micrometers, <2 micrometers = 13 percent; Patuxent River silt (com- 

 posite less organic matter fraction 11.5 percent of dry weight), 

 median size = <0.8 micrometers, <2 micrometers = 72 percent; Fuller's 

 earth, montmorillonite and attapulgite (Fisher No. F-90) , median 

 size = <0.5 micrometers, <2 micrometers = 82 percent. 



These data have been presented in such a way that graphic solu- 

 tions (Folk, 1974) 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 A-2 and Table A-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 used in our work (Tables A-1 and A-2, Figs. A-1 and A-2) 

 are comparable with those reported by May (1973) in the mudflow from 

 a shell dredge (Table A-3) . 



2. Organic Matter Content . 



Organic matter content of natural sediment samples tended to 

 increase throughout the stammer of 1973 from a low of 8.9 percent in 

 June to values in excess of 11 percent in August and September (Table 

 A-4) . A cdfciparison of mean organic matter values (Table A-5) showed 

 that these differences between earlier and later samples were signifi- 

 cant. These differences may indicate significant importation of 

 organic matter, which has settled out at Long Point, from marshes 

 which line the shores of the Patuxent watershed. These organic matter 

 values are as high as those reported by Masch and Espey (1967) for 

 Galveston Bay. 



Organic matter analyses were conducted on the mineral solids. No 

 significant weight loss from ashing was detectable in the Si02 and 

 Fuller's earth solids. 



3. Heavy Metals . 



The mineral solids contained metal amounts that were considered 

 biologically insignificant (Table A-6) . The values reported for 

 Patuxent silt (collected at Long Point) are in the "natural" range 

 of metal amounts found in similar estuarine salinity ranges by Huggett 

 (Virginia Institute of Marine Science, 1973, personal communication) 

 in the York, James, and Elizabeth Rivers which drain into the 

 Virginia part of the Chesapeake Bay system. 



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