Effects of Iron and Dissolved Organic Matter on Bioavailability of Arsenite under Anaerobic Conditions
Why this work is in the frame
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Bibliographic record
Abstract
Understanding the effects of water chemistry on the availability of arsenic (As) to biota is important for predicting the environmental fate of As. The “dissolved” fraction of As (<0.22 μm) is often used as a proxy for bioavailable As. However, As speciation is also influenced by binding to dissolved organic matter (DOM) and colloidal iron (Fe) (oxy)hydroxides, which can impact bioavailability. Here, we use a recently developed Escherichia coli anaerobic biosensor to elucidate the effects of DOM and Fe on arsenite (As(III)) bioavailability under anaerobic conditions, where As can be highly mobile. Microbial As(III) uptake decreased with greater DOM and Fe(III) concentrations, while Fe(II) had no effect. Higher organic sulfur content in DOM was associated with decreased biouptake at low As(III)/C ratios, and X-ray absorption spectroscopy indicated that this was due to binding of As(III) to sulfur ligands like thiols. The 0.1–0.5 kDa size fraction of As was most closely related to the bioavailable As fraction. Because the aquaporin channels mediating As(III) uptake into both microbes and rice plants are structurally similar, our results may also have relevance for understanding of how biogeochemical conditions in rice paddies regulate the plant availability of arsenic.
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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) | 0.002 | 0.001 |
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 it