scholarly journals Transport of colloids in unsaturated porous media: A pore-scale observation of processes during the dissolution of air-water interface

2003 ◽  
Vol 39 (12) ◽  
Author(s):  
Sanya Sirivithayapakorn ◽  
Arturo Keller
Keyword(s):  
Porous Media ◽  
Water Interface ◽  
Pore Scale ◽  
Unsaturated Porous Media ◽  
Air Water Interface

scholarly journals Adsorption of PFOA at the Air–Water Interface during Transport in Unsaturated Porous Media

2018 ◽  
Vol 52 (14) ◽  
pp. 7745-7753 ◽  
Author(s):  
Ying Lyu ◽  
Mark L. Brusseau ◽  
Wei Chen ◽  
Ni Yan ◽  
Xiaori Fu ◽  
...  
Keyword(s):  
Porous Media ◽  
Water Interface ◽  
Unsaturated Porous Media ◽  
Air Water Interface

Adhesion of Colloids and Bacteria to Porous Media: A Critical Review

2019 ◽  
Vol 7 (4) ◽  
pp. 417-460 ◽  
Author(s):  
Runwei Li ◽  
Changfu Wei ◽  
Hefa Cheng ◽  
Gang Chen
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Bacterial Adhesion ◽  
Fate And Transport ◽  
Theoretical Models ◽  
Water Interface ◽  
Subsurface Soil ◽  
Air Water Interface ◽  
Surface Physicochemical Properties ◽  
The Impact

Adhesion of colloids and bacteria to various surfaces is important for a variety of environmental phenomena including microbial biofouling and contamination prevention. Under saturated conditions, both colloids and bacteria have the opportunity to attach to porous medium surfaces. Under water unsaturated conditions or in the presence of the air-water interface, besides the porous medium surfaces, colloids and bacteria can also attach to the air-water interface, including the air-water-solid threephase interface. The magnitudes of adhesion of colloids and bacteria are correlated to the interactions of the colloids and bacteria with the surfaces, which are a function of their surface physicochemical properties. In this review, adhesion theories are revisited and adhesion of colloids and bacteria to porous media and the air-water interface is discussed. The interaction forces are quantified using various theoretical models including the DLVO models and used to interpret related adhesion. The impact of surfactants on colloid and bacterial adhesion is also discussed. The review also includes the implementation of the adhesion theory in interpreting colloid and bacterial fate and transport in the subsurface soil.

Hysteresis in the electrical resistivity of partially saturated sandstones

Geophysics ◽  
1991 ◽  
Vol 56 (12) ◽  
pp. 2139-2147 ◽  
Author(s):  
Rosemary Knight
Keyword(s):  
Electrical Resistivity ◽  
Unsaturated Zone ◽  
Geophysical Data ◽  
Fluid Distribution ◽  
Water Interface ◽  
Pore Scale ◽  
Laboratory Measurements ◽  
Partially Saturated ◽  
Air Water Interface ◽  
Saturation History

Laboratory measurements of the resistivity of three sandstone samples collected during imbibition (increasing Sw) and drainage (decreasing Sw) show pronounced hysteresis in resistivity throughout much of the saturation range. The variation in resistivity can be related to changes in pore‐scale fluid distribution caused by changes in saturation history. The form of the hysteresis is such that resistivity measured during imbibition is consistently less than that measured, at the same saturation, during drainage. This can be attributed to the presence of conduction at the air/water interface in partially saturated samples; an effect that is enhanced by fluid geometries associated with the imbibition process. The results of this study suggest that the dependence of geophysical data on saturation history should be considered when interpreting data from the unsaturated zone.

scholarly journals Assessing the Role of Pseudomonas aeruginosa Surface-Active Gene Expression in Hexadecane Biodegradation in Sand

2002 ◽  
Vol 68 (5) ◽  
pp. 2509-2518 ◽  
Author(s):  
P. A. Holden ◽  
M. G. LaMontagne ◽  
A. K. Bruce ◽  
W. G. Miller ◽  
S. E. Lindow
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Porous Media ◽  
Liquid Culture ◽  
Sand Culture ◽  
Water Interface ◽  
Unsaturated Porous Media ◽  
Wild Type ◽  
Active Compounds ◽  
Surface Active ◽  
Surface Active Compounds

ABSTRACT Low pollutant substrate bioavailability limits hydrocarbon biodegradation in soils. Bacterially produced surface-active compounds, such as rhamnolipid biosurfactant and the PA bioemulsifying protein produced by Pseudomonas aeruginosa, can improve bioavailability and biodegradation in liquid culture, but their production and roles in soils are unknown. In this study, we asked if the genes for surface-active compounds are expressed in unsaturated porous media contaminated with hexadecane. Furthermore, if expression does occur, is biodegradation enhanced? To detect expression of genes for surface-active compounds, we fused the gfp reporter gene either to the promoter region of pra, which encodes for the emulsifying PA protein, or to the promoter of the transcriptional activator rhlR. We assessed green fluorescent protein (GFP) production conferred by these gene fusions in P. aeruginosa PG201. GFP was produced in sand culture, indicating that the rhlR and pra genes are both transcribed in unsaturated porous media. Confocal laser scanning microscopy of liquid drops revealed that gfp expression was localized at the hexadecane-water interface. Wild-type PG201 and its mutants that are deficient in either PA protein, rhamnolipid synthesis, or both were studied to determine if the genetic potential to make surface-active compounds confers an advantage to P. aeruginosa biodegrading hexadecane in sand. Hexadecane depletion rates and carbon utilization efficiency in sand culture were the same for wild-type and mutant strains, i.e., whether PG201 was proficient or deficient in surfactant or emulsifier production. Environmental scanning electron microscopy revealed that colonization of sand grains was sparse, with cells in small monolayer clusters instead of multilayered biofilms. Our findings suggest that P. aeruginosa likely produces surface-active compounds in sand culture. However, the ability to produce surface-active compounds did not enhance biodegradation in sand culture because well-distributed cells and well-distributed hexadecane favored direct contact to hexadecane for most cells. In contrast, surface-active compounds enable bacteria in liquid culture to adhere to the hexadecane-water interface when they otherwise would not, and thus production of surface-active compounds is an advantage for hexadecane biodegradation in well-dispersed liquid systems.

scholarly journals Pore-scale mechanisms for the enhancement of mixing in unsaturated porous media and implications for chemical reactions

2015 ◽  
Vol 42 (13) ◽  
pp. 5316-5324 ◽  
Author(s):  
Joaquín Jiménez-Martínez ◽  
Pietro de Anna ◽  
Hervé Tabuteau ◽  
Régis Turuban ◽  
Tanguy Le Borgne ◽  
...  
Keyword(s):  
Porous Media ◽  
Chemical Reactions ◽  
Pore Scale ◽  
Unsaturated Porous Media
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