiting our ability to model effects and direct mitigation.

Here, we propose to use multiple isotopes for BC (D14C and d13C) and CO (d13C, d17O and d18O) to provide top-down constraints of the relative contributions from major sources to the outflow from South Asia, and to compare these results with model predictions.Filter (BC) and flask (CO) samples will be collected at three Observatories in India, Bangladesh and an Indian Ocean receptor site during high pollution winter periods.

These samples will then be analyzed at at Stockholm University. For CO, we will directly address the isotope effects from photo-chemical processing.

The isotope signatures will then be used to compute relative source contributions through a statistical Bayesian isotopic mass balance model. The observational results will then be compared with bottom-up estimates using an atmospheric transport model.

Taken together this project will provide novel isotope-constrained sources and model-observation comparisons for the vast BC and CO emissions from South Asia.