Water and contaminant flux estimation from multi-layer passive flux meter measurements

Abstract

The passive flux meter (PFM) enables the measurement of cumulative water and contaminant mass fluxes in porous aquifers. It consists of a sorbent material, which is installed in a monitoring well to intercept groundwater flow. Tracer losses and contaminant retention on the sorbent are used to estimate water and contaminant mass fluxes through the device. In the multi-layer PFM different (sorbent) materials are used in an annulus (layer-type) configuration. This allows leached tracers inside the PFM (no tracer release into aquifer) to be retained and facilitates simultaneous deployment of different sorbent types in a single device. In order to estimate undisturbed ambient fluxes in the aquifer, measurements need to be corrected for flow convergence or divergence induced by the well and PFM components. We make use of an analytical solution to the potential flow problem of uniform flow disturbed by a system of concentric rings of contrasting hydraulic conductivities. A flow convergence factor is defined as a function of PFM ring conductivities and radii, where tracer elution and contaminant sorption may occur in arbitrary layers. The results are used for calibration of convergence factors of a multi-layer PFM to laboratory sand box experiments. © 2012 WIT Press.