Microbial community composition at an ethane pyrolysis plant site at different hydrocarbon inputs
Bibliographic record
Abstract
Aerobic biodegradation of C5+, a contaminant at ethane pyrolysis plants, consisting mainly of benzene, toluene, xylene, styrene, dicyclopentadiene (DCPD) and naphthalene, removes all components except the recalcitrant DCPD. The number (N) of total culturable heterotrophs in contaminated and uncontaminated soil cultures increased up to three orders of magnitude upon incubation with C5+, or with C5+ components other than DCPD. Exposure of soil cultures to C5+ for 2-4 weeks and to DCPD for a further 43-52 weeks caused N to increase 3, then decrease two orders of magnitude. Early microbial communities (up to 13 weeks) were dominated by Pseudomonas spp. and late communities (40-60 weeks) by Alcaligenes spp., especially in contaminated soil cultures. The hydrocarbon used (C5+ or one of its components) was a less important determinant of community composition than incubation time. Rates of aerobic degradation of benzene, toluene and styrene by the soil cultures were greater for the pure components than for the components in the C5+ mixture. The difference was less pronounced for m-xylene. The exception, naphthalene, was degraded more slowly when in pure form. However, the combined rate of all C5+ components in the mixture was similar to the highest rates observed for pure components. We conclude that soil communities efficiently metabolize a C5+ mixture or its pure components and that the community composition is hardly affected by different hydrocarbon inputs. Consequently, determination of the community composition does not provide a good indicator of the hydrocarbons being metabolized.
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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) | 0.000 | 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) | 0.001 | 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".