Spirit Lake, Mount St. Helens, Washington: Limnological and Bacteriological Investigations. Volume 1

摘要

The cataclysmic eruption of Mount St. Helens, Washington, on 18 May 1980, filled nearby Spirit Lake with timber and volcanic debris and completely blocked the lake's natural outlet. The lake, which the outlet had previously kept in hydrological balance, was hence-forth impounded in a closed, hydrologically unstable basin by a debris dam 150-180m thick. This event greatly altered the limnology of Spirit Lake and resulted in extremely poor water quality. Some post-eruption water quality characteristics included whole-lake anoxia, which persisted for months; and extraordinarily high concentrations of sulfides, methane, reduced iron and manganese, phosphorus, and dissolved organic matter. Concentrations of total bacteria were thought to be unprecedented for natural lakes. Keywords: Limnology, Water quality, Bacteriology, Biogeochemical processes, Volcanic effects, Lakes.