Brown, G. H. and Hubbard, B. and Seagren, A.G. (2001)

Modelled solute acquisition from suspended sediment in a theoretical 4-cell subglacial hydrological system

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58th Eastern Snow Conference, Ottawa, Canada
Twenty-five laboratory dissolution experiments have been conducted to quantify rates of solute acquisition, measured as Ca2+ concentration against time, from glacigenic sediments suspended in cold, dilute waters. Suspended sediment character was constrained by field-calibrated ranges of both concentration in meltwater (g cm–3) and specific surface area by sediment mass (cm2 g–1). This constraint yielded, for the first time in a glacier hydrochemical study, dissolution rate data as a function of the specific sediment surface area by water volume (SSAv; cm2 cm–3). The resulting experimental data have been used to calibrate a kinetic dissolution model (Brown et al., in press), where the rate of solute acquisition is considered in terms of an initial concentration reflecting rapid ion-exchange reactions (C0), an ultimate steady-state concentration (Cs), and a rate parameter (k). The results, which allow the dissolution equation parameters C0, Cs, and k to be expressed in terms of SSAv, are used here to drive dynamic predictive model of within-channel solute acquisition in a theoretical, 4-cell subglacial channel. Using realistic values of SSAv and residence time, this allows the magnitude of WSA to be predicted at any distance from the head of the channelised drainage system to the glacier snout.