A novel method using a silicone diffusion membrane for continuous 222Rn measurements for the quantification of groundwater discharge to streams and rivers

Hofmann, Harald, Gilfedder, Benjamin S. and Cartwright, Ian (2011) A novel method using a silicone diffusion membrane for continuous 222Rn measurements for the quantification of groundwater discharge to streams and rivers. Environmental Science and Technology, 45 20: 8915-8921. doi:10.1021/es202683z


Author Hofmann, Harald
Gilfedder, Benjamin S.
Cartwright, Ian
Title A novel method using a silicone diffusion membrane for continuous 222Rn measurements for the quantification of groundwater discharge to streams and rivers
Formatted title
A novel method using a silicone diffusion membrane for continuous 222Rn measurements for the quantification of groundwater discharge to streams and rivers
Journal name Environmental Science and Technology   Check publisher's open access policy
ISSN 0013-936X
1520-5851
Publication date 2011-10-01
Sub-type Article (original research)
DOI 10.1021/es202683z
Volume 45
Issue 20
Start page 8915
End page 8921
Total pages 7
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Formatted abstract
222Rn is a natural radionuclide that is commonly used as tracer to quantify groundwater discharge to streams, rivers, lakes, and coastal environments. The use of sporadic point measurements provides little information about short- to medium-term processes (hours to weeks) at the groundwater–surface water interface. Here we present a novel method for high-resolution autonomous, and continuous, measurement of 222Rn in rivers and streams using a silicone diffusion membrane system coupled to a solid-state radon-in-air detector (RAD7). In this system water is pumped through a silicone diffusion tube placed inside an outer air circuit tube that is connected to the detector. 222Rn diffuses from the water into the air loop, and the 222Rn activity in the air is measured. By optimizing the membrane tube length, wall thickness, and water flow rates through the membrane, it was possible to quantify radon variations over times scales of about 3 h. The detection limit for the entire system with 20 min counting was 18 Bq m–3 at the 3σ level. Deployment of the system on a small urban stream showed that groundwater discharge is dynamic, with changes in 222Rn activity doubling on the scale of hours in response to increased stream flow.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Earth Sciences Publications
 
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Created: Thu, 13 Mar 2014, 23:43:43 EST by Ashleigh Paroz on behalf of School of Earth Sciences