Char-EC and soot-EC in the atmosphere produced from different fuel combustion have distinct optical properties which lead to different radiative forcing. Pollutants transported into high-altitude environment could have a long-lasting radiative effect due to being free of deposition. In this study, the mass absorption cross- (MAC), the sources, transport pathways and the direct radiative effects (DREs) of soot-EC and char-EC were investigated at a peak of Mountain Hua (Mt. Hua) in China. The measurement results showed that soot-EC and char-EC account for 15.7 % and 84.3 % of EC, respectively. The mean MAC (lambda = 633 nm) of soot-EC (13.7 +/- 3.8 m(2)/g) was much higher than that of char-EC (5.4 +/- 2.5 m(2)/g), indicating a stronger light absorption ability for soot-EC. During the study period, 62.1 % char-EC was from anthracite chunk coal, 24.3 % of it from liquid fuel combustion. By contrast, 59.0 % soot-EC from liquid fuel combustion and 36.6 % of it from anthracite chunk coal. EC (both char-EC and soot-EC) produced from anthracite chunk coal reached the peak of the Mt. Hua primarily through the raising of the planetary boundary layer (PBL), while the EC produced from liquid fuel arrived the peak mainly by the regional transport above the PBL of the site. Although soot-EC has a stronger ability (2.8 times higher) to absorb the light compared with char-EC, its DRE (5.7 +/- 3.9 W m(-2)) was lower than that of char-EC (11.6 +/- 6.9 W m(-2)) due to the smaller mass quantity. Liquid fuel consumption contributed 3.5 +/- 2.9 W m(-2) DRE of soot-EC, while the combustion of anthracite chunk coal contributed 7.5 +/- 5.7 W m(-2) DRE of char-EC. This study highlights the differences in DREs of soot-EC and char-EC from fossil fuel combustion and the DRE mass efficiency of soot-EC and char-EC. The results emphasize the divergent climate warming effects caused by the combustion of different fossil fuels and imply that setting path to a green transition of energy use would benefit reducing the EC perturbation to the radiation balance of earth-atmosphere.

This study inspects the concentrations of fine particulate matter (PM2.5) mass and carbonaceous species, including organic carbon (OC) and elemental carbon (EC), as well as their thermal fractions in the Indian Himalayan glacier region at the western Himalayan region (WHR; Thajiwas glacier, 2799 m asl), central Himalayan region (CHR; Gomukh glacier, 3415 m asl), and eastern Himalayan region (EHR; Zemu glacier, 2700 m asl) sites, throughout the summer and winter periods of 2019-2020. Ambient PM2.5 samples were collected on quartz fiber filters using a low-volume sampler, followed by carbon (OC and EC) quantification using the IMPROVE_A thermal/optical reflectance methodology. Different seasonal variations in PM2.5 and carbonaceous species levels were found at all three sites investigated. Averaged PM2.5 mass ranged 55-87 mu g m-3 with a mean of 55.45 +/- 16.30 mu g m-3 at WHR, 86.80 +/- 35.73 mu g m-3 at CHR, and 72.61 +/- 24.45 mu g m-3 at EHR. Among the eight carbon fractions, high-temperature OC4 (evolved at 580 degrees C in the helium atmosphere) was the most prevalent carbon fraction, followed by low-temperature OC2 (280 degrees C) and EC1 (580 degrees C at 2% oxygen and 98% helium). Char-EC representing incomplete combustion contributed to 56, 67, and 53% of total EC, whereas soot EC contributed to 38, 26, and 43% of total EC in WHR, CHR, and EHR, respectively. The measured OC/EC ratios imply the presence of secondary organic carbon, whereas char-EC/soot-EC ratios suggested that biomass burning could be the predominant source of carbon at CHR, whereas coal combustion and vehicular emission might be dominant sources at WHR and EHR sites.