A multiple approach to the determination of radon fluxes from sediments

Abstract

Determination of sedimentary fluxes of 222Rn via diffusion was required as an input for a mass balance model of radon in a freshwater lake. We obtained these fluxes by: (1) direct measurement in the laboratory using a simulated sediment bed and water column; (2) a "sediment equilibration" technique; and (3) porewater modeling. The first method, analogous to an in situ benthic chamber approach, uses direct observation of the increasing 222Rn activity in water overlying a sediment bed packed in plastic columns. This allows one to directly measure the fluxes and determine the effective wet bulk sediment diffusion coefficient (Ds). Radon flux estimates using these three techniques agreed to within approximately 10 15%.Introductionw + diffusion coefficient,

Quantifying groundwater discharge to Cockburn River, southeastern Australia, using dissolved gas tracers 222Rn and SF6

“…[37] The importance of radon fluxes from sediments has been recognized when considering the radon mass balance of lakes [Corbett et al, 1998], estuaries [Hammond et al, 1977;Hussain et al, 1999] and the oceans [Martens et al, 1980]. However, although a number of studies have used 222 Rn activities in streams to quantify rates of groundwater inflow [Ellins et al, 1990;Lee and Hollyday, 1993;Cook et al, 2003], the importance of the exchange of water between rivers and their hyporheic zones on radon budgets has not previously been considered.…”

Investigating the spatio-temporal variability in groundwater and surface water interactions: a multi-technique approach

“…The uncertainties associated with groundwater end members can be reduced by combining groundwater measurements with laboratory experiments in which the 222 Rn activity of water in equilibrium with the river sediments is determined (Burnett et al, 2008;Cook et al, 2006;Corbett et al, 1998;Martens et al, 1980;Peterson et al, 2010). Recent studies have also focussed on better quantifying processes such as hyporheic exchange and gas transfer, making the use of 222 Rn more reliable (Cook et al, 2006;Lamontagne and Cook, 2007;Mullinger et al, 2007).…”

Assessing methodologies for measuring groundwater discharge to the ocean

“…concentration of 222 Rn in the sediment pore water.The relevant 222 Rn concentration within the interstitial fluids was estimated by perform ing sediment equilibration experiments in a manner similar to that described by Corbett et al[1998].…”