Meaduring thoron (220Rn) in natural waters

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Abstract

We have been using radon-in-air monitors coupled together with a water-air exchanger to measure 222Rn in coastal waters as a tool to locate and quantify direct groundwater discharge into the sea. Recently, we began to investigate the possibility of making concurrent analysis of 220Rn (thoron, t1/2= 56 s) to “prospect” for points of entry. While the half-life of thoron makes its assay sensitive to variations in air and water flow rates, the short half-life is also an advantage because its detection ensures that one must be close to a source. Another useful application of thoron analyses in water is to locate radium-rich deposits that develop in oil/gas and water supply pipelines. This can be done via 220Rn analysis at points along a pipeline, or at a single site while varying the water flow rate. Determination of the precise location of radioactive scale could avoid expensive and unnecessary remediation or at least affect distribution system maintenance programs. We present here the theoretical basis and some examples from public water supplies in New Jersey where some thorium-series radioactive decay products were already known to be elevated. We present a system for making continuous thoron-in-water measurements and show how one can estimate the volume, distance, and source strength of the contamination.

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Additional publication details

Publication type Book chapter
Publication Subtype Book Chapter
Title Meaduring thoron (220Rn) in natural waters
Year Published 2007
Language English
Publisher Royal Society of Chemistry
Contributing office(s) New Jersey Water Science Center
Description 14 p.
First page 24
Last page 37
Country United States
State New Jersey
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