Spectral dependence of aerosol light absorption over Camagüey obtained from an integrating sphere spectral system

2019 ◽  
Author(s):  
Sandra Mogo ◽  
Boris Barja ◽  
Victoria Cachorro ◽  
Ana Barroso ◽  
Rafhael Monteiro ◽  
...  
Keyword(s):  
Light Absorption ◽  
Spectral Dependence ◽  
Integrating Sphere ◽  
Spectral System

scholarly journals Dynamic light absorption of biomass-burning organic carbon photochemically aged under natural sunlight

2014 ◽  
Vol 14 (3) ◽  
pp. 1517-1525 ◽  
Author(s):  
M. Zhong ◽  
M. Jang
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Dynamic Change ◽  
Wood Smoke ◽  
Integrating Sphere ◽  
Natural Sunlight ◽  
Wood Burning ◽  
Polycyclic Aromatic ◽  
Uv Visible

Abstract. Wood-burning aerosol produced under smoldering conditions was photochemically aged with different relative humidity (RH) and NOx conditions using a 104 m3 dual outdoor chamber under natural sunlight. Light absorption of organic carbon (OC) was measured over the course of photooxidation using a UV–visible spectrometer connected to an integrating sphere. At high RH, the color decayed rapidly. NOx slightly prolonged the color of wood smoke, suggesting that NOx promotes the formation of chromophores via secondary processes. Overall, the mass absorption cross section (integrated between 280 and 600 nm) of OC increased by 11–54% (except high RH) in the morning and then gradually decreased by 19–68% in the afternoon. This dynamic change in light absorption of wood-burning OC can be explained by two mechanisms: chromophore formation and sunlight bleaching. To investigate the effect of chemical transformation on light absorption, wood smoke particles were characterized using various spectrometers. The intensity of fluorescence, which is mainly related to polycyclic aromatic hydrocarbons (PAHs), rapidly decreased with time, indicating the potential bleaching of PAHs. A decline of levoglucosan concentrations evinced the change of primary organic aerosol with time. The aerosol water content measured by Fourier transform infrared spectroscopy showed that wood-burning aerosol became less hygroscopic as photooxidation proceeded. A similar trend in light absorption changes has been observed in ambient smoke aerosol originating from the 2012 County Line wildfire in Florida. We conclude that the biomass-burning OC becomes less light absorbing after 8–9 h sunlight exposure compared to fresh wood-burning OC.

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

2017 ◽  
Author(s):  
Jianzhong Sun ◽  
Guorui Zhi ◽  
Regina Hitzenberger ◽  
Yingjun Chen ◽  
Chongguo Tian ◽  
...  
Keyword(s):  
Light Absorption ◽  
Climate Modeling ◽  
Emission Factors ◽  
Volatile Matter ◽  
Integrating Sphere ◽  
Brown Carbon ◽  
Carbonaceous Particles ◽  
Coal Burning ◽  
Anthracite Coal ◽  
Climate Cooling

Abstract. Brown carbon (BrC) draws increasing attention due to its effects on climate and other fields. In China, household coal burned for heating/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 7 coals jointly covering geological maturity from low to high were burned in 4 typical stoves at both chunk and briquette styles. The optical integrating sphere (IS) method was applied to measure the emission factors (EFs) of BrC and BC via an iterative process using the different spectral dependence of light absorption for BrC and BC. It is found that (i) the average EFs of BrC for anthracite coal chunks and briquettes are (1.08 ± 0.80) g kg−1 and (1.52 ± 0.16) g kg−1, respectively, and those for bituminous coal chunks and briquettes are (8.59 ± 2.70) g kg−1 and (4.01 ± 2.19) g kg−1, respectively, reflecting a more significant decline of 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) absorption Ångström exponent (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, and (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.

scholarly journals Quantifying light absorption and its source attribution of insoluble light-absorbing particles in Tibet an Plateau glaciers from 2013–2015

2018 ◽  
Author(s):  
Xin Wang ◽  
Hailun Wei ◽  
Jun Liu ◽  
Baiqing Xu ◽  
Mo Wang
Keyword(s):  
Light Absorption ◽  
Mineral Dust ◽  
Chemical Elements ◽  
Melting Process ◽  
Integrating Sphere ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Soil Dust ◽  
Carbonaceous Particles ◽  
Mountain Glaciers

