scholarly journals Evaluation of the performance of a particle concentrator for on-line instrumentation

2014 ◽  
Vol 7 (3) ◽  
pp. 2737-2781
Author(s):  
S. Saarikoski ◽  
S. Carbone ◽  
M. J. Cubison ◽  
R. Hillamo ◽  
P. Keronen ◽  
...  
Keyword(s):  
Trace Elements ◽  
Size Distribution ◽  
Organic Compounds ◽  
Laboratory Tests ◽  
Water Soluble ◽  
Urban Site ◽  
Small Shift ◽  
On Line ◽  
Particle Sizer ◽  
Ambient Measurements

Abstract. The performance of the miniature Versatile Aerosol Concentration Enrichment System (m-VACES, Geller et al., 2005) was investigated in laboratory and field studies using on-line instruments. Laboratory tests focused on the behavior of monodisperse ammonium sulfate (AS) or dioctyl sebacate (DOS) particles in the m-VACES measured with the Aerodynamic Particle Sizer (APS) and Scanning Mobility Particle Sizer (SMPS). The ambient measurements were conducted at an urban site in Helsinki, Finland, where the operation of the m-VACES was explored in conjunction with a Soot Particle Aerosol Mass Spectrometer (SP-AMS) in addition to the SMPS. In laboratory tests, the growth of particles in water vapor produced a stable droplet size distribution independent of the original particle size. However, when the droplets were dried with the goal of measuring the original size distribution, a shift to larger particles was observed for small particle sizes (up to ~ 200 nm in mobility diameter). That growth was probably caused by water-soluble organic compounds absorbed on the water droplets from the gas phase, but not evaporated in the drying phase. In ambient measurements, similar enrichment factors (EFs) were observed for nitrate, sulfate, organics and refractory black carbon. Size-dependent EFs showed a small shift in the accumulation mode peak size after the m-VACES. The presence of acidic ambient particles affected the enrichment of ammonium and chloride. Gaseous ammonia was observed to be absorbed on acidic particles in the m-VACES, neutralizing the aerosol. As a result the contribution of ammonium to particle mass increased from 6% for ambient to 9% for concentrated aerosol. The opposite trend was observed for chloride, since a fraction of chloride evaporated from acidic particles upon neutralization. Organic artifacts were quite small but a small positive artifact for hydrocarbons and nitrogen-containing organic compounds was observed. However, the oxidation state of organics remained nearly the same before and after the m-VACES. Ambient and concentrated OA was analyzed further with Positive Matrix Factorization (PMF). A three-factor solution was chosen for both of the data sets but the factors were slightly different for the ambient and concentrated OA. That could reflect the sensitivity of PMF to minor changes in OA composition; however, the data set used for the PMF analysis was limited in size and therefore had substantial uncertainty. Eight trace elements (Al, V, Fe, Zn, Rb, Sr, Zr and Cd) were detected with the SP-AMS of which three (Sr, Zr and Cd) were observed only with the m-VACES. Trace elements seemed to be enriched in the m-VACES similar to major inorganic and organic species. Overall, the operation of the m-VACES was not found to lead to any severe sampling artifacts. The effect of acidity could be an issue in locations where the aerosol is acidic, however, in those cases the use of a denuder (which was not used in this study) is recommended.

scholarly journals Evaluation of the performance of a particle concentrator for online instrumentation

2014 ◽  
Vol 7 (7) ◽  
pp. 2121-2135 ◽  
Author(s):  
S. Saarikoski ◽  
S. Carbone ◽  
M. J. Cubison ◽  
R. Hillamo ◽  
P. Keronen ◽  
...  
Keyword(s):  
Size Distribution ◽  
Organic Compounds ◽  
Laboratory Tests ◽  
Water Soluble ◽  
Urban Site ◽  
Gaseous Ammonia ◽  
Scanning Mobility Particle Sizer ◽  
Data Set ◽  
Particle Sizer ◽  
Ambient Measurements

