Now, this is indeed what we found in our recent and previous studies. PCBs and 
presumably other chemicals are found in higher concentrations in the depositional basins. 
A multi-station design (Figure 2) in Boston Harbor and several different regions in 
Massachusetts Bay and Cape Cod Bay was used to examine distributions of toxic organic 
compounds. Companion studies were conducted to determine concentrations and benthic 
biological parameters. The biological studies were conducted by Dr. Peter Larsen at 
Bigelow Laboratory. 
As Table 1 shows, we found that of course, the concentrations of PAHs, PCBs, and 
coprostanol, the sewage indicator, are very high in the Harbor. There is a large range in 
the Harbor as I mentioned previously. Region 2 (Figure 2) is the northern area of 
Massachusetts Bay. Concentrations of toxics in this region are elevated over other 
offshore areas. Ranges of PAH concentrations at several stations in Region 2 reveal 
values which approach some found in Boston Harbor. These stations are located in small 
depositional basins (Stations MB6, 7, and 8). 
As we look at sediment results farther offshore and to the south in the region of 
Stellwagen Basin, we find higher values of PCBs and PAHs in these depositional areas. In 
general, we find the elevated PCBs are found in northern Massachusetts Bay. The data 
suggest that sewage inputs either from the Harbor or from some of the northern 
communities, such as South Essex, Lynn, may be deposited in these regions. 
Two depositional areas, Stations MB-6 and MB-8, exhibit some of the higher values 
in the offshore region. Values are low compared to those in the Harbor, but are high for 
similar offshore regions elsewhere. One of the problems we have in evaluating these data 
is that we do not have a firm handle on the trends of contaminants in the region because 
not many surveys have been done which occupy the same stations over time. A survey 
was conducted by New England Aquarium in 1976. However, our study represented the 
first statistically rigorous sampling where replicate samples and analyses were obtained at 
each station. We really do not have any statistically valid trend analyses to show whether 
concentrations are increasing or decreasing at these stations over time. 
We are seeing relatively higher concentrations at several stations, which are perhaps 
related to the proximity of the "foul" area, (near Station MB-6) a dumpsite for dredged 
material. Potential offshore transport of pollutants from the Harbor may be occurring as 
well. We strongly suspect that catch basins exist offshore that are acquiring and 
accumulating elevated levels of organic contaminants. 
We use many source indicators to interpret geochemical data, one of which is 
related to the composition of PCBs. We find that in the Harbor, trichlorobiphenyls (PCBs 
with three chlorine atoms) are prevalent and are related to sewage inputs. Such PCB 
compositional plots are useful in examining likely sources of PCBs (such as those which 
may be sewage-related). Station MB-6 is located far offshore. However, PCB 
compositional plots indicate that sewage input is evident. We have come to the 
conclusion, based on PCB compositional plots and on levels of coprostanol in the 
67 
