Gas Permeability of Frozen Sediments: Implications for Modeling Gas and Water Transport in Permafrost

Abstract We measure the gas permeability of two permafrost sediments at a range of ice saturations and use van Genuchten‐Mualem equations to model the relative gas ( k rg ) and water ( k rw ) permeabilities of frozen sediments. We show that our frozen sediment k rg data and model display the same functional form as frozen and unfrozen sediment k rg data from literature. Likewise, we show that our frozen sediment k rw model displays the same functional form as unfrozen sediment and hydrate‐bearing sediment k rw data from literature. These results indicate that gas is the least‐wetting phase in frozen and unfrozen sediments and that ice is the intermediate‐wetting phase in frozen sediments. Therefore, k rg and k rw for frozen sediments can be obtained from simpler experiments using unfrozen sediments. Our results give experimental validation for a common approach to model frozen sediment k rg and k rw using unfrozen sediment data. We demonstrate a path to seamlessly model the flow of carbon in the gas and water phases across the 0°C isotherm with a simple form that can be incorporated into large‐scale climate simulations.