Geophysics and Subsea Permafrost 229 Measurements of the electrical conductivity of interstitial water in subsea permafrost
Interstitial water samples have been obtained from the thawed layer beneath the sea bed at Prud-hoe Bay, Alaska, using a probe method. The electrical conductivities of the water samples, and there-fore the salinities, are about 25 per cent higher than those of normal sea water. This difference may b...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.569.6436 http://pubs.aina.ucalgary.ca/cpc/CPC4-229.pdf |
| Summary: | Interstitial water samples have been obtained from the thawed layer beneath the sea bed at Prud-hoe Bay, Alaska, using a probe method. The electrical conductivities of the water samples, and there-fore the salinities, are about 25 per cent higher than those of normal sea water. This difference may be due to a density-filtering process caused by convection of the interstitial water. The high salinity causes the phase boundary temperature at the bottom of the thawed layer, where ice-bearing perma-frost exists, to be lower than the freezing point of normal sea water. A rather uniform value of- 2.4OC, corresponding to a salinity of about 43 per mille, is found out to 3.5 km from shore. A downward salt flux exists at the bottom of the thawed layer, and the electrical conductivity of the interstitial water at one site shows evidence for a thin boundary layer there, in which the salt transport regime seems to change from convective to diffusive. Above this layer, the salinity gradients are low, as would be expected in a well-developed convective regime. A characteristic interstitial water speed at a site 700 m from shore appears to be of the order of a few tenths of a metre per year. On a prelevk des echantillons d'eau interstitielle dans la couche degelee du fond sous-marin de la baie de Prudhoe en Alaska, a I'aide d'une sonde. La conductivite, et par suite la salinitk des echantil-Ions d'eau, etaient de 25 pour cent superieures aux valeurs caracterisant I'eau de mer normale; il s'est peut-hre produit un filtrage suivant les densites, cause par la convection de I'eau interstitielle. La sali- |
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