Light-absorbing organic carbon (OC), sometimes known as Brown Carbon (BrC), has been recognized as an important fraction of carbonaceous aerosols substantially affecting radiative forcing. This study firstly developed a bottom-up estimate of global primary BrC, and discussed its spatiotemporal distribution and source contributions from 1960 to 2010. The global total primary BrC emission from both natural and anthropogenic sources in 2010 was 7.26 (5.98-8.93 as an interquartile range) Tg, with 43.5% from anthropogenic sources. High primary BrC emissions were in regions such as Africa, South America, South and East Asia with natural sources (wild fires and deforestation) contributing over 70% in the former two regions, while in East Asia, anthropogenic sources, especially residential solid fuel combustion, accounted for over 80% of the regional total BrC emissions. Globally, the historical trend was mainly driven by anthropogenic sources, which increased from 1960 to 1990 and then started to decline. Res-idential emissions significantly impacted on emissions and temporal trends that varied by region. In South and Southeast Asia, the emissions increased obviously due to population growth and a slow transition from solid fuels to clean modern energies in the residential sector. It is estimated that in primary OC, the global average was about 20% BrC, but this ratio varied from 13% to 47%, depending on sector and region. In areas with high residential solid fuel combustion emissions, the ratio was generally twice the value in other areas. Uncertainties in the work are associated with the concept of BrC and measurement technologies, pointing to the need for more studies on BrC analysis and quantification in both emissions and the air. (c) 2022 The Authors. Published by Elsevier B.V. on behalf of Chinese Society for Environmental Sciences, Harbin Institute of Technology, Chinese Research Academy of Environmental Sciences. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

India is currently the second-largest emitter of black carbon (BC) in the world, with emissions projected to rise steadily in the coming decades. In view of the large variations associated with BC emission inventories in this region, model outputs of BC mass and radiative forcing (RF) need to be validated against long-term regionally representative atmospheric measurements. Such measurements are highly scattered spatially as well as temporally in India, and a systematic evaluation of BC data is non-existent so far. To address this issue, we present here a comprehensive review of BC measurements in India from a survey of > 140 studies spanning 2002-2018. In addition to summarizing baseline BC levels in urban, semi-urban, rural and remote locations, we report impacts of anomalous environmental and/or emission conditions, e.g., truck/general strikes, firework events, fog/haze episodes, large-scale biomass burning events, etc. We also present a discussion on major BC sources and climate impacts (in terms of direct RF) in major land-use categories, mitigation strategies currently employed on a national scale, and recent advances in measuring brown carbon (BrC) in India. We identify key areas for improvement, such as - i) the need for long-term BC monitoring networks, especially in regions where estimated emissions are high but measurement coverage is low; ii) the general lack of understanding, despite some recent reports, of BC aerosol mixing states, aging and direct climate effects in the Indian context; iii) the need to shift from qualitative approaches of BC source apportionment to robust quantitative measures; and iv) the prospects for coupled chemical-optical characterization of BrC for a better understanding of its sources and climate effects. We list potential research directions for the scientific community to address these knowledge gaps. We also believe that this review will be beneficial to policymakers for prioritizing BC mitigation efforts.

This study presents a comprehensive review of estimated black carbon (BC) emissions in Russia from a range of studies. Russia has an important role regarding BC emissions given the extent of its territory above the Arctic Circle, where BC emissions have a particularly pronounced effect on the climate. We assess underlying methodologies and data sources for each major emissions source based on their level of detail, accuracy and extent to which they represent current conditions. We then present reference values for each major emissions source. In the case of flaring, the study presents new estimates drawing on data on Russia's associated petroleum gas and the most recent satellite data on flaring. We also present estimates of organic carbon (OC) for each source, either based on the reference studies or from our own calculations. In addition, the study provides uncertainty estimates for each source. Total BC emissions are estimated at 688 Gg in 2014, with an uncertainty range 401 Gg-1453 Gg, while OC emissions are 9224 Gg with uncertainty ranging between 5596 Gg and 14,736 Gg. Wildfires dominated and contributed about 83% of the total BC emissions: however, the effect on radiative forcing is mitigated in part by OC emissions. We also present an adjusted estimate of Arctic forcing from Russia's BC and OC emissions. In recent years, Russia has pursued policies to reduce flaring and limit particulate emissions from on-road transport, both of which appear to significantly contribute to the lower emissions and forcing values found in this study. (C) 2017 Published by Elsevier Ltd.

