An experimental study of lake water-sediment interaction rates

Dissolution rates of sediments obtained from the Oued Cherf reservoir were measured in closed-system batch reactors at 25 °C in fluids sampled concurrently from the same locations as the sediments. The BET surface areas of the sediments ranged from 16 to 45 m²/g and consisted primarily of quartz, calcite, and clay minerals. After a brief initial period, release rates of Si, Mg, Ca, Cl, SO₄, and NO₃ from these sediments are approximately linear with time over the course of the experiments, which lasted from 3 to 5 months. BET surface area normalized Si release rates ranged from 10^–17.4 to 10^–18.4 mol/cm²/s. These release rates match closely Si release rates from quartz and clay minerals determined from laboratory dissolution rates reported in the literature. This coherence suggests that laboratory measured silicate dissolution rates can be used with confidence to predict the dissolution behavior of sediments in natural surface waters.