Source Impact Analysis Using Char-EC/Soot-EC Ratios in the Central Indo-Gangetic Plain (IGP) of India

Abstract

This study reports one year (December 2016-November 2017) observations of carbonaceous aerosols in fine particulate matter (fPM; dia. < 2.5µm, n = 102 samples) over an urban location(Prayagraj) in central Indo-Gangetic Plain (IGP). The fPM concentrations exhibited a very large variability ranging from 22-367 (Avg. ± SD: 149 ± 87) µg m -3 during the entire study period. The carbonaceous aerosols (Organic Carbon (OC), Water soluble OC (WSOC) and Elemental Carbon (EC)) constituted about 40% of the annual fPM mass. Furthermore, based on several diagnostic ratios (EC/fPM, OC/EC, char-EC/soot-EC, and WSOC/OC), the characteristic features of carbonaceous aerosols were inferred to be significantly different in each season. The variation in the abundance pattern of carbonaceous aerosols appears to have influence of emission sources, seasonal meteorology, and atmospheric chemistry. The trajectory analysis at the sampling site has revealed that higher concentration of fPM and carbonaceous aerosols, mainly during the postmonsoon and winter season, was associated with the northwesterly air masses originated from the northwestern part of India. However, during summer and monsoon seasons the study site was likely to have influence from air masses of mixed origins (continental/marine) with the dominance of local anthropogenic sources. The char-EC/soot-EC ratio coupled to OC/EC ratio has been utilized in this study for source impact identification. Accordingly, the cross plots of char-EC/soot-EC and OC/EC ratio indicated the more of influence biomass burning during winter and postmonsoon season. However, during the summer and monsoon season, the cross plot indicated the predominant impact of fossil-fuel combustion sources. This study highlights the utility of char-EC/soot-EC ratio as a better indicator to trace out the impact of biomass burning and fossil-fuel combustion sources of carbonaceous aerosols compared to OC/EC over the IGP region.

Atmospheric Abundance of PM2.5 Carbonaceous Matter and Their Potential Sources at Three High-Altitude Glacier Sites over the Indian Himalayan Range

“…The optical method is used to determine pyrolyzed organic carbon (OP) when the reflectance approaches its starting value quickly after the injection of mixed gas (at 580 °C). At low temperatures, fractions of OC evolved in the presence of pure He and catalyst manganese dioxide (MnO 2 ), whereas fractions of EC evolved in the presence of 98% He with 2% O 2 at high temperatures . Char-EC is calculated by subtracting OP from EC1, while the sum of EC2 and EC3 is expressed as soot-EC. , To ensure accuracy, autocalibration was performed after every eight samples by using methane (CH 4 ) gas.…”

Mitigation of Carbonaceous Indoor Aerosols through Behavioural Change Soft Approach in Cooking at Selected Rural Sites (India)

“…Continuous laser reflectance signals were utilized to correct for any pyrolysis of OC, if it occurred. Estimation of Char-EC = EC1 -Pyrolized OC and Soot-EC = EC2 + EC3 followed the established approach (Mishra and Kulshrestha, 2021).…”

Char dominates black carbon aerosol emission and its historic reduction in China

“…Therefore, we recommend that future effort to reduce BC emissions in China and other countries, such as India, Nigeria, Congo, Indonesia 17 , should prioritize on controlling sources with high char emissions. In these countries, significantly high R C/S values were often observed from urban ambient PM 2.5 samples (e.g., R C/S exceeded 2.0 in urban environmental samples in India [52][53][54] ). Thus, there is a significant opportunity for reducing both BC and char through the adoption of advanced combustion and after-treatment technologies.…”