scholarly journals Ozonolysis of α-pinene: parameterization of secondary organic aerosol mass fraction

2007 ◽  
Vol 7 (1) ◽  
pp. 1941-1967 ◽  
Author(s):  
R. K. Pathak ◽  
A. A. Presto ◽  
T. E. Lane ◽  
C. O. Stanier ◽  
N. M. Donahue ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Organic Aerosol ◽  
Basis Set ◽  
Smog Chamber ◽  
Equilibrium Partitioning ◽  
Research Teams ◽  
Aerosol Mass ◽  
Wide Range ◽  
Mass Fractions ◽  
Dry Conditions

Abstract. Existing parameterizations tend to underpredict the α-pinene aerosol mass fraction (AMF) by a factor of 2–5 at low organic aerosol concentrations (<5 μg m−3). A wide range of smog chamber results obtained at various conditions (low/high NOx, presence/absence of UV radiation, dry/humid conditions, and temperatures ranging from 15–40°C) collected by various research teams during the last decade are used to derive new parameterizations of the SOA formation from α-pinene ozonolysis. Parameterizations are developed by fitting experimental data to a basis set of saturation concentrations (from 10−2 to 104 μg m−3) using an absorptive equilibrium partitioning model. Separate parameterizations for α-pinene SOA mass fractions are developed for: 1) Low NOx, dark, and dry conditions, 2) Low NOx, UV, and dry conditions, 3) Low NOx, dark, and high RH conditions, 4) High NOx, dark, and dry conditions, 5) High NOx, UV, and dry conditions. According to the proposed parameterizations the α-pinene SOA mass fractions in an atmosphere with 5 μg m−3 of organic aerosol range from 0.032 to 0.1 for reacted α-pinene concentrations in the 1 ppt to 5 ppb range.

scholarly journals Ozonolysis of α-pinene: parameterization of secondary organic aerosol mass fraction

2007 ◽  
Vol 7 (14) ◽  
pp. 3811-3821 ◽  
Author(s):  
R. K. Pathak ◽  
A. A. Presto ◽  
T. E. Lane ◽  
C. O. Stanier ◽  
N. M. Donahue ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Organic Aerosol ◽  
Basis Set ◽  
Smog Chamber ◽  
Equilibrium Partitioning ◽  
Research Teams ◽  
Aerosol Mass ◽  
Wide Range ◽  
Mass Fractions ◽  
Dry Conditions

Abstract. Existing parameterizations tend to underpredict the α-pinene aerosol mass fraction (AMF) or yield by a factor of 2–5 at low organic aerosol concentrations (<5 µg m−3). A wide range of smog chamber results obtained at various conditions (low/high NOx, presence/absence of UV radiation, dry/humid conditions, and temperatures ranging from 15–40°C) collected by various research teams during the last decade are used to derive new parameterizations of the SOA formation from α-pinene ozonolysis. Parameterizations are developed by fitting experimental data to a basis set of saturation concentrations (from 10−2 to 104 µg m−3) using an absorptive equilibrium partitioning model. Separate parameterizations for α-pinene SOA mass fractions are developed for: 1) Low NOx, dark, and dry conditions, 2) Low NOx, UV, and dry conditions, 3) Low NOx, dark, and high RH conditions, 4) High NOx, dark, and dry conditions, 5) High NOx, UV, and dry conditions. According to the proposed parameterizations the α-pinene SOA mass fractions in an atmosphere with 5 µg m−3 of organic aerosol range from 0.032 to 0.1 for reacted α-pinene concentrations in the 1 ppt to 5 ppb range.

scholarly journals Volatility of organic aerosol and its components in the megacity of Paris

2016 ◽  
Vol 16 (4) ◽  
pp. 2013-2023 ◽  
Author(s):  
Andrea Paciga ◽  
Eleni Karnezi ◽  
Evangelia Kostenidou ◽  
Lea Hildebrandt ◽  
Magda Psichoudaki ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Basis Set ◽  
Transfer Model ◽  
Collaborative Project ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Combining Data ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Effective Saturation

