scholarly journals Assessment of online water-soluble brown carbon measuring systems for aircraft sampling

2021 ◽  
Author(s):  
Linghan Zeng ◽  
Amy P. Sullivan ◽  
Rebecca A. Washenfelder ◽  
Jack Dibb ◽  
Eric Scheuer ◽  
...  
Keyword(s):  
Global Climate ◽  
Reaction Rates ◽  
Sampling Time ◽  
Water Soluble ◽  
Brown Carbon ◽  
Baseline Drift ◽  
Adverse Health Effects ◽  
Liquid Waveguide Capillary Cell ◽  
Online Measurements ◽  
Mist Chamber

Abstract. Brown carbon (BrC) consists of particulate organic species that preferentially absorb light at visible and ultraviolet wavelengths. Ambient studies show that as a component of aerosol particles, BrC affects photochemical reaction rates and regional to global climate. Some organic chromophores are especially toxic linking BrC to adverse health effects. The lack of direct measurements of BrC has limited our understanding of its prevalence, sources, evolution, and impacts. We describe the first direct, online measurements of water-soluble BrC on research aircraft by three separate instruments. Each instrument measured light absorption over a broad wavelength range using a liquid waveguide capillary cell (LWCC) and grating spectrometer, with particles collected into water by a Particle-into-Liquid Sampler (CSU PILS-LWCC and NOAA PILS-LWCC) or a mist chamber (MC-LWCC). The instruments were deployed on the NSF C-130 aircraft during WE-CAN 2018 as well as the NASA DC-8 and the NOAA Twin Otter aircraft during FIREX-AQ 2019, where they sampled fresh and moderately aged wildfire plumes. Here, we describe the instruments, calibrations, data analysis, and corrections for baseline drift and hysteresis. Detection limits (3σ) at 365 nm were 1.53 Mm−1 (MC-LWCC; 2.5 min sampling time), 0.89 Mm−1 (CSU PILS-LWCC; 30 s sampling time), and 0.03 Mm−1 (NOAA PILS-LWCC; 30 s sampling time). Measurement uncertainties were 28 % (MC-LWCC), 12 % (CSU PILS-LWCC), and 11 % (NOAA PILS-LWCC). The MC-LWCC system agreed well with offline measurements from filter samples, with a slope of 0.91 and R2 = 0.89. Overall, these instruments provide soluble BrC measurements with specificity and geographical coverage that is unavailable by other methods, but their sensitivity and time resolution can be challenging for aircraft studies where large and rapid changes in BrC concentrations may be encountered.

scholarly journals Assessment of online water-soluble brown carbon measuring systems for aircraft sampling

2021 ◽  
Vol 14 (10) ◽  
pp. 6357-6378
Author(s):  
Linghan Zeng ◽  
Amy P. Sullivan ◽  
Rebecca A. Washenfelder ◽  
Jack Dibb ◽  
Eric Scheuer ◽  
...  
Keyword(s):  
Global Climate ◽  
Reaction Rates ◽  
Sampling Time ◽  
Water Soluble ◽  
Brown Carbon ◽  
Baseline Drift ◽  
Adverse Health Effects ◽  
Liquid Waveguide Capillary Cell ◽  
Online Measurements ◽  
Mist Chamber

Abstract. Brown carbon (BrC) consists of particulate organic species that preferentially absorb light at visible and ultraviolet wavelengths. Ambient studies show that as a component of aerosol particles, BrC affects photochemical reaction rates and regional to global climate. Some organic chromophores are especially toxic, linking BrC to adverse health effects. The lack of direct measurements of BrC has limited our understanding of its prevalence, sources, evolution, and impacts. We describe the first direct, online measurements of water-soluble BrC on research aircraft by three separate instruments. Each instrument measured light absorption over a broad wavelength range using a liquid waveguide capillary cell (LWCC) and grating spectrometer, with particles collected into water by a particle-into-liquid sampler (CSU PILS-LWCC and NOAA PILS-LWCC) or a mist chamber (MC-LWCC). The instruments were deployed on the NSF C-130 aircraft during WE-CAN 2018 as well as the NASA DC-8 and the NOAA Twin Otter aircraft during FIREX-AQ 2019, where they sampled fresh and moderately aged wildfire plumes. Here, we describe the instruments, calibrations, data analysis and corrections for baseline drift and hysteresis. Detection limits (3σ) at 365 nm were 1.53 Mm−1 (MC-LWCC; 2.5 min sampling time), 0.89 Mm−1 (CSU PILS-LWCC; 30 s sampling time), and 0.03 Mm−1 (NOAA PILS-LWCC; 30 s sampling time). Measurement uncertainties were 28 % (MC-LWCC), 12 % (CSU PILS-LWCC), and 11 % (NOAA PILS-LWCC). The MC-LWCC system agreed well with offline measurements from filter samples, with a slope of 0.91 and R2=0.89. Overall, these instruments provide soluble BrC measurements with specificity and geographical coverage that is unavailable by other methods, but their sensitivity and time resolution can be challenging for aircraft studies where large and rapid changes in BrC concentrations may be encountered.

