Numerical tools to estimate the flux of a gas across the air–water interface and assess the heterogeneity of its forcing functions

Abstract. A numerical tool was developed for the estimation of gas fluxes across the air water interface. The primary objective is to use it to estimate CO2 fluxes. Nevertheless application to other gases is easily accomplished by changing the values of the parameters related to the physical properties of the gases. A user friendly software was developed allowing to build upon a standard kernel a custom made gas flux model with the preferred parametrizations. These include single or double layer models; several numerical schemes for the effects of wind in the air-side and water-side transfer velocities; the effect of turbulence from current drag with the bottom; and the effects on solubility of water temperature, salinity, air temperature and pressure. It was also developed an analysis which decomposes the difference between the fluxes in a reference situation and in alternative situations into its several forcing functions. This analysis relies on the Taylor expansion of the gas flux model, requiring the numerical estimation of partial derivatives by a multivariate version of the collocation polynomial. Both the flux model and the difference decomposition analysis were tested with data taken from surveys done in the lagoonary system of Ria Formosa, south Portugal, in which the CO2 fluxes were estimated using the IRGA and floating chamber method whereas the CO2 concentrations were estimated using the IRGA and degasification chamber. Observations and estimations show a remarkable fit.

Download Full-text

Turbulent Gas Flux Measurements near the Air-Water Interface in a Grid-Stirred Tank

Environmental Science and Engineering - Transport at the Air-Sea Interface ◽

10.1007/978-3-540-36906-6_2 ◽

2008 ◽

pp. 25-41

Author(s):

Herlina Jirka ◽

Gerhard H. Jirka

Keyword(s):

Stirred Tank ◽

Water Interface ◽

Gas Flux ◽

Air Water Interface ◽

Flux Measurements

Download Full-text

Mass Transport of Gases across the Air–Water Interface: Implications for Aldehyde Emissions in the Uinta Basin, Utah, USA

Atmosphere ◽

10.3390/atmos11101057 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1057

Author(s):

Marc L. Mansfield

Keyword(s):

Mass Transport ◽

Vapor Phase ◽

Current Model ◽

Molecular Forms ◽

Water Interface ◽

Uinta Basin ◽

Transport Models ◽

Air Water Interface ◽

The Difference ◽

Pass Through

When they dissolve in water, aldehydes become hydrated to gem-diols: R−COH+H2O↔RCH(OH)2. Such reactions can complicate air–water transport models. Because of a persistent belief that the gem-diols do not exist in the vapor phase, typical models do not allow them to pass through the air–water interface, but in fact, they do. Therefore, transport models that allow both molecular forms to exist in both phases and to pass through the interface are needed. Such a model is presented here as a generalization of Whitman’s two-film model. Since Whitman’s model has fallen into disuse, justification of its use is also given. There are hypothetical instances for which the flux predicted by the current model is significantly larger than the flux predicted when models forbid the diol form from passing through the interface. However, for formaldehyde and acetaldehyde, the difference is about 6% and 2%, respectively.

Download Full-text

Surface Temperature Field Statistics at an Air/Water Interface for Grid-Generated Sub-Surface Turbulence

Volume 1: Fora, Parts A and B ◽

10.1115/fedsm2002-31132 ◽

2002 ◽

Author(s):

Karen A. Flack ◽

Geoffrey B. Smith

Keyword(s):

Surface Temperature ◽

Infrared Camera ◽

Temperature Fields ◽

Interface Temperature ◽

Water Interface ◽

Bulk Fluid ◽

Air Water Interface ◽

Evaporative Convection ◽

The Difference ◽

Oscillation Frequencies

Surface temperature fields and statistics are presented for the case of sub-surface grid-generated turbulence impacting an air/water interface. Temperature measurements are obtained with an infrared camera, sensitive in the 3–5 micron wavelength range. Results indicate that increased grid oscillation frequencies, and shallower grid depths, lead to increased surface mixing, yielding lower values of RMS temperature. Non-dimensionalization of the RMS temperatures using the difference in the average surface and the bulk fluid temperatures, collapses the data obtained for different grid depths and oscillation frequencies. This scaling is related to the thermal boundary layer thickness. The results are compared to the baseline case of turbulence due to evaporative convection without an oscillating grid.

