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We reported the seasonal variations of columnar aerosol optical depth (AOD) and equivalent black carbon (EBC) from December 2018 to November 2019 in semi-arid station, Anantapur. Furthermore, using the two-component source apportionment model, we estimated the contribution of biomass burning (EBCbb) and fossil fuel combustion (EBCff) to the total EBC. The high AOD values at shorter wavelengths indicate that particle loading occurs primarily in fine mode aerosols. The high AOD500 was observed in the month of May (0.77 ± 0.19), and the low was in July (0.32 ± 0.11). The seasonal highest mean AOD500 was noticed during the summer (0.67 ± 0.12) followed by winter (0.49 ± 0.01), post-monsoon (0.43 ± 0.15) and monsoon (0.43 ± 0.17). The results revealed that both local emissions and long-range transported aerosols are primarily responsible for a significant spectral and temporal variability in AOD. In winter, the Angstrom exponent (α) was relatively high, whereas it was low in monsoon season. The mass concentrations of EBC, EBCff and EBCbb showed a strong diurnal and seasonal variations with in the study period. The highest and lowest EBC was noticed in winter and monsoon that is 2.64 ± 0.32, and 0.625 ± 0.16 μg/m3, respectively. The percentage contribution of annual mean EBC was 52.13% during the day and 47.86% during the night, respectively. With an average of 91.48%, EBCff contributes the most to total EBC during the study period. Furthermore, during all seasons, the hourly mean concentrations of EBC showed good agreement (r = 80) between the observed (Aethalometer) and MERRA-2 (Modern-Era Retrospective Study for Research and Applications). According to the MERRA-2 winds and Moderate Resolution Imaging Spectroradiometer (MODIS), the prevalence of fine mode particles throughout winter and summer is connected with continental air masses originating from India's central and northern regions. [ABSTRACT FROM AUTHOR]

We have studied the black carbon (BC) mass concentrations, contributions from Fossil Fuels (FF), and Biomass burning (BB) to total BC mass concentrations using a 7-wavelength Aethalometer (Model, AE-31; Make, Magee Scientific, USA) at a rural continental location in the northeastern India. We have taken the continuous measurements of BC from January 2011 to December 2017 (excluding the year 2016 due to nonavailability of data). The annual mean BC concentration at 880 nm is observed maximum 12.56±5.06 µgm-3 in the year 2011 with a minimum of 7.26±2.76 µgm-3 during the year 2015." is the final sentence. BC, BCff, and BCbb mass concentrations show significant variation during morning, afternoon, evening, and night hours. The significant monthly, seasonal, and annual variabilities in the BC concentration, equivalent BC from FF and BB, are due to seasonal change in the emission sources, boundary layer dynamics, and dispersion and dilution conditions. The determination of Angstrom exponent (α) for the BC emitted during burning of different biofuels by performing a burning experiment is an important part of the present study. We have conducted a survey in and around the study location to know the different biofuels used by the people for daily household activities, and those biofuels are used in the burning experiment. As a result of biomass burning experiment to determine Angstrom exponent, we have found the α values to be ranging from 1.20 to 2.37 for flaming and a range from 1.59 to 2.33 for smoldering conditions for different biofuels. Annual mean contributions of BCff and BCbb to the total BC are found to be dominated by FF emissions during the whole study period. The percentage contribution of BCff and BCbb is found to be 56% and 44% during winter season due to increase in wood and biomass burning activities for various purposes. We have found the higher percentage contribution from BCff (85%) during monsoon season due to reduction in usage of biofuels. [ABSTRACT FROM AUTHOR]