43 



concentrations over the past century and are probably representative of 

 pre-industrial levels. Two other estuaries, the Saco and Kennebec, 

 exhibit recent anthropogenic enrichment due to industrial and/or sewage 

 inputs. Armstrong et al. (1976) determined trace metal values of the 

 sediments of the Great Bay estuary which has been historically subjected 

 to industrial discharges. Lyons and Gaudette (1979) investigated 

 concentrations in Jeffreys Basin, a fine-grained depositional area off 

 the coast of southern Maine and New Hampshire. They concluded that the 

 relatively high levels found there are the result of fine-grained 

 sediment export from estuaries. Two southern New England estuaries, the 

 unpolluted Mystic River estuary and the impacted Branford Harbor, were 

 contrasted by Lyons and Fitzgerald (1980). Finally, Greig et al. (1977) 

 analyzed a large number of sediment samples from Long Island Sound, a 

 large, highly "urbanized" estuary. For purposes of comparison we have 

 used only their results from the eastern half of the Sound, stations 

 72-143, to avoid the overbearing influence of inputs from the New York 

 City area. 



Trace metal levels at the 11 New England sites are contrasted in 

 Table 6. It is important to remember that trace metal distributions in 

 Casco Bay are very heterogenous and the mean values are only a gross 

 representation of the conditions in a given subarea. Cadmium levels in 

 Casco Bay compare favorably with the three other sites having reported 

 values. The mean value is close to that of the unimpacted Mystic River 

 estuary and considerably lower than the values reported for Branford 

 Harbor and eastern Long Island Sound. Casco Bay sediments appear to be 

 moderately enriched in terms of chromium. The mean concentration is 

 nearly twice that of the pre-industrial levels of northern New 