A black carbon (BC) emission inventory for Mexico is presented. Estimate was performed by using two approaches, based on fuel consumption and emission factors in a top-down scheme, and the second from PM25 emission data and its correlation with black carbon by source category, assuming that black carbon = elemental carbon. Results show that black carbon emissions are in interval 53-473 Gg using the fuel consumption approach and between 62 and 89 using the sector method. Black carbon key sources come from biomass burning in the rural sector, with 47 percent share to the National total. Mobile sources emissions account to 16% to the total. An opportunity to reduce, in the short-term, carbon dioxide equivalent (CO2-eq) emissions by reducing black carbon emissions would be obtained in reducing emissions mainly from biomass burning in rural housing sector and diesel emissions in the transport sector with important co-benefits in direct radiative forcing, public health and air quality. (C) 2014 Elsevier B.V. All rights reserved.

Direct radiative forcing at top of the atmosphere for black carbon aerosols from two inventories comes out to be +0.33 W m(-2) for Global Emission Inventory Activity (GEIA) and +0.14 W m(-2) for BOND (Bond et al., 2004). However, for organic matter aerosols, it is simulated as -0.44 W m(-2) for GEIA and -0.11 W m(-2) with BOND inventory. Simulated annual global burden and aerosol optical depth of carbonaceous aerosols from GEIA and BOND are also compared. Normalised differences plots show that model simulates generally higher values of carbonaceous aerosols with GEIA, which are far superior in some parts of the globe as compared to those simulated with BOND emission inventory. An evaluation of these quantities with the median of the response of the AeroCom models is considered here as a benchmark - shows that while simulations with GEIA inventory have closer agreement, values of radiative forcing with BOND inventory are comparatively of smaller magnitudes over most parts of the globe. The reasons for this disparity in results for the latter may possibly be attributed to key differences between the two inventories. The main conclusion of this study is that the radiative forcing appears to be highly sensitive to carbonaceous content in aerosol compositions.

A box model has been used to compare the burdens, optical depths and direct radiative forcing from anthropogenic PM2.5 aerosol constituents over the Indian subcontinent. A PM2.5 emission inventory from India for 1990, compiled for the first time, placed anthropogenic aerosol emissions at 12.6 Tg yr(-1). The contribution from various aerosol constituents was 28% sulphate, 25% mineral (clay), 23% fly-ash, 20% organic matter and 4% black carbon. Fossil fuel combustion and biomass burning accounted for 68% and 32%, respectively, of the combustion aerosol emissions. The monthly mean aerosol burdens ranged from 4.9 to 54.4 mg m(-2) with an annual average of 18.4 +/- 22.1 mg m(-2). The largest contribution was from fly-ash from burning of coal (40%), which has a high average ash content of 30%. This was followed by contributions of organic matter (23 %) and sulphate (22%). Alkaline constituents of fly-ash could neutralise rainfall acidity and contribute to the observed high rainfall alkalinity in this region. The estimated annual average optical depth was 0.08 +/- 0.06, with sulphate accounting For 36%, organic matter for 32% and black carbon for 13%, in general agreement with those of Satheesh et al. (1999). The mineral aerosol contribution (5%) was lower than that from the previous study because of wet deposition from high rainfall in the months of high emissions and the complete mixing assumption in the box model. The annual average radiative forcing was - 1.73 +/- 1.93 W m-2 with contributions of 49% from sulphate aerosols, followed by organic matter (26%), black carbon (11%) and fly-ash (11%). These results indicate the importance of organic matter and fly-ash to atmospheric optical and radiative effects. The uncertainties in estimated parameters range 80-120% and result largely from uncertainties in emission and wet deposition rates. Therefore, improvement is required in the emissions estimates and scavenging ratios, to increase confidence in these predictions. (C) 2000 Elsevier Science Ltd. All rights reserved.