distribution of metals in different size classes, sediment was collected on 
the same cruises from control station 2. 
Figures 10A and 10B show the distribution of sediment in weight percent 
among various size classes for sediments collected on different cruises at 
these three locations. For cruise 4, all three stations have similar modes 
and less than 1 percent silt plus clay. The size distributions are similar on 
both sampling dates, except that the sample at station 5-2 has modal size in 
the 500-1,000 um range for cruise 10 and modal size in the 210-510 um range 
for cruise 4. 
At control station 2, the Ba inventory among the different size classes 
(fig. 11A) is distributed in the same pattern as the sediments are distributed 
(fig. 10A, B). Most of the Ba (more than 80 percent) is contained in the 
modal size class of 210-500 um. However, the Ba concentrations of the fine 
fractions are higher than in the coarser fractions (fig. 11B), and there are 
only minor differences between samples from cruises 4 and 10 at this location. 
The inventory of Ba and the concentration of Ba among the different size 
classes at station 5-2 are considerably different on cruises 4 and 10 
(figs. 12A, B). The concentration of Ba in the finer sediments is much lower 
on cruise 10 than cruise 4. The differences indicate that while the rig was 
operating (cruise 4), fine-grained sediments containing high levels of Ba were 
being deposited (accumulating) in the sediments, and that since drilling has 
ended, the processes of sediment transport have preferentially removed the 
fine material. In the time between cruises 4 and 10, the Ba contained in the 
30-60 um fraction decreases from about 50 percent to 10 percent (fig. 12A). 
The distribution of Ba is bimodal for each cruise, but the distribution 
changes from one in which the fines are rer a large Ba inventory as a 
result of drilling mud accumulation (cruise 4) to one which begins to resemble 
the distribution of Ba in the uncontaminated sediment (cruise 10). 
38 
