Rapid Determination of Total Reactive Sulfur in Mine Impacted Waters
Notice bibliographique
Résumé
Acidification of water bodies due to mining related activities is considered to be one of the greatest pollution challenges faced by the mining industry. While traditional monitoring methods have primarily addressed potential acidity stemming from the oxidation of mineral associated sulfides, they often overlook various aqueous sulfur compounds such as thiosulfate and polythionates which are known to occur in mine impacted wastewater (MIW) as by-products of sulfide mineral processing which may also generate acidity. Mines are hampered by the limitations of the currently available, inefficient, expensive and time-consuming analytical methods to monitor these reactive sulfur compounds that can pose acidity, toxicity and contamination risks to receiving environments if not mitigated by treatment technologies prior to discharge. This thesis presents results of a developed, expeditious, inexpensive and near real time method to quantify the total concentration of reactive sulfur species (Sreactive; all sulfur atoms of oxidation state less than 6+ (i.e., SO42-, Whaley Martin et al. 2020)) for aqueous samples. The results of this thesis provide a promising method for rapid determination of [Sreactive], compatible with field and laboratory based analytical methods, by difference between the initial SO42- concentration in a sample, prior to oxidation, and the final SO42- concentration taken after exposure to a strong oxidizing agent, which converts all Sreactive in a sample to SO42-. Results determined the method to be quantitative within a pH range of 5 to 9, using 200 µL 10% - 15% NaClO (Sigma Aldrich) as the oxidant to oxidize all Sreactive species present in a 10.0 mL sample to SO42- within a time period of 5 minutes.The final method developed uses a portable HACH DR2800 spectrophotometer and 10-15% NaClO (Sigma Aldrich) as the oxidant with a ratio of 200 µL oxidant per 10.0 mL of sample volume and a 5 minute reaction time. The method was determined to be quantifiable in a pH range of 5 to 9 for samples with SO42- concentrations ranging from 7 mg/L to 70 mg/L. Initial tests of the developed method on field samples yielded promising results, with spike recoveries generally within +/-15% of expected values in reference (unaffected) water, receving water, tailings reservoir water, pilot reclamation pit lake water, treatment pond water and mill effluent. As the HACH DR2800 has not been widely validated for use with MIW, results obtained by HACH DR2800 were compared to IC determined values throughout all stages of research to ensure accuracy and were generally found be in good agreement with the exception of treatment pond water, although spike recoveries were still within +/-15% of expected values. Additionally, the method successfully detected naturally occurring baseline Sreactive in all field samples analyzed, including the unaffected natural waterbody samples, indicating potential for broader utility of this method for determination of Sreactive in a variety of contexts.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».