scholarly journals Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

2015 ◽  
Vol 15 (8) ◽  
pp. 4161-4178 ◽  
Author(s):  
A. Worringen ◽  
K. Kandler ◽  
N. Benker ◽  
T. Dirsch ◽  
S. Mertes ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Metal Oxides ◽  
Relative Number ◽  
Carbonaceous Material ◽  
Submicron Particles ◽  
Research Station ◽  
Mixing State ◽  
Separation Techniques ◽  
Potential Measurement ◽  
Virtual Impactor

Abstract. In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20–70%) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200–400 nm in geometric diameter. In a few cases, a second supermicron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the sub-micrometer range. Silicates and Ca-rich particles were mainly found with diameters above 1 μm (using ISI and FINCH), in contrast to the Ice-CVI which also sampled many submicron particles of both groups. Due to changing meteorological conditions, the INP/IPR composition was highly variable if different samples were compared. Thus, the observed discrepancies between the different separation techniques may partly result from the non-parallel sampling. The differences of the particle group relative number abundance as well as the mixing state of INP/IPR clearly demonstrate the need of further studies to better understand the influence of the separation techniques on the INP/IPR chemical composition. Also, it must be concluded that the abundance of contamination artifacts in the separated INP and IPR is generally large and should be corrected for, emphasizing the need for the accompanying chemical measurements. Thus, further work is needed to allow for routine operation of the three separation techniques investigated.

scholarly journals Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

2014 ◽  
Vol 14 (16) ◽  
pp. 23027-23073 ◽  
Author(s):  
A. Worringen ◽  
K. Kandler ◽  
N. Benker ◽  
T. Dirsch ◽  
S. Weinbruch ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Metal Oxides ◽  
Carbonaceous Material ◽  
Submicron Particles ◽  
Research Station ◽  
Mixing State ◽  
Potential Measurement ◽  
Virtual Impactor ◽  
Alpine Research ◽  
Mixed Phase Clouds

Abstract. In the present work, three different techniques are used to separate ice-nucleating particles (INP) and ice particle residuals (IPR) from non-ice-active particles: the Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI), which sample ice particles from mixed phase clouds and allow for the analysis of the residuals, as well as the combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Virtual Impactor (IN-PCVI), which provides ice-activating conditions to aerosol particles and extracts the activated ones for analysis. The collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Samples were taken during January/February 2013 at the High Alpine Research Station Jungfraujoch. All INP/IPR-separating techniques had considerable abundances (median 20–70%) of contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). Also, potential measurement artifacts (soluble material) occurred (median abundance < 20%). After removal of the contamination particles, silicates and Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types separated by all three techniques. Minor types include soot and Pb-bearing particles. Sea-salt and sulfates were identified by all three methods as INP/IPR. Lead was identified in less than 10% of the INP/IPR. It was mainly present as an internal mixture with other particle types, but also external lead-rich particles were found. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH yielded silicates and Ca-rich particles mainly with diameters above 1 μm, while the Ice-CVI also sampled many submicron particles. Probably owing to the different meteorological conditions, the INP/IPR composition was highly variable on a sample to sample basis. Thus, some part of the discrepancies between the different techniques may result from the (unavoidable) non-parallel sampling. The observed differences of the particles group abundances as well as the mixing state of INP/IPR point to the need of further studies to better understand the influence of the separating techniques on the INP/IPR chemical composition.

scholarly journals Chemical composition and mixing-state of ice residuals sampled within mixed phase clouds

2011 ◽  
Vol 11 (6) ◽  
pp. 2805-2816 ◽  
Author(s):  
M. Ebert ◽  
A. Worringen ◽  
N. Benker ◽  
S. Mertes ◽  
E. Weingartner ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Carbonaceous Material ◽  
Mixed Phase ◽  
Research Station ◽  
Mixing State ◽  
Anthropogenic Component ◽  
Significant Enrichment ◽  
Alpine Research ◽  
Main Component ◽  
Mixed Phase Clouds