Abstract. Amounts of insoluble light-absorbing particles (ILAPs) deposited on the surface of snow and ice can significantly reduce the snow albedo and accelerate the snow melting process. In this study, ~ 67 snow/ice samples were collected in 7 high mountain glaciers over the Tibetan Plateau (TP) regions from May 2013 to October 2015. The mixing ratio of black carbon (BC), organic carbon (OC), and mineral dust (MD) was measured using an integrating sphere/integrating sandwich spectrophotometer (ISSW) system associated with the chemical analysis by assuming the light absorption of mineral dust due to iron oxide. The results indicate that mass mixing ratios of BC, ISOC, and MD show a large variation of 10–3100 ng g-1, 10–17000 ng g-1, 10–3500 ng g-1, with a mean value of 218 ± 397 ng g-1, 1357 ± 2417 ng g-1, 241 ± 452 ng g-1 on TP glaciers during the entire snow field campaign, respectively. The chemical elements and the selected carbonaceous particles were also analyzed of the attributions of the particulate light absorption based on a positive matrix factorization (PMF) receptor model. On average, the industrial pollution (33.1 %), biomass/biofuel burning (29.4 %), and soil dust (37.5 %) were the major sources of the ILAPs in TP glaciers. Although the soil dust assumed to be the highest contributor to the mass loading of ILAPs, we noted that the averaged light absorption of BC (50.7 %) and ISOC (33.2 %) was largely responsible for the measured light absorption in the high mountain glaciers at the wavelengths of 450–600 nm.

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

2017 ◽  
Vol 17 (7) ◽  
pp. 4769-4780 ◽  
Author(s):  
Jianzhong Sun ◽  
Guorui Zhi ◽  
Regina Hitzenberger ◽  
Yingjun Chen ◽  
Chongguo Tian ◽  
...  
Keyword(s):  
Light Absorption ◽  
Climate Modeling ◽  
Emission Factors ◽  
Volatile Matter ◽  
Integrating Sphere ◽  
Brown Carbon ◽  
Carbonaceous Particles ◽  
Coal Burning ◽  
Anthracite Coal ◽  
Climate Cooling

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.

scholarly journals Quantifying the light absorption and source attribution of insoluble light-absorbing particles on Tibetan Plateau glaciers between 2013 and 2015

2019 ◽  
Vol 13 (1) ◽  
pp. 309-324 ◽  
Author(s):  
Xin Wang ◽  
Hailun Wei ◽  
Jun Liu ◽  
Baiqing Xu ◽  
Mo Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Light Absorption ◽  
Chemical Elements ◽  
Melting Process ◽  
Integrating Sphere ◽  
The Tibetan Plateau ◽  
Source Attribution ◽  
Carbonaceous Particles ◽  
Mean Values ◽  
Mixing Ratios

Abstract. The deposition of insoluble light-absorbing particles (ILAPs) on snow and ice surfaces can significantly reduce albedo, thereby accelerating the melting process. In this study, 67 ice samples were collected from seven glaciers located on the Tibetan Plateau (TP) between May 2013 and October 2015. The mixing ratios of black carbon (BC), organic carbon (OC), and mineral dust (MD) were measured with an integrating sphere/integrating sandwich spectrophotometer (ISSW) system, which assumes that the light absorption of MD is due to iron oxide (Fe). Our results indicate that the mass-mixing ratios of BC, OC, and Fe exhibit considerable variability (BC: 10–3100 ng g−1; OC: 10–17 000 ng g−1; Fe: 10–3500 ng g−1) with respective mean values of 220±400 ng g−1, 1360±2420 ng g−1, and 240±450 ng g−1 over the course of the field campaign. We observed that for wavelengths of 450–600 nm, the measured light absorption can be largely attributed to the average light absorption of BC (50.7 %) and OC (33.2 %). Chemical elements and selected carbonaceous particles were also analyzed for source attributions of particulate light absorption based on a positive matrix factorization (PMF) receptor model. Our findings indicate that on average, industrial pollution (33.1 %), biomass or biofuel burning (29.4 %), and MD (37.5 %) constitute the principal sources of ILAPs deposited on TP glaciers.

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