Biodegradation potential assessment of sediments from Lac Mégantic (Québec, Canada) contaminated with light residual oil
Bibliographic record
Abstract
In July 2013, a tragic incident occurred in Lac Mégantic (LM), Quebec, which led to crude oil contamination of regional surface water,soil and sediment in the LM Lake. The purpose of this study is to investigate spilled crude oil degradation potential by using the sediments from the LM Lake. In the present study, sediments collected from the spill site were used as a source of microorganisms. An aliquot of collected sediment was sterilized and used as the control of the study. Two oils having similar physicochemical properties, the LM spill source oil and Alberta Sweet Mix Blend oil (ASMB) as a reference oil, were tested for comparison purpose. This biodegradation study was performed at two different temperatures and incubation period: 22°C for 4 weeks, and 4°C for 8 weeks. The chemical composition, including total petroleum hydrocarbons (TPH), total saturate hydrocarbons (TSH), total aromatic hydrocarbons (TAH), unresolved complex mixture (UCM), polycyclic aromatic hydrocarbons (PAHs) and their alkylated congeners (APAHs), n-alkanes, and selected petroleum biomarkers, was analyzed and assessed to evaluate their potential degradation ability. Results show that there is no significant difference in degradation efficiency for the two oils used; while different incubation conditions had an impact on their biodegradation potential. For the two oils, the degradation rates followed the order of resolved components > TSH > UCM >TAH. The degradation of TPH in different carbon range followed the C10− C16 >the C16− C34 >the > C34 range. Higher temperature is favorable to the degradation of all petroleum hydrocarbons, despite that biomarker are far less biodegradable than other petroleum hydrocarbons. Specifically, almost 100% normal alkanes were degraded at 22 oC, but the degradation rates at 4 oC was less than at 22 oC, especially for pristine, phytane and some high molecular weight n-alkanes. For PAHs and APAHs, their degradation rates generally decreased with the increased number of aromatic rings and alkylated degree under the two incubation conditions, while their degradation was limited for the other 3−6 ring parent PAHs at 4 oC due to the limited bacteria activity. LM sediment can degrade contaminated petroleum hydrocarbons effectively if appropriate ambient temperature is supplied for the growth of the in-situ natural bacteria.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".