Exploring 222Rn as a tool for tracing groundwater inflows from eskers and moraines into slope peatlands of the Amos region of Quebec, Canada

Berthot, Laureline; Pinti, Daniele L.; Larocque, Marie; Gagné, Sylvain; Ferlatte, Miryane et Cloutier, Vincent (2016). « Exploring 222Rn as a tool for tracing groundwater inflows from eskers and moraines into slope peatlands of the Amos region of Quebec, Canada ». Journal of Environmental Radioactivity, 164, pp. 344-353.

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Résumé

Peatlands can play an important role in the hydrological dynamics of a watershed. However, interactions between groundwater and peat water remain poorly understood. Here, we present results of an exploratory study destined to test radon (222Rn) as a potential tracer of groundwater inflows from fluvioglacial landform aquifers to slope peatlands in the Amos region of Quebec, Canada. 222Rn occurs in groundwater but is expected to be absent from peat water because of its rapid degassing to the atmosphere. Any 222Rn activity detected in peat water should therefore derive from groundwater inflow. 222Rn activity was measured in groundwater from municipal, domestic wells and newly drilled and instrumented piezometers from the Saint-Mathieu-Berry and Barraute eskers (n = 9), from the Harricana Moraine (n = 4), and from the fractured bedrock (n = 3). Forty measurements of 222Rn activity were made from piezometers installed in five slope peatlands, along six transects oriented perpendicular to the fluvioglacial deposits. The relationship between 222Rn and total dissolved solids (TDS) measured in water from the mineral deposits underlying the peat layer suggests that 222Rn is introduced by lateral inflow from eskers and moraine together with salinity. This input is then diluted by peat water, depleted in both TDS and 222Rn. The fact that a relationship between TDS and 222Rn is visible calls for a continuous inflow of groundwater from lateral eskers/moraines, being 222Rn rapidly removed from the system by radioactive decay. Although more research is required to improve the sampling and tracing techniques, this work shows the potential of 222Rn tracer to identify groundwater inflow areas from granular aquifers found in eskers and moraines to slope peatlands.

Type:	Article de revue scientifique
Mots-clés ou Sujets:	Peatland, Esker, Moraine, 222Rn, Groundwater discharge, Québec
Unité d'appartenance:	Centres institutionnels > Centre de recherche en géochimie et géodynamique (GEOTOP) Faculté des sciences > Département des sciences de la Terre et de l'atmosphère
Déposé par:	Marie Larocque
Date de dépôt:	27 sept. 2016 14:50
Dernière modification:	01 déc. 2018 00:10
Adresse URL :	http://archipel.uqam.ca/id/eprint/8907

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