Investigation of molecular markers to identify sources of nitrate contamination in groundwater
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Notice bibliographique
Résumé
Molecular markers were investigated as potential tools for differentiating between the sources of elevated nitrate-N in the Hopington AB Aquifer. Residential use (septic systems) and agriculture (livestock) have been identified as key land use activities, which overlay the Hopington AB Aquifer, and thus possible contributors of nitrate-N to the groundwater. Harmful levels of nitrate-N concentrations above the drinking water limit of 10 mg/L have been detected in the well of a private resident (14 mg/L) and spring water (17 mg/L), which were located on the aquifer. DAS 1 (a diaminostilbene) and DSBP (a distyrylbiphenyl) are fluorescent whitening agents (FWAs), which in the Fraser Valley are present in 3 out of 4 popular laundry detergents, and have been detected in domestic wastewater at concentrations of 7.84 and 2.36 μg/L respectively; thus they are suitable markers for septic systems in Langley. Sulfamethazine, which is an antimicrobial approved solely for veterinary use in Canada, is widely used in the livestock industry. Good maximum recoveries for DAS 1 (60%), DSBP (125%) and sulfamethazine (125%), coupled with low method detection limits ranging from of 0.01 — 0.04 μg/L implied that solid phase extraction (SPE) and high-performance liquid chromatography (HPLC) with an ultra violet (UV) detector were adequate for the determination of the molecular markers. The detection of DAS 1 (3.14 μg/L) and DSBP (0.05 μg/L) in the final effluent at a BNR (biological nutrient removal) pilot plant suggested that the FWAs were not completely removed by wastewater treatment processes including primary clarification, biological (aerobic and anaerobic), and membrane filtration; thus, once released, these FWAs may persists in the environment. In this study, DAS 1 (0.01 — 0.13 μg/L) was detected in 4 wells belonging to private residences, which were located on the Hopington Aquifer. DAS 1 (0.05 μg/L) and DSBP (0.02 μg/L) were also detected in spring water, which were located down gradient of septic systems. These results suggested that septic tank systems have contributed to the overall nitrate in the aquifers. The non-detection of the FWAs at the two control sites (Hopington C and Abbottsford) confirmed the specificity of DAS 1 and DSBP in relation to source. Overall, the FWAs exhibited fairly conservative behaviours due to their abilities to be source specific and persistent in the environment. As a result, they are useful tools for the identification of septic system sources of contamination in the environment. Sulfamethazine was not detected in any of the Hopington AB wells; however, further research is needed in order to determine if this antimicrobial was an appropriate molecular marker for livestock activities.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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) | 0,000 | 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 découle