DISSOLVED-OXYGEN VARIATIONS IN ALPINE GLACIAL MELTWATERS

Recent models of chemical weathering in alpine glacial meltwaters suggest that sulphide oxidation is a major source of solute in the distributed component of the subglacial hydrological system. This reaction requires O2, and may lower dissolved oxygen levels to below saturation with respect to the atmosphere. This should result in an inverse association between SO4(2-) and dissolved oxygen saturation. However, measurements Of 02 saturation in bulk meltwaters draining the Haut Glacier d'Arolla, Switzerland, show that there is a positive association between SO(4)2- and 02 saturation. The 02 content of glacial meltwaters depends on the initial content of snow and icemelt, which may be controlled by the rate of melting, and the kinetic balance between 02 losses (e.g. sulphide oxidation, microbial respiration) and gains (e.g. diffusion Of 02 into solution).