ZIWR Weekly Seminar
Wednesday, January 9th, 2019 at 13:15
Seminar room, Old Administration Building
The role of atmospheric conditions and interface properties on gas transport at the Earth-atmosphere boundary
Gas movement within the Earth's subsurface and its exchange with the atmosphere is one of the principal processes in soil, ecosystem and atmospheric environments. In this talk, I will focus on the role of atmospheric conditions and matrix properties on gas transport at the Earth-atmosphere interface in two specific matrices – porous media (e.g., soils) and boreholes.
In porous media, we explored the gas transport magnitude as a function of the average surface wind speed and soil permeability. Five columns, each filled with homogeneous dry soil or soil-aggregates of different permeabilities were installed in a bare field. Data collected included atmospheric parameters (wind speed, air temperature, barometric pressure, etc.) outside the columns and soil parameters (temperature and CO2 concentration at -0.2 m) within the columns. Results showed that gas transport increased with increasing wind speed and/or soil permeability. The complete data set was used for establishing an empirical model that predicts the gas transport magnitude as a function of wind speed and soil permeability.
With respect to boreholes, we investigated the effect of atmospheric conditions, namely atmospheric pressure and temperature, on air, CO2 and radon transport inside three boreholes across Israel. Using high-resolution spatiotemporal measurements within the boreholes, we concluded that diurnal atmospheric pressure oscillations and borehole-atmospheric temperature differences controlled the air transport within the boreholes. In addition, for one of the boreholes, we quantified the air velocities and CO2 emissions to the atmosphere (up to ~6 m/min and ~5 g-CO2/min, respectively). This reveals the role of boreholes as an additional source of greenhouse gas emissions.