10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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A Study on Light Absorbing Carbon Soot Particles and Their Speciation over Semiarid Region of Indo-Gangetic Basin
PRATIMA GUPTA, Ashok Jangid, Ranjit Kumar, DEI, Dayalbagh, Agra, India
Abstract Number: 466 Working Group: Carbonaceous Aerosol
Abstract The light absorbing soot particles has high global warming potential after green house gases and affects climate change. The absorbing properties of soot particles are influenced by the nature of surrounding particles. Hence, speciation of carbon soot particles has been done using aethalometer and SEM-EDX over semiarid region of Indo-Gangetic basin. The average mass concentrations of carbon soot particles were found to be 7.4±3.4 𝜇gm-3. The highest soot particle concentration has been seen in winter followed by post-monsoon, summer and monsoon. It may be due to variation in source strength and meteorological conditions. The anthropogenic sources viz., biomass/fossil fuel burning enhances the concentration during winter. The concentration of carbon soot particle at shorter wavelength (UV range) to longer wavelength (IR range) has shown large variations. The monthly spectral variation of soot particles with the fraction of different types of soot particle have been shown at seven wavelengths (370-950 nm). The monthly spectral variation shows the higher concentration of carbon soot particle at 370 nm (UVPM). The variations of aerosol light absorption with wavelength have been extended from the near-ultraviolet to the near infrared. Brown carbon (UVPM370) consists of light absorbing organic matter originates from biomass burning. The daily average of UVPM at 370 nm was 9.3±10.2 µg m-3. The daily average of blue carbon at 440 nm is 7.6±7.8 µg m-3. The blue carbon at 440 nm is a certain classes of organic compounds (such as polycyclic aromatic hydrocarbons). The soot particles at 520 nm are known as green carbon. The daily average of yellow carbon at 590 nm is 7.2±8.3 µg m-3. SEM-EDX analysis revealed the most abundant group of particle of soot carbon is influenced by tobacco smoke. The daily average concentration of RC660 is 6.7±3.7 µg m-3. Hematite mineral dust (Fe2O3) has absorption bands in the red region of the spectrum and hence the abundance of this material can increase response of 660 nm channel. Carbon soot particle also gives significant response at IR-II (950 nm). Certain inorganic compounds may show the onset of molecular absorption in the near-infra-red: their presence may increase the apparent result in the 880-nm and 950-nm. Light absorption by aerosols collected in biomass burning smoke varied more strongly with wavelength than aerosols dominated by motor vehicle emissions. The SEM-EDX analysis of carbon soot particles reveals the confirmation of the various elements which are emitted from various sources like burning of biomass and fossil fuel, tobacco smoke, dust particles, sand particles, vehicular emission and mineral dust. This analysis also reveals the confirmation of carbon soot particle associated with the various other elements viz., C, Al, Si, K, Na, F, Ca, Fe, Zn, Cu, etc.