Optical properties of atmospheric brown carbon (BrC) for photochemical and biomass burning-dominated aerosol regimes in India.

2020 ◽  
Author(s):  
Archita Rana ◽  
Supriya Dey ◽  
Sayantan Sarkar
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Global Climate ◽  
Strong Association ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Tropospheric Chemistry ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Fluorescence Measurements

<p>Black and brown carbon (BC and BrC) are potent climate forcing agents with pronounced effects on global climate and tropospheric chemistry. Given the large heterogeneities in BC emission inventories from India and the paucity of studies on BrC characteristics, field-based measurements of BC and BrC sources and optical properties are essential to understand their impacts on regional climate. To address this issue, we report the first ground-based measurements of BC and BrC from a rural location in the highly polluted eastern Indo-Gangetic Plain (IGP) during May-November 2018 encompassing the photochemistry-dominated summer (May-June) and regional biomass burning (BB)-dominated post-monsoon (October-November) periods. A 7-wavelength Aethalometer was used for time-resolved measurements of BC mass and was supplemented by UV-Vis and fluorescence measurements of time-integrated (24 h) aqueous and organic BrC fractions, and measurements of OC, EC, WSOC, and ionic species.<br>The daily averaged BC increased 4 times during the BB regime (12.3 ± 3.9 μg m<sup>-3</sup>) as compared to summer (4.2 ± 0.8 μg m<sup>-3</sup>), while aqueous and organic BrC fractions demonstrated light absorption (babs_365) enhancements of 3-5 times during BB. For aqueous BrC, the averaged AE of 5.9-6.2 and a prominent fluorescence peak at ~420 nm suggested the presence of humic-like substances (HULIS), potentially from secondary photochemical formation during summer and primary emission during BB periods. Fluorescence and UV-Vis spectra also indicated the presence of nitroaromatic compounds, presumably from OH oxidation in summer and nighttime NO3- oxidation in the presence of enhanced NOx and precursor emission during BB. The latter was supported by the strong association between water-soluble organic carbon (WSOC; a proxy for aqueous BrC) and aerosol NO<sub>3</sub><sup>-</sup> (r=0.70, p<0.05). During BB, the fraction of water-insoluble (i.e., organic) BrC increased from 41% at 330 nm to 59 % at 550 nm while during the photochemistry-dominated summer period, the water-insoluble BrC fraction decreased from 73% at 400 nm to 41% at 530 nm, possibly due to photobleaching in the presence of OH. The BB-related BrC aerosol was also characterized by higher aromaticity and increased molecular weights of organic components as evidenced by mass absorption efficiency (MAE) ratios (MAE<sub>250</sub>/MAE<sub>365</sub>). Overall, this study established that BrC is a significant component of light-absorbing aerosol in the eastern IGP and that BrC optical properties may vary significantly in this region depending on the relative dominance of aerosol emissions and atmospheric processes.</p>

scholarly journals Sources of water-soluble Brown Carbon at a South-Eastern European Site

2021 ◽  
Author(s):  
Charalampia Baliaka ◽  
Christos Kaltsonoudis ◽  
Kalliopi Florou ◽  
Spiro Jorga ◽  
Christina Vasilakopoulou ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Light Absorption ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Automated System ◽  
Urban Site ◽  
Multiple Sources ◽  
Brown Carbon ◽  
Liquid Waveguide Capillary Cell ◽  
Primary Emissions

