Summary of significant results from studies of triazine herbicides and their degradation products in surface water, ground water, and precipitation in the midwestern United States during the 1990s
Notice bibliographique
Résumé
Nonpoint-source contamination of water resources from triazine herbicides has been a major water-quality issue during the 1990s in the United States. To address this issue, studies of surface water, ground water, and precipitation have been carried out by the U.S. Geological Survey in the Midwestern United States. Reconnaissance studies of 147 streams were conducted to determine the geographic and seasonal distribution of atrazine, cyanazine, propazine, and simazine. These studies showed that high concentrations of herbicides were flushed from cropland and transported through the stream system as pulses in response to spring and summer rainfall. The studies also revealed the persistence of herbicides and their degradation products in streams. An investigation of 76 reservoirs showed that the occurrence and temporal distribution of herbicides and their degradation products in reservoir outflow could be related to reservoir and drainage-basin characteristics, water and land use, herbicide use, and climate. Significant findings showed that concentrations of atrazine and its degradation products remained elevated all summer and into the fall and that recently applied atrazine mixed with atrazine applied the previous year as water moved through a reservoir. Reconnaissance studies of 303 ground-water wells were completed to determine hydrogeological and seasonal occurrence, concentration, and distribution of herbicides and their degradation products. Samples collected from across the Midwestern United States consistently revealed that triazine herbicide degradation products commonly were found more frequently than their parent herbicide and that ground-water age could be an important factor in explaining variations in herbicide contamination. A final study investigated precipitation in the Midwestern United States, northeast to the Atlantic Ocean, and northward to the Canadian border. It found that the highest herbicide concentrations in precipitation occurred following herbicide application to cropland. Atrazine was detected most often, followed by deethylatrazine, cyanazine, and deisoproplyatrazine. Mass deposition of herbicides by precipitation was greatest in areas where herbicide use was intense and decreased with distance from the Midwest. Findings of the 1990s studies include an improved understanding of the occurrence, persistence, chemistry, and transport of triazine herbicides and their degradation products in the hydrologic environment. A significant increase in knowledge of triazine herbicides and development and improvement of analytical methods were accomplished in the past decade. The results produced are not only significant for the present (2005) but provide an important data set for future use.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
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 | 0,002 | 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 | 0,002 |
| 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 découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, 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 ».