Biomagnification of α- and γ-Hexabromocyclododecane Isomers in a Lake Ontario Food Web
Bibliographic record
Abstract
The extent of bioaccumulation of hexabromocyclododecane (HBCD) isomers (alpha, beta, and gamma) was determined in the Lake Ontario pelagic food web using liquid chromatography tandem mass spectrometry (LC/MS/MS). Concentrations of the alpha-isomer were consistently higher than that of the gamma-isomer. The beta-isomer was below method detection limits in all samples. Whole body concentrations (ng/g, wet wt) of alpha- and gamma-HBCD were highest in the top predator lake trout samples ranging from 0.4 to 3.8 ng/g for the alpha-isomer and 0.1 to 0.8 ng/g for the gamma-isomer. For the prey fish species, the trends in alpha- and gamma-HBCD levels were slimy sculpin > smelt > alewife. Mean concentrations of total (sigma) HBCD (sum of alpha- and gamma-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 sigmaHBCD concentrations (wet wt) and trophic level based on delta15N suggesting that HBCD biomagnifies in the Lake Ontario food web. The trophic magnification factor (TMF = 6.3) derived from the slope of the sigmaHBCD - trophic level relationship was slightly higher than TMFs for p,p'-DDE (6.1) and sigmaPCBs (5.7) found previously. Biomagnification factors (BMF, calculated as the ratio of lipid corrected concentration in predator/lipid corrected concentration in prey) were variable between feeding relationships and ranged from 0.4 to 10.8 for the alpha-isomer and from 0.2 to 10 for gamma-isomers.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.004 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".