Arsenic-Imposed Effects on Schwertmannite and Jarosite Formation in Acid Mine Drainage and Coupled Impacts on Arsenic Mobility
Bibliographic record
Abstract
This study explores interactions between As and Fe(III) minerals, predominantly schwertmannite and jarosite, in acid mine drainage (AMD) via observations at a former mine site combined with mineral formation and transformation experiments. Our objectives were to examine the effect of As on Fe(III) mineralogy in strongly acidic AMD while also considering associated controls on As mobility. AMD at the former mine site was strongly acidic (pH 2.4 to 2.8), with total aqueous Fe and As decreasing down the flow-path from ∼400 to ∼20 mg L<sup>-1</sup> and ∼33,000 to ∼150 μg L<sup>-1</sup>, respectively. This trend was interrupted by a sharp rise in aqueous As(III) and Fe(II) caused by reductive dissolution of As-bearing Fe(III) phases in a sediment retention pond. Attenuation of Fe and As mobility occurred via formation of As(V)-rich schwertmannite, As(V)-rich jarosite, and amorphous ferric arsenate (AFA), resulting in solid-phase As concentrations spanning ∼13 to ∼208 g kg-1. Schwertmannite and jarosite retained As(V) predominantly by structural incorporation involving AsO<sub>4</sub>-for-SO<sub>4</sub> substitution at up to ∼40 and ∼22 mol %, respectively. Arsenic strongly influenced Fe(III) mineral formation, with high As(V) concentrations causing formation of AFA over schwertmannite. Arsenic also strongly influenced Fe(III) mineral evolution over time. In particular, increasing levels of As(V) incorporation within schwertmannite were shown, for the first time, to enhance the transformation of schwertmannite to jarosite. This significant discovery necessitates a re-evaluation of the prevailing paradigm that As(V) retards schwertmannite transformation.
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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".