Articles | Volume 17, issue 7
https://doi.org/10.5194/acp-17-4769-2017
https://doi.org/10.5194/acp-17-4769-2017
Research article
 | 
12 Apr 2017
Research article |  | 12 Apr 2017

Emission factors and light absorption properties of brown carbon from household coal combustion in China

Jianzhong Sun, Guorui Zhi, Regina Hitzenberger, Yingjun Chen, Chongguo Tian, Yayun Zhang, Yanli Feng, Miaomiao Cheng, Yuzhe Zhang, Jing Cai, Feng Chen, Yiqin Qiu, Zhiming Jiang, Jun Li, Gan Zhang, and Yangzhi Mo

Abstract. Brown carbon (BrC) draws increasing attention due to its effects on climate and other environmental factors. In China, household coal burned for heating and cooking purposes releases huge amounts of carbonaceous particles every year; however, BrC emissions have rarely been estimated in a persuasive manner due to the unavailable emission characteristics. Here, seven coals jointly covering geological maturity from low to high were burned in four typical stoves as both chunk and briquette styles. The optical integrating sphere (IS) method was applied to measure the emission factors (EFs) of BrC and black carbon (BC) via an iterative process using the different spectral dependence of light absorption for BrC and BC and using humic acid sodium salt (HASS) and carbon black (CarB) as reference materials. The following results have been found: (i) the average EFs of BrC for anthracite coal chunks and briquettes are 1.08 ± 0.80 and 1.52 ± 0.16 g kg−1, respectively, and those for bituminous coal chunks and briquettes are 8.59 ± 2.70 and 4.01 ± 2.19 g kg−1, respectively, reflecting a more significant decline in BrC EFs for bituminous coals than for anthracites due to briquetting. (ii) The BrC EF peaks at the middle of coal's geological maturity, displaying a bell-shaped curve between EF and volatile matter (Vdaf). (iii) The calculated BrC emissions from China's residential coal burning amounted to 592 Gg (1 Gg  =  109 g) in 2013, which is nearly half of China's total BC emissions. (iv) The absorption Ångström exponents (AAEs) of all coal briquettes are higher than those of coal chunks, indicating that the measure of coal briquetting increases the BrC ∕ BC emission ratio and thus offsets some of the climate cooling effect of briquetting. (v) In the scenario of current household coal burning in China, solar light absorption by BrC (350–850 nm in this study) accounts for more than a quarter (0.265) of the total absorption. This implies the significance of BrC to climate modeling.

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This paper investigates the emission factors and the light absorption properties of brown carbon (BrC) from China’s household coal burning. Seven coals of various ranks were burned in four typical stoves as both chunk and briquette styles. The optical integrating sphere (IS) method was employed to quantify BrC and black carbon (BC). We conclude that, in the scenario of current household coal burning in China, solar light absorption by BrC accounts for 26.5 % of the total absorption.
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