Fig. 4. Gas–liquid interfacial surface area per bulk volume of a 40/50 grade of quartz sand as a function of effective aqueous-phase saturation, calculated using the Brooks–Corey water retention model with n = 0.332, _bc = 8.85, h_b = 26.5 cm, = 0.993 g cm^–3, g = 981 cm s^–2, and = 72.8 mN m^–1.