Algal bioaccumulation and toxicity of platinum are increased in the presence of humic acids
Bibliographic record
Abstract
Environmental context The growth in demand for platinum has led to an increase in the presence of this metal in the environment but little is known about its toxicity to aquatic organisms. The presence of organic matter should contribute to decreasing metal bioavailability but the opposite was found for platinum. How ubiquitous natural organic matter can alter the accumulation and effects of platinum group elements remains to be fully elucidated. Rationale There is a growing interest for platinum in ecotoxicology, mainly because of its use in automobile exhaust catalysts. When it reaches aquatic ecosystems, platinum can interact with ligands such as natural organic matter. According to the Biotic Ligand Model, the formation of such complexes should reduce metal bioavailability. As a consequence, toxicity should decrease in the presence of organic matter. Methodology This study focused on the uptake of platinum by two microalgae species (Chlorella fusca and Chlamydomonas reinhardtii) and its subsequent inhibitory effects on growth (96 h). Cells were exposed to platinum (5–300 µg L−1) at three concentrations (0, 10 and 20 mg C L−1) of standard Suwannee River humic acid (SRHA). Platinum bound to humic acid was determined experimentally using partial ultrafiltration to relate metal uptake and toxicity to speciation. Results Unexpectedly, results show that platinum toxicity, expressed as ultrafiltrable Pt (not bound to humic acid) and total Pt concentrations, is enhanced in the presence of humic acid for both algae. For C. fusca, the half maximal effective concentration (EC50) values decreased from 93 to 37 and 35 µg L−1 of ultrafiltrable Pt in the presence of 10 and 20 mg C L−1 SRHA and from 89 to 36 and 0.31 µg L−1 for C. reinhardtii. Discussion In contradiction with the Biotic Ligand Model, the results show that the presence of SRHA can significantly and importantly increase platinum uptake and toxicity as determined in two unicellular green algae, C. reinhardtii and C. fusca. The present work raises the issue of the impact of platinum on microalgae under realistic environmental conditions (ubiquitous presence of organic matter), primary producers being of great ecological importance.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".