Influences on the fraction of hydrophobic and hydrophilic black  carbon in the atmosphere

Abstract. Black carbon (BC) is a short term climate forcer that directly warms the atmosphere, slows convection, and hinders quantification of the effect of greenhouse gases on climate change. The atmospheric lifetime of BC particles with respect to nucleation scavenging in clouds is controlled by their ability to serve as cloud condensation nuclei (CCN). To serve as CCN under typical conditions hydrophobic BC particles must acquire hygroscopic coatings. However, the quantitative relationship between coatings and hygroscopic properties for ambient BC particles is not known nor is the time scale for hydrophobic-to-hydrophilic conversion. Here we introduce a method for measuring the hygroscopicity of externally and internally mixed BC particles by coupling a single particle soot photometer with a humidified tandem differential mobility analyzer. We test this technique using uncoated and coated laboratory generated model BC compounds and apply it to characterize the hygroscopicity distribution of ambient BC particles. From these data we derive that the observed number fraction of BC that is CCN active at 0.2% supersaturation is generally low in an urban area near sources and that it varies with the trajectory of the airmass. We anticipate that our method can be combined with measures of air parcel physical and photochemical age to provide the first quantitative estimates for characterizing hydrophobic-to-hydrophilic conversion rates in the atmosphere.

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Influences on the fraction of hydrophobic and hydrophilic black carbon in the atmosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-5099-2011 ◽

2011 ◽

Vol 11 (10) ◽

pp. 5099-5112 ◽

Cited By ~ 77

Author(s):

G. R. McMeeking ◽

N. Good ◽

M. D. Petters ◽

G. McFiggans ◽

H. Coe

Keyword(s):

Black Carbon ◽

Cloud Condensation Nuclei ◽

Quantitative Relationship ◽

Differential Mobility ◽

Short Term ◽

Atmospheric Lifetime ◽

Hygroscopic Properties ◽

Quantitative Estimates ◽

Conversion Rates ◽

Nucleation Scavenging

Abstract. Black carbon (BC) is a short term climate forcer that directly warms the atmosphere, slows convection, and hinders quantification of the effect of greenhouse gases on climate change. The atmospheric lifetime of BC particles with respect to nucleation scavenging in clouds is controlled by their ability to serve as cloud condensation nuclei (CCN). To serve as CCN under typical conditions, hydrophobic BC particles must acquire hygroscopic coatings. However, the quantitative relationship between coatings and hygroscopic properties for ambient BC particles is not known nor is the time scale for hydrophobic-to-hydrophilic conversion. Here we introduce a method for measuring the hygroscopicity of externally and internally mixed BC particles by coupling a single particle soot photometer with a humidified tandem differential mobility analyzer. We test this technique using uncoated and coated laboratory generated model BC compounds and apply it to characterize the hygroscopicity distribution of ambient BC particles. From these data we derive that the observed number fraction of BC that is CCN active at 0.2 % supersaturation is generally low in an urban area near sources and that it varies with the trajectory of the airmass. We anticipate that our method can be combined with measures of air parcel physical and photochemical age to provide the first quantitative estimates for characterizing hydrophobic-to-hydrophilic conversion rates in the atmosphere.

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Design and Application of an Unattended Multifunctional H-TDMA System

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-12-00129.1 ◽

2013 ◽

Vol 30 (6) ◽

pp. 1136-1148 ◽

Cited By ~ 26

Author(s):

Haobo Tan ◽

Hanbing Xu ◽

Qilin Wan ◽

Fei Li ◽

Xuejiao Deng ◽

...

Keyword(s):

