tion may be questionable since small grains of sediment cannot be expected 

 to behave in the same manner as drifters of large surface area and vari- 

 able buoyancy. 



As mentioned earlier, of 1,886 surface drifters released by the SHL, 

 497 (26 percent) were recovered. Of 2,190 seabed drifters released, 710 

 (32 percent) were recovered. The surface and seabed drift studies con- 

 ducted by the SHL indicate qualitatively a general circulation pattern 

 for the Bight. These data and analyses were summarized in the results 

 section by reporting the percent drifter recovery from the various 

 release locations, but not on the basis of specific shore recovery loca- 

 tions. Such data would have been more informative (SAC, 1972). 



Based on recovery of its drifters, SHL concluded that there is a sub- 

 stantial shoreward migration of surface and bottom drifters, since over 

 29 percent of all the drifters released found their way to shore. SHL 

 also suggested that its data indicate a strong flow at the bottom along 

 the axis of the Hudson-Ambrose Channel into the mouth of the Hudson Estuary. 

 This pattern of circulation is partially supported by a drifter study of 

 the middle Atlantic Bight area conducted by Bumpus (1965) . This study 

 indicated that nearshore, the tendency for the flow was in a westerly or 

 southerly direction with a component toward the coast; but Bumpus con- 

 cluded that the onshore -offshore component was difficult to distinguish 

 from, more or less, isotropic dispersion because only those drifters 

 carried onshore yielded any information. His study, like that of Harrison 

 et al, (1967) indicated that there is a definite residual bottom drift 

 towards the mouths of estuaries. According to the SHL report (SHL, 1972), 

 such inflow to the Hudson Estuary mouth is expected as a normal consequence 

 of estuarine circulation driven by fresh water outflow, and has been widely 

 observed in other situations (Conomos et al., 1970; Gross, Morse and Barnes, 

 1969). 



As indicated earlier, under tidal circulation the ebb in the Lower 

 Bay is generally stronger than the flood by 10 percent or more, and a net 

 transport of water moves outward from the Hudson Estuary. The quantity 

 of water entering Lower Bay is limited, and waste material in suspension 

 in this water mass would be too diluted to be of concern. It is doubtful 

 that ocean dumping affects significantly the quality of the waters of the 

 Lower Hudson Estuary. 



Another conclusion of the SHL study is that there is a general clock- 

 wise circulation in the Bight. Such clockwise circualtion has been also 

 observed by Bumpus and Lauzier (1965) . There is no basis however for 

 the suggestion in the SHL study that this type of circulation can be 

 associated with bifurcation in the head of the Hudson Channel. Finally, 

 while surface drift patterns obtained by the SHL suggest strong seasonality, 

 there was only mild seasonal variation in the bottom returns. During 

 winter, surface flow in the Bight appears to be predominantly to the south- 

 east, away from the coast. At other time flow tended northwards Long Island 

 (SHL, 1972). 



110 



