Chemical Sorting Effect at the Base of an Alpine Glacier

Open Access
Publisher Website
Google Scholar
Abstract
A frozen mud layer plastered at the base of the Glacier d’Argentière in the Western Alps acts as an ion-exchange membrane for the interstitial water passing through it, causing electrolyte filtration and relative retardation of cations. This interstitial water, which is forced under a pressure gradient of about 3 bar cm−1, refreezes in the form of ice accretions.A comparison of the chemical composition of these ice accretions and water held at their surface (corresponding to the situation after the forcing) and the water in contact with the mud layer (corresponding to the situation before the forcing) shows a desalinating effect, a monovalent-divalent cation species separation, and a sorting effect between the alkalies as well as between the alkaline-earths. This phenomenon has to be taken into account in the study of the chemical composition of stratified ice containing interbedded mud layers which occurs in the basal part of several glaciers.