Particle Size ◽

Growth Factor ◽

Cloud Condensation Nuclei ◽

Polystyrene Latex ◽

Hygroscopic Growth ◽

Differential Mobility Analyzer ◽

Differential Mobility ◽

China Meteorological Administration ◽

Hygroscopic Properties ◽

Calibration Methods

Abstract The hygroscopic properties of aerosols have a significant impact on aerosol particle number size distributions (PNSD), formation of cloud condensation nuclei, climate forcing, and atmospheric visibility, as well as human health. To allow for the observation of the hygroscopic growth of aerosols with long-term accuracy, an unattended multifunctional hygroscopicity-tandem differential mobility analyzer (H-TDMA) system was designed and built by the Institute of Tropical and Marine Meteorology (ITMM), China Meteorological Administration (CMA), in Guangzhou, China. The system is capable of measuring dry and wet PNSD, hygroscopic growth factor by particle size, and mixing states. This article describes in detail the working principles, components, and calibration methods of the system. Standard polystyrene latex (PSL) spheres with five different diameters were chosen to test the system’s precision and accuracy of particle size measurement. Ammonium sulfate was used to test the hygroscopic response of the system for accurate growth factor measurement. The test results show that the deviation of the growth factor measured by the system is within a scope of −0.01 to −0.03 compared to Köhler theoretical curves. Results of temperature and humidity control performance tests indicate that the system is robust. An internal temperature gradient of less than 0.2 K for a second differential mobility analyzer (DMA2) makes it possible to reach a set-point relative humidity (RH) value of 90% and with a standard deviation of ±0.44%, sufficient for unattended field observation.

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Hygroscopic properties of the ambient aerosol in southern Sweden – a two year study

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-6601-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 6601-6650

Author(s):

E. O. Fors ◽

E. Swietlicki ◽

B. Svenningsson ◽

A. Kristensson ◽

G. P. Frank ◽

...

Keyword(s):

Seasonal Variation ◽

Growth Factors ◽

Radiative Forcing ◽

Cloud Condensation Nuclei ◽

Hygroscopic Growth ◽

Differential Mobility ◽

Hygroscopic Properties ◽

Modeling Uncertainties ◽

Hydrophobic Particles ◽

Particle Sizer

Abstract. The hygroscopic growth of the atmospheric aerosol is a critical parameter for quantifying the anthropogenic radiative forcing. Until now, there has been a lack of long term measurements due to limitations in instrumental techniques. In this work, for the first time the seasonal variation of the hygroscopic properties of a continental background aerosol has been described, based on more than two years of continuous measurements. In addition to this, the diurnal variation of the hygroscopic growth has been investigated, as well as the seasonal variation in CCN concentration. These physical properties of the aerosol have been measured with a Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA), a Differential Mobility Particle Sizer (DMPS), and a Cloud Condensation Nuclei Counter (CCNC). The results show that smaller particles are generally less hygroscopic than larger ones, and that there is a clear difference in the hygroscopic properties between the Aitken and the accumulation mode. A seasonal cycle was found for all particle sizes. In general, the average hygroscopic growth is lower during wintertime, due to an increase in the relative abundance of less hygroscopic or hydrophobic particles. Monthly averages showed that the hygroscopic growth factors of the two dominating hygroscopic modes (one barely hygroscopic and one more hygroscopic) were relatively stable. The hygroscopic growth additionally showed a diurnal cycle, with higher growth factors during day time. CCN predictions based on H-TDMA data underpredicted the activated CCN concentration with 7% for 1% water supersaturation (s). The underprediction increases with decreasing $s$, most likely due to a combination of measurement and modeling uncertainties. It was found that although the aerosol is often externally mixed, recalculating to an internal mixture with respect to hygroscopicity did not change CCN parameterizations significantly.

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Hygroscopic properties of the ambient aerosol in southern Sweden – a two year study

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-8343-2011 ◽

2011 ◽

Vol 11 (16) ◽

pp. 8343-8361 ◽

Cited By ~ 54

Author(s):

E. O. Fors ◽

E. Swietlicki ◽

B. Svenningsson ◽

A. Kristensson ◽

G. P. Frank ◽

...

Keyword(s):

