High uncertainty in optical properties of black carbon (BC) involving heterogeneous chemistry has recently attracted increasing attention in the field of atmospheric climatology. To fill the gap in BC optical knowledge so as to estimate more accurate climate effects and serve the response to global warming, it is beneficial to conduct site-level studies on BC light absorption enhancement (E-abs) characteristics. Real-time surface gas and particulate pollutant observations during the summer and winter over Wuhan were utilized for the analysis of E-abs simulated by minimum R squared (MRS), considering two distinct atmospheric conditions (2015 and 2017). In general, differences in aerosol emissions led to E-abs differential behaviors. The summer average of E-abs (1.92 +/- 0.55) in 2015 was higher than the winter average (1.27 +/- 0.42), while the average (1.11 +/- 0.20) in 2017 summer was lower than that (1.67 +/- 0.69) in winter. E-abs and R-BC (representing the mass ratio of non-refractory constituents to elemental carbon) constraints suggest that E-abs increased with the increase in R-BC under the ambient condition enriched by secondary inorganic aerosol (SIA), with a maximum growth rate of 70.6% in 2015 summer. However, E-abs demonstrated a negative trend against R-BC in 2017 winter due to the more complicated mixing state. The result arose from the opposite impact of hygroscopic SIA and absorbing OC/irregular distributed coatings on amplifying the light absorbency of BC. Furthermore, sensitivity analysis revealed a robust positive correlation (R > 0.9) between aerosol chemical compositions (including sulfate, nitrate, ammonium and secondary organic carbon), which could be significantly perturbed by only a small fraction of absorbing materials or restructuring BC through gaps filling. The above findings not only deepen the understanding of BC, but also provide useful information for the scientific decision-making in government to mitigate particulate pollution and obtain more precise BC radiative forcing.

Continuous long-term monitoring of black carbon (BC) mass concentration and aerosol light scattering coefficient (sigma(SCA)), supplemented by number size distribution and chemical composition, are utilized in this study to understand the temporal changes in aerosol properties, associated source processes and radiative effects at Ny-angstrom lesund (79 degrees N) in the Svalbard Archipelago. A statistically significant decreasing trend in BC (- 24.7 ng m(-3) decade(-1)) is observed during spring of 2010-2019. In contrast, sigma SCA depicted a general increasing trend (5.2 Mm(-1) decade(-1)) during 2011-2016. BC and sigma(SCA) were higher during winter and spring. Aerosol single scattering albedo was highest in May similar to 0.95 (during spring) and lowest in September similar to 0.87 (during summer). Fractional share of BC to total aerosol mass was higher in winter and summer. Anthropogenic SO42- and NO3- (after ssNa(+)) species dominated the summer, when total number and mass concentrations of aerosols were at their minimum. Elemental Carbon (EC) and Organic Carbon (OC) showed higher concentrations in spring with EC-to-OC ratio similar to 0.08 - 0.22. The columnar AOD varied between 0.01 and 0.20 (annual mean similar to 0.09), resulting in aerosol radiative forcing (in the top of the atmosphere) similar to 0.15 - 2.69 Wm(-2) in the month of April (during spring). Potential source contribution function (PSCF) revealed the dominant source areas to be over Europe and Russia in terms of contributing to the seasonal high BC mass concentrations at Ny-angstrom lesund. Our study has also revealed an unusual impact of biomass burning aerosols (advected from the Alaska wildfire) during July 2015.

Total suspended particulates were collected from the marine boundary layer of Bay of Bengal (BOB) as part of the Integrated Campaign for Aerosols gases & Radiation Budget (ICARB) conducted under the Geosphere Biosphere Programme of Indian Space Research Organisation during pre-monsoon period. These samples were analyzed to quantify various chemical species and to bring out a comprehensive and quantitative picture of the chemical composition of aerosols in the marine environment of Bay of Bengal. Almost all the species showed highest mass concentration over north/head BoB. On the other hand, their mass fractions were high over mid/south BoB which has implications on the radiative forcing in this region. The source characteristics of various species were identified using specific chemical components as tracers. Presence of significant amount of non-sea-salt aerosols (similar to 7-8 times of sea-salt) and several trace species like Ni, Pb, Zn, etc were observed in this marine environment indicating significant continental/anthropogenic influence. An approximate estimate of the contributions of anthropogenic and natural aerosols to the total aerosol mass loading showed prominence of anthropogenic component over mid and south BoB also. Based on this study first-cut aerosol chemical models were evolved for BoB region. (C) 2014 Elsevier Ltd. All rights reserved.