2. 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 loss of dry weight on igni- 
tion. There was no appreciable loss of inorganic carbonate during the 
ashing procedure as evidenced by nonsignificant weight losses of calcium 
carbonate (CaC03) samples which were ashed along with the ovendried natural 
sediments. 
3. Heavy Metals. 
Amounts of extractable cations in the mineral solids and the natural 
sediment samples were determined with mild acid extraction and atomic 
absorption analysis at the Seafood Processing Laboratory, Crisfield, 
Maryland. Routine procedures for inorganically bound cations, as des- 
cribed by Perkin-Elmer Corporation (1971) and Soil Testing and Plant 
Analysis Laboratory (1970), were conducted for zinc, copper, iron, manga- 
nese, lead, cobalt, nickel, chromium, and cadmium. Mercury values reported 
are for total mercury from sediments digested for 1 minute in boiling 
aqua regia (Dow Method, CAS-AM-70.13, revised 22 June 1970, Chlorine Insti- 
tute, Madison Avenue, New York, New York). Metal values are reported as 
milligram kilograms! dry weight of solids. 
III. RESULTS AND DISCUSSION 
1. Size Distributions. 
Particle-size distributions of the extremely fine mineral solids and 
natural sediment used in this project are presented in Figure A-1 and 
Table A-1. Useful descriptions of these materials ranked coarsest to 
finest by median size are as follows: 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; and kaolinite,Hydrite-10, (Georgia Kaolin Com- 
pany), median size = <0.5 micrometer, <2 micrometers = 92 percent. 
These data have been presented in such a way that 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 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). 
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