Abstract. During an intensive campaign at the high alpine research station Jungfraujoch, Switzerland, in February/March 2006 ice particle residuals within mixed-phase clouds were sampled using the Ice-counterflow virtual impactor (Ice-CVI). Size, morphology, chemical composition, mineralogy and mixing state of the ice residual and the interstitial (i.e., non-activated) aerosol particles were analyzed by scanning and transmission electron microscopy. Ice nuclei (IN) were identified from the significant enrichment of particle groups in the ice residual (IR) samples relative to the interstitial aerosol. In terms of number lead-bearing particles are enriched by a factor of approximately 25, complex internal mixtures with silicates or metal oxides as major components by a factor of 11, and mixtures of secondary aerosol and carbonaceous material (C-O-S particles) by a factor of 2. Other particle groups (sulfates, sea salt, Ca-rich particles, external silicates) observed in the ice-residual samples cannot be assigned unambiguously as IN. Between 9 and 24% of all IR are Pb-bearing particles. Pb was found as major component in around 10% of these particles (PbO, PbCl2). In the other particles, Pb was found as some 100 nm sized agglomerates consisting of 3–8 nm sized primary particles (PbS, elemental Pb). C-O-S particles are present in the IR at an abundance of 17–27%. The soot component within these particles is strongly aged. Complex internal mixtures occur in the IR at an abundance of 9–15%. Most IN identified at the Jungfraujoch station are internal mixtures containing anthropogenic components (either as main or minor constituent), and it is concluded that admixture of the anthropogenic component is responsible for the increased IN efficiency within mixed phase clouds. The mixing state appears to be a key parameter for the ice nucleation behaviour that cannot be predicted from the sole knowledge of the main component of an individual particle.

scholarly journals Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic site

2006 ◽  
Vol 6 (11) ◽  
pp. 3407-3421 ◽  
Author(s):  
A. Virkkula ◽  
K. Teinilä ◽  
R. Hillamo ◽  
V.-M. Kerminen ◽  
S. Saarikoski ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Atlantic Ocean ◽  
Biomass Burning ◽  
High Volume ◽  
Sea Salt ◽  
Saharan Dust ◽  
Submicron Particles ◽  
Research Station ◽  
Anthropogenic Influence ◽  
Anthropogenic Aerosol

Abstract. Aerosol chemical composition was measured over the Atlantic Ocean in November–December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass apportionment was calculated for high volume filter samples (Dp<3 μm). North of the equator 70–80% of the aerosol consisted of non-sea-salt species. The contribution of sea salt was ~25% in the polluted latitudes, >80% in the Southern Ocean, and <10% at Aboa. The contribution of organic carbon was >10% in most samples, also at Aboa. The correlation of biomass-burning-related aerosol components with 210Pb was very high compared with that between nss calcium and 210Pb which suggests that 210Pb is a better tracer for biomass burning than for Saharan dust. The ratio of the two clear tracers for biomass burning, nss potassium and oxalate, was different in European and in African samples, suggesting that this ratio could be used as an indicator of biomass burning type. The concentrations of continent-related particles decreased exponentially with the distance from Africa. The shortest half-value distance, ~100 km, was for nss calcium. The half-value distance of particles that are mainly in the submicron particles was ~700±200 km. The MSA to nss sulfate ratio, R, increased faster than MSA concentration with decreasing anthropogenic influence, indicating that the R increase could largely be explained by the decrease of anthropogenic sulfate.

scholarly journals Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic site

2006 ◽  
Vol 6 (1) ◽  
pp. 455-491 ◽  
Author(s):  
A. Virkkula ◽  
K. Teinilä ◽  
R. Hillamo ◽  
V.-M. Kerminen ◽  
S. Saarikoski ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Atlantic Ocean ◽  
Biomass Burning ◽  
High Volume ◽  
Sea Salt ◽  
Saharan Dust ◽  
Submicron Particles ◽  
Research Station ◽  
Anthropogenic Influence ◽  
Anthropogenic Aerosol

Abstract. Aerosol chemical composition was measured over the Atlantic Ocean in November–December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass balance was calculated for high volume filter samples (Dp<3 μm). North of the equator 70–80% of the aerosol consisted of non-sea-salt species. The contribution of sea salt was ~25% in the polluted latitudes, >80% in the Southern Ocean, and <10% at Aboa. The contribution of organic carbon was >10% in most samples, also at Aboa. The correlation of biomass-burning-related aerosol components with 210Pb was very high compared with that between nss calcium and 210Pb which suggests that 210Pb is a better tracer for biomass burning than for Saharan dust. The ratio of the two clear tracers for biomass burning, nss potassium and oxalate, was different in European and in African samples, suggesting that this ratio could be used as an indicator of biomass burning type. The concentrations of continent-related particles decreased exponentially with the distance from Africa. The shortest half-value distance, ~100 km, was for nss calcium. The half-value distance of particles that are mainly in the submicron particles was ~700±200 km. The MSA to nss sulfate ratio, R, increased faster than MSA concentration with decreasing anthropogenic influence, indicating that the R increase could largely be explained by the decrease of anthropogenic sulfate.

