10-2 



with increased contaminant levels even where they occur. The tolerable 

 levels, the degrees of irreversible sequestering and other factors all 

 must enter into the evaluation of man's impact on the environment. 



In this report I discuss what we now know of the factors in- 

 fluencing controls on trace-metal distribution in New Haven Harbor and 

 Long Island Sound and the subsequent effects on resident biota. Con- 

 sideration is also given to possible effects of New Haven Harbor Station 

 on harbor trace-metal concentrations. I draw on the published and 

 unpublished work of our group at Yale, as well as the results of several 

 other studies done at other institutions. 



TRACE METALS IN SEDIMENTS 



Controls on Trace-Metal Distribution in Sediments 



Stream Supplij 



The dissolved trace-metal concentration of streams is controlled 

 not only by input from the weathering of rocks and from aerosols but 



also by the chemical reactions occurring within the streams. The evidence 



210 

 from studies utilizing Pb as a tracer for heavy metal behavior m 



streams indicates rapid scavenging by particles associated with the 



flowing water (Benninger, Lewis and Turekian, 1975; Lewis, 1977). 



Surfaces of organic debris and manganese and iron oxide coatings appear 



to be the primary agents. Competing with this process is the foirmation 



of dissolved organic-chelated compounds. Much of the dissolved iron 



found in streams, for instance, is in this form (Sholkovitz, 1976). 



A study of Connecticut streams (Turekian, 1971) indicated that 

 the trace-metals, cobalt and silver, are maintained in solution at low 

 concentrations as the result of the scavenging action of suspended 

 particles. Even where acid industrial wastes are dumped into the stream, 

 as in the Naugatuck River which joins the Housatonic River, suspended 



particles act to lower the dissolved concentrations. I infer from 



210 

 studies involving the behavior of Pb in the Susquehanna River and of 



