Novel methods for measuring air-water interfacial area in unsaturated porous media.
Interfacial partitioning tracer tests (IPTT) are used to measure air-water interfacial area for unsaturated porous media. The standard IPTT method involves conducting tests wherein an aqueous surfactant solution is introduced into a packed column under unsaturated flow conditions. Surfactant-induced drainage has been observed to occur for this method in some cases, which can complicate data analysis and impart uncertainty to the measured values. Two novel alternative approaches for conducting IPTTs are presented herein that are designed in part to prevent surfactant-induced drainage. The two methods are termed the dual-surfactant IPTT (IPTT-DS) and the residual-air IPTT (IPTT-RA). The two methods were used to measure air-water interfacial areas for two natural porous media. System monitoring during the tests revealed no measurable surfactant-induced drainage. The measured interfacial areas compared well to those obtained with the standard IPTT method conducted in such a manner that surfactant-induced drainage was prevented.
Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, USA; Hydrology and Water Resources Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, USA. Electronic address: Brusseau@email.arizona.edu.
Mark L
ML
Brusseau
Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, USA.
Asma
A
El Ouni
Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, USA.
Juliana B
JB
Araujo
Soil, Water and Environmental Science Department, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Bldg., Tucson, AZ 85721, USA.
Hua
H
Zhong
D000388:Air; D008962:Models, Theoretical; D016062:Porosity; D011791:Quartz / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014872:Water Movements
D012987:Soil; D012996:Solutions; D013501:Surface-Active Agents; D014867:Water; D011791:Quartz
Air-water interface; Fluid–fluid interface; Partitioning tracer; Tracer test