A multi-detector continuous monitor for assessment of &lt;Superscript&gt;222&lt;/Superscript&gt;Rn in the coastal ocean

Dulai, Henrietta; Peterson, Richard N.; Burnett, William C.; Lane-Smith, Derek

doi:10.1007/s10967-005-0063-8

Cited by 186 publications

(90 citation statements)

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“…Lake water, active layer water, and river water samples were collected in August 2011 and July 2012 following standard procedures for 224 Ra activities (35,36), 222 Rn activities (37)(38)(39), and CH 4 concentration (40,41). Surface lake water samples were collected from both the interior and perimeter areas of the lake.…”

Section: Methodsmentioning

confidence: 99%

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Paytan

Lecher

Dimova

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 104 nM, 61.6 dpm⋅m−3, and 4.5 × 105 dpm⋅m−3 compared with 1.3 × 102 nM, 5.7 dpm⋅m−3, and 4.4 × 103 dpm⋅m−3, respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m−2⋅y−1) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r2 > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs.

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Section: Methodsmentioning

confidence: 99%

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Paytan

Lecher

Dimova

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…One of these 76 instruments is a modified radon surveying system (Dulaiova et al, 2005), which consists 77 of 3 commercially available radon-in-air analyzers (RAD7, manufactured by Durridge, 78…”

Section: Methods 75mentioning

confidence: 99%

Coupled radon, methane and nitrate sensors for large-scale assessment of groundwater discharge and non-point source pollution to coastal waters

Dulai

Camilli

Henderson

et al. 2010

Journal of Environmental Radioactivity

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1We constructed a survey system of radon/methane/nitrate/salinity to find sites of 2 submarine groundwater discharge (SGD) and groundwater nitrate input. We deployed 3 the system in Waquoit Bay and Boston Harbor, MA where we derived SGD rates using a 4 mass balance of radon with methane serving as a fine resolution qualitative indicator of 5 groundwater. In Waquoit Bay we identified several locations of enhanced groundwater 6 discharge, out of which two (Childs and Quashnet Rivers) were studied in more detail. 7The Childs River was characterized by high nitrate input via groundwater discharge, 8 while the Quashnet River SGD was notable but not a significant source of nitrate. Our 9 radon survey of Boston Harbor revealed several sites with significant SGD, out of these 10Inner Harbor and parts of Dorchester Bay and Quincy Bay had groundwater fluxes 11 accompanied by significant water column nitrogen concentrations. The survey system 12 has proven effective in revealing areas of SGD and non-point source pollution. 13 14

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“…An automated radon monitor (Burnett et al, 2001;Burnett and Dulaiova, 3003, 2006) was used for continuous measurement of 222 Rn in coastal waters. 222 Rn mapping was accomplished by integrating several radon detectors with GPS navigation, water depth and temperature/conductivity measurements (Dulaiova et al, 2005). A constant stream of water is delivered by a submersible pump to an air-water exchanger where radon in the water phase equilibrates with radon in a closed air loop.…”

Section: Rn Measurementsmentioning

confidence: 99%

Isotopic, geophysical and biogeochemical investigation of submarine groundwater discharge: IAEA-UNESCO intercomparison exercise at Mauritius Island

Povinec¹,

Burnett²,

Beck³

et al. 2012

Journal of Environmental Radioactivity

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Submarine groundwater discharge (SGD) into a shallow lagoon on the west coast of Mauritius Island (Flic-en-Flac) was investigated using radioactive ( 3 H, 222 Rn, 223 Ra, 224 Ra, 226 Ra, 228 Ra) and stable ( 2 H, 18 O) isotopes and nutrients. SGD intercomparison exercises were carried out to validate the various approaches used to measure SGD including radium and radon measurements, seepage-rate measurements using manual and automated meters, sediment bulk conductivity and salinity surveys. SGD measurements using benthic chambers placed on the floor of the Flic-en-Flac Lagoon showed discharge rates up to 500 cm/day. Large variability in SGD was observed over distances of a few meters, which were attributed to different geomorphological features. Deployments of automated seepage meters captured the spatial and temporal variability of SGD with a mean seepage rate of 10 cm/day. The stable isotopic composition of submarine waters was characterized by significant variability and heavy isotope enrichment and was used to predict the contribution of fresh terrestrially derived groundwater to SGD (range from a few % to almost 100 %). The integrated SGD flux, estimated from seepage meters placed parallel to the shoreline, was 35 m 3 /m day, which was in a reasonable agreement with results obtained from hydrologic water balance calculation (26 m 3 /m day). SGD calculated from the radon inventory method using in situ radon measurements were between 5 and 56 m 3 /m per day. Low concentrations of radium isotopes observed in the lagoon water reflected the low abundance of U and Th in the basalt that makes up the island. High SGD rates contribute to high nutrients loading to the lagoon, potentially leading to eutrophication. Each of the applied methods yielded unique information about the character and magnitude of SGD. The results of the intercomparison studies have resulted a better understanding of groundwater-seawater interactions in coastal regions. Such information is an important pre-requisite for the protection management of coastal freshwater resources.

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A multi-detector continuous monitor for assessment of <Superscript>222</Superscript>Rn in the coastal ocean

Cited by 186 publications

References 1 publication

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

Coupled radon, methane and nitrate sensors for large-scale assessment of groundwater discharge and non-point source pollution to coastal waters

Isotopic, geophysical and biogeochemical investigation of submarine groundwater discharge: IAEA-UNESCO intercomparison exercise at Mauritius Island

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