SECTION VII 

 ANALYSIS OF SAFE HARBOR SEDIMENTS 



HEAVY METALS IN THE SEDIMENTS 



Initial analyses of the effluent showed a significant output of 

 copper (Table III) from the desalination plant and analyses of 

 sediments of Safe Harbor showed that copper levels were higher 

 than normal in the upper layers of sediment (Fig. 20). Since 

 copper antifouling paints are used on boats moored in the harbor, 

 it was impossible to determine precisely how much copper was 

 derived from antifouling paint, how much from the desalination 

 plant, and how much was originally in the harbor. 



Sediment cores were taken by divers to obtain a record of sediments 

 laid down in the harbor since its construction. Changes in parti- 

 cle size and hydrogen sulfied deposits left clearly delineated 

 strata in the sediments. Age determinations of these strata were 

 made by two independent techniques and cross-checked with measure- 

 ments of present day sedimentation rates. A graph was prepared 

 based on these data, showing age in years versus the depth of dif- 

 ferent strata from the sediment-water interface (Fig. 21). This 

 graph provided dating information for analyzed samples of various 

 strata in the cores. Strata were analyzed for copper and nickel 

 content, species diversity of foraminifera and their population 

 levels. 



Copper and nickel levels increased markedly in the strata layed 

 down after construction of the desalination plant. In a core taken 

 from one of the shrimp boat basins (near the center of the middle 

 shrimp boat basin on the western side of the harbor) at a depth of 

 32 feet (9.7m), copper levels increased first in 1960 and then again 

 in 1968, about a year after completion of the desalination plant 

 (Fig. 22). Nickel levels, closely followed copper levels in the 

 shrimp boat basin during the 1968 increase. Since the amount of 

 nickel did not increase in 1960 along with a copper increase of about 

 470 percent, it can be assumed that the source of copper was from 

 shrimp boat antifouling paints which leach copper but not nickel 

 ions. After the desalination plant began operating copper levels 

 increased another 360 percent (Fig. 22), accompanied by a 270 percent 

 increase in nickel. 



Near the desalination plant, in a core taken 100 feet (32.8m) off the 

 north end of the cement sea wall in 32 feet (10m) of water, there 

 was no increase in copper until about one year after the plant began 

 operation and nickel did not begin increasing until two years after 

 operation began (Fig. 23). 



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