fc 



to iron and therefore, have characteristics similar to western Long Island 

 Sound Sites rather than northern New England areas. Unless cleaner areas can 

 be defined within these disposal sites, differentiation of new spoils on the 

 basis of chemical characteristics is doubtful. 



Biochemical Studies 



Reference samples of M. modi ol us from Hal fWay Rock, northeast of Marblehead, 

 Mass. were placed on the Boston Foul Ground and Lightship disposal sites in May, 

 1978. Although information was obtained from the Foul Ground mussels in August 

 '78 the release mechanism on the mooring at the. Lightship failed and no samples 

 were obtained. Data from the reference station at Halfway Rock and the August . 

 '78 Foul Ground sample are presented in Table D-3 and .Figure D-S. Chromium 

 at the reference station mussels was the only metal to show a significant con- 

 centration increase during the monitoring period. However, significant decreases 

 in Cu at the reference and disposal site and Pb at the disposal site occur in 

 August, 1978. 



It should be noted that the August, 1978 samples have concentrations of Cd , 

 Cr, Cu, Hg and Zn from th? Boston Foul Ground that are consistantly lower than 

 concentrations from the Halfway Rock reference samples. Such differences may 

 have resulted from pollution by land based sources at Hal fV/ay Rock, which is 

 located close to shore. Such a conclusion would mean that the effect of dredge 

 spoils, which the sediment samples have shown to be rich in heavy metals, is 

 minimal with regard to dissolved or suspended metals that may be ingested by 

 the mussels. Obviously, more temporal and spatial data are needed before a 

 defi native statement can be made. 



