Creosote toxicity to photosynthesis and plant growth in aquatic microcosms
Bibliographic record
Abstract
To assess photosynthesis as a bioindicator of toxicity from polycyclic aromatic hydrocarbons (PAHs), the response of chlorophyll-a fluorescence to creosote exposure was compared with effects on population-level plant growth. Large, outdoor, freshwater microcosms containing Eurasian watermilfoil (Myriophyllum spicatum) received either a single application or multiple applications of liquid creosote at nominal concentrations from 0.109 to 32.7 mg L(-1). For several weeks following treatment, photosynthetic electron transport was measured using pulse amplitude-modulated chlorophyll-a fluorescence. The maximum efficiency of photosystem II electron transport (Fv/Fm) and the quantum yield of photochemistry (deltaF/F'm) were diminished in plants shortly after the addition of creosote. In microcosms that received a single treatment of creosote only, the 50% effective concentrations (EC50s), expressed as the aqueous concentration of 15 of the most abundant PAHs, were 0.28 mg L(-1) for Fv/Fm and 0.30 mg L(-1) for deltaF/F'm. Chlorophyll-a fluorescence was diminished to a greater extent in microcosms that received multiple treatments of creosote, with EC50s of 0.13 mg L(-1) for Fv/Fm and 0.10 mg L(-1) for deltaF/F'm. Plant biomass accumulation was inhibited in a concentration-dependent manner in all microcosms treated with creosote, but this inhibition occurred to a greater degree in microcosms treated with multiple creosote applications. The response of chlorophyll-a fluorescence, measured only 8 d after creosote treatment, was similar to plant growth over the entire growing season, indicating that this technique can be used to estimate potential effects of contaminants before detrimental impacts on populations.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| 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 source (direct Gemma or distilled Codex), 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".