Metal concentrations in the sediments of Massachusetts Bay, reported in a study 
undertaken by the New England Aquarium in 1976, are similar to recent data generated by 
NOAA although concentrations reported in the NOAA data tend to be somewhat lower (V. 
Zdanowicz, NOAA, Sandy Hook, NJ; pers. comm.). Of interest in the New England 
Aquarium's sediment data for chromium (Figure 6) is the apparent shoreward increase in 
concentration in the vicinity of Salem Sound. This distribution is consistent with what 
little we know about discharges in this area. The South Essex Sewage District discharges 
primary, or until recently, raw sewage effluent into Salem Harbor. Analyses of this 
effluent in the past have found rather remarkable concentrations of chromium (in the 
mg/1 range) in the effluent (South Essex Sewage District 301h Waiver Application). 
The existing data for metals in Massachusetts Bay sediments do not clearly indicate 
a spatial pattern that would implicate Boston Harbor as a source of the observed metals. 
This lack of a pattern is not surprising considering the variable nature of the sediments in 
Massachusetts Bay, especially the occurrence of coarse-grained sediments inshore 
(Fitzgerald, 1980). However, potential long-range transport of metals to Massachusetts 
Bay from Boston Harbor and their subsequent deposition at offshore locations is a distinct 
possibility in this environment. 
Copper concentrations (Figure 7) tend to increase towards Boston Harbor although 
there is a gap in the data in the area immediately adjacent to the Harbor, perhaps because 
of the difficulty in sampling coarse-grain sediments in that area. Indeed, knowledge of 
the fate of the contaminant-laden sludge discharged at the mouth of the Harbor over the 
past two decades is non-existent. The short- and long-term fate of this material is 
essentially unknown. Local deposition in the Harbor, if Fitzgerald's (1980) estimates are 
correct is, a minor sink for metals discharged from the treatment plants. 
Assessing the degree of contamination in a region simply on the basis of bulk 
sediment metal concentrations, however, is difficult because grain size and organic 
content of the sediments are important variables influencing sediment metal 
concentrations; and, these variables may or may not be associated with pollutant sources. 
Unfortunately, much of the sediment sampling and analyses performed on Boston Harbor 
and Massachusetts Bay samples have not included appropriate analyses of the different 
size fractions present. 
Sediment geochronology in conjunction with contaminant analysis has been shown to 
be useful in documenting the pollution history of regional sediments (Goldberg et al., 
1977). Data from a core taken in Dorchester Bay by Fitzgerald (1980) represents a similar 
effort to assess the pollution history of Boston Harbor sediments (Figure 8). Well-known 
problems are associated with the use of lead-210 in sediment geochronology, particularly 
associated with the biological mixing of surficial sediments. However, for the purposes of 
this discussion, we will accept Fitzgerald's assignment of 1900 as the age of sediment 
found at 39 cm in the Dorchester Bay core. 
Most of the metal concentrations increase dramatically with core height above the 
1900 horizon. The more recently deposited sediments in the core have much higher 
46 