Abstract. Using a mass transfer model and the volatility basis set, we estimate the volatility distribution for the organic aerosol (OA) components during summer and winter in Paris, France as part of the collaborative project MEGAPOLI. The concentrations of the OA components as a function of temperature were measured combining data from a thermodenuder and an aerosol mass spectrometer (AMS) with Positive Matrix Factorization (PMF) analysis. The hydrocarbon-like organic aerosol (HOA) had similar volatility distributions for the summer and winter campaigns with half of the material in the saturation concentration bin of 10 µg m−3 and another 35–40 % consisting of low and extremely low volatility organic compounds (LVOCs with effective saturation concentrations C* of 10−3–0.1 µg m−3 and ELVOCs C* less or equal than 10−4 µg m−3, respectively). The winter cooking OA (COA) was more than an order of magnitude less volatile than the summer COA. The low-volatility oxygenated OA (LV-OOA) factor detected in the summer had the lowest volatility of all the derived factors and consisted almost exclusively of ELVOCs. The volatility for the semi-volatile oxygenated OA (SV-OOA) was significantly higher than that of the LV-OOA, containing both semi-volatile organic components (SVOCs with C* in the 1–100 µg m−3 range) and LVOCs. The oxygenated OA (OOA) factor in winter consisted of SVOCs (45 %), LVOCs (25 %) and ELVOCs (30 %). The volatility of marine OA (MOA) was higher than that of the other factors containing around 60 % SVOCs. The biomass burning OA (BBOA) factor contained components with a wide range of volatilities with significant contributions from both SVOCs (50 %) and LVOCs (30 %). Finally, combining the bulk average O : C ratios and volatility distributions of the various factors, our results are placed into the two-dimensional volatility basis set (2D-VBS) framework. The OA factors cover a broad spectrum of volatilities with no direct link between the average volatility and average O : C of the OA components.

scholarly journals Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere

2013 ◽  
Vol 13 (19) ◽  
pp. 9819-9835 ◽  
Author(s):  
A. Wonaschütz ◽  
M. Coggon ◽  
A. Sorooshian ◽  
R. Modini ◽  
A. A. Frossard ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Marine Atmosphere ◽  
Hygroscopic Growth ◽  
Organic Mass ◽  
Aerosol Mass ◽  
Hygroscopic Properties ◽  
Mass Fractions

Abstract. During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs): between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH) of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm−3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C) and water-soluble organic mass (WSOM) increased with plume age: from < 0.001 to 0.2, and from 2.42 to 4.96 μg m−3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

scholarly journals Volatility of organic aerosol and its components in the Megacity of Paris

2015 ◽  
Vol 15 (16) ◽  
pp. 22263-22289 ◽  
Author(s):  
A. Paciga ◽  
E. Karnezi ◽  
E. Kostenidou ◽  
L. Hildebrandt ◽  
M. Psichoudaki ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Basis Set ◽  
Transfer Model ◽  
Collaborative Project ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Combining Data ◽  
Wide Range ◽  
Volatile Organic ◽  
Order Of Magnitude

Abstract. Using a mass transfer model and the volatility basis set, we estimate the volatility distribution for the organic aerosol (OA) components during summer and winter in Paris, France as part of the collaborative project MEGAPOLI. The concentrations of the OA components as a function of temperature were measured combining data from a thermodenuder and an aerosol mass spectrometer (AMS) with Positive Matrix Factorization (PMF) analysis. The hydrocarbon-like organic aerosol (HOA) had similar volatility distributions for the summer and winter campaigns with half of the material in the saturation concentration bin of 10 μg m−3 and another 35–40 % consisting of low and extremely low volatility organic compounds (LVOCs and ELVOCs, respectively). The winter cooking OA (COA) was more than an order of magnitude less volatile than the summer COA. The low volatility oxygenated OA (LV-OOA) factor detected in the summer had the lowest volatility of all the derived factors and consisted almost exclusively of ELVOCs. The volatility for the semi-volatile oxygenated OA (SV-OOA) was significantly higher than that of the LV-OOA, containing both semi-volatile organic components (SVOCs) and LVOCs. The oxygenated OA (OOA) factor in winter consisted of SVOCs (45 %), LVOCs (25 %) and ELVOCs (30 %). The volatility of marine OA (MOA) was higher than that of the other factors containing around 60 % SVOCs. The biomass burning OA (BBOA) factor contained components with a wide range of volatilities with significant contributions from both SVOCs (50 %) and LVOCs (30 %). Finally, combining the O : C ratio and volatility distributions of the various factors, we incorporated our results into the two-dimensional volatility basis set (2D-VBS). Our results show that the factors cover a broad spectrum of volatilities with no direct link between the average volatility and average O : C of the OA components. Agreement between our findings and previous publications is encouraging for our understanding of the evolution of atmospheric OA.

