The natural sediments collected from the Patuxent River were analyzed 

 as follows: Preliminary work showed this material was approximately 75- 

 to 80-percent salt and water by weight. Appropriate triplicate volumes 

 of natural sediments were removed from the holding tanks. The volumes were 

 calculated to contain between 5- and 10-gram inorganic dry solids, and 

 were corrected upward for the weight of organic matter present (see method 

 of analysis below). Measured quantities of solids were placed in 1-liter- 

 capacity Pyrex beakers and an appropriate amount of 30-percent hydrogen 

 peroxide (H2O2) was added. The volume of H2O2 needed to oxidize the organic 

 matter present in the sediment produced a final 5-percent concentration of 

 H2O2 in the sediment volume. The oxidation reaction was initially violent. 

 It proceeded overnight in a hood with air bubbling slowly through the sedi- 

 ment-H202 mixture to remove the excess H2O2. 



When gas evolution had ceased, 750 milliliters of deionized, glass- 

 distilled water were added to each beaker. The sediment was resuspended 

 by stirring with a glass rod and allowed to settle. The supernatant was 

 carefully decanted, and another 750 milliliters rinse of deionized, glass- 

 distilled water was added to each beaker. 



A 0. 2-milliliter sample of supernatant water was taken from each beaker 

 and the dissolved ion concentration of each solution was determined with 

 the freezing-point depression osmometer. Salt concentration was read from 

 a standard curve relating freezing-point depression and osmolal concentra- 

 tion to sodium chloride (NaCl) concentration in milligram per kilogram 

 (mg kg"^) water. If the salt concentration was greater than 300 mg NaCl kg"-' 

 water, the suspension was allowed to settle, the clear supernatant was 

 decanted, and an additional rinse of 750-milliliter deionized distilled 

 water was added to each beaker. The sediment was resuspended and allowed 

 to settle. The clear supernatant was decanted and the beaker containing 

 the washed sediment was filled to 500 milliliters with fresh, deionized, 

 glass-distilled water and placed into an ultrasonic bath (45 kilohertz) for 

 30 minutes. The suspension was placed in a glass cylinder, made up to 

 volume with deionized distilled water, and analyzed as described in American 

 Society for Testing and Materials (1968), but the dispersing agent sodium 

 pyrophosphate (Nai+P207), was not added. 



Values are reported as percent by weight remaining in suspension (per- 

 cent finer than) plotted against equivalent spherical diameters according 

 to Stokes' law. 



b. Organic Matter Content . Samples of the natural sediment collected 

 from the Patuxent River at Long Point were ovendried for 24 hours at 100° 

 Celsius, ground fine with a porcelain mortar and pestle, and ashed for 3 

 hours at 500° Celsius. Organic matter values are reported as percent of 

 dry weight lost on ignition. No appreciable loss of inorganic carbonate 

 occurred during the ashing procedure, as evidenced by nonsignificant weight 

 losses of calcium carbonate (CaC03) samples ashed along with the ovendried 

 natural sediments. 



8t 



