Enhancing naphthenic acid attenuation in mesocosm wetlands: The role of temperature, plant species, and microbial communities
Bibliographic record
Abstract
Abstract Oil sands process‐affected water (OSPW) is a by‐product of bitumen extraction from oil sands surface mining in Alberta, Canada. A major group of organics in OSPW known as naphthenic acid fraction compounds (NAFCs) are of concern due to their persistence and toxicity. Constructed wetland treatment systems have emerged as potential biological treatment approaches for reducing NAFC concentrations within OSPW. In this study, greenhouse‐scale mesocosms simulating a constructed wetland consisting of coarse sand tailings (CST) and OSPW were used to evaluate the ability of Scirpus microcarpus , Triglochin maritima , and unplanted controls to attenuate NAFCs under spring/fall and summer temperatures (10°C/5°C and 20°C/10°C day/night). Overall, in this mesocosm system, NAFC attenuation was similar regardless of different design parameters such as plant type, plant presence, and temperature. By the end of the study, NAFCs attenuation was 30% to 50% lower than the initial OSPW depending on plant species, plant presence, and temperature. The relative abundance of the acutely toxic O 2 ‐NAFCs decreased over time, with an increase in the less toxic O 3 , O 4 , and SO 3 classes. Various hydrocarbon‐degrading microbial families such as Comamonadaceae and Xanthobacteraceae were found to be dominant in OSPW, while cyanobacteria ( Trichormus ) were enriched in the CST. Principal component analysis indicated that only time led to distinct clusters for NAFC composition, while plant type, temperature, and time influenced the microbial communities. Shifts in microbial communities over time corresponded to shifts in NAFCs, possibly due to a decrease in toxicity with increased oxidation of NAFCs and/or an increase in available nutrients from a decrease in plant fitness in the planted mesocosms. Practitioner Points Constructed wetland mesocosms for NAFC attenuation from OSPW comparing three planted/unplanted conditions under two temperatures. Mesocosms had 30%–50% removal of total NAFCs, with a decrease in O 2 ‐NAFCs and increase in O 3 , O 4 , and SO 3 classes. NAFC composition only shifted with time, while microbial communities were influenced by plant type, temperature, and time. Lack of difference in NAFC attenuation between treatments could indicate a high level of functional redundancy between the microbial communities.
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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 | 0.001 |
| 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 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".