APPENDIX 
ANAYLSES OF SEDIMENTS 
I. INTRODUCTION 
Experimental work during 1971 and 1972 utilized artificial, commercially 
available mineral solids to provide base-line data for biological effects 
of (a) concentrations of solids, (b) different particle-size distributions, 
and (c) different mineral types of solids. 
Work during 1973 concentrated heavily on the biological effects of 
naturally occurring sedimentary material which was collected by anchor 
dredge at Long Point (38°29'30" N., 76°39'45" W.) in the Patuxent River, 
Maryland, and stored in large polyethylene tanks before use in the experi- 
ments. The sediment surface was covered with a layer of water (salinity 
range 4 to 6 parts per thousand) to maintain natural ionic equilibria 
between the sediment and water, as would naturally occur in the Patuxent 
River. A microoxidized sediment layer developed at the sediment-water 
interface in tanks after a few days of storage. 
This appendix contains the results of analyses which were performed 
on both the commercially available mineral solids and the naturally occur- 
ring sediments. Sediment characteristics measured were organic matter con- 
tent (weight loss on ignition), inorganically bound heavy metals (atomic 
absorption analysis), and particle-size distributions (settling diameter 
analysis). 
The particle-size distributions were determined in distilled water, 
and may represent the basic or fundamental unit particles which can form 
aggregates with other units and be strongly bound by molecular and atomic 
forces. These composite units are stable under dispersion methods. Also, 
the basic particles may form agglomerates in saline water. These com- 
posites are relatively weakly bonded by electrostatic forces, surface 
tension, and "sticky" organic matter. 
II. MATERIALS AND METHODS 
1. Size Distribution. 
Fuller's earth (Fisher F-90) and kaolinite (Hydrite-10, Georgia Kaolin 
Company) were the artificial sediments (mineral solids) used in this study. 
Particle-size distributions of these materials were determined by the 
sedimentation method (American Society of Testing and Materials, 1968) for 
paper-coating clays. In addition, a finer particle-size distribution of 
Silica (Si09) was generated from a commercially available Fisher No. S-135 
by allowing these solids to settle for 25 minutes through a specified dis- 
tance in a column of distilled water at 20° Celsius. The solids finer by 
weight than 15 micrometers were calculated to be remaining in suspension 
in this column of water from tables presented by Trask (1968) and from 
Casagrande's nomographic solution of Stokes' law given in American Society 
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