Modeling of gas generation from the river adjacent to the manufactured gas plant

Abstract

Ebullition of gas bubbles through sediment can enhance the migration of gases through the subsurface and potentially affect the emission of important greenhouse gases to the atmosphere. To better understand the parameters controlling ebullition, investigations of gas ebullition in the Grand Calumet river (Indiana, USA) were conducted. We found that gas ebullition might shift and change with different vertical hydraulic gradients and temperatures. CO₂ and CH₄ flux for each site increased with an increase in temperature. A comparatively simple linear relationship existed between the gas flux and the measured parameters (G_F = 0.316T + 300.66i, R² = 0.82). The gas flux in the sand cap was more variable than that in sediment. Moreover, the total field gas fluxes varied from 10 to 180 mmol m⁻² d⁻¹ for sediment and from 5 to 35 mmol m⁻² d⁻¹ for the sand cap, which proved an in situ sand cap could provide effective remediation. The analysis presented here has shown that gas fluxes and reactive transport modeling can provide effective means of investigating ebullition and quantifying gas transport.