title: Evaluating the roles of biotransformation, spatial concentration differences, organism home range, and field sampling design on trophic magnification factors.
abstract: Trophic magnification factors (TMFs) are field-based measurements of the bioaccumulation behavior of chemicals in food-webs. TMFs can provide valuable insights into the bioaccumulation behavior of chemicals. However, bioaccumulation metrics such as TMF may be subject to considerable uncertainty as a consequence of systematic bias and the influence of confounding variables. This study seeks to investigate the role of systematic bias resulting from spatially-variable concentrations in water and sediments and biotransformation rates on the determination of TMF. For this purpose, a multibox food-web bioaccumulation model was developed to account for spatial concentration differences and movement of organisms on chemical concentrations in aquatic biota and TMFs. Model calculated and reported field TMFs showed good agreement for persistent polychlorinated biphenyl (PCB) congeners and biotransformable phthalate esters (PEs) in a marine aquatic food-web. Model testing showed no systematic bias and good precision in the estimation of the TMF for PCB congeners but an apparent underestimation of model calculated TMFs, relative to reported field TMFs, for PEs. A model sensitivity analysis showed that sampling designs that ignore the presence of concentration gradients may cause systematically biased and misleading TMF values. The model demonstrates that field TMFs are most sensitive to concentration gradients and species migration patterns for substances that are subject to a low degree of biomagnification or trophic dilution. The model is useful in anticipating the effect of spatial concentration gradients on the determination of the TMF; guiding species collection strategies in TMF studies; and interpretation of the results of field bioaccumulation studies in study locations where spatial differences in chemical concentration exist.
authors.affiliation: Health and Environmental Sciences, Dow Corning Corporation, 2200 W. Salzburg Road, Auburn, MI 48611, USA.
authors.forename: Jaeshin
authors.initials: J
authors.lastname: Kim
authors.affiliation: School of Resource & Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
authors.forename: Frank A P C
authors.initials: FA
authors.lastname: Gobas
authors.affiliation: ARC Arnot Research and Consulting Inc., 36 Sproat Avenue, Toronto, Ontario M4M 1W4, Canada; Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Arnot
authors.affiliation: Health and Environmental Sciences, Dow Corning Corporation, 2200 W. Salzburg Road, Auburn, MI 48611, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Powell
authors.affiliation: Health and Environmental Sciences, Dow Corning Corporation, 2200 W. Salzburg Road, Auburn, MI 48611, USA.
authors.forename: Rita M
authors.initials: RM
authors.lastname: Seston
authors.affiliation: Health and Environmental Sciences, Dow Corning Corporation, 2200 W. Salzburg Road, Auburn, MI 48611, USA.
authors.forename: Kent B
authors.initials: KB
authors.lastname: Woodburn
mesh_terms: D000818:Animals; D001711:Biotransformation; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D020387:Food Chain; D008956:Models, Chemical; D011078:Polychlorinated Biphenyls / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls
keywords: Bioaccumulation; Biotransformation; Concentration gradient; Home range; Sediment-water fugacity ratio; Trophic magnification factor (TMF)