T9 AM Bioaccumulation and Biomagnification
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 339-340

(LAW-1117-776133) Calibration and Validation of a Bioenergetic PCB Bioaccumulation Model for the Housatonic River, Massachusetts.

Lawrence, G.¹, Clough, J.², Svirsky, S.³, ¹ EVS Environment Consultants, North Vancouver, British Columbia, Canada.² Warren Pinnacle Consulting, Warren, Vermont, USA.³ Environmental Protection Agency, Boston, Massachusetts, USA.

ABSTRACT- A time-dependent, bioenergetic PCB bioaccumulation model was applied to simulate the fate of polychlorinated biphenyls (PCBs) in the aquatic habitat of the Housatonic River, Massachusetts, USA. The model is linked to watershed, hydrodynamic, and PCB fate models and will ultimately be used to compare various response and restoration scenarios as part of site management. The model simulates both total PCBs and several PCB congeners found in site contamination (derived from Aroclor 1254 and 1260). The model simulates PCB uptake via dietary accumulation and respiration, and simulates PCB loss via growth dilution and chemical excretion. The model was calibrated to an 11-mile stretch of the river over the calibration period (1995-2000). The spatial domain included multiple habitat types, species assemblages, and food webs. The model was calibrated using abundant site-specific biological and chemical data, supplemented by general natural history information from the literature. Model parameters were constrained within scientifically plausible ranges during calibration. Comparison of model simulations to measured tissue burdens indicated that mean total PCB and congener concentrations for each representative species and reach were generally within a factor of two, with no significant bias as a function of fish age, species, river reach, etc. Monte Carlo simulations were used to evaluate model uncertainty, using distributions of important model variables identified during sensitivity analyses. Validation of the model is in progress, and entails extension of the calibrated model to a longer term data set and to adjacent reaches of the Housatonic River.

Key words: bioaccumulation model, polychlorinated biphenyls, bioenergetics, Housatonic River