attempts have been to match toxicity data to various sediment guidelines, but there are no 
published reports of a study which used all of the available guidelines to predict and explain 
toxicity in the samples. 
In this project, the sediment guidelines (i.e., which are based on the equilibrium partitioning 
[EqP] model) will be applied using a toxic unit model to determine whether concentrations of 
chemicals measured commonly in sediment monitoring programs (cationic metals, PAHs, PCBs 
and other non-PAH narcotic chemicals, and pesticides) appear sufficient to explain observed 
toxicity (EPA 2000a,b,c,d). Where they are not, it may be inferred either that unmeasured 
chemicals (e.g., ammonia) or measured chemicals not included in the toxic unit model are 
contributing to toxicity, or that the EqP model does not provide protective guidelines. Part of 
this effort will be to improve the EqP model to correct these potential errors. 
Products 
As a result of this project, a data set will be generated describing the effects of those factors 
resulting in non-equilibrium conditions including seasonality, suspended sediments, and unusual 
binding phases. This research recognizes the equilibrium assumption of existing guidelines as a 
potential weakness which may compromise their utility if not better understood. Further, we will 
perform an assessment of how effective current guidelines are for predicting field effects. 
FY02 Report to OW on the effectiveness of ESGs in the prediction of amphipod mortality in 
sediments. 
FY02 Peer-reviewed journal article on the usefulness of EqP in the prediction of amphipod 
mortality in sediments. • 
FY05 Report to OW on the importance of seasonality and resuspension in predicting the 
biological effects of contaminants in sediments. 
FY06 Report to OW on the importance of unusual binding phases in predicting the biological 
effects of contaminants in sediments . 
Benefits of Products 
Currently, the usefulness of the Agency’s sediment guidelines, which are based on EqP is 
potentially limited in regard to field application by our poor understanding of the effects of 
seasonality, resuspension, and unusual binding phases. For example, A VS has been used to 
develop ESGs for metals, but its application is limited. Better understanding of the biological 
effects of contaminants under non-equilibrium conditions would greatly increase the applicability 
of the guidelines in the field. 
The Office of Water has chosen EqP as the method for developing ESGs, but before these 
guidelines can be accepted in the scientific and regulatory community, they must receive further 
validation in the field. This research is one step in that validation. 
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