Exposure pathways (diet, dissolved or particulate substrate) of rare earth elements to aquatic organisms
Bibliographic record
Abstract
The global extraction and use of rare earth elements (REEs) continue to rise as they are implemented in technologies that improve human and environmental livelihoods. However, the general understanding of transfer processes and fates of REEs in aquatic systems remains limited. Here, we aim to determine the REEs' main exposure pathways, e.g., particulate fraction, diet, or dissolved (ionic) fractions, to three benthic and three pelagic organisms. They were maintained under laboratory conditions and exposed to natural river water , with or without a sand substrate and an adapted diet. The organisms include northern clearwater crayfish ( Faxonius propinquus ), chinese mystery snail ( Cipangopaludina chinensis ), black sandshell mussel (Ligumia recta ), striped shiner minnows ( Luxilus chrysocephalus ), Daphnia magna , and Euglena gracilis . The combined results of REE concentrations, fractionations, and anomalies highlighted that pelagic organisms are characterized by heavy REEs enrichment indicating they mainly uptake REEs in the dissolved form with high bioaccumulation potential, i.e., bioconcentration (BCF) > 1 and diet accumulation factors (DAF) < 1. Pelagic organisms exhibited relatively low REE concentrations in their tissues ([La] ranging from 4.6 to 57.7 µg kg −1 in minnows, 18.4 µg kg −1 in whole body D. magna , and 32.2 µg kg −1 in E. gracilis ). On the other hand, snails and mussels were enriched in light REEs showing they mainly uptake REEs through their respective diets and particulate sand substrate. Relative to pelagic organisms, mussels and snails have higher DAFs (161.2 and 18.6, respectively) and REE levels in their soft tissues ([La] of 5700 µg kg −1 and 650 µg kg −1 , respectively), but DAF for crayfish remains < 1. In summary, under environmental-relevant conditions, the six aquatic organisms has the potential to accumulate REEs through various uptake pathways. Nevertheless, our results confirming preferential uptake pathways of the six organisms can help select appropriate species in future studies to monitor REE exposure from vaious fractions: dissolved, particulate forms or in the food webs (i.e., diet).
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.017 | 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".