To determine the inventories of Ba within the 6-km-radius circle 
(fig. 1B), the Ba concentrations on each ring of the sample pattern were 
averaged and used to estimate a representative concentration for each annulus 
around the drill site. We assume that the Ba added by the introduction of 
drilling mud is contained within the sampling depth interval of 0 to 2 cm. 
This is a valid assumption until at least cruise 5, based on core profiles 
from station 5-1 reported in the second year final report. For comparison to 
the amount of BaSO, used in the drilling operation, we have converted both 
predrilling and postdrilling Ba concentrations to BaS0,. The inventory of 
barite is calculated from the field data with the following relation: 
Total=) A+d+Z+C+(BaS0,/Ba) 
where A=area of each annulus, d=bulk density of dry sediment (1.6 g/cc), 
Z=depth interval (0-2 cm), C=concentration of Ba (ug/g), and BaSO,/Ba is the 
ratio of molecular weights. 
We estimate that the inventory of BaSO, in the upper 2 cm of sediment in 
the 6 km circle totals 0.59x10® to 0.62x10® 1b before drilling began 
(cruises 1 and 2). The inventory increases to 0.86x10© 1b on cruise 5 just 
after drilling stops (net increase of 0.27x106 lb) and decreases to values 
between 0.68x10® and 0.60x10® 1b for the last four cruises (fig. 18). 
The total barium sulfate used in drilling the exploratory well at 
block 312 was 2,387,800 1b (Danenberger, 1983). An estimated 630,000 1b was 
left in the hole when the rig moved off location. If there were no losses of 
mud to porous subsurface rock formations while drilling, which is highly 
unlikely, then the total barite discharged to the ocean was 1,757,800 1b. 
This estimate is considered an upper limit because some loss to porous 
formations is expected. E. P. Danenberger (iinerais Management Service, oral 
commun., September 21, 1983) estimated that, on the basis of drilling records, 
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