Abstract

Analysis of meltwater streams from nine Alaskan valley glaciers eroding five different bedrock types showed: (1) the streams are similar in that Ca is the most abundant ion of those analyzed and the cold waters have a basic pH, and (2) total (Na + K + Ca + Mg + Si) and suspended load concentrations vary in streams from glaciers on different bedrock types, from different glaciers on similar bedrock, and from the same glaciers during different sampling periods. The results indicate bedrock type is probably not the most important factor controlling the quantity of total (Na + K + Ca + Mg + Si) in glacial meltwater and suspended load concentration is controlled by stream conditions at the time of sampling.

Comparative chemistry of aliquots of water samples, millipore filtered immediately upon collection and after 2 to 120 days storage prior to filtration, indicate ions are introduced to meltwater by partial dissolution of suspended load and that in terms of absolute concentrations more Ca than other ions is introduced in this manner. Ca was also found to be the most readily mobilized ion from suspended load in samples from three of the streams. These experimental results for Ca, plus the greater abundance of Ca than other ions in the meltwater, suggest a relation between ions and suspended load in glacial streams. The results also point out the necessity of immediate filtration of samples for accurate determinations of the chemical composition of water.

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