Parameterization of secondary organic aerosol mass fractions from smog chamber data

2008 ◽  
Vol 42 (10) ◽  
pp. 2276-2299 ◽  
Author(s):  
Charles O. Stanier ◽  
Neil Donahue ◽  
Spyros N. Pandis
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Smog Chamber ◽  
Aerosol Mass ◽  
Mass Fractions

scholarly journals Constraining a hybrid volatility basis set model for aging of wood burning emissions using smog chamber experiments

2016 ◽  
Author(s):  
Giancarlo Ciarelli ◽  
Imad El Haddad ◽  
Emily Bruns ◽  
Sebnem Aksoyoglu ◽  
Ottmar Möhler ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Organic Aerosol ◽  
Reaction Rates ◽  
Box Model ◽  
Basis Set ◽  
Smog Chamber ◽  
Aerosol Mass ◽  
Volatile Organic ◽  
Different Temperatures

Abstract. Semi-volatile and intermediate volatility organic compounds (SVOCs, IVOCs) are not included in the current non-methane volatile organic compounds (NMVOCs) emission inventories but may be important for the formation of secondary organic aerosol (SOA). In this study, novel wood combustion aging experiments performed at different temperatures (263 K and 288 K) in a ~7 m3 smog chamber were modelled using a hybrid volatility basis set (VBS) box model, representing the emission partitioning and their oxidation against OH. We combine aerosol-chemistry box model simulations with unprecedented measurements of nontraditional volatile organic compounds (NTVOCs) from a high-resolution proton transfer reaction mass spectrometer (PTR-MS) and with organic aerosol measurements from an aerosol mass spectrometer (AMS). In so-doing, we are able to observationally-constrain the amounts of different NTVOCs aerosol precursors (in the model) relative to low-volatility and semi-volatile primary organic material (OMsv) which is partitioned based on current published volatility distribution data. By comparing the NTVOCs/OMsv ratios at different temperatures, we determine the enthalpies of vaporization of primary biomass burning organic aerosols. Further, the developed model allows for evaluating the evolution of oxidation products of the semi-volatile and volatile precursors with aging. More than 30,000 box model simulations were performed to retrieve the combination of parameters that fit best the observed organic aerosol mass and O:C ratios. The parameters investigated include the NTVOC reaction rates and yields as well as enthalpies of vaporization and the O:C of secondary organic aerosol surrogates. Our results suggest an average ratio of NTVOCs to the sum of non-volatile and semi-volatile organic compounds of ~4.75. The mass yields of these compounds determined for a wide range of atmospherically relevant temperatures and organic aerosol (OA) concentrations were predicted to vary between 8 and 30 % after 5 hours of continuous aging. Based on the reaction scheme used, reaction rates of the NTVOC mixture range from 3.0 × 10–11 cm3 molec−1 s−1 to 4.0 × 10–11 cm3 molec−1 s−1. The average enthalpy of vaporization of SOA surrogates was determined to be between 55,000 J mol−1 and 35,000 J mol−1 which implies a yield increase of 0.03–0.06 % K−1 with decreasing temperature. The improved VBS scheme is suitable for implementation into chemical transport models to predict the burden and oxidation state of primary and secondary biomass burning aerosols.

scholarly journals Constraining a hybrid volatility basis-set model for aging of wood-burning emissions using smog chamber experiments: a box-model study based on the VBS scheme of the CAMx model (v5.40)

2017 ◽  
Vol 10 (6) ◽  
pp. 2303-2320 ◽  
Author(s):  
Giancarlo Ciarelli ◽  
Imad El Haddad ◽  
Emily Bruns ◽  
Sebnem Aksoyoglu ◽  
Ottmar Möhler ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Organic Aerosol ◽  
Reaction Rates ◽  
Box Model ◽  
Basis Set ◽  
Smog Chamber ◽  
Model Simulations ◽  
Aerosol Mass ◽  
Volatile Organic ◽  
Different Temperatures

