concentrations of metals than those below the 1900 horizon. Similar observations have 
been made in cores taken in other areas of the world. To my knowledge, there are no 
similar data for Massachusetts Bay sediments. Such data would be of value in assessing 
the relative increase in metal concentrations of Boston Harbor and Massachusetts Bay 
sediment^ as well as the potential influence of the Boston Harbor discharges on 
Massachusetts Bay sediment quality. 
While sediments of estuarine and coastal marine environments are a known sink for 
contaminants, the efficiency with which these sediments trap metals and other 
contaminants is not well understood (Turekian, 1977; Nixon et al., 1984). The efficiency 
with which the sediments of Boston Harbor retain metals introduced into the Harbor was 
erroneously stated in the original version of Fitzgerald's thesis to be about 33 percent for 
metals emanating from the effluent of the two treatment plants. In fact, when later 
corrected for an order of magnitude error used in his calculation, Fitzgerald's estimate of 
this trapping efficiency becomes only 3 percent. The implication that metals in the 
Harbor sediments represent only a very small portion of the total loading to the Harbor 
suggests that most of the metals introduced into the Harbor are transported offshore into 
Massachusetts Bay and either dispersed or accumulated in the fine-grained deposits that 
were referred to by Dr. Boehm. At this point it is probably most accurate to say that the 
mass balance of metals has not been established and that the fate of metals introduced 
into the Boston Harbor/Massachusetts Bay system is not well understood. 
While sediment concentrations serve to qualitatively integrate the history of metal 
pollution in coastal environments, water column concentrations reflect the shorter time 
frame of pollution. However, it is difficult to accurately measure water column 
concentrations of metals in the nanomolar and picomolar range. Because of the frequent 
poor quality of such data, meaningful interpretation of the distribution of metals and, 
consequently, the identification of processes critical to understanding their fate and 
transport in nearshore environments have remained obscure. 
Previously reported water column concentrations of metals in Boston Harbor have 
been shown to be erroneously high, in some cases by as much as three orders of magnitude 
(Wallace et al., in press). Data in Figure 9 compare the recently obtained range in 
concentrations of selected metals in the Harbor by Wallace et al. with those reported by 
the Massachusetts Division of Water Pollution Control (DWPC). Concentrations observed 
by the DWPC for these metals in Deer Island sewage treatment plant effluent are also 
given for comparison. Metal concentrations in the Harbor as determined by the DWPC 
are frequently in the same range as concentrations they reported to be present in the 
sewage effluent. Because Harbor waters have a salinity in the range of 30 o/oo and, 
therefore, contain only a small fraction of sewage effluent, the metal concentrations 
reported by the DWPC for the Harbor are probably incorrect. 
The data of Wallace et al. (in press) were acquired using techniques suitable for use 
in open-ocean waters that have analytical resolutions orders of magnitude lower than 
those used by most non-academic institutions. Although concentrations for all the metals 
analyzed (copper, zinc, nickel, cadmium, and lead) ranged from 10 to 1,000 times lower 
50 
