Atmospheric mercury deposition in alpine snow, northern British Columbia and southwestern Yukon, Canada
Notice bibliographique
Résumé
High mercury (Hg) levels have been measured in fish in Kusawa Lake (KL), a subalpine, partly glacier-fed lake situated in the southwestern Yukon, Canada, but it is presently unknown where this Hg comes from. One possible source may be atmospheric deposition of Hg in snow and subsequent release by melt into the lake. In this study, the amounts of total Hg (THg) deposited in sampled alpine snow and glacial ice from the KL catchment area were measured in order to quantify this input. Samples of snow and glacial firn were also collected from another site (DIV) located on an icefield in the central St. Elias Mountains, to investigate possible spatial variations in Hg deposition as a function of altitude or distance from the Pacific Ocean. The samples were analysed for THg, major ions (incl. Ca2+, K+, Mg2+, Na+, NH4+, Cl-, and SO42-) and stable O/H isotopes. These analyses were performed to obtain clues on the sources/conditions of atmospheric Hg deposition in snow, and identify possible relationships between THg and other snow chemical properties. This is the first study to provide data on Hg deposition in snow from this vast mountain region. Measured THg concentrations ranged from 0.24 to 6.17 ng L-1 in snow and from 0.20 to 1.57 ng L-1 in glacial ice, which are comparable values to those measured at other sites in the North American subarctic and Arctic. The calculated net accumulation rates of THg varied from 0.57 to 0.71 µg m-2 a-1, which are relatively high compared to rates reported for the eastern Canadian Arctic. This could indicate that wet deposition in snowfall may be particularly important in promoting THg accumulation in mountains of the subarctic Yukon, when compared to the polar desert of the High Arctic. The stable O/H isotope data indicate that snowfall in the study area is primarily derived from moisture of marine origin, with only minor continental contributions, which points to the nearby Gulf of Alaska as the main source. The major ion analyses suggest a local dust source containing Ca2+ and SO42- at KL, and a local dust source containing mostly Mg2+ and Ca2+ but also SO42- at DIV. High correlation between NO3- and SO42- in snow could be due to distant pollution sources, and higher concentrations at DIV than KL could indicate a higher impact of these sources at higher-altitude sites. High correlation was found among the analysed sea salt ions at both sites. No correlations were found between THg and major ions, except that relatively high THg and ionic concentrations were often found in the surface and bottom samples of the snowpits, which correspond to the current and previous summer surfaces. The higher THg concentrations in the summer layers suggests that Hg attaches itself to dust particles either in the air prior to deposition, and/or in the snowpack after deposition, thereby limiting migration or losses in percolating meltwater.
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| 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 ».