Water uptake of humic and fulvic acid: measurements and modelling using single parameter Köhler theory

2009 ◽  
Vol 6 (5) ◽  
pp. 380 ◽  
Author(s):  
Courtney D. Hatch ◽  
Kelly M. Gierlus ◽  
James Zahardis ◽  
Jennifer Schuttlefield ◽  
Vicki H. Grassian
Keyword(s):  
Thin Films ◽  
Surface Tension ◽  
Ftir Spectroscopy ◽  
Fulvic Acid ◽  
Water Uptake ◽  
Fulvic Acids ◽  
Single Parameter ◽  
Critical Parameters ◽  
Hygroscopic Growth ◽  
Kohler Theory

Environmental context. Humic and fulvic acids are macromolecular, multifunctional, polyacidic compounds that are important proxies for humic-like substances (HULIS), which are ubiquitous components of tropospheric particulate matter. The hygroscopic nature of these substances suggests that they can contribute to direct and indirect climate forcing. Thus, the effects of water uptake in humic-like particles in the atmosphere must be well understood. Abstract. The water uptake of humic and fulvic acid aerosols was determined by hygroscopic tandem differential mobility analysis (hTDMA) and extinction Fourier transform infrared (FTIR) spectroscopy. Water uptake on humic and fulvic acid thin films was also investigated using attenuated total reflectance (ATR) FTIR spectroscopy. The hygroscopic growth of monodisperse, 100-nm (dry) Suwannee River fulvic acid (SRFA) and humic acid sodium salt (NaHA) aerosols was determined and modelled using Köhler theory. A single parameter, the ionic density (ρion), which contains physical properties that are not well established for these substances, was determined for SRFA and NaHA to be 2.1 × 10–3 and 7.0 × 10–3 mol cm–3 respectively. The hygroscopic growth was then modelled using the ρion-Köhler equation and the critical parameters determined. The critical percent supersaturation of SRFA and NaHA was determined to be 0.60 and 0.33% respectively using the surface tension of water; and 0.35 and 0.19% respectively using the surface tension of aqueous HULIS. κ-Köhler theory, was also used to calculate the critical supersaturation and was found to be in good agreement with the ρion representation. Both extinction FTIR of aerosols and ATR-FTIR absorption measurements of thin films confirm enhanced water uptake with increasing relative humidity (RH).

scholarly journals Aerosol water parameterisation: a single parameter framework

2016 ◽  
Vol 16 (11) ◽  
pp. 7213-7237 ◽  
Author(s):  
Swen Metzger ◽  
Benedikt Steil ◽  
Mohamed Abdelkader ◽  
Klaus Klingmüller ◽  
Li Xu ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Water Uptake ◽  
Climate Model ◽  
Mixed Solution ◽  
Hygroscopic Growth ◽  
Simple Method ◽  
Aerosol Model ◽  
Kohler Theory ◽  
Comprehensive Comparison ◽  
Term Evaluation

Abstract. We introduce a framework to efficiently parameterise the aerosol water uptake for mixtures of semi-volatile and non-volatile compounds, based on the coefficient, νi. This solute-specific coefficient was introduced in Metzger et al. (2012) to accurately parameterise the single solution hygroscopic growth, considering the Kelvin effect – accounting for the water uptake of concentrated nanometer-sized particles up to dilute solutions, i.e. from the compounds relative humidity of deliquescence (RHD) up to supersaturation (Köhler theory). Here we extend the νi parameterisation from single to mixed solutions. We evaluate our framework at various levels of complexity, by considering the full gas–liquid–solid partitioning for a comprehensive comparison with reference calculations using the E-AIM, EQUISOLV II and ISORROPIA II models as well as textbook examples. We apply our parameterisation in the EQuilibrium Simplified Aerosol Model V4 (EQSAM4clim) for climate simulations, implemented in a box model and in the global chemistry–climate model EMAC. Our results show (i) that the νi approach enables one to analytically solve the entire gas–liquid–solid partitioning and the mixed solution water uptake with sufficient accuracy, (ii) that ammonium sulfate mixtures can be solved with a simple method, e.g. pure ammonium nitrate and mixed ammonium nitrate and (iii) that the aerosol optical depth (AOD) simulations are in close agreement with remote sensing observations for the year 2005. Long-term evaluation of the EMAC results based on EQSAM4clim and ISORROPIA II will be presented separately.

scholarly journals Aerosol water parameterization: a single parameter framework

2015 ◽  
Vol 15 (22) ◽  
pp. 33493-33553
Author(s):  
S. Metzger ◽  
B. Steil ◽  
M. Abdelkader ◽  
K. Klingmüller ◽  
L. Xu ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Water Uptake ◽  
Climate Model ◽  
Mixed Solution ◽  
Hygroscopic Growth ◽  
Simple Method ◽  
Aerosol Model ◽  
Kohler Theory ◽  
Comprehensive Comparison ◽  
Term Evaluation

