Understanding Enhanced Microbial MeHg Production in Mining-Contaminated Paddy Soils under Sulfate Amendment: Changes in Hg Mobility or Microbial Methylators?
Bibliographic record
Abstract
Elevated methylmercury (MeHg) production in mining-contaminated paddy soils, despite the high fraction of refractory HgS(s), has been frequently reported, while the underlying mechanisms are not fully understood. Here, we hypothesized that sulfate input, via fertilization, rainfall, and irrigation, is critical in mobilizing refractory HgS(s) and thus enhancing Hg methylation in mining-contaminated paddy soils. To test this hypothesis, the effects of sulfate amendment on Hg methylation and MeHg bioaccumulation in mining-contaminated soil-rice systems were examined. The results indicated 28–61% higher net MeHg production in soils under sulfate amendment (50–1000 mg kg–1), which in turn increased grain MeHg levels by 22–55%. The enhancement of Hg methylation by Hg mobilization in sulfate-amended soils was supported by two observations: (1) the increased Hg(aq) release from HgS(s), the dominant Hg species in the paddy soils, in the presence of sulfide produced following sulfate reduction and (2) the decreases of refractory HgS(s) in soils under sulfate amendment. By contrast, changes in the abundances/activities of potential microbial Hg methylators in different Hg-contaminated soils were not significant following sulfate amendment. Our results highlight the importance to consider enhanced Hg mobility and thus methylation in soils under sulfate amendment.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".