The Impact of Biostimulation Agents on Diesel-Degrading Microbes in Cold-Regions Soils Has Seasonal Specificity
Bibliographic record
Abstract
On-site bioremediation is a cost-effective option for northern petroleum-contaminated sites, and nutrient biostimulation is commonly implemented. Microcosm experiments were conducted using soils from a sub-Arctic site dosed with Arctic diesel (D), with and without biostimulants, under three different temperature regimes reflective of summer and spring/fall. The biostimulation of alkane degraders and bacteria overall was assessed by alkane hydroxylase (alkB) and 16S rRNA genomics and transcriptomics and hydrocarbon degradation trends. At 7 °C, both water (W) and nitrogen and phosphorus (NP) additions provided initial stimulation of petroleum hydrocarbon degraders and the overall community. This resulted in 42 and 57% hydrocarbon degradation for DW and DWNP after 36 days compared with 24% in systems with neither stimulant. Under constant frozen conditions (−5 °C) adding WNP was less stimulatory than adding W for diesel degradation (80 days DW: 22%, DWNP:15%), and for the bacteria in both diesel-amended systems and diesel-free controls. Under freeze–thaw, whereas W and NP had additive impacts on bacteria overall, they had indistinguishable impacts on hydrocarbon degraders and hydrocarbon degradation (∼40%), suggesting freeze–thaw-induced changes in soil structure and associated hydrocarbon bioavailability as rate-limiting. Our study shows that impacts of biostimulation by addition of W or WNP have seasonal specificity.
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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) | 0.000 | 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".