Abstract. We introduce a framework to efficiently parameterize the aerosol water uptake for mixtures of semi-volatile and non-volatile compounds, based on the coefficient, νi. This solute specific coefficient was introduced in Metzger et al. (2012) to accurately parameterize the single solution hygroscopic growth, considering the Kelvin effect – accounting for the water uptake of concentrated nanometer sized particles up to dilute solutions, i.e., from the compounds relative humidity of deliquescence (RHD) up to supersaturation (Köhler-theory). Here we extend the νi-parameterization from single to mixed solutions. We evaluate our framework at various levels of complexity, by considering the full gas-liquid-solid partitioning for a comprehensive comparison with reference calculations using the E-AIM, EQUISOLV II, ISORROPIA II models as well as textbook examples. We apply our parameterization in EQSAM4clim, the EQuilibrium Simplified Aerosol Model V4 for climate simulations, implemented in a box model and in the global chemistry-climate model EMAC. Our results show: (i) that the νi-approach enables to analytically solve the entire gas-liquid-solid partitioning and the mixed solution water uptake with sufficient accuracy, (ii) that, e.g., pure ammonium nitrate and mixed ammonium nitrate – ammonium sulfate mixtures can be solved with a simple method, and (iii) that the aerosol optical depth (AOD) simulations are in close agreement with remote sensing observations for the year 2005. Long-term evaluation of the EMAC results based on EQSAM4clim and ISORROPIA II will be presented separately.

scholarly journals Joint effect of organic acids and inorganic salts on cloud droplet activation

2011 ◽  
Vol 11 (8) ◽  
pp. 3895-3911 ◽  
Author(s):  
M. Frosch ◽  
N. L. Prisle ◽  
M. Bilde ◽  
Z. Varga ◽  
G. Kiss
Keyword(s):  
Surface Tension ◽  
Sodium Chloride ◽  
Organic Acids ◽  
Aqueous Solutions ◽  
Fulvic Acid ◽  
Water Activity ◽  
Inorganic Salt ◽  
Cloud Droplet ◽  
Surface Partitioning ◽  
Kohler Theory

Abstract. We have investigated CCN properties of internally mixed particles composed of one organic acid (oxalic acid dihydrate, succinic acid, adipic acid, citric acid, cis-pinonic acid, or Nordic reference fulvic acid) and one inorganic salt (sodium chloride or ammonium sulphate). Surface tension and water activity of aqueous model solutions with concentrations relevant for CCN activation were measured using a tensiometer and osmometry, respectively. The measurements were used to calculate Köhler curves and critical supersaturations, which were compared to measured critical supersaturations of particles with the same chemical compositions, determined with a cloud condensation nucleus counter. Surfactant surface partitioning was not accounted for. For the aqueous solutions containing cis-pinonic acid and fulvic acid, a depression of surface tension was observed, but for the remaining solutions the effect on surface tension was negligible at concentrations relevant for cloud droplet activation. The surface tension depression of aqueous solutions containing both organic acid and inorganic salt was approximately the same as or smaller than that of aqueous solutions containing the same mass of the corresponding pure organic acids. Water activity was found to be highly dependent on the type and amount of inorganic salt. Sodium chloride was able to decrease water activity more than ammonium sulphate and both inorganic salts are predicted to have a smaller Raoult term than the studied organic acids. Increasing the mass ratio of the inorganic salt led to a decrease in water activity. Water activity measurements were compared to results from the E-AIM model and values estimated from both constant and variable van't Hoff factors. The correspondence between measurements and estimates was overall good, except for highly concentrated solutions. Critical supersaturations calculated with Köhler theory based on measured water activity and surface tension, but not accounting for surface partitioning, compared well with measurements, except for the solutions containing sodium chloride and oxalic acid or one of the more surface active organic compounds. In such cases, significantly lower values were obtained from Köhler theory than the measured critical supersaturations with deviations above 50% for a 60 nm particle containing 50% (dry mass) of Nordic reference fulvic acid, suggesting that surfactant partitioning and/or an effect of sodium chloride on solubility of the organic component is important.

scholarly journals Reconciliation of measurements of hygroscopic growth and critical supersaturation of aerosol particles in central Germany

2010 ◽  
Vol 10 (23) ◽  
pp. 11737-11752 ◽  
Author(s):  
M. Irwin ◽  
N. Good ◽  
J. Crosier ◽  
T. W. Choularton ◽  
G. McFiggans
Keyword(s):  
Growth Factors ◽  
Water Uptake ◽  
Single Parameter ◽  
Hygroscopic Growth ◽  
Aerosol Composition ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Hygroscopic Properties ◽  
Critical Supersaturation ◽  
Activity Measurements

