Effects of atmospheric pressures on gas transport in the vadose zone

Journal Article · Sun Mar 01 00:00:00 EST 1992 · Water Resources Research; (United States)

DOI:https://doi.org/10.1029/91WR02766· OSTI ID:5245238

Massmann, J ^[1]; Farrier, D F ^[2]

---

1. Univ. of Washington, Seattle (United States)
2. Shell Oil Co., Atlanta, GA (United States)

Temporal variations in barometric pressure due to weather patterns may induce air intrusion into the subsurface. This air intrusion can affect monitoring activities aimed at characterizing the composition and movement of gases in the vadose zone. Expressions are presented to estimate gas fluxes due to the combined effects of Knudsen diffusion, multicomponent molecular diffusion, and viscous flow. These expressions are used to evaluate the validity of the single-component advection-dispersion equation for simulating gas transport in the presence of atmospheric pressure variations. The single-component equation provides reasonable results when used to simulate transport in media with relatively high gas permeability. Computer simulations of vertical transport at sites with homogeneous soils indicate that fresh' air can migrate several meters into the subsurface during a typical barometric pressure cycle. Horizontal pressure gradients can develop at sites with near-surface heterogeneities. These gradients may cause fresh air to intrude meters or tens of meters into the vadose zone during a storm event.

• OSTI ID: 5245238
• Journal Information: Water Resources Research; (United States), Vol. 28:3; ISSN 0043-1397
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ENVIRONMENTAL TRANSPORT
MATHEMATICAL MODELS
SUBSURFACE ENVIRONMENTS
GAS FLOW
ATMOSPHERIC PRESSURE
COMPUTERIZED SIMULATION
PERMEABILITY
PRESSURE EFFECTS
SOILS
FLUID FLOW
MASS TRANSFER
SIMULATION
540220* - Environment
Terrestrial- Chemicals Monitoring & Transport- (1990-)