Annual mass fluxes of selected metals entering the Harbor in Deer Island effluent 
are shown in Figure 2. While there is a hint of a trend downward in some of the later 
data, the 1982 and 1983 values are discouraging and indicate that the mass flux for some 
metals remains quite high and is likely to remain so until an effective pretreatment plan 
is instituted. 
Annual inputs of copper and lead to a number of estuaries and coastal waters have 
been compiled by Nixon et al. (1986). When the effluent inputs of these same two metals 
are calculated for Boston Harbor, their annual mass loadings are second only to that for 
the Hudson Raritan Bay system (Figure 3). The estimate for Boston Harbor excludes 
contributions from the CSOs or non-point sources. Also an unknown fraction of the input 
is most likely rapidly transported into Massachusetts Bay. However, until additional data 
become available, these estimates are probably of the right order of magnitude and valid 
for comparative purposes. 
Sediments are a known sink for contaminants in aquatic environments. Fine¬ 
grained, organic-rich sediments are most efficient in retaining pollutants. The 
distribution of sediment types in Boston Harbor, shown in Figure 4, includes large 
extensive regions of these fine-grained, organic rich muds, some having an organic 
content greater than 10 percent, and, therefore, representing potentially efficient traps 
of both inorganic and organic pollutants introduced into Harbor waters. 
Lead distribution in the sediments of Boston Harbor illustrates this fact (Figure 5). 
Sediment lead concentrations in the Inner Harbor and in the vicinity of Moon Island 
(Figure 5 ) are much higher than lead concentrations found in sediments sampled in 
Massachusetts Bay (Table 2). The particularly high sediment concentrations of lead in the 
vicinity of Moon Island are probably associated with the Moon Island discharge, which is 
used as an emergency by-pass upon system failure and results in the discharge of raw 
sewage to that area. However, because of the absence of data, transport and deposition 
of metal-laden particulate matter from other regions of the Harbor to the sediments in 
the vicinity of Moon Island cannot be ruled out. High sediment concentrations of lead 
similar to those found in the vicinity of Moon Island are also observed in sediments in the 
Inner Harbor. Again, the sources of lead in Inner Harbor sediments have not been 
accurately defined, but may reflect the large number of CSOs discharging into this part of 
the Harbor. 
The concentrations of a selected number of metals in Boston Harbor sediments are 
compared with those sampled in other contaminated areas such as the New York Bight, 
Massachusetts Bay, and Commencement Bay (a Superfund site) in Table 2. Metal 
concentrations in Massachusetts Bay sediments are comparable with those observed in 
sediments at the sludge dump site in the New York Bight (Carmody et al., 1973). Metal 
concentrations in Boston Harbor are comparable to, and in some cases substantially 
exceed, those in Commencement Bay and at some sites reach the mg/g (parts per 
thousand) dry weight range. Most of the highest metal concentrations have been observed 
in an area of the Harbor known as the Fort Point Channel, which receives approximately 
40 percent of the total CSO discharges to Boston's Inner Harbor (see Figure 1). 
40 
