Exploring 222Rn as a tool for tracing groundwater inflows from eskers and moraines into slope peatlands of the Amos region of Quebec, Canada. (November 2016)

• Record Type: Journal Article
• Authors: Berthot, Laureline; Pinti, Daniele L.; Larocque, Marie; Gagné, Sylvain; Ferlatte, Miryane; Cloutier, Vincent
• Is Part Of: Journal of environmental radioactivity. Volume 164(2016:Nov.)
• Page Start: 344
• Page End: 353
• Publication Date: 2016-11
• Subjects: Peatland -- Esker -- Moraine -- 222Rn -- Groundwater discharge -- Québec; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2016.07.038
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: 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 ( 222 Rn) as a potential tracer of groundwater inflows from fluvioglacial landform aquifers to slope peatlands in the Amos region of Quebec, Canada. 222 Rn occurs in groundwater but is expected to be absent from peat water because of its rapid degassing to the atmosphere. Any 222 Rn activity detected in peat water should therefore derive from groundwater inflow. 222 Rn 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 222 Rn activity were made from piezometers installed in five slope peatlands, along six transects oriented perpendicular to the fluvioglacial deposits. The relationship between 222 Rn and total dissolved solids (TDS) measured in water from the mineral deposits underlying the peat layer suggests that 222 Rn 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 222 Rn. The fact that a relationship between TDS and 222 Rn is visible calls for a continuous inflow of groundwater from lateral eskers/moraines, being 222 Rn 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 222 Rn tracer to identify groundwater inflow areas from granular aquifers found in eskers and moraines to slope peatlands. Highlights: Radon measured in eskers and connected peatlands in Quebec. Radon is tested as novel tracer of groundwater inflow in peatlands. Shallower peat water is depleted in radon by degassing to atmosphere. Radon and TDS relation suggests inflow from esker and short residence time.