scholarly journals Chemical composition and mixing-state of ice residuals sampled within mixed phase clouds

2010 ◽  
Vol 10 (10) ◽  
pp. 23865-23894 ◽  
Author(s):  
M. Ebert ◽  
A. Worringen ◽  
N. Benker ◽  
S. Mertes ◽  
E. Weingartner ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Mixed Phase ◽  
Research Station ◽  
Mixing State ◽  
Transmission Electron ◽  
Anthropogenic Component ◽  
Significant Enrichment ◽  
Alpine Research ◽  
The Individual ◽  
Mixed Phase Clouds

Abstract. During an intensive campaign at the high alpine research station Jungfraujoch, Switzerland, in February/March 2006 ice particle residuals within mixed-phase clouds were sampled using the Ice-counterflow virtual impactor (Ice-CVI). Size, morphology, chemical composition, mineralogy and mixing state of the ice residual and the interstitial (i.e., non-activated) aerosol particles were analyzed by scanning and transmission electron microscopy. Ice nuclei (IN) were identified from the significant enrichment of particle groups in the ice residual (IR) samples relative to the interstitial aerosol. In terms of number lead-bearing particles are enriched by a factor of approximately 25, complex internal mixtures with silicates or metal oxides as major components by a factor of 11, and mixtures of secondary aerosol and soot (C-O-S particles) by a factor of 2. Other particle groups (sulfates, sea salt, Ca-rich particles, external silicates) observed in the ice-residual samples cannot be assigned unambiguously as IN. Between 9 and 24% of all IR are Pb-bearing particles. Pb was found as major component in around 10% of these particles (PbO, PbCl2). In the other particles, Pb was found as some 100 nm sized agglomerates consisting of 3–8 nm sized primary particles (PbS, elemental Pb). C-O-S particles are present in the IR at an abundance of 17–27%. The soot component within these particles is strongly aged. Complex internal mixtures occur in the IR at an abundance of 9–15%. Most IN identified at the Jungfraujoch station are internal mixtures containing anthropogenic components (either as main or minor constituent), and it is concluded that admixture of the anthropogenic component is responsible for the increased IN efficiency within mixed phase clouds. The mixing state appears to be a key parameter for the ice nucleation behaviour that cannot be predicted from the separate components contained within the individual particles.

scholarly journals Mixing state and compositional effects on CCN activity and droplet growth kinetics of size-resolved CCN in an urban environment

2012 ◽  
Vol 12 (21) ◽  
pp. 10239-10255 ◽  
Author(s):  
L. T. Padró ◽  
R. H. Moore ◽  
X. Zhang ◽  
N. Rastogi ◽  
R. J. Weber ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Water Soluble ◽  
Anthropogenic Sources ◽  
Droplet Growth ◽  
Mixing State ◽  
Aerosol Composition ◽  
Activation Kinetics ◽  
Aerosol Mixing State ◽  
Kinetics Of ◽  
Ccn Activity

Abstract. Aerosol composition and mixing state near anthropogenic sources can be highly variable and can challenge predictions of cloud condensation nuclei (CCN). The impacts of chemical composition on CCN activation kinetics is also an important, but largely unknown, aspect of cloud droplet formation. Towards this, we present in-situ size-resolved CCN measurements carried out during the 2008 summertime August Mini Intensive Gas and Aerosol Study (AMIGAS) campaign in Atlanta, GA. Aerosol chemical composition was measured by two particle-into-liquid samplers measuring water-soluble inorganic ions and total water-soluble organic carbon. Size-resolved CCN data were collected using the Scanning Mobility CCN Analysis (SMCA) method and were used to obtain characteristic aerosol hygroscopicity distributions, whose breadth reflects the aerosol compositional variability and mixing state. Knowledge of aerosol mixing state is important for accurate predictions of CCN concentrations and that the influence of an externally-mixed, CCN-active aerosol fraction varies with size from 31% for particle diameters less than 40 nm to 93% for accumulation mode aerosol during the day. Assuming size-dependent aerosol mixing state and size-invariant chemical composition decreases the average CCN concentration overprediction (for all but one mixing state and chemical composition scenario considered) from over 190–240% to less than 20%. CCN activity is parameterized using a single hygroscopicity parameter, κ, which averages to 0.16 ± 0.07 for 80 nm particles and exhibits considerable variability (from 0.03 to 0.48) throughout the study period. Particles in the 60–100 nm range exhibited similar hygroscopicity, with a κ range for 60 nm between 0.06–0.076 (mean of 0.18 ± 0.09). Smaller particles (40 nm) had on average greater κ, with a range of 0.20–0.92 (mean of 0.3 ± 0.12). Analysis of the droplet activation kinetics of the aerosol sampled suggests that most of the CCN activate as rapidly as calibration aerosol, suggesting that aerosol composition exhibits a minor (if any) impact on CCN activation kinetics.

