Gordia MacInnis

Biomagnification of α- and γ-Hexabromocyclododecane Isomers in a Lake Ontario Food Web

The extent of bioaccumulation of hexabromocyclododecane (HBCD) isomers (α, β, and γ) was determined in the Lake Ontario pelagic food web using liquid chromatography tandem mass spectrometry (LC/MS/MS). Concentrations of the α-isomer were consistently higher than that of the γ-isomer. The β-isomer was below method detection limits in all samples. Whole body concentrations (ng/g, wet wt) of α- and γ-HBCD were highest in the top predator lake trout samples ranging from 0.4 to 3.8 ng/g for the α-isomer and 0.1 to 0.8 ng/g for the γ-isomer. For the prey fish species, the trends in α- and γ-HBCD levels were slimy sculpin > smelt > alewife. Mean concentrations of total (Σ) HBCD (sum of α- and γ-isomers) in the macrozooplankter Mysis relicta (0.14 ± 0.02 ng/g wet wt) and in the benthic invertebrate Diporeia hoyi (0.16 ± 0.02 ng/g, wet wt) were similar and approximately twice as high as in plankton (0.06 ± 0.02 ng/g, wet wt). A strong positive linear relationship was found between ΣHBCD concentrations (wet wt) and...