Abstract. In this study, novel wood combustion aging experiments performed at different temperatures (263 and 288 K) in a ∼ 7 m3 smog chamber were modelled using a hybrid volatility basis set (VBS) box model, representing the emission partitioning and their oxidation against OH. We combine aerosol–chemistry box-model simulations with unprecedented measurements of non-traditional volatile organic compounds (NTVOCs) from a high-resolution proton transfer reaction mass spectrometer (PTR-MS) and with organic aerosol measurements from an aerosol mass spectrometer (AMS). Due to this, we are able to observationally constrain the amounts of different NTVOC aerosol precursors (in the model) relative to low volatility and semi-volatile primary organic material (OMsv), which is partitioned based on current published volatility distribution data. By comparing the NTVOC ∕ OMsv ratios at different temperatures, we determine the enthalpies of vaporization of primary biomass-burning organic aerosols. Further, the developed model allows for evaluating the evolution of oxidation products of the semi-volatile and volatile precursors with aging. More than 30 000 box-model simulations were performed to retrieve the combination of parameters that best fit the observed organic aerosol mass and O : C ratios. The parameters investigated include the NTVOC reaction rates and yields as well as enthalpies of vaporization and the O : C of secondary organic aerosol surrogates. Our results suggest an average ratio of NTVOCs to the sum of non-volatile and semi-volatile organic compounds of ∼ 4.75. The mass yields of these compounds determined for a wide range of atmospherically relevant temperatures and organic aerosol (OA) concentrations were predicted to vary between 8 and 30 % after 5 h of continuous aging. Based on the reaction scheme used, reaction rates of the NTVOC mixture range from 3.0 × 10−11 to 4. 0 × 10−11 cm3 molec−1 s−1. The average enthalpy of vaporization of secondary organic aerosol (SOA) surrogates was determined to be between 55 000 and 35 000 J mol−1, which implies a yield increase of 0.03–0.06 % K−1 with decreasing temperature. The improved VBS scheme is suitable for implementation into chemical transport models to predict the burden and oxidation state of primary and secondary biomass-burning aerosols.

scholarly journals The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

2012 ◽  
Vol 12 (18) ◽  
pp. 8711-8726 ◽  
Author(s):  
T. E. Kleindienst ◽  
M. Jaoui ◽  
M. Lewandowski ◽  
J. H. Offenberg ◽  
K. S. Docherty
Keyword(s):  
Nitrogen Oxides ◽  
Phthalic Anhydride ◽  
Mass Fraction ◽  
Phthalic Acid ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Primary Sources ◽  
Smog Chamber ◽  
Mass Fractions ◽  
Presence And Absence

Abstract. Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA) formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2-MN, respectively). Laboratory smog chamber irradiations were conducted in a flow mode to ensure adequate collection of the aerosol at reasonably low reactant concentrations and in the presence and absence of nitrogen oxides. Phthalic acid and methyl analogs were identified following BSTFA derivatization of the aerosol extract. These compounds were examined to determine whether they could serve as reasonable molecular tracers to estimate the contributions of these precursors to ambient PM2.5. Measurements were also made to determine aerosol parameters from secondary organic aerosol from naphthalene, 1-MN, and 2-MN. A mass fraction approach was used to establish factors which could be applied to phthalic acid concentrations in ambient aerosols, assuming a negligible contribution from primary sources. Phthalic anhydride uptake (and hydrolysis) was tested and found to represent a moderate filter artifact in filter measurements with and without in-line denuders. This study provided the opportunity to examine differences using authentic standards for phthalic acid compared to surrogate standards. While the mass fraction based on a surrogate compounds was somewhat lower, the differences are largely unimportant. For naphthalene, mass fractions of 0.0199 (recommended for ambient samples) and 0.0206 were determined in the presence and absence of nitrogen oxides, respectively, based on phthalic acid standards. The mass fractions determined from the laboratory data were applied to ambient samples where phthalic acid was found and expressed "as naphthalene" since phthalic acid was found to be produced in the particle phase from other methylnaphthalenes. The mass fraction values were applied to samples taken during the 2005 SOAR Study in Riverside, CA and 2010 CalNex Study in Pasadena. In both studies an undetermined isomer of methylphthalic acid was detected in addition to phthalic acid. Laboratory experiment retention times and mass spectra suggest that the major precursor for this compound is 2-MN. For the CalNex Study, SOC values for the 2-ring precursor PAHs (as naphthalene) were found to range from below the detection limit to 20 ngC m−3 which with the laboratory mass fraction data suggests an upper limit of approximately 1 μg m−3 for SOA due to 2-ring PAHs. Temporal data over the course of the one-month CalNex study suggest that primary sources of phthalic acid were probably negligible during this study period. However, the values must still be considered upper limits given a potential hydrolysis reaction or uptake of phthalic anhydride (subsequently hydrolyzed) onto the collection media.

