Geophysics and Subsea Permafrost 229 Measurements of the electrical conductivity of interstitial water in subsea permafrost

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Ice; permafrost; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.569.6436; http://pubs.aina.ucalgary.ca/cpc/CPC4-229.pdf

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-