Seasonal Variation ◽

Growth Factors ◽

Radiative Forcing ◽

Cloud Condensation Nuclei ◽

Hygroscopic Growth ◽

Differential Mobility ◽

Supersaturation Ratio ◽

Hygroscopic Properties ◽

Modeling Uncertainties ◽

Particle Sizer

Abstract. The hygroscopic growth of the atmospheric aerosol is a critical parameter for quantifying the anthropogenic radiative forcing. Until now, there has been a lack of long term measurements due to limitations in instrumental techniques. In this work, for the first time the seasonal variation of the hygroscopic properties of a continental background aerosol has been described, based on more than two years of continuous measurements. In addition to this, the diurnal variation of the hygroscopic growth has been investigated, as well as the seasonal variation in CCN concentration. These physical properties of the aerosol have been measured with a Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA), a Differential Mobility Particle Sizer (DMPS), and a Cloud Condensation Nuclei Counter (CCNC). The results show that smaller particles are generally less hygroscopic than larger ones, and that there is a clear difference in the hygroscopic properties between the Aitken and the accumulation mode. A seasonal cycle was found for all particle sizes. In general, the average hygroscopic growth is lower during wintertime, due to an increase in the relative abundance of less hygroscopic or barely hygroscopic particles. Monthly averages showed that the hygroscopic growth factors of the two dominating hygroscopic modes (one barely hygroscopic and one more hygroscopic) were relatively stable. The hygroscopic growth additionally showed a diurnal cycle, with higher growth factors during day time. CCN predictions based on H-TDMA data underpredicted the activated CCN number concentration with 7 % for a 1 % water supersaturation ratio. The underprediction increases with decreasing s, most likely due to a combination of measurement and modeling uncertainties. It was found that although the aerosol is often externally mixed, recalculating to an internal mixture with respect to hygroscopicity did not change the CCN concentration as a function of supersaturation significantly.

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Droplet activation behaviour of atmospheric black carbon particles in fog as a function of their size and mixing state

10.5194/acp-2018-811 ◽

2018 ◽

Author(s):

Ghislain Motos ◽

Julia Schmale ◽

Joel Christopher Corbin ◽

Marco Zanatta ◽

Urs Baltensperger ◽

...

Keyword(s):

Black Carbon ◽

Single Particle ◽

Radiative Forcing ◽

Cloud Condensation Nuclei ◽

Mixing State ◽

Scanning Mobility Particle Sizer ◽

Carbon Particles ◽

Hygroscopic Properties ◽

Droplet Activation ◽

Aerosol Cloud Interactions

Abstract. Among the variety of particle types present in the atmosphere, black carbon (BC), emitted by combustion processes, is uniquely associated with harmful effects to the human body and substantial radiative forcing of the Earth. Pure BC is known to be non-hygroscopic, but its ability to acquire a coating of hygroscopic organic and inorganic material leads to increased hygroscopicity as well as diameter, facilitating droplet activation. This affects BC radiative forcing through aerosol-cloud interactions (aci) and BC life cycle. To gain insights into these processes, we performed a field campaign in winter 2015/16 in a residential area of Zurich which aimed at distinguishing different particle mixing states regarding hygroscopic properties in the cloud condensation nuclei (CCN)-activated fraction spectrum of urban aerosol and establishing relations between the mixing state of BC and its activation to form droplets in fog. This was achieved by operating a CCN counter (CCNC), a scanning mobility particle sizer (SMPS), a single particle soot photometer (SP2) and an aerosol chemical speciation monitor (ACSM) behind a combination of a total- and an interstitial-aerosol inlet. Our results indicate that, depending on the time of the day, we sampled both heavily aged internally mixed BC from background air advected to the site and freshly emitted externally mixed BC from local or regional traffic sources. During rush hours in the morning of weekdays, we found clear evidence that the enhanced traffic emissions caused peaks in the number fraction of externally mixed BC particles which do not act as CCN within the CCNC. The mixing state of BC particles was also found to play a key role in their ability to form fog droplets. The very low effective peak supersaturations (SSpeak) occurring in fog (between approximately 0.03 and 0.06 % during this campaign) restrict droplet activation to a minor fraction of the aerosol burden (around 0.5 to 1 % of total particle number concentration between 20 and 593 nm) leading to very selective criteria on diameter and chemical composition. We show that bare BC cores are unable to activate to fog droplets at such low SSpeak, while BC particles surrounded by thick coating have a very similar activation behavior as BC-free particles. The threshold coating thickness required for activation was shown to decrease with increasing BC core size. Using simplified κ-Köhler theory combined with the ZSR mixing rule assuming spherical core-shell particle geometry constrained with single particle measurements of respective volumes, we found good agreement between the predicted and the directly observed size and mixing state resolved droplet activation behaviour of BC-containing particles in fog. This successful closure demonstrates the predictability of their droplet activation in fog with a simplified theoretical model only requiring size and mixing state information, which can also be applied in a consistent manner in model simulations.

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The Dynamic Response of Nitrogen Transformation to the Dissolved Oxygen Variations in the Simulated Biofilm Reactor

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18073633 ◽

2021 ◽

Vol 18 (7) ◽

pp. 3633

Author(s):

Qianqian Lu ◽

Nannan Zhang ◽

Chen Chen ◽

Miao Zhang ◽

Dehua Zhao ◽

...