<p>Atmospheric brown carbon (BrC) is a highly uncertain, but potentially important contributor to light absorption in the atmosphere. Laboratory and field studies have shown that BrC can be produced from multiple sources, including primary emissions from fossil fuel combustion and biomass burning (BB), as well as secondary formation through a number of reaction pathways. It is currently thought that the dominant source of atmospheric BrC is primary emissions from BB, but relatively few studies demonstrate this in environments with complex source profiles.</p><p>A field campaign was conducted during a month-long wintertime period in 2020 on the campus of the University of Peloponnese in the southwest of Patras, Greece which represents an urban site. During this time, ambient filter samples (a total of 35 filters) were collected from which the water-soluble BrC was determined using a semi-automated system similar to Hecobian et al. (2010),  where absorption was measured over a 1 m path length. To measure the BrC, a UV-Vis Spectrophotometer was coupled to a Liquid Waveguide Capillary Cell and the light absorption intensity was recorded at 365 and 700 nm. The latter was used as a reference wavelength. We found that the average BrC absorption in Patras at a wavelength of 365 nm was 8.5 ± 3.9 Mm<sup>-1</sup> suggesting that there was significant BrC in the organic aerosol during this period. Attribution of sources of BrC was done using simultaneous chemical composition data observations (primarily organic carbon, black carbon, and nitrate) combined with Positive Matrix Factorization analysis. This analysis showed that in addition to the important role of biomass burning (a contribution of about 20%) and other combustion emissions (also close to 20%), oxidized organic aerosol (approximately 40%) is also a significant contributor to BrC in the study area.</p><p><strong>Reference</strong></p><p>Hecobian, A., Zhang, X., Zheng, M., Frank, N., Edgerton, E.S., Weber, R.J., 2010. Water-soluble organic aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United States. Atmos. Chem. Phys. 10, 5965–5977. https://doi.org/10.5194/acp-10-5965-2010</p><p> </p>

scholarly journals The global impact of bacterial processes on carbon mass

2019 ◽  
Author(s):  
Barbara Ervens ◽  
Pierre Amato
Keyword(s):  
Cell Growth ◽  
Organic Carbon ◽  
Growth Conditions ◽  
Water Soluble ◽  
Microbial Processes ◽  
Cloud Formation ◽  
Cloud Droplets ◽  
Spatial And Temporal Scales ◽  
Adverse Health Effects ◽  
Oh Reactions

Abstract. Many recent studies have identified biological material as a major fraction of ambient aerosol loading. A small fraction of these bioaerosols consist of bacteria that have attracted a lot of attention due to their role in cloud formation and adverse health effects. Current atmospheric models consider bacteria as inert quantities and neglect cell growth and multiplication. We provide here a framework to estimate the production of secondary biological aerosol (SBA) mass in clouds by microbial cell growth and multiplication. The best estimate of SBA formation rates of 3.7 Tg yr-1 are comparable to previous model estimates of the primary emission of bacteria into the atmosphere, and thus might represent a previously unrecognized source of biological aerosol material. We discuss in detail the large uncertainties associated with our estimates based on the rather sparse available data on bacteria abundance, growth conditions and properties. Additionally, the loss of water-soluble organic carbon (WSOC) due to microbial processes in cloud droplets has been suggested to compete under some conditions with WSOC loss by chemical (OH) reactions. Our estimates suggest that microbial and chemical processes might lead to a global loss of WSOC of 8–11 Tg yr-1 and 8–20 Tg yr-1, respectively. While also this estimate is very approximate, the analysis of the uncertainties and ranges of all parameters gives hints about the conditions under which microbial processes cannot be neglected as organic carbon sinks in clouds. Our estimates also highlight the urgent needs for more data concerning microbial concentrations, fluxes and activity in the atmosphere to evaluate the role of bacterial processes as net aerosol sink or source on various spatial and temporal scales.

Brown carbon in the continental outflow to the North Indian Ocean

2019 ◽  
Vol 21 (6) ◽  
pp. 970-987 ◽  
Author(s):  
Srinivas Bikkina ◽  
Manmohan Sarin
Keyword(s):  
Indian Ocean ◽  
Soluble Fraction ◽  
North Indian Ocean ◽  
Water Soluble ◽  
Gangetic Plain ◽  
Brown Carbon ◽  
Water Soluble Fraction ◽  
The North ◽  
Continental Outflow ◽  
Indo Gangetic Plain

In this paper, we synthesize the size distribution and optical properties of the atmospheric water-soluble fraction of light-absorbing organic carbon (brown carbon; BrC) in the continental outflow from the Indo-Gangetic Plain (IGP) in South Asia to the North Indian Ocean.