Abstract. Aerosol physical, chemical and hygroscopic properties were measured in a range of airmasses during COPS (Convective and Orographically-induced Precipitation Study) ground-based in June and July of 2007 at the Hornisgrinde mountain site in the Black Forest, Southwest Germany. Non-refractory aerosol composition was measured with an Aerosol Mass Spectrometer, simultaneous to hygroscopic growth factors at 86% relative humidity and CCN activity measurements for particles of dry (<20%) diameters 27 to 217 nm, with particle water uptake exhibiting substantial variability with time and with particle size. Variability in the measurements of hygroscopic growth factor and critical supersaturation for particles of similar sizes indicates significant compositional impact on particle water affinity. Critical supersaturation prediction using a single parameter hygroscopicity approximation derived from measured HTDMA mean growth factors deviate, beyond measurement uncertainties, from critical supersaturations derived from CCN measurements. These led to differences averaging around 35% in the number of CCN (NCCN) for the most reliable measurements depending on averaging methodology, often very much larger for individual time periods. This indicates aspects of water uptake behaviour unresolved in this experiment by the single parameter representation which, depending on its origin, may have important consequences on its generalised use.

scholarly journals A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 3: Including surfactant partitioning

2012 ◽  
Vol 12 (9) ◽  
pp. 22687-22712 ◽  
Author(s):  
M. D. Petters ◽  
S. M. Kreidenweis
Keyword(s):  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Condensation Nucleus ◽  
Single Parameter ◽  
Cloud Condensation Nucleus ◽  
Extended Model ◽  
Hygroscopic Growth ◽  
Analytical Approximations ◽  
Critical Supersaturation ◽  
Kohler Theory

Abstract. Atmospheric particles can serve as cloud condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of cloud condensation nucleus activity. The presented formulation incorporates the analytical approximations introduced by Raatikainen and Laaksonen to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code. We apply this extended model to discuss several uncertainties that hinder our ability to precisely pinpoint the role of surface tension in cloud droplet activation with current measurement and data analysis approaches.

scholarly journals Discontinuities in hygroscopic growth below and above water saturation for laboratory surrogates of oligomers in organic atmospheric aerosols

2016 ◽  
Vol 16 (19) ◽  
pp. 12767-12792 ◽  
Author(s):  
Natasha Hodas ◽  
Andreas Zuend ◽  
Katherine Schilling ◽  
Thomas Berkemeier ◽  
Manabu Shiraiwa ◽  
...  
Keyword(s):  
Surface Tension ◽  
Molecular Mass ◽  
Water Uptake ◽  
Atmospheric Aerosols ◽  
Water Saturation ◽  
Ambient Atmosphere ◽  
Hygroscopic Growth ◽  
Water Diffusivity ◽  
Molecular Masses ◽  
Ccn Activity

Abstract. Discontinuities in apparent hygroscopicity below and above water saturation have been observed for organic and mixed organic–inorganic aerosol particles in both laboratory studies and in the ambient atmosphere. However, uncertainty remains regarding the factors that contribute to observations of low hygroscopic growth below water saturation but enhanced cloud condensation nuclei (CCN) activity for a given aerosol population. Utilizing laboratory surrogates for oligomers in atmospheric aerosols, we explore the extent to which such discontinuities are influenced by organic component molecular mass and viscosity, non-ideal thermodynamic interactions between aerosol components, and the combination of these factors. Measurements of hygroscopic growth under subsaturated conditions and the CCN activity of aerosols comprised of polyethylene glycol (PEG) with average molecular masses ranging from 200 to 10 000 g mol−1 and mixtures of PEG with ammonium sulfate (AS) were conducted. Experimental results are compared to calculations of hygroscopic growth at thermodynamic equilibrium conducted with the Aerosol Inorganic Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model, and the potential influence of kinetic limitations on observed water uptake was further explored through estimations of water diffusivity in the PEG oligomers. Particle-phase behavior, including the prevalence of liquid–liquid phase separation (LLPS), was also modeled with AIOMFAC. Under subsaturated relative humidity (RH) conditions, we observed little variability in hygroscopic growth across PEG systems with different molecular masses; however, an increase in CCN activity with increasing PEG molecular mass was observed. This effect is most pronounced for PEG–AS mixtures, and, in fact, an enhancement in CCN activity was observed for the PEG10000–AS mixture as compared to pure AS, as evidenced by a 15 % reduction in critical activation diameter at a supersaturation of 0.8 %. We also observed a marked increase in apparent hygroscopicity for mixtures of higher molecular mass PEG and AS under supersaturated conditions as compared to subsaturated hygroscopic growth. AIOMFAC-based predictions and estimations of water diffusivity in PEG suggest that such discontinuities in apparent hygroscopicity above and below water saturation can be attributed, at least in part, to differences in the sensitivity of water uptake behavior to surface tension effects. There is no evidence that kinetic limitations to water uptake due to the presence of viscous aerosol components influenced hygroscopic growth. For the systems that display an enhancement in apparent hygroscopicity above water saturation, LLPS is predicted to persist to high RH. This indicates a miscibility gap and is likely to influence bulk-to-surface partitioning of PEG at high RH, impacting droplet surface tension and CCN activity. This work provides insight into the factors likely to be contributing to discontinuities in aerosol water-uptake behavior below and above water saturation that have been observed previously in the ambient atmosphere.

