Implications of salt fingering processes for salt movement in thawed coarse-grained subsea permafrost

Baker, G.C.; Osterkamp, T. E.

doi:10.1016/0165-232x(88)90037-7

Cited by 13 publications

(13 citation statements)

References 7 publications

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“…In the presented model, we assume a static ground mineralization, excluding salt diffusion, salt fingering and buoyancy‐driven flows. We further acknowledge that the omitted phenomena may be important to the sub‐sea permafrost modeling [ Baker and Osterkamp , 1988; Hutter and Straughan , 1997]. The salt transport is considered in a well‐verified 2‐D thermo‐hydro‐chemical model, which was applied to investigate permafrost dynamics for a 115,000 year glacial cycle at a potential repository for spent nuclear fuel at Forsmark, Sweden [ Hartikainen et al , 2010].…”

Section: Discussionmentioning

confidence: 99%

Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

et al. 2012

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[1] Models of sub-sea permafrost evolution vary significantly in employed physical assumptions regarding the paleo-geographic scenario, geological structure, thermal properties, initial temperature distribution, and geothermal heat flux. This work aims to review the underlying assumptions of these models as well as to incorporate recent findings, and hence develop an up-to-date model of the sub-sea permafrost dynamics at the Laptev Sea shelf. In particular, the sub-sea permafrost model developed here incorporates thermokarst and land-ocean interaction theory, and shows that the sediment salinity and a temperature-based parametrization of the unfrozen water content are critical factors influencing sub-sea permafrost dynamics. From the numerical calculations, we suggest development of open taliks may occur beneath submerged thaw lakes within a large area of the shelf.

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Section: Discussionmentioning

confidence: 99%

Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

et al. 2012

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“…The absenceof a measurable salinebyer just under the interface and the salinity profiles in the unfrozen region indicate that the convective velocity of salt movement was significantly greater than the maximum freezing rate (19.3 mm d-I). Several supplementary experiments [Baker and Osterkamp, 1988a] showed that gravity-driven convection (salt fingering) produced soil solution velocities of about 10-30 mm h -• over distances of 0.1-0.4 m. These experiments indicate that salt fingering may be responsible for the rapid convective motion of the soil solution in the unfrozen region of the freezing columns. Figure 4 shows that values of S u (for the experiment shown in Figures 2 and 3) increased almost linearly with distance above the interface for about 50-100 mm and at later times were nearly constant above this level reflecting nearly constant temperatures.…”

Section: Interface Between the Frozen And Unfrozen Regionsmentioning

confidence: 96%

Salt redistribution during freezing of saline sand columns at constant rates

Baker¹,

Osterkamp²

1989

Water Resources Research

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Columns of sand with grain sizes from about 250 to 600/am were saturated with a sodium chloride solution with a concentration of 35 parts per thousand (ppt) and frozen at constant rates ranging from 1 to 20 mm d -•. Electrical conductivity of the soil solution, water content, and temperature were measured during the experiments. The interface between the frozen and unfrozen regions was sharply defined and mechanically hard with no evidence for a soft, ice-bearing transition region thicker than a millimeter. Ice content near the interface was less than 50%. Substantial salt redistribution occurred with downward freezing but not with upward freezing. For downward freezing, the amount of salt rejected near the interface decreased with increasing freezing rate and increased with the salinity of the soil solution in the unfrozen region. Salt redistribution consisted of salt rejection and brine drainage from an extended partially frozen region just above the interface. Brine drained from this partially frozen region until the ice content reached about 900-950 ppt. Brine drained through the interface and mixed rapidly in the unfrozen region, apparently by salt fingering. No evidence could be found for a salt-enriched layer just below the interface. There was a layer just above the interface, moving with it, which was undersaturated at low and oversaturated at high freezing rates. An effective distribution coefficient may be useful in describing salt redistribution during freezing of saline sands.

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“…The problem of the salt transport mechanism has been studied at a site -0 700 m from shore near the West Dock at Prudhoe Bay, Alaska; the investigations that inspired this work are by Sellmann [1980], Harrison and Osterkamp [1978, Harrison [1982], Osterkamp and Harrison [1982], Swift et al [1983], Swift and Harrison [1984], Baker and Osterkamp [1988] and Osterkarnp et al [1989]. According to Harrison [1982, p. 6], the base of the thawed layer, also called the phase boundary because it is a liquid-solid H20 interface, has a strikingly well-defined parabolic shape from 440 m to several km from shore [ Figure 1].…”

Section: The Field Observationsmentioning

confidence: 99%

Models for convection in thawing porous media in support for the subsea permafrost equations

Hutter¹,

Straughan²

1999

J. Geophys. Res.

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Abstract. When permafrost becomes submerged because of shore line erosion, the covering ocean acts as a thermal insulator, and the submerged permafrost starts to melt. The thawed layer is bounded above by the ocean bed through which salt may intrude and by the phase boundary which for a fixed offshore position is known to progress with the square root of time. This situation gives rise to nonsteady doublediffusion coupling B•nard convection and liquefaction which can be described by the Darcy-Oberbeck-Boussinesq equations. The boundary value problem is formulated, and scalings are introduced which orient themselves on the relative magnitudes of phase boundary and convective bulk velocities of the salt convective regime identified by Harrison [1982]. The multiscale perturbation analysis that is introduced not only verifies the observed thaw rates with a parabolic-in-time phase boundary retreat, it equally automatically generates the equations for the corresponding perturbative equations such as the double-diffusion B•nard problem, the associated eigenvalue problem, its corrections and possible convective flows induced by the various possible currents induced by the ocean circulation overlying the thawed permafrost layer. The demonstration of this systematic approach is the main purpose of this paper.

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Implications of salt fingering processes for salt movement in thawed coarse-grained subsea permafrost

Cited by 13 publications

References 7 publications

Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region

Salt redistribution during freezing of saline sand columns at constant rates

Models for convection in thawing porous media in support for the subsea permafrost equations

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