Glyphosate residues in Alberta's atmospheric deposition, soils and surface waters
Notice bibliographique
Résumé
Glyphosate is a non-selective herbicide used for the control of annual and perennial grasses and broadleaf weeds.Registered for use in Canada in 1974, it is currently registered and used in over 125 countries.With annual sales in Alberta (1998) exceeding 2.6 million kg of active ingredient, it is by far the most commonly used pesticide in the province.Long considered by scientists and farmers around the world as an effective and environmentally friendly herbicide, recent studies have shown some persistence and mobility in the environment.This study was designed to explore some of the pathways of glyphosate to surface waters such as atmospheric deposition, emissions during spraying, and persistence in soil; the study also included the monitoring of water from selected streams and wetlands.The sampling year 2002 proved to be a difficult year to undertake a glyphosate residue study due to environmental factors.The severe drought conditions in east central Alberta hampered canola growth and subsequently greatly reduced the amount of glyphosate used in this growing and sampling season.Despite the drought and reduced usage, glyphosate was found in many environmental samples.Atmospheric deposition was measured at three sites in east central Alberta.Rainfall and particulate matter were collected as total deposition at seven-day intervals throughout the growing season.The three precipitation sites had glyphosate detections throughout the sampling time period.Glyphosate deposition rates ranged from <0.001 to 1.51 ligW/day.Volatile and particulate emissions of glyphosate were measured before and after the spraying of a canola field with Roundup®.This study component was conducted in the Mannville area on a field with glyphosate tolerant canola.Pre-event air samples were taken two weeks prior to spraying.Post-event air sampling was conducted for 24-hour periods beginning at 1-hour post spray, 25-hour post spray and 49-hour post spray.Glyphosate was not detected in any of the air samples collected with polyurethane foam (PUF) samples but it was detected in some of the particulate samples.The detection of glyphosate in soil samples 10 months after spraying was indicative of some persistence.Glyphosate was detected in most of the wetlands and streams sampled for this project.Concentrations were generally close to the detection limit ( 0.2 |Lig/L).Higher levels were recorded at some sites: Wetland #5 sample (1.066 |ug/L), two Haynes Creek samples (1.105 and 0.425 |ig/L) and a sample from the St. Mary's River Irrigation District (6.079 fig/L).This study determined that glyphosate is transported in association with particulate matter (dust) and not as vapour.Detections in precipitation are more likely due to glyphosate associated with dust particles being washed down with rain than to glyphosate dissolved in rain.A follow up study is recommended to document residue levels in a year where glyphosate use and moisture patterns are closer to normal for that part of the province.As well, the persistence of glyphosate in soils warrants further studies under different climatic conditions.Glyphosate Residues in Alberta's Atmospheric Deposition, Soils and Surface Waters i ACKNOWLEDGEMENTS This project had complex technical and logistic demands that required teamwork from staff at the Alberta Research Council-Vegreville (ARC), Alberta Environment (AENV), and Alberta Agriculture Food and Rural Development (AAFRD).These three organizations were involved in the design of the study and in field-sampling aspects and contributed to the production of the technical report and interpretation of results.
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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 | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 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) | 0,005 | 0,002 |
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 ».