Effect of Hydrological Regimes on Groundwater Phosphorus Transfer in a Riparian Wetland
Notice bibliographique
Résumé
Riparian wetlands are important areas for regulating phosphorus (P) transfer in shallow groundwater. Limited knowledge is currently available regarding the effects of hydrological regimes on the transfer process of various P forms in shallow groundwater in upland-riparian-stream continuums in agricultural areas. This study focuses on P transfer in shallow groundwater within and between the riparian zone and hyporheic zone in Spencer Creek, and considers the effects on P transfer caused by flooding from the drawdown of the upstream Valens Reservoir, Hamilton, southern Ontario. A series of piezometer nests (each nest consisted of three piezometers at the depths of 50 cm, 100 cm and 150 cm) and corresponding wells were installed at the upland-riparian interface, riparian corridor and riparian-stream interface along two transects with different vegetation covers. Water chemistry was measured in groundwater and the stream from May 10 to October 20, 2006. The chemistry parameters included total phosphorus (TP), soluble reactive phosphorus (SRP), soil-extractable phosphorus, dissolved oxygen (DO), total dissolved solids (TDS) and pH. Water table elevation, hydraulic head and saturated hydraulic conductivity (Ksat) were measured at each location along the transects. \nGroundwater TP concentrations at the two transects ranged from 11.8 µg/L to 2685.6 µg/L with an average (mean ± standard error) of 365.2 ± 25.9 µg/L and from 12.7 µg/L to 8485.5 µg/L with an average of 742.4 ± 109.0 µg/L during baseflow and flood conditions, respectively. The groundwater SRP concentrations ranged from 3.6 µg/L to 417.9 µg/L with an average of 44.0 ± 3.8 µgL-1 and from 2.1 µg/L to 280.4 µg/L with an average of 33.9 ± 5.2 µg/L during baseflow and flood conditions, respectively. For both transects, mean TP and SRP concentrations in piezometers tended to increase with increasing distance from the field during both baseflow and flood. This trend was poorly correlated with depth. SRP concentrations in groundwater did not show the same decreasing trend by depth. The flood caused by the drawdown of upstream Valens Reservoir significantly increased TP concentrations (p=0.002) but significantly decreased SRP concentrations (p<0.001) in groundwater in the riparian zone. The TP concentrations at three depths were all significantly lower at transect T1 (predominantly grass cover) than T4 (predominantly forest cover) (50 cm: p=0.001; 100 cm: p<0.001; 150 cm: p<0.001). The SRP concentrations at 50 cm were significantly lower at transect T1 than T4 (p=0.003). \nThe results of this study suggested that hydrology was a dominant factor regulating groundwater P transfer within the upland-riparian-stream continuum while other factors such as vegetation type and substrate characteristics were less important. The effectiveness of riparian zones to reduce P transport in groundwater from agricultural fields to adjacent streams will depend highly on site-specific hydrological regimes.
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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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 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 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 ».