scholarly journals Hygroscopic properties of organic aerosol particles emitted in the marine atmosphere

2013 ◽  
Vol 13 (5) ◽  
pp. 11919-11969 ◽  
Author(s):  
A. Wonaschütz ◽  
M. Coggon ◽  
A. Sorooshian ◽  
R. Modini ◽  
A. A. Frossard ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Cloud Condensation Nuclei ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Marine Atmosphere ◽  
Hygroscopic Growth ◽  
Organic Mass ◽  
Aerosol Mass ◽  
Hygroscopic Properties ◽  
Mass Fractions

Abstract. During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced and emitted into the marine atmosphere from aboard the research vessel R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, hygroscopic growth factors (GFs) at a relative humidity (RH) of 92% were low, but increased at higher plume ages: from 1.05 to 1.09 for 30 nm and from 1.05 to 1.1 for 150 nm dry size (contrasted by an average marine background GF of 1.6). Simultaneously, ratios of oxygen to carbon (O:C) increased from < 0.001 to 0.2, water-soluble organic mass (WSOM) concentrations increased from 2.42 to 4.96 μg m−3, and organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). New particles were produced in large quantities (several 10 000 cm−3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07–0.88%. High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions. An average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, a GF of 1.04 for an organic mass fraction of 0.35.

scholarly journals The formation of SOA and chemical tracer compounds from the photooxidation of naphthalene and its methyl analogs in the presence and absence of nitrogen oxides

2012 ◽  
Vol 12 (5) ◽  
pp. 12163-12201 ◽  
Author(s):  
T. E. Kleindienst ◽  
M. Jaoui ◽  
M. Lewandowski ◽  
J. H. Offenberg ◽  
K. S. Docherty
Keyword(s):  
Nitrogen Oxides ◽  
Gas Phase ◽  
Phthalic Anhydride ◽  
Mass Fraction ◽  
Phthalic Acid ◽  
Organic Aerosol ◽  
Primary Sources ◽  
Smog Chamber ◽  
Mass Fractions ◽  
Presence And Absence

Abstract. Laboratory smog chamber experiments have been carried out to investigate secondary organic aerosol (SOA) formation from the photooxidation of naphthalene and its methyl analogs, 1- and 2-methylnaphthalene (1-MN and 2-MN, respectively). Laboratory smog chamber irradiations were conducted in a flow mode to ensure adequate collection of the aerosol at reasonably low reactant concentrations and in the presence and absence of nitrogen oxides. Phthalic acid and methyl analogs were identified following BSTFA derivatization of the aerosol extract. These compounds were examined to determine whether they could serve as reasonable molecular tracers to estimate the contributions of these precursors to ambient PM2.5. Measurements were also made to determine aerosol parameters from secondary organic aerosol from naphthalene, 1-MN, and 2-MN. A mass fraction approach was used to establish factors which could be applied to phthalic acid concentrations in ambient aerosols, assuming a negligible contribution from primary sources. In addition, the hydrolysis of phthalic anhydride was tested and found to represent a moderate filter artifact in side-by-side filter measurements with and without in-line denuders. This study also provided the opportunity to examine numeric differences using authentic standards for phthalic acid compared to surrogate standards. While the mass fraction based on a surrogate compounds was somewhat lower, the differences are largely unimportant. For naphthalene, mass fractions of 0.023 and 0.019 were determined in the presence and absence of nitrogen oxides, respectively, based on the phthalic acid standards. The mass fractions determined from the laboratory data were then applied to ambient samples where phthalic acid was found and expressed "as naphthalene" since phthalic acid was found to be produced in the particle phase from other PAHs tested. The mass fraction values were applied to samples taken during the 2005 SOAR Study in Riverside, CA and 2010 CalNex Study in Pasadena. In both studies an undetermined isomer of methylphthalic acid was detected in addition to phthalic acid. Laboratory experiment retention times and mass spectra suggest that the major precursor for this compound is 2-MN. For the CalNex Study, SOC values for the gas-phase PAHs (as naphthalene) were found to range from below the detection limit to 20 ng C m−3 which together with the laboratory mass fraction data suggests an upper limit of 1 μg m−3 for SOA due to PAHs. Temporal data over the course of the one-month CalNex study suggest that primary sources of phthalic acid were probably negligible during this study period. However, the values must still be considered upper limits given a potential gas-phase hydrolysis reaction or uptake of phthalic anhydride (subsequently hydrolyzed) onto the collection medium.

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