Light absorption properties of elemental carbon (EC) and water-soluble brown carbon (WS–BrC) in the Kathmandu Valley, Nepal: A 5-year study

2020 ◽  
Vol 261 ◽  
pp. 114239 ◽  
Author(s):  
Pengfei Chen ◽  
Shichang Kang ◽  
Lekhendra Tripathee ◽  
Kirpa Ram ◽  
Maheswar Rupakheti ◽  
...  
Keyword(s):  
Light Absorption ◽  
Elemental Carbon ◽  
Water Soluble ◽  
Kathmandu Valley ◽  
Absorption Properties ◽  
Brown Carbon

scholarly journals Chemical and optical properties of carbonaceous aerosols in Nanjing, eastern China: regionally transported biomass burning contribution

2019 ◽  
Vol 19 (17) ◽  
pp. 11213-11233 ◽  
Author(s):  
Xiaoyan Liu ◽  
Yan-Lin Zhang ◽  
Yiran Peng ◽  
Lulu Xu ◽  
Chunmao Zhu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Solar Energy ◽  
Energy Absorption ◽  
Biomass Burning ◽  
Eastern China ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Southeastern China ◽  
Brown Carbon

Abstract. Biomass burning can significantly impact the chemical and optical properties of carbonaceous aerosols. Here, the biomass burning impacts were studied during wintertime in a megacity of Nanjing, eastern China. The high abundance of biomass burning tracers such as levoglucosan (lev), mannosan (man), galactosan (gal) and non-sea-salt potassium (nss-K+) was found during the studied period with the concentration ranges of 22.4–1476 ng m−3, 2.1–56.2 ng m−3, 1.4–32.2 ng m−3 and 0.2–3.8 µg m−3, respectively. The significant contribution of biomass burning to water-soluble organic carbon (WSOC; 22.3±9.9 %) and organic carbon (OC; 20.9±9.3 %) was observed in this study. Backward air mass origin analysis, potential emission sensitivity of elemental carbon (EC) and MODIS fire spot information indicated that the elevations of the carbonaceous aerosols were due to the transported biomass-burning aerosols from southeastern China. The characteristic mass ratio maps of lev∕man and lev∕nss-K+ suggested that the biomass fuels were mainly crop residuals. Furthermore, the strong correlation (p < 0.01) between biomass burning tracers (such as lev) and light absorption coefficient (babs) for water-soluble brown carbon (BrC) revealed that biomass burning emissions played a significant role in the light-absorption properties of carbonaceous aerosols. The solar energy absorption due to water-soluble brown carbon and EC was estimated by a calculation based on measured light-absorbing parameters and a simulation based on a radiative transfer model (RRTMG_SW). The solar energy absorption of water-soluble BrC in short wavelengths (300–400 nm) was 0.8±0.4 (0.2–2.3) W m−2 (figures in parentheses represent the variation range of each parameter) from the calculation and 1.2±0.5 (0.3–1.9) W m−2 from the RRTMG_SW model. The absorption capacity of water-soluble BrC accounted for about 20 %–30 % of the total absorption of EC aerosols. The solar energy absorption of water-soluble BrC due to biomass burning was estimated as 0.2±0.1 (0.0–0.9) W m−2, considering the biomass burning contribution to carbonaceous aerosols. Potential source contribution function model simulations showed that the solar energy absorption induced by water-soluble BrC and EC aerosols was mostly due to the regionally transported carbonaceous aerosols from source regions such as southeastern China. Our results illustrate the importance of the absorbing water-soluble brown carbon aerosols in trapping additional solar energy in the low-level atmosphere, heating the surface and inhibiting the energy from escaping the atmosphere.

scholarly journals The global impact of bacterial processes on carbon mass

2020 ◽  
Vol 20 (3) ◽  
pp. 1777-1794
Author(s):  
Barbara Ervens ◽  
Pierre Amato
Keyword(s):  
Cell Growth ◽  
Growth Conditions ◽  
Water Soluble ◽  
Cloud Formation ◽  
Cloud Droplets ◽  
Spatial And Temporal Scales ◽  
Adverse Health Effects ◽  
Oh Reactions ◽  
Carbon Mass ◽  
High Concentrations

