10-6 



distance from the several sewage treatment plants discharging into the 

 harbor (Figure 10-3) . As is the case with most of the older New England 

 cities, storm sewers are combined with sanitary sewers and the effluent 

 is j'rocessed throug?i the sewage treatment plants. During periods of high 

 dischairqi" asr.ociatod with large storms, the treatment plant is byi'assed 

 and the unprocessed effluent is debouched directly into the harbor, 

 resulting in organic carbon and metal enrichment of the sediment around 

 the outfalls. We found high Pb, Zn and Cu associated with the sewer 

 outfall south of Long Wharf. Our most detailed study of the sedimentary 

 organic and heavy metal content association with sewer outfalls was 

 made prior to construction of New Haven Harbor Station on the East Shore 

 just off the Harbor Station property (old Coke Works site) . Detailed 

 studies of the tissue heavy metals concentration of bivalves from the 

 same area will be discussed later. A plot of the zinc concentration 

 versus volatile solids (assumed to be mainly organic material) for New 

 Haven Harbor is shown in Figure 10-4. Comparison with a site in central 

 Long Island Sound grax^hically shows the role of near-shore outfall 

 contamination . 



Thus we see that the trace-metal patterns in near-shore sedi- 

 ments of the Connecticut shore of Long Island Sound are determined 

 primarily by the location of sewer outfalls. The stream supply of 

 industrial contamination is expressed where damming does not act as a 

 sediment trap between the point of injection and the entry into the 

 estuary. 



Maintenance or construction-related dredging of metal-contam- 

 inated sediments results in the transport of the material to other 

 locations in the Sound where the dredge spoil is dumped. The identi- 

 fication of such dumping has been made in the New York Bight using trace 

 metals and organic content as well as other indicators (Gross, 1976; 

 Carmody, Pearce and Yasso, 1973) but, as we shall see, other factors 

 operate in Long Island Sound to attenuate the effect of maintaining a 

 local identity. 