scholarly journals A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 3: Including surfactant partitioning

2013 ◽  
Vol 13 (2) ◽  
pp. 1081-1091 ◽  
Author(s):  
M. D. Petters ◽  
S. M. Kreidenweis
Keyword(s):  
Cloud Condensation Nuclei ◽  
Condensation Nucleus ◽  
Single Parameter ◽  
Cloud Condensation Nucleus ◽  
Hygroscopic Growth ◽  
Analytical Approximations ◽  
Critical Supersaturation ◽  
Kohler Theory ◽  
Surface Active ◽  
Surface Active Compounds

Abstract. Atmospheric particles can serve as cloud condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of cloud condensation nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code.

scholarly journals Secondary aerosol formation promotes water uptake by organic-rich wildfire haze particles in Equatorial Asia

2017 ◽  
Author(s):  
Jing Chen ◽  
Sri Hapsari Budisulistiorini ◽  
Takuma Miyakawa ◽  
Yuichi Komazaki ◽  
Mikinori Kuwata
Keyword(s):  
Water Uptake ◽  
Mass Fraction ◽  
Water Soluble ◽  
Submicron Particles ◽  
Chemical Information ◽  
Hygroscopic Growth ◽  
Aerosol Formation ◽  
Secondary Formation ◽  
Soluble Organic Fraction ◽  
Haze Episode

Abstract. Diameter growth factors (GF) of 100 nm haze particles at 85 % relative humidity and chemical characteristics were simultaneously monitored at Singapore in October 2015 during a pervasive wildfire haze episode, which was caused by peatland burning in Indonesia. Non-refractory submicron particles (NR-PM1) were dominated by organics (approximating 77.1 % in total mass), whereas sulfate was the most abundant inorganic constituent (11.7 % on average). A statistical analysis of the organic mass spectra showed that most of organics (36.0 % of NR-PM1 mass) were highly oxygenated. Diurnal variations of GF, number fraction of highly hygroscopic mode particles, mass fraction of sulfate, and mass fraction of oxygenated organics (OOA) synchronized well, peaking during daytime. The mean hygroscopicity parameter (κ) of haze particles was 0.189 ± 0.087, and mean κ values of organics were 0.157 ± 0.108 (κorg, bulk organics) and 0.287 ± 0.193 (κOOA, OOA), demonstrating the important roles of both sulfate and highly oxygenated organics in hygroscopic growth of wildfire haze particles. κorg was also affected by the water-soluble organic fraction to some extent. These results show the importance of secondary formation processes in promoting water uptake properties of wildfire haze particles, including both inorganic and organic species. Further detailed size-resolved as well as molecular level chemical information of organics will be necessary for more profound exploration of water uptake by wildfire haze particles in Equatorial Asia.

scholarly journals A thermodynamic description for the hygroscopic growth of atmospheric aerosol particles

2018 ◽  
Vol 18 (20) ◽  
pp. 14939-14948 ◽  
Author(s):  
Dimitri Castarède ◽  
Erik S. Thomson
Keyword(s):  
Radiative Forcing ◽  
Thermodynamic Description ◽  
Liquid Droplets ◽  
Hygroscopic Growth ◽  
Salt Particle ◽  
Aerosol Radiative Forcing ◽  
Condensation Nucleation ◽  
Kohler Theory ◽  
Kelvin Effect ◽  
Brine Layer

Abstract. The phase state of atmospheric particulate is important to atmospheric processes, and aerosol radiative forcing remains a large uncertainty in climate predictions. That said, precise atmospheric phase behavior is difficult to quantify and observations have shown that “precondensation” of water below predicted saturation values can occur. We propose a revised approach to understanding the transition from solid soluble particles to liquid droplets, typically described as cloud condensation nucleation – a process that is traditionally captured by Köhler theory, which describes a modified equilibrium saturation vapor pressure due to (i) mixing entropy (Raoult's law) and (ii) droplet geometry (Kelvin effect). Given that observations of precondensation are not predicted by Köhler theory, we devise a more complete model that includes interfacial forces giving rise to predeliquescence, i.e., the formation of a brine layer wetting a salt particle at relative humidities well below the deliquescence point.

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