interpret this as evidence for a small recent addition of Ba. Also to the 
east, along transect I, we have measured Ba increases in some of the 
postdrilling samples, although these are of smaller magnitude than those at 
stations 10 and 12. There is no evidence of an increase in Ba at stations 13 
or 13A from the analysis of surface samples or from sediment cores, although a 
small signal is more difficult to identify here because of a _ higher 
predrilling Ba concentration. 
A rough calculation made in an earlier report (Bothner and others, 1983) 
suggested that 69 percent of the barite discharged by all eight exploratory 
wells could be accounted for in the sediments within the western half of a 
circle 130 km in diameter and centered on station 5. Inclusion of areas to 
the east of station 5, particularly in light of the small increases in Ba 
measured during the third year at stations 2 and 3, would increase the 
percentage of drilling-related Ba accounted for in the sediments. 
We conclude that the barite from drilling mud is associated with the fine 
sediment fraction in low concentration and is widely distributed. 
The overall results of this study have important implications in 
predicting the fate and effects of any contaminants discharged on Georges Bank 
which have an affinity for sediments or suspended particulates. For those 
contaminants that are rendered harmless by dilution, the tidal and storm 
currents are sufficient to disperse material over wide areas. Benthic 
organisms can assist in dispersing a contaminant added to the sea floor to 
deeper horizons in the sediments. These processes act quickly; half of the 
barite inventory at the station 5 drill site was removed from the 0-2-cm 
sediment layer in 0.34 years. For those contaminants known or presently 
unknown to be dangerous at any concentration, or for those contaminants that 
are added in excess of the system's capacity to dilute, the same energetic 
processes of dispersion will endanger a wide area of the bank. 
66 
