Development of Site-Specific BSAFs for Development of Remediation Goals in Sediment and Floodplain Soils

摘要

Background/Objectives. Developing site-specific preliminary remediation goals (PRGs)is a complex process requiring detailed analysis and stakeholder acceptance. Biotasediment/soil accumulation factors (BSAFs) were developed during the remedial investigation(RI) at Superfund site consisting of an 80-acre oxbow lake. These BSAFs weredeveloped for mercury accumulation in fish from sediment using site-specific data.Approach/Activities. Tissue data for predatory fish and forage fish were paired withsediment samples collected within a typical home range of each fish group in the oxbowlake. Data pairs were plotted, and a variety of regression analyses were performed tochoose the regression with the best fit. Data pairs were evaluated in various ways (i.e., byyear of collection and by fish species) to determine an acceptable regression modelcorrelating site sediment and tissue data. Acceptable regression models were developedin consensus with EPA and were identified as having a R~2 greater than 0.70 and a p-valueless than 0.05. The regression model with the higher R~2 values and the lowest p-valuewas chosen as the sediment-to-fish BSAF. The sediment-to-fish BSAF regression equationswere utilized in the remediation goal calculations for sediment intended to beprotective of fish and the aquatic environment.A similar exercise was performed for calculating mercury bioaccumulation factors(BAFs) in insects from adjacent floodplain soils. Insect tissue samples were collectedfrom the floodplain along with collocated soil samples in the 0-6 inch depth interval.Data pairs included collocated soil samples as well as samples within close proximity tothe location of insect collection. Acceptable regression models were considered to have aR2 greater than 0.70 and a p-value less than 0.05. The regression model with the higherR2 and the lowest p-value was chosen as the soil-to-insect BAF. This BAF regressionequation was utilized in the remediation goal calculations for floodplain soils intended tobe protective of the terrestrial environment.Results/Lessons Learned. Use of the BSAF/BAF method resulted in USEPA-acceptablePRGs for mercury in sediment and floodplain soils.