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sediment will accumulate unevenly over a bottom, with some locations gathering much sediment, 

 and others gathering much less or even eroding. 



The importance of geoaccumulation for Massachusetts Bay is significant. EfTluent will 

 bring with it a variety of toxic chemicals (e.g., copper, PCB's, mercury, dieldrin) which may be 

 accumulated by sediments. Dcpocentcrs have been identified within the Bay system, where 

 accumulation of toxics might take place. Once in the sediments in large concentrations, these 

 toxics might be introduced into the food chain by benthic organisms, and ultimately can be 

 introduced directly to the endangered species in question (see comments by R. Kenney). This 

 benthic conveyor belt has been ignored in the Work Plan - a significant gap. The ESTM should 

 evaluate the potential for adverse effects or impacts resulting from this linkage. In order to address 

 this issue, the ESTM may have to await model results which incorporate a realistic sedimentation 

 and "scrubbing" process model, perhaps added to the water quality model. Without such 

 calculations and elucidation of food chain dynamics, these impacts cannot be quantified. 