Download Full-text

Characterization of Monoolein Langmuir Monolayers Spread at The Salt Solution/Air Interface

10.21203/rs.3.rs-158120/v2 ◽

2021 ◽

Author(s):

Balaji Sopanrao Dhopte ◽

V. N. Lad

Keyword(s):

Physicochemical Properties ◽

Molecular Layer ◽

Langmuir Monolayers ◽

Langmuir Monolayer ◽

Compression Isotherm ◽

Water Interface ◽

Air Interface ◽

Special Groups ◽

Air Water Interface ◽

The Difference

Abstract The Langmuir monolayer is commonly described at interfaces for an insoluble homogenous single molecular layer. Langmuir monolayers have demonstrated various issues regarding soft matters and complex fluids by forming ideal uniform two-dimensional structures over the air-water interface. This monolayer has advantages for evaluating physicochemical properties at interfaces and, for the insoluble molecules, can be applied simultaneously to the different interaction occurrences at interfaces. For this experiment, monoolein lipid was used as a spreading solvent to create a Langmuir monolayer, and five different types of salt sub-phases were applied for the physicochemical properties’ interaction studies. On the air-water interface, the surface properties of monoolein lipids were investigated for interfacial phase behaviors, using the Wilhelmy plate pressure sensor technique compression isotherm (π-A). Data and analysis were also contributed to the correspondent, precise verification of physical state behavior with the surface pressure measurements on the interfaces through the compressibility modulus and the elasticity modulus parameters on the surface. In the experiments, the interfacial activity of the monoolein lipids was found to be stable on the aqueous sub-phase, while the area per molecule over the interface did not have much impact as a sub-phase with a change in salts. The repeatability and reproducibility of tests were affirmed by the difference in the Langmuir monolayer’s particular phase transition orientation behavior and the stability of colloidal lipid dispersion. However, Langmuir monolayer formation contributes to several special groups being restructured and is found to be a more remarkable natural process for their attractive organic dynamic structural properties over the interface, but the interfacial molecular dynamics have proven to be difficult to calculate.

Download Full-text

Characterization of Monoolein Langmuir Monolayers Spread at The Salt Solution/Air Interface

10.21203/rs.3.rs-158120/v3 ◽

2021 ◽

Author(s):

Balaji Sopanrao Dhopte ◽

V. N. Lad

Keyword(s):

Physicochemical Properties ◽

Molecular Layer ◽

Langmuir Monolayers ◽

Langmuir Monolayer ◽

Compression Isotherm ◽

Water Interface ◽

Air Interface ◽

Special Groups ◽

Air Water Interface ◽

The Difference

Abstract The Langmuir monolayer is commonly described at interfaces for an insoluble homogenous single molecular layer. Langmuir monolayers have demonstrated various issues regarding soft matters and complex fluids by forming ideal uniform two-dimensional structures over the air-water interface. This monolayer has advantages for evaluating physicochemical properties at interfaces and, for the insoluble molecules, can be applied simultaneously to the different interaction occurrences at interfaces. For this experiment, monoolein lipid was used as a spreading solvent to create a Langmuir monolayer, and five different types of salt sub-phases were applied for the physicochemical properties’ interaction studies. On the air-water interface, the surface properties of monoolein lipids were investigated for interfacial phase behaviors, using the Wilhelmy plate pressure sensor technique compression isotherm (π-A). Data and analysis were also contributed to the correspondent, precise verification of physical state behavior with the surface pressure measurements on the interfaces through the compressibility modulus and the elasticity modulus parameters on the surface. In the experiments, the interfacial activity of the monoolein lipids was found to be stable on the aqueous sub-phase, while the area per molecule over the interface did not have much impact as a sub-phase with a change in salts. The repeatability and reproducibility of tests were affirmed by the difference in the Langmuir monolayer’s particular phase transition orientation behavior and the stability of colloidal lipid dispersion. However, Langmuir monolayer formation contributes to several special groups being restructured and is found to be a more remarkable natural process for their attractive organic dynamic structural properties over the interface, but the interfacial molecular dynamics have proven to be difficult to calculate.

Download Full-text