Role of microbial reducing activity in antimony and arsenic release from an unpolluted wetland soil: a lab scale study using sodium azide as a microbial inhibiting agent
Bibliographic record
Abstract
Environmental context Antimony and arsenic are toxic elements occurring naturally in the environment. We found that arsenic release to water from an unpolluted wetland soil is related to microbial reducing activity only, whereas antimony can still be released when this activity is inhibited, suggesting the involvement of additional processes. The findings show that microbial/non-microbial mechanisms control arsenic and antimony release and can thereby impact water quality at wetland outlets. Abstract In wetland soils, the mobility of geogenic metal(loid)s is usually associated with direct or indirect microbial-induced processes (solubilisation of mineral and organic components, pH induced desorption, competition effects, dissimilatory reduction). To identify the role of microbial reducing activity in As and Sb release, we conducted two series of soil incubations (sodium azide-treated (NaN3-T) and non-treated (NT)) in closed batches for 36 days. During the incubation period, we monitored the evolution of dissolved As, Sb, Mn, FeII, organic carbon (DOC), humic substances (HS) and proteins (PN) with their apparent molecular weight distribution (aMW) as well as pH, reduction potential (Eh) and alkalinity. Results showed that the release of As and Sb occurred when microbially reducing conditions prevailed (NT soil Eh ~0 mV and FeII > 40 mg L–1) and was inhibited for As in the absence of microbial reducing activity (NaN3-T soil; Eh > 250 mV and Fe < 1 mg L–1). In contrast, Sb behaved differently since its release was only slowed down when microbially reducing conditions were inhibited. We concluded that soil microbial reducing activity fully controls the release of As and to a lesser extent that of Sb when NaN3 is used as a microbial inhibiting agent. Since Sb release and dissolved organic matter (DOM) solubilisation (NaN3-induced artefact) occurred simultaneously in the absence of microbially reducing conditions, we concluded that organic matter could be one key factor controlling Sb mobilisation in the given conditions, which is not the case for As.
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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) | 0.001 | 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 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".