Quantitative Biomonitoring in the Detroit River Using Elliptio complanata: Verification of Steady State Correction Factors and Temporal Trends of PCBs in Water Between 1998 and 2015.

Quantitative biomonitoring methods were applied to determine PCB concentrations in water from the Detroit River over a 17 year period. During 2014, mussels were deployed for and extended duration (21-364 days) and time dependent PCB concentrations were fit to a bioaccumulation model to estimate elimination coefficients (ktot) and provide site specific calibration of mussel toxicokinetics. The site specific calibration and different ktot versus KOW relationships from the literature were used to correct for steady state. ∑PCB concentrations in water were not significantly dependent on the ktot values used indicating that individual variation exceeds error contributed by steady state correction factors. The model was then applied to estimate ∑PCB concentrations in water using the long term (1998-2015) data. ∑PCBs concentrations in water exhibited a significant decreasing trend with a half life of 9.12 years resulting in a drop in yearly geometric mean residues from 198.1 to 43.6 pg/L.

Spatial and temporal variability of PCBs in Detroit River water assessed using a long term biomonitoring program.

An assessment of polychlorinated biphenyls (PCBs) in water of the Detroit River, North America, was performed using mussel biomonitoring data generated between 1996 and 2010. The study included a temporal monitoring program at six locations and an enhanced spatial survey performed during 2002. Mussels were transplanted at biomonitoring stations and collected after 21-226 d. A toxicokinetic model was used to perform steady state and control corrections followed by an equilibrium partitioning model to estimate bioavailable water concentrations of PCBs. Bioavailable water concentrations of PCBs were similar in magnitude and trends to dissolved water concentrations reported in previous studies using direct sampling approaches. PCB concentrations exhibited complex temporal patterns at the six biomonitoring stations with multi-year declines in PCB trajectories between 1996 and 2002 and less consistent trends occurring across stations in later years. Spatial patterns of PCBs during 2002 revealed significantly higher water contamination on the US side of the river (seasonal average mean ± standard error (SE) sum PCB concentration of 0.63 ± 0.11 ng L(-1)) compared to the Canadian side (mean ± SE sum PCB concentration of 0.09 ± 0.01 ng L(-1)). Spatial/temporal variability of bioavailable PCB concentrations was greatest between countries, followed by moderate variation across years and by river reach (upstream, midstream and downstream sections within a country) and lowest when comparing intra-seasonal variation.