with a glass tube, and the upper 2 cm of material were (1) collected with a 
noncontaminating utensil, (2) placed in an acid-washed polyethylene container, 
and (3) frozen until analyzed. Because individual grab samples’ were 
subsampled for both trace-metal and hydrocarbon analyses, the grab sampler was 
rinsed with distilled methanol and hexane before each use. 
Sediment cores were collected on other USGS cruises in the study area 
with a hydraulically damped gravity corer similar to the one described by 
Pamatmat (1971). This apparatus has a slow rate of penetration controlled by 
a water-filled piston, and it collects cores as long as 70 cm (in mud) with 
minimal disturbance of the sediment. Cores containing the undisturbed water- 
sediment interface were collected in thin-walled fiberglass core barrels and 
were frozen after collection. The samples were later extruded, thawed, and 
cut into l-cm sections for analysis. 
Core 83G9-B was collected from the Continental Slope (fig. 1A) using a 
conventional box corer. A subcore was sectioned into l-cm depth intervals. 
The depth distribution of metals also was determined on samples removed in 
2-cm depth intervals from grab samples. 
In the laboratory, the samples were thawed, homogenized, and subsampled 
under a laminar flow hood. Aliquots from individual grabs and sample blends, 
made up of equal weights from the individual grabs, were separated for 
chemical and textural analyses. Samples for chemical analyses were dried to a 
constant weight at 70°C in an oven having teflon-coated surfaces and a 
filtered nitrogen atmosphere. Dried samples were ground in an agate grinder 
after shell or sediment particles larger than 2 mm were removed. Drill 
cuttings, identified by their angular edges and unusual color, were not 
removed. These samples are referred to as bulk sediments (undifferentiated 
with respect to size) throughout this report. 