Abstract. The performance of the miniature Versatile Aerosol Concentration Enrichment System (m-VACES; Geller et al., 2005) was investigated in laboratory and field studies using online instruments. Laboratory tests focused on the behavior of monodisperse ammonium sulfate (AS) or dioctyl sebacate (DOS) particles in the m-VACES measured with the aerodynamic particle sizer (APS) and scanning mobility particle sizer (SMPS). The ambient measurements were conducted at an urban site in Helsinki, Finland, where the operation of the m-VACES was explored in conjunction with a Soot Particle Aerosol Mass Spectrometer (SP-AMS) in addition to the SMPS. In laboratory tests, the growth of particles in water vapor produced a stable droplet size distribution independent of the original particle size. However, when the droplets were dried with the goal of measuring the original size distribution, a shift to larger particles was observed for small particle sizes (up to ~ 200 nm in mobility diameter). That growth was probably caused by water-soluble organic compounds absorbed on the water droplets from the gas phase, but not evaporated in the drying phase. In ambient measurements, a similar enrichment was observed for nitrate and sulfate in the m-VACES whereas the presence of acidic ambient particles affected the enrichment of ammonium. Gaseous ammonia was likely to be absorbed on acidic particles in the m-VACES, neutralizing the aerosol. For organics, the enrichment efficiency was comparable with sulfate and nitrate but a small positive artifact for hydrocarbons and nitrogen-containing organic compounds was noticed. Ambient and concentrated organic aerosol (OA) was analyzed further with positive matrix factorization (PMF). A three-factor solution was chosen for both of the data sets but the factors were slightly different for the ambient and concentrated OA, however, the data set used for the PMF analysis was limited in size (3 days) and therefore had substantial uncertainty. Overall, the operation of the m-VACES was not found to lead to any severe sampling artifacts. The effect of acidity could be an issue in locations where the aerosol is acidic, however, in those cases the use of a denuder (which was not used in this study) is recommended. Further ambient tests are needed for the characterization of the m-VACES as the time period for the ambient measurements was only 5 days in this study. Especially for OA additional tests are important as the chemical properties of organics can differ widely depending on time and location.

scholarly journals Size-resolved particulate water-soluble organic compounds in the urban, mountain and marine atmosphere

2010 ◽  
Vol 10 (7) ◽  
pp. 17467-17490
Author(s):  
G. Wang ◽  
K. Kawamura ◽  
M. Xie ◽  
S. Hu ◽  
B. Zhou ◽  
...  
Keyword(s):  
Size Distribution ◽  
Organic Compounds ◽  
Fine Particles ◽  
Geometric Mean ◽  
Inversion Layer ◽  
Water Soluble ◽  
Urban Site ◽  
Marine Atmosphere ◽  
Marine Aerosols ◽  
Sugar Alcohols

Abstract. Primary (i.e., sugars and sugar alcohols) and secondary water-soluble organic compounds (WSOCs) (i.e., dicarboxylic acids and aromatic acids) were characterised on a molecular level in size-segregated aerosols from the urban and mountain atmosphere of China and from the marine atmosphere in the outflow region of East Asia. Levoglucosan is the most abundant WSOCs in the urban and mountain atmosphere, whose accumulated concentrations in all stages are 1–3 orders of magnitude higher than those of marine aerosols. In contrast, malic, succinic and phthalic acids are dominant in the marine aerosols, which are 3–6 times more abundant than levoglucosan. This suggests that a continuous formation of secondary organic aerosols is occurring in the marine atmosphere during the long-range transport of air mass from inland China to the North Pacific. Sugars and sugar-alcohols, except for levoglucosan, gave a bimodal size distribution in the urban and mountain areas, peaking at 0.7–1.1 μm and >3.3 μm, and a unimodal distribution in the marine region, peaking at >3.3 μm. In contrast, levoglucosan and all the secondary WSOCs, except for benzoic and azelaic acids, showed a unimodal size distribution with a peak at 0.7–1.1 μm. Geometric mean diameters (GMDs) of the WSOCs in fine particles (<2.1 μm) at the urban site are larger in winter than in spring, due to an enhanced coagulation effect under the development of an inversion layer. However, GMDs of levoglucosan and most of the secondary WSOCs in the coarse mode are larger in the mountain and marine air and smaller in the urban air. This is most likely caused by an enhanced hygroscopic growth due to the high humidity of the mountain and marine atmosphere.

scholarly journals A temporally and spatially resolved validation of emission inventories by measurements of ambient volatile organic compounds in Beijing, China

2014 ◽  
Vol 14 (12) ◽  
pp. 5871-5891 ◽  
Author(s):  
M. Wang ◽  
M. Shao ◽  
W. Chen ◽  
B. Yuan ◽  
S. Lu ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Measurement Data ◽  
Suburban Area ◽  
Urban Site ◽  
Emission Inventories ◽  
Relative Contribution ◽  
Volatile Organic ◽  
Current Emission ◽  
Ambient Measurements

