Fluids for use in deep ice-core drilling

Environmentally appropriate fluids were sought to support the deep ice coring objectives of the glaciological programs of the U.S. National Science Foundation. In the past several decades, three types of fluids have been used for ice coring activities: 1) fuel oil (DFA) usually containing several percent of a dense halogenated solvent; 2) aqueous ethanol or glycol solutions; and 3) butyl acetate. Each has advantages and disadvantages. Primary criteria for the search for acceptable ice coring fluids was that its density be close to that of the ice, that it be usable to about -56^oC, and that it be as environmentally acceptable and non toxic as possible. The best candidate drilling fluid for ice coring that emerged was n-butyl acetate. This fluid is presently in use in Greenland. Regardless of the fluid chosen, proper practices should be adopted for adequate protection of human health and the natural environment.