Evaluating the roles of biotransformation, spatial concentration differences, organism home range, and field sampling design on trophic magnification factors

• Published in: The Science of the total environment Vol. 551-552; pp. 438 - 451
• Main Authors: Kim, Jaeshin, Gobas, Frank A.P.C., Arnot, Jon A., Powell, David E., Seston, Rita M., Woodburn, Kent B.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2016
• Subjects: Animals; Bioaccumulation; Biotransformation; chemical concentration; Concentration gradient; Environmental Monitoring - methods; Environmental Pollutants - analysis; Food Chain; food webs; Home range; Models, Chemical; phthalates; polychlorinated biphenyls; Polychlorinated Biphenyls - analysis; Sediment-water fugacity ratio; sediments; Trophic magnification factor (TMF); uncertainty; Trophic magnification factor (TMF); Home range; Sediment-water fugacity ratio; Bioaccumulation; Biotransformation; Concentration gradient
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.02.013

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. [Display omitted] •A new model was developed to evaluate bioaccumulation in aquatic food webs.•Model parameters having the greatest influence on bioaccumulation were evaluated.•Model results in excellent agreement with field results for a well-studied ecosystem.•Spatial concentration differences may bias interpretation of bioaccumulation.•Model is useful for a priori design and a posteriori evaluation of field studies.