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TitreExamining the relationship between mercury and organic matter in lake sediments along a latitudinal transect in subarctic Canada
AuteurGalloway, J M; Sanei, H; Parsons, M; Swindles, G T; Macumber, A L; Patterson, R T; Palmer, M; Falck, H
SourceGeophysical Research Abstracts vol. 18, 2016.
LiensOnline - En ligne
Année2016
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160120
ÉditeurEuropean Geosciences Union
RéunionEuropean Geosciences Union General Assembly; Vienna; AT; avril 17-22, 2016
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceTerritoires du Nord-Ouest; Yukon; Nunavut
Sujetsmercure; effets sur l'environnement; matières organiques; sediments lacustres; algues; milieux lacustres; sedimentation
ProgrammeOutils d'adaptation et d'impacts sur l'environnement pour les mines de métaux, Géosciences de l'environnement
Résumé(disponible en anglais seulement)
The accumulation of Hg in aquatic environments at both high and low latitudes can be controlled by organic matter through algal scavenging, thus complicating the interpretation of historical Hg profiles in lake sediments1,2,3. However, other recent studies suggest that algal scavenging is not important in governing Hg flux to sediments4, in some cases because of dilution by inorganic materials5. This study examines relationships between Hg and organic matter (OM) in over 100 lakes located between 60.5 and 65.4 \'0eN and crossing the latitudinal tree-line in subarctic Canada. The latitudinal gradient approach in our study offers an opportunity to better understand climate and environmental controls on OM accumulation and its role in influencing Hg deposition in subarctic lacustrine environments. We used Rock Eval 6 pyrolysis to determine total organic carbon (TOC%), S1 (soluble OM consisting of degradable lipids and algal pigments), S2 (OM derived from highly aliphatic biomacromolecule structure of algal cell walls), and S3 (OM dominated by carbohydrates, lignins, and plant materials). Total Hg in sediments was measured using thermal decomposition, amalgamation, and atomic absorption spectrophotometry. In these lake sediments, S2 composes the majority of TOC (Pearson's r = 0.978, p<0.01) and is negatively
correlated with latitude (r = -0.475, p<0.01). S1 and TOC are also negatively correlated with latitude (r = -0.237 and -0.452, respectively, p<0.01). These associations are interpreted to reflect less autochthonous OM production and proportionally higher allochthonous OM input to more northern lakes (oxygen index vs. latitude r = 0.371, p<0.01). Similar to previous studies1,2,3 Mercury displays a significant positive association with S1 (r = 0.556, p<0.01), S2 (r = 0.518, p<0.01), and TOC (r = 0.504, p<0.01),supporting the hypothesis that OM influences Hg
accumulation in subarctic lake sediments.
Résumé(Résumé en langage clair et simple, non publié)
Dans cette contribution, nous avons exploré la relation entre le mercure et la matière organique. Nous démontrons en utilisant un plus de 100 échantillons d'interface sédiment-eau de lacs couvrant plus de 5 degrés de latitude du Canada sub-arctique et arctique que la matière organique hautement soluble est un important contrôle potentiel de l'accumulation de mercure dans les sédiments lacustres.
GEOSCAN ID299042