Solute flux in meltwaters draining from a glacierized basin in the Karakoram mountains

Abstract

Abstract:Electrical conductivity of meltwaters in the Batura river which drains from the portal of Batura glacier in the Karakoram mountains was recorded continuously, together with stage, throughout an ablation season with the aim of estimating the annual total solute¯ux from the 56% glacier-covered basin. Through-time variations of meltwater cationic concentration were obtained from the electrical conductivity record using a rating curve established between sums of cations determined in periodically-collected samples of meltwater and electrical conductivity measured at the times of sampling. Hourly average cationic¯ux was then obtained as the product of cationic concentration and discharge, error arising as a result of inaccuracy in river gauging and use of the rating relationship. Electrical conductivity varied diurnally inversely with discharge, overall level decreasing as discharge increased in spring, continuing subdued through July and August irrespective of episodic discharge¯uctuations. In contrast, solute¯ux mimicked discharge variation, low solute concentrations being oset by the volume of water¯owing. Total annual cationic¯ux from Batura basin was 1 . 03 Meq+$ 15%. Assuming almost all of the¯ux was derived subglacially, the solute¯ux from beneath Batura glacier was 2Á64 + 0Á40 eq m À2 a À1 . These rates of cationic denudation, substantially higher than the continental average, are at the top end of the global range of reasonably-reliable estimates for other smaller glacierized basins. Carbonate lithology, high annual runo, high sediment concentration in meltwaters, and long subglacial pathways account for the high solute¯ux from Batura glacier. Through longer residence times of meltwater in transit under ice and higher discharges, dissolution kinetics and¯ow couple to enhance solute¯uxes from larger glaciers. Although subglacial chemical denudation in the Karakoram mountains is signi®cant in carbon cycling at the continental scale, such carbonate dissolution probably contributes little to net consumption of carbon dioxide from the atmosphere.

Seasonality of Solute Flux and Water Source Chemistry in a Coastal Glacierized Watershed Undergoing Rapid Change: Wolverine Glacier Watershed, Alaska

“…Classification of flow regimes in glacierized watersheds in particular has been applied to determine water sources and storages (e.g., Hannah et al., 2000; Swift et al., 2005), suspended sediment loading (e.g., Leggat et al., 2015; Orwin et al., 2010), and hydrograph prediction under continued glacier mass loss (e.g., Fleming & Clarke, 2005; Stahl & Moore, 2006). However, only a few studies have applied a classification scheme to determine time‐varying solute fluxes over a melt season (Collins, 1999; Rasch et al., 2000). We suggest that this classification system could be expanded upon and used elsewhere to better contextualize solute export when sampling is temporally limited or to reanalyze previous data (e.g., Anderson et al., 1997; Axtmann & Stallard, 1995) to refine chemical weathering and solute flux estimates.…”

Spatiotemporal Drivers of Hydrochemical Variability in a Tropical Glacierized Watershed in the Andes

“…This C‐Q pattern is unique compared to previously studied temperate glacierized systems. Many temperate studies showed clear non‐chemostatic dilution behavior during the melt season (e.g., Brown, 2002; Collins, 1979; Collins, 1983, 1999; Hindshaw et al., 2011; Kumar et al., 2019), while others showed strong chemostatic (Clow & Mast, 2010; Wlostowski et al., 2018) or mobilizing (Lewis et al., 2012; Stachnik et al., 2016) behavior during melt seasons due to accelerated mineral dissolution and increased hydrological connectivity. At Gavilan Machay, because of the year‐round ablation and humid conditions, solute mobilization by melt inputs is subtle relative to discharge variability; instead, melt coinciding with large precipitation events produce peak surface runoff contributions throughout the year that generate episodic dilution.…”

Comparative Assessment of Spatial Variability and Trends of Flows and Sediments under the Impact of Climate Change in the Upper Indus Basin

“…The sediment is mainly transported by snow and ice melt process. Collins [51] estimated that for Hunza basin and Indus at Bashem Qila drives 60% and 40% of sediment loads annually from glacier melting. Own et al [52] concluded that debris transport is an important contributor in glacierized regions of the UIB.…”