Abstract. Many recent studies have identified biological material as a major fraction of ambient aerosol loading. A small fraction of these bioaerosols consist of bacteria that have attracted a lot of attention due to their role in cloud formation and adverse health effects. Current atmospheric models consider bacteria as inert quantities and neglect cell growth and multiplication. We provide here a framework to estimate the production of secondary biological aerosol (SBA) mass in clouds by microbial cell growth and multiplication. The best estimate of SBA formation rates of 3.7 Tg yr−1 is comparable to previous model estimates of the primary emission of bacteria into the atmosphere, and thus this might represent a previously unrecognized source of biological aerosol material. We discuss in detail the large uncertainties associated with our estimates based on the rather sparse available data on bacteria abundance, growth conditions, and properties. Additionally, the loss of water-soluble organic carbon (WSOC) due to microbial processes in cloud droplets has been suggested to compete under some conditions with WSOC loss by chemical (OH) reactions. Our estimates suggest that microbial and chemical processes might lead to a global loss of WSOC of 8–11 and 8–20 Tg yr−1, respectively. While this estimate is very approximate, the analysis of the uncertainties and ranges of all parameters suggests that high concentrations of metabolically active bacteria in clouds might represent an efficient sink for organics. Our estimates also highlight the urgent need for more data concerning microbial concentrations, fluxes, and activity in the atmosphere to evaluate the role of bacterial processes as net aerosol sinks or sources on various spatial and temporal scales.

scholarly journals Measurement Report: Optical properties and sources of water-soluble brown carbon in Tianjin, North China: insights from organic molecular compositions

2022 ◽  
Author(s):  
Junjun Deng ◽  
Hao Ma ◽  
Xinfeng Wang ◽  
Shujun Zhong ◽  
Zhimin Zhang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Light Absorption ◽  
Radiative Forcing ◽  
North China ◽  
Water Soluble ◽  
Formation Mechanisms ◽  
Chemical Compositions ◽  
Brown Carbon ◽  
Near Ultraviolet

Abstract. Brown carbon (BrC) aerosols exert vital impacts on climate change and atmospheric photochemistry due to their light absorption in the wavelength range from near-ultraviolet (UV) to visible light. However, the optical properties and formation mechanisms of ambient BrC remain poorly understood, limiting the estimation of their radiative forcing. In the present study, fine aerosols (PM2.5) were collected during 2016–2017 on a day/night basis over urban Tianjin, a megacity in North China, to obtain seasonal and diurnal patterns of atmospheric water-soluble BrC. There were obvious seasonal but no evident diurnal variations in light absorption properties of BrC. In winter, BrC showed much stronger light absorbing ability since mass absorption efficiency at 365 nm (MAE365) (1.54 ± 0.33 m2 g−1), which was 1.8 times larger than that (0.84 ± 0.22 m2 g−1) in summer. Direct radiative effects by BrC absorption relative to black carbon in the UV range were 54.3 ± 16.9 % and 44.6 ± 13.9 %, respectively. In addition, five fluorescent components in BrC, including three humic-like fluorophores and two protein-like fluorophores were identified with excitation-emission matrix fluorescence spectrometry and parallel factor (PARAFAC) analysis. The lowly-oxygenated components contributed more to winter and nighttime samples, while more-oxygenated components increased in summer and daytime samples. The higher humification index (HIX) together with lower biological index (BIX) and fluorescence index (FI) suggest that the chemical compositions of BrC were associated with a high aromaticity degree in summer and daytime due to photobleaching. Fluorescent properties indicate that wintertime BrC were predominantly affected by primary emissions and fresh secondary organic aerosol (SOA), while summer ones were more influenced by aging processes. Results of source apportionments using organic molecular compositions of the same set of aerosols reveal that fossil fuel combustion and aging processes, primary bioaerosol emission, biomass burning, and biogenic and anthropogenic SOA formation were the main sources of BrC. Biomass burning contributed much larger to BrC in winter and at nighttime, while biogenic SOA contributed more in summer and at daytime. Especially, our study highlights that primary bioaerosol emission is an important source of BrC in urban Tianjin in summer.

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