An empirical method for source apportionment of black carbon aerosol: Results from Aethalometer observations at five different locations in India

• Published in: Environmental pollution (1987) Vol. 254; no. Pt A; p. 112932
• Main Authors: Ravi Kiran, V., Venkat Ratnam, M., Krishna Murthy, B.V., Kant, Yogesh, Prasad, P., Roja Raman, M., Rao, S.V.B., Lakshmi Kumar, T.V., Maitra, Animesh
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2019
• Subjects: Aerosols - analysis; Air Pollutants - analysis; Bio mass burning; Black carbon; Carbon Monoxide - analysis; Climate; Environmental Monitoring - methods; Fossil fuel combustion; Fossil Fuels - analysis; India; Soot - analysis; Source apportionment; India; Bio mass burning; Black carbon; Source apportionment; Fossil fuel combustion
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2019.07.100

Black carbon (BC) aerosol emitted in incomplete combustion processes is known for causing warming in the climate system also poses serious health issues. Identification of the sources of BC is essential for the development of mitigation strategies to regulate their effects in changing climate. Among different observational and analytical techniques currently available, source apportionment methods based on optical measurements are relatively simple. For example, ‘Aethalometer model’ was developed based on Aethalometer observations. However, there are a few limitations with this model arising from assumption of wavelength and angstrom exponent pairs. We have developed an empirical method which also relies on Aethalometer observations named as ‘Two alpha method’ which assumes angstrom exponent from fossil fuel as 1 and estimates bio-mass fraction and angstrom exponent for bio-mass burning. This method has been applied to Aethalometer observations from five different locations (rural, semi-urban and urban) over Indian sub-continent to quantify sources of BC. Fossil fuel is found to be the major source of BC (∼70%) irrespective of the location. Collocated measurements of Carbon Monoxide (CO) over rural site correlated well with derived bio-mass fraction. Results from this study demonstrated the capabilities of empirical method and shall provide spatio-temporal variability in sources of BC if applied to more locations. We have developed an empirical method for the source apportionment of black carbon aerosol which relies on Aethalometer observations named as ‘Two alpha method’. This method assumes angstrom exponent from fossil fuel as 1 and estimates bio-mass fraction and angstrom exponent for bio-mass burning. It is shown that this new method is unique when compared to existing methods in several aspects. This method has been applied to Aethalometer observations from five different locations (rural, semi-urban and urban) over Indian sub-continent to quantify sources of BC and found that fossil fuel as a dominant source irrespective of the location. [Display omitted] •Quantification of sources of Black Carbon over different locations in India.•An empirical method is developed using spectral absorption properties from Aethalometer.•Results show that fossil fuel is major source of BC irrespective of a location.•The method can be applied for obtaining spatiotemporal variability of sources of BC. An empirical method has been developed for source apportionment of black aerosol using Aethalometer observations. The results indicate fossil fuel as major source of BC.