10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Light Absorption by Carbonaceous Aerosol Emissions from Biomass Cookstoves in India
APOORVA PANDEY, Sameer Patel, Pratim Biswas, Shamsh Pervez, Rajan K. Chakrabarty, Washington University in St Louis
Abstract Number: 1333 Working Group: Carbonaceous Aerosol
Abstract Combustion of solid biomass in traditional cookstoves in south Asia is the largest source of carbonaceous aerosols emissions in the region. Estimates of the radiative impact of aerosol emissions from biomass cookstoves have a high level of uncertainty arising from the underlying uncertainties in aerosol mass concentration distributions and optical properties–key input parameters in climate models. As a step towards resolving the uncertainties, our objectives were to (1) develop particulate mass emission factors for in-field operation of traditional biomass cookstoves, and (2) estimate wavelength dependent Mass Absorption Cross-sections (MAC) of the emitted aerosols and their light absorbing organic carbon (LAOC) components.
A field study was conducted in Raipur, Chhattisgarh (a central Indian state) in December 2015. Common types of biomass fuels from different regions of India were used in a traditional mud chulha to prepare typical meals in a household kitchen. Particle samples were collected on Teflon and quartz fiber filters during the ignition, steady flaming and smoldering phases of the combustion cycle. The Teflon filters were used for gravimetric analysis and UV-vis spectrophotometry. Thermo-optical (IMPROVE-TOR) analysis on the quartz filters yielded the elemental and organic carbon fractions. Emission factors (PM2.5, EC, OC and CO) were calculated using the carbon balance method. These emission factors together with the thermal fractions of the total carbon content of different fuels were compared with existing lab-based profiles. Empirical relationships between filter transmission spectra and particle light absorption were developed through laboratory studies of biomass burning. These relationships were applied to the spectrophotometer data to calculate the total aerosol MAC, which was apportioned to Black Carbon and LAOC using the two-component model. The total contribution of LAOC to aerosol light absorption was estimated by integrating its absorption coefficient with solar irradiance in the 300-900 nm wavelength range. The links between carbonaceous aerosol composition (OC- to-EC mass ratios and thermal carbon fractions) and aerosol optical properties are explored.