The effect of groundwater advection on salinity in pore waters of permeable sediments

Rapaglia, John P., Henry J. Bokuniewicz

Limnol. Oceanogr., 54(2), 2009, 630-643 | DOI: 10.4319/lo.2009.54.2.0630

ABSTRACT: Measurements of the upward advection and pore-water profiles of salinity were made at three coastal settings (the Venice Lagoon, Italy; Jamaica Bay, New York; and Mattituck, New York). Coincident measurements of seepage rates using vented benthic chambers and profiles of salinity in pore water collected with a piezometer are used to quantify the coefficient of dispersive mixing. Three mathematical methods were used to quantify this coefficient: a simple, linearized salt balance and two analytical solutions to the steady-state, one-dimensional, advection-diffusion equation in either a slab or a semi-infinite medium. The majority of dispersive mixing coefficients in fine- to medium-grained silty sand were calculated to be between 0.04 and 0.8 m2 d-1. In some cases, the dispersive mixing seemed to involve small-scale preferred pathways for vertical transport, such as would be the case for bioirrigation, gravitational convection, or salt fingering.

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