scholarly journals Measured and modelled cloud condensation nuclei number concentration at the high alpine site Jungfraujoch

2010 ◽  
Vol 10 (16) ◽  
pp. 7891-7906 ◽  
Author(s):  
Z. Jurányi ◽  
M. Gysel ◽  
E. Weingartner ◽  
P. F. DeCarlo ◽  
L. Kammermann ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Hydrological Cycle ◽  
Cloud Condensation Nuclei ◽  
Sensitivity Study ◽  
Research Station ◽  
Condensation Nuclei ◽  
Composition Data ◽  
Particle Mobility ◽  
Kohler Theory ◽  
Highly Correlated

Abstract. Atmospheric aerosol particles are able to act as cloud condensation nuclei (CCN) and are therefore important for the climate and the hydrological cycle, but their properties are not fully understood. Total CCN number concentrations at 10 different supersaturations in the range of SS=0.12–1.18% were measured in May 2008 at the remote high alpine research station, Jungfraujoch, Switzerland (3580 m a.s.l.). In this paper, we present a closure study between measured and predicted CCN number concentrations. CCN predictions were done using dry number size distribution (scanning particle mobility sizer, SMPS) and bulk chemical composition data (aerosol mass spectrometer, AMS, and multi-angle absorption photometer, MAAP) in a simplified Köhler theory. The predicted and the measured CCN number concentrations agree very well and are highly correlated. A sensitivity study showed that the temporal variability of the chemical composition at the Jungfraujoch can be neglected for a reliable CCN prediction, whereas it is important to know the mean chemical composition. The exact bias introduced by using a too low or too high hygroscopicity parameter for CCN prediction was further quantified and shown to be substantial for the lowest supersaturation. Despite the high average organic mass fraction (~45%) in the fine mode, there was no indication that the surface tension was substantially reduced at the point of CCN activation. A comparison between hygroscopicity tandem differential mobility analyzer (HTDMA), AMS/MAAP, and CCN derived κ values showed that HTDMA measurements can be used to determine particle hygroscopicity required for CCN predictions if no suitable chemical composition data are available.

scholarly journals Agronomic traits and chemical composition of single hybrids of sweet corn

2011 ◽  
Vol 29 (4) ◽  
pp. 531-536 ◽  
Author(s):  
Angela Kwiatkowski ◽  
Edmar Clemente ◽  
Carlos Alberto Scapim
Keyword(s):  
Chemical Composition ◽  
Crop Yield ◽  
Combining Ability ◽  
Grain Quality ◽  
Sweet Corn ◽  
Agronomic Traits ◽  
Block Design ◽  
Research Station ◽  
Randomized Block Design ◽  
Fixed Model

In Brazil, the greengrocery market of sweet corn has been expanding along the country. In contrast, there have been few agri-industries canning sweet corn (Zea mays) because of the lack of cultivars with agronomic characteristics proper to industrial purposes. The purpose of this study was to evaluate the general combining ability (GCA) of seven inbred lines of sweet corn, and the specific combining ability (SCA) of their hybrid combinations based on their agronomic traits, and the chemical composition of the grain. In the growing season 2006/2007, twenty-one single hybrids were evaluated in the Iguatemi Research Station, Maringá County, Northwestern Paraná, in Brazil using a complete randomized block design with four replications. Data were subjected to the analysis of variance and the genotypes were clustered by the Scott-Knott test. We estimated the GCA and SCA effects using the Griffing's method IV with the fixed model for plant height (PH), height of ear (EH), dehusked ears yield (DEY), reducing (RS) and total sugars (TS), starch (ST), proteins (PTN), ether extract (EE) and fibers (FB). The inbred line L4, which was originated from the 'Doce de Cuba', had the best GCA for crop yield and grain quality and therefore should be used in the next hybrid combinations. The hybrids L4xL5 and L3xL7 were the most promising with regard to crop yield and grain quality.

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