Abstract. Understanding the sources of volatile organic compounds (VOCs) is essential for ground-level ozone and secondary organic aerosol (SOA) abatement measures. We made VOC measurements at 27 sites and online observations at an urban site in Beijing from July 2009 to January 2012. Based on these measurement data, we determined the spatial and temporal distribution of VOCs, estimated their annual emission strengths based on their emission ratios relative to carbon monoxide (CO), and quantified the relative contributions of various sources using the chemical mass balance (CMB) model. These results from ambient measurements were compared with existing emission inventories to evaluate the spatial distribution, species-specific emissions, and source structure of VOCs in Beijing. The measured VOC distributions revealed a hotspot in the southern suburban area of Beijing, whereas current emission inventories suggested that VOC emissions were concentrated in downtown areas. Compared with results derived from ambient measurements, the annual inventoried emissions of oxygenated VOC (OVOC) species and C2–C4 alkanes may be underestimated, while the emissions of styrene and 1,3-butadiene may be overestimated by current inventories. Source apportionment using the CMB model identified vehicular exhaust as the most important VOC source, with the relative contribution of 49%, in good agreement with the 40–51% estimated by emission inventories. The relative contribution of paint and solvent utilization obtained from the CMB model was 14%, significantly lower than the value of 32% reported by one existing inventory. Meanwhile, the relative contribution of liquefied petroleum gas (LPG) usage calculated using the CMB model was 6%, whereas LPG usage contribution was not reported by current emission inventories. These results suggested that VOC emission strengths in southern suburban area of Beijing, annual emissions of C2–C4 alkanes, OVOCs and some alkenes, and the contributions of solvent and paint utilization and LPG usage in current inventories all require significant revisions.

Diurnal variation in the size distribution of water soluble organic compounds

2001 ◽  
Vol 32 ◽  
pp. 689-698 ◽  
Author(s):  
D. Temesi ◽  
A. Molnár ◽  
T. Feczkó ◽  
E. Mészáros
Keyword(s):  
Diurnal Variation ◽  
Size Distribution ◽  
Organic Compounds ◽  
Water Soluble

scholarly journals A method for on-line measurement of water-soluble organic carbon in ambient aerosol particles: Results from an urban site

2004 ◽  
Vol 31 (13) ◽  
pp. n/a-n/a ◽  
Author(s):  
A. P. Sullivan ◽  
R. J. Weber ◽  
A. L. Clements ◽  
J. R. Turner ◽  
M. S. Bae ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Aerosol Particles ◽  
Water Soluble ◽  
Urban Site ◽  
Ambient Aerosol ◽  
Line Measurement ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
On Line

scholarly journals Validation of emission inventories by measurements of ambient volatile organic compounds in Beijing, China

2013 ◽  
Vol 13 (10) ◽  
pp. 26933-26979 ◽  
Author(s):  
M. Wang ◽  
M. Shao ◽  
W. Chen ◽  
B. Yuan ◽  
S. Lu ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Ground Level ◽  
Suburban Area ◽  
Industrial Processes ◽  
Urban Site ◽  
Emission Inventories ◽  
Relative Contribution ◽  
Volatile Organic ◽  
Ambient Measurements

Abstract. Understanding the sources of volatile organic compounds (VOCs) is essential for ground-level ozone and secondary organic aerosols (SOA) abatement measures. We made measurements at 28 sites and online observations at an urban site in Beijing from July 2009 to January 2012. From these we determined the spatial and temporal distributions of VOCs, estimated their annual emission strengths based on their emission ratios relative to CO, and quantified the relative contributions of various sources using the chemical mass balance (CMB) model. The results from ambient measurements were compared with existing emission inventories to evaluate the spatial distribution, species-specific emissions, and source structure of VOCs. The measured VOC distributions revealed a hotspot in the southern suburban area of Beijing, whereas current emission inventories suggested that VOC emissions were concentrated in downtown areas. Compared with results derived from ambient measurements, the annual inventoried emissions of oxygenated VOC (OVOC) species and C2–C4 alkanes might be underestimated, while the emissions of styrene and 1,3-butadiene might be overestimated by current inventories. Source apportionment using the CMB model identified vehicular exhaust as the most important VOC source, contributing 46%, in good agreement with the 40–51% assumed by emission inventories. However, the relative contribution of solvent and paint usage obtained from the CMB model was only 5%, significantly lower than the values reported by emission inventories (14–32%). Meanwhile, the relative contribution of industrial processes calculated using the CMB model was 17%, slightly higher than that in emission inventories. These results suggested that VOCs emission strengths in southern suburban area of Beijing, annual emissions of alkenes and OVOCs, and the contributions of solvent and paint usage and industrial processes in current inventories, all require significant revision.

scholarly journals Rapid measurement of RH-dependent aerosol hygroscopic growth using a humidity-controlled fast integrated mobility spectrometer (HFIMS)

