c. Heavy Metals . Ajuounts of ejctractable cations in the mineral 

 solids and in the natural sediment samples were determined through mild 

 acid extraction and atomic absorption analysis by Mr. David Boon, Seafood 

 Processing Laboratory, Crisfield, Maryland. Tests for inorganically bound 

 cations as described by Soil Testing and Plant Analysis Laboratory (1970) 

 and Perkin-Elmer Corporation C1971) were conducted for zinc, copper, iron, 

 manganese, lead, cobalt, nickel, chromium, and cadmium. Total mercury 

 values are reported from sediments digested for 1 minute in boiling aqua 

 regia (Dow Method, CAS-AM-70. 13, 22 June 1970 revised, Chlorine Institute, 

 Madison Avenue, New York, New York). Metal values are mg kg"-^ dry weight 

 of solids. 



3. Results and Discussion . 



a. Size Distributions . Particle-size distributions of the extremely 

 fine mineral solids and the natural sediment are listed in Figure D-1 and 

 Table D-1. Materials are ranked coarsest to finest by median size as 

 follows: Hydrite MP, kaolinite (Georgia Kaolin Company), median size = 

 9.5 micrometers, <2 micrometers = 12 percent; Hydrite Flat-D, kaolinite 

 (Georgia Kaolin Company), medium size = 4.5 micrometers, <2 micrometers 



= 34 percent; Patuxent River silt (composite less organic matter fraction, 

 11.5 percent of dry weight), median size = <0.8 micrometer, <2 micrometers 

 = 72 percent; fuller's earth, montmorillonite, and attapulgite (Fisher 

 No. F-90), median size = <0.5 micrometer, <2 micrometers = 82 percent; 

 Hydrite-10, kaolinite (Georgia Kaolin Company), median size = <0.5 micro- 

 meter, <2 micrometers = 92 percent. Graphic solutions (Folk, 1968) and 

 mathematical calculations (Trask, 1968) can be used to determine the 

 second, third, and fourth moments of these distributions. 



Additional size-distribution analyses for the natural sediments (by 

 date of collection) are presented in Figure D-2 and Table D-2. Median 

 sizes ranged from a high of approximately 1.1 to a low of <0.5 micrometer 

 (August collection). Fraction by weight finer than 2 micrometers ranged 

 from a high of approximately 82 percent to a low of 65 percent (August 

 collection). These particle-size distributions of solids (Tables D-1 and 

 D-2, Figs. D-1 and D-2) are comparable with those reported by May (1973) 

 in the mudflow from a shell dredge (Table D-3) . 



b. Organic Matter Content . Organic matter content of natural sediment 

 samples tended to increase throughout the summer of 1973 from 8.9 percent 

 in June to over 11 percent in August and September (Table D-4). A compar- 

 ison of mean organic matter values (Table D-5) showed the differences 

 between early and late samples were significant. Organic matter, which 

 has settled out at Long Point, may come from marshes which line the shores 

 of the Patuxent watershed. 



Organic matter analyses were also conducted on the mineral solids. 

 Ashing caused no significant weight loss in fuller's earth solids. Sub- 

 stantial weight losses in the kaolinites (about 11 percent of dry weight) 

 were attributed to the bound water lost (at temperatures of 500° Celsius) 



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