Keyword(s):

Dissolved Oxygen ◽

Copy Number ◽

Stable State ◽

Quantitative Relationship ◽

Nitrogen Transformation ◽

Biofilm Reactor ◽

Short Term ◽

Nirs Gene ◽

Biofilm Reactors ◽

Recovery Times

Lab-scale simulated biofilm reactors, including aerated reactors disturbed by short-term aeration interruption (AE-D) and non-aerated reactors disturbed by short-term aeration (AN-D), were established to study the stable-state (SS) formation and recovery after disturbance for nitrogen transformation in terms of dissolved oxygen (DO), removal efficiency (RE) of NH4+-N and NO3−-N and activity of key nitrogen-cycle functional genes amoA and nirS (RNA level abundance, per ball). SS formation and recovery of DO were completed in 0.56–7.75 h after transition between aeration (Ae) and aeration stop (As). In terms of pollutant REs, new temporary SS formation required 30.7–52.3 h after Ae and As interruptions, and seven-day Ae/As interruptions required 5.0% to 115.5% longer recovery times compared to one-day interruptions in AE-D and AN-D systems. According to amoA activity, 60.8 h were required in AE-D systems to establish new temporary SS after As interruptions, and RNA amoA copies (copy number/microliter) decreased 88.5%, while 287.2 h were required in AN-D systems, and RNA amoA copies (copy number/microliter) increased 36.4 times. For nirS activity, 75.2–85.8 h were required to establish new SSs after Ae and As interruptions. The results suggested that new temporary SS formation and recovery in terms of DO, pollutant REs and amoA and nirS gene activities could be modelled by logistic functions. It is concluded that temporary SS formation and recovery after Ae and As interruptions occurred at asynchronous rates in terms of DO, pollutant REs and amoA and nirS gene activities. Because of DO fluctuations, the quantitative relationship between gene activity and pollutant RE remains a challenge.

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Combined analyses of hygroscopic properties of organic and inorganic components of three representative black carbon samples recovered from pyrolysis

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.145393 ◽

2021 ◽

Vol 771 ◽

pp. 145393

Author(s):

Minli Wang ◽

Yiqun Chen ◽

Heyun Fu ◽

Xiaolei Qu ◽

Guofeng Shen ◽

...

Keyword(s):

Black Carbon ◽

Hygroscopic Properties ◽

Inorganic Components

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Short-Term Association between Black Carbon Exposure and Cardiovascular Diseases in Pakistan’s Largest Megacity

Atmosphere ◽

10.3390/atmos9110420 ◽

2018 ◽

Vol 9 (11) ◽

pp. 420 ◽

Cited By ~ 1

Author(s):

Daniel Malashock ◽

Haider Khwaja ◽

Zafar Fatmi ◽

Azhar Siddique ◽

Yi Lu ◽

...

Keyword(s):

Cardiovascular Diseases ◽

Black Carbon ◽

Hospital Admissions ◽

Statistical Significance ◽

Fine Particulate Matter ◽

Tertiary Care ◽

Short Term ◽

Residential Site ◽

Fine Particulate ◽

Tertiary Care Hospitals

This study investigated the association between black carbon (BC) exposure and hospital admissions (HAs) and outpatient department/emergency room (OPD/ER) visits for cardiovascular diseases (CVD) among residents of Karachi, the largest city in Pakistan. We measured daily concentrations of BC in fine particulate matter (PM2.5) and collected records of HAs and OPD/ER visits for CVD from 2 major tertiary care hospitals serving Karachi for 6 weeks continuously during each quarter over 1 year (August 2008–August 2009). We subsequently analyzed daily counts of hospital and BC data over 0–3 lag days. Daily mean BC concentrations varied from 1 to 32 µg/m3. Results suggest that BC concentrations are associated with CVD HAs and OPD/ER visits. However, associations were generally only observed when modeled with BC from Tibet Center, the commercial-residential site, as compared to Korangi, the industrial-residential site. Overall, low statistical significance suggests that while BC may be a valuable indicator for CVD health risks from combustion-derived particles, further evaluation of the constituents of PM2.5 and their relative contributions to CVD health impacts is necessary.

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