Bioaccumulation Studies

Fish in EFPC have historically had elevated amounts of mercury and PCBs relative to fish in uncontaminated reference streams. EFPC fish are monitored regularly for mercury and PCB's in order to assess spatial and temporal trends in bioaccumulation associated with ongoing remedial activities and Plant operations. As part of this monitoring effort, redbreast sunfish (Lepomis auritus) are sampled from six sites along EFPC and analyzed for tissue concentrations of these two environmental contaminants. Largemouth bass (Micropterus salmoides) are also collected to monitor the maximum bioaccumulation in larger piscivorous fish of the stream.

High levels of mercury contamination continue to occur upstream of Lake Reality, suggesting that Y-12 Plant discharges remain an important source of mercury to fish in the upper reaches of EFPC. However, mercury concentrations in fish have decreased significantly in upper EFPC over the last few years in conjunction with similar decreases in water concentrations of mercury (Figure 1).
PCB concentrations in sunfish sampled from EFPC remain highest in Lake Reality and the upper reaches of EFPC above Lake Reality, indicating a continuing source or sources within the Y-12 Plant (Figure 2).


Figure 1. Average mercury concentration in redbreast sunfish muscle fillets, East Fork Poplar Creek upstream and downstream of Lake Reality, and monthly average total mercury concentration in water at Station 17, 1994-1998.


Figure 2. Mean concentrations of PCBs in redbreast sunfish muscle fillets, East Fork Poplar Creek upstream and downstream of Lake Reality, 1985-1998.

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Last Modified: April 17, 2001
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