In Massachusetts Bay, we find that PCB levels in the dab, a flat fish (winter flounder 
were not sampled offshore) are much lower than they are in Boston Harbor. This finding 
is not surprising. PCB values in crabs in Massachusetts Bay are fairly close to Boston 
Harbor, illustrating that PCBs are probably transported offshore. To what extent this 
transport is occurring, we do not know, but it is impacting the levels of PCBs in crabs. 
In summary, I have quickly presented our knowledge of the types of organic 
concentrations offshore. As I mentioned before, one of the existing data gaps pertains to 
our knowledge of the other components of potential pollutant inputs into the system. We 
know a reasonable, yet incomplete amount about sewage inputs. Although a considerable 
number of analyses have been performed, we do not know, on a mass balance basis, what 
pollutants are coming out of the rivers and are coming out of the many combined sewage 
overflows. 
Therefore, we cannot really address, from a toxic organics viewpoint, the overall 
management questions, "What will happen if we turn off a certain pollutant source? What 
will happen to concentrations over time during a recovery of the system?" The residence 
times of contaminants in sediments and in the water column, which can only be computed 
from a knowledge of inputs and ambient concentrations, are very poorly known in relation 
to well studied systems where the sources have been studied with greater detail. We need 
to know just where the various pollutants are coming from and what will happen if we turn 
one or more of these sources off or place it elsewhere? 
We know very little about water column particulate organic pollutant concentrations 
as they relate to established EPA water quality criteria. Little is known regarding fluxes 
from the Harbor to Massachusetts Bay. Even in our surveys on Massachusetts Bay and 
Boston Harbor, we are looking at temporal snapshots, so we have to infer from where the 
materials are coming. Looking at the coupling between the Harbor and the Bay, we know 
very little about the extent of offshore transport of pollutants originating in Boston 
Harbor. 
Furthermore, we know very little about the fate of sewage plumes and associated 
pollutants. Sewage is discharged on the ebb tide, and we assume that it goes eastward 
into Massachusetts Bay. But we do not know where or how much of it may "slosh" back 
over a tidal cycle and be deposited into Boston Harbor. 
We do not know very much at all about temporal trends in pollutant concentrations. 
Monitoring data are almost totally lacking to determine if pollutant concentrations are on 
the increase over the last ten years. We are just beginning to get that information, and 
we certainly cannot make any assessment of how our various management decisions (such 
as, upgrading sewage treatment to secondary treatment) will affect the system until we 
have that type of information. We also have very little information on other 
contaminants (such as pesticides) of concern other than PCBs, PAHs, and heavy metals. 
More than 100 other compounds are on EPA's priority pollutant list, many of which are far 
more toxic than PAHs and PCBs, and we have very little data on those types of 
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