2021 ◽  
Vol 14 (8) ◽  
pp. 5625-5635
Author(s):  
Jiaoshi Zhang ◽  
Steven Spielman ◽  
Yang Wang ◽  
Guangjie Zheng ◽  
Xianda Gong ◽  
...  
Keyword(s):  
Size Distribution ◽  
Rapid Evolution ◽  
Particle Sizes ◽  
Hygroscopic Growth ◽  
Scanning Mobility Particle Sizer ◽  
Ambient Aerosols ◽  
Dual Channel ◽  
Wide Range ◽  
Particle Sizer ◽  
Ambient Measurements

Abstract. The ability of aerosol particles to uptake water (hygroscopic growth) is an important determinant of aerosol optical properties and radiative effects. Aerosol hygroscopic growth is traditionally measured by humidified tandem differential mobility analyzers (HTDMA), in which size-selected dry particles are exposed to elevated relative humidity (RH), and the size distribution of humidified particles is subsequently measured using a scanning mobility particle sizer. As a scanning mobility particle sizer can measure only one particle size at a time, HTDMA measurements are time consuming, and ambient measurements are often limited to a single RH level. Pinterich et al. (2017b) showed that fast measurements of aerosol hygroscopic growth are possible using a humidity-controlled fast integrated mobility spectrometer (HFIMS). In HFIMS, the size distribution of humidified particles is rapidly captured by a water-based fast integrated mobility spectrometer (WFIMS), leading to a factor of ∼10 increase in measurement time resolution. In this study we present a prototype HFIMS that extends fast hygroscopic growth measurements to a wide range of atmospherically relevant RH values, allowing for more comprehensive characterizations of aerosol hygroscopic growth. A dual-channel humidifier consisting of two humidity conditioners in parallel is employed such that aerosol RH can be quickly stepped among different RH levels by sampling from alternating conditioners. The measurement sequence is also optimized to minimize the transition time between different particle sizes. The HFIMS is capable of measuring aerosol hygroscopic growth of six particle diameters under five RH levels ranging from 20 % to 85 % (30 separate measurements) every 25 min. The performance of this HFIMS is characterized and validated using laboratory-generated ammonium sulfate aerosol standards. Measurements of ambient aerosols are shown to demonstrate the capability of HFIMS to capture the rapid evolution of aerosol hygroscopic growth and its dependence on both size and RH.

scholarly journals Rapid measurement of RH-dependent aerosol hygroscopic growth using a humidity-controlled fast integrated mobility spectrometer (HFIMS)

2021 ◽  
Author(s):  
Jiaoshi Zhang ◽  
Steven Spielman ◽  
Yang Wang ◽  
Guangjie Zheng ◽  
Xianda Gong ◽  
...  
Keyword(s):  
Size Distribution ◽  
Rapid Evolution ◽  
Particle Sizes ◽  
Hygroscopic Growth ◽  
Scanning Mobility Particle Sizer ◽  
Ambient Aerosols ◽  
Dual Channel ◽  
Wide Range ◽  
Particle Sizer ◽  
Ambient Measurements

Abstract. The ability of aerosol particles to uptake water (hygroscopic growth) is an important determinant of aerosol optical properties and radiative effects. Aerosol hygroscopic growth is traditionally measured by humidified tandem differential mobility analyzers (HTDMA), in which size-selected dry particles are exposed to elevated relative humidity (RH), and the size distribution of humidified particles are subsequently measured using a scanning mobility particle sizer. As a scanning mobility particle sizer can measure only one particle size at a time, HTDMA measurements are time-consuming, and ambient measurements are often limited to a single RH level. Pinterich et al. (2017b) showed that fast measurements of aerosol hygroscopic growth are possible using a humidity-controlled fast integrated mobility spectrometer (HFIMS). In HFIMS, the size distribution of humidified particles is rapidly captured by a water-based fast integrated mobility spectrometer (WFIMS), leading to a factor of ~10 increase in measurement time resolution. In this study we present a prototype HFIMS that extends fast hygroscopic growth measurements to a wide range of atmospherically relevant RH values, allowing for more comprehensive characterizations of aerosol hygroscopic growth. A dual-channel humidifier consisting of two humidity conditioners in parallel is employed such that aerosol RH can be quickly stepped among different RH levels by sampling from alternating conditioners. The measurement sequence is also optimized to minimize the transition time between different particle sizes. The HFIMS is capable of measuring aerosol hygroscopic growth of six particle diameters under five RH levels ranging from 20 % to 85 % (30 separate measurements) every 25 min. The performance of this HFIMS is characterized and validated using laboratory-generated ammonium sulfate aerosol standards. Measurements of ambient aerosols are shown to demonstrate the capability of HFIMS to capture the rapid evolution of aerosol hygroscopic growth, and its dependence on both size and RH.

Sign in / Sign up

Export Citation Format

Share Document