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<br />33 <br /> <br />the solution, As the flow becomes increasingly saline, this <br />W <br />~ gradient will decrease, causing a corresponding decrease in <br />W <br />00 dissolution rate. In general, one-half the final value of flow EC <br /> <br />(reached after two hours contact with the shale) was obtained prior <br /> <br />to twenty minutes. The diffusion gradient explanation suggests that <br /> <br />the lower velocities would'reach the same equilibrium value in a <br /> <br />longer time period than the high velocity flows, <br /> <br />2,2 Dissolution Changes with Agitation and Dilution <br />2.2.1 Procedure <br /> <br />A jar test using varying concentrations of Mancos Shale in <br /> <br />water was designed to demonstrate the effects of agitation and <br /> <br />extended contact time between water and sediment on solute concentration. <br /> <br />Each sample of shale was exposed to three water samples of high <br /> <br />quality to demonstrate the effect of dilution on high solute <br /> <br />concentrations. <br /> <br />For jar test number one, 100 g of weathered Mancos Shale were <br /> <br />added to 2000 ml of good quality water and agitated for 30 seconds. <br /> <br />Measurements of EC were taken at 2, 4, 8, 12 minutes,S hours, and <br /> <br />43 hours after the agitation. The mixture was reagitated and sampled <br /> <br />at one minute and 24 hours, This agitation cycle was repeated until <br /> <br />the EC was not significantly increased by the agitation, At this <br /> <br />point, 1500 ml of water in the mixture was replaced with 1500 ml of <br /> <br />fresh water, Agitation and sampling were repeated until there were <br /> <br />no increases in EC measured in the water-sediment mixture. A third <br /> <br />'to:::. ~ <br />