Hydroclimate Drives Seasonal Riverine Export Across a Gradient of Glacierized High‐Latitude Coastal Catchments

Jenckes, Jordan; Munk, LeeAnn; Ibarra, Daniel E.; Boutt, D. F.; Fellman, Jason B.; Hood, Eran

doi:10.1029/2022wr033305

Cited by 10 publications

(36 citation statements)

References 88 publications

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“…We queried the NWIS database so that only samples in which HCO 3 concentrations were derived from alkalinity determined by titration methods were returned. For samples collected by Jenckes et al (2023) HCO 3 was calculated from alkalinity concentrations obtained by titration methods. In this study, we use HCO 3 concentrations primarily for graphical representation of the variability in water chemistry across our chosen study sites.…”

Section: Hydrochemical Data Compilationmentioning

confidence: 99%

“…The NADP sites are situated at the north, west, and east extremes of the GoA region. We supplement these data with precipitation chemistry collected by Jenckes et al (2023) within the southern KP region. Quality control for river water samples included removing any samples where the charge of the anions (SO 4 and Cl) exceeded the charge of the cations (Ca, Mg, Na, K; see Cole et al, 2022).…”

Section: Hydrochemical Data Compilationmentioning

confidence: 99%

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Geochemical Weathering Variability in High Latitude Watersheds of the Gulf of Alaska

Jenckes,

Muñoz,

Ibarra

et al. 2024

JGR Earth Surface

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High latitude regions across the globe are undergoing severe modifications due to changing climate. A high latitude region of concern is the Gulf of Alaska (GoA), where these changes in hydroclimate undoubtedly affect the hydrogeochemistry of freshwater discharging to the nearshore ecosystems of the region. To fill the knowledge gap of our understanding of freshwater stream geochemistry with the GoA, we compile stream water chemistry data from 162 stream sites across the region. With an inverse model, we estimate fractional contributions to solute fluxes from weathering of silicate, carbonate, and sulfide minerals, and precipitation. We assess weathering rates across the region and compare them against global river yields. The median fractional contribution of carbonate weathering to total weathering products is 78% across all stream sites; however, there are several streams where silicate weathering is a dominant source of solutes. Weathering by sulfuric acid is elevated in glacierized watersheds. Finally, cation weathering rates are lower in GoA streams compared to the world's largest rivers; however, weathering rates are similar when compared to a global dataset of glacier fed streams. We suggest that hydrologic changes driven by glacier ice loss and increased precipitation will alter river water quality and chemical weathering regimes such that silicate weathering may become a more important source of solutes and sulfide oxidation may decrease. This contribution provides a platform to build from for future investigations into changes to stream water chemistry in the region and other high latitude watersheds.

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Section: Hydrochemical Data Compilationmentioning

confidence: 99%

Section: Hydrochemical Data Compilationmentioning

confidence: 99%

Geochemical Weathering Variability in High Latitude Watersheds of the Gulf of Alaska

Jenckes,

Muñoz,

Ibarra

et al. 2024

JGR Earth Surface

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“…The seasonal cycles of solute chemistry and discharge and their data sets were published by Jenckes et al (2023). Monthly water sampling in the five watersheds spanned March through September of 2019, 2020, and 2021.…”

Section: Water Samplingmentioning

confidence: 99%

“…Mountain glaciers impact watershed hydrology by modifying the supply of water (Immerzeel et al, 2010), the timing of peak runoff (Jansson et al, 2003) and influencing both riverine and coastal water quality (Hood et al, 2015;Jenckes et al, 2022Jenckes et al, , 2023. They store water on short and long time scales and have the capacity to decrease or increase runoff depending on their long-term mass gain or loss (Jansson et al, 2003).…”

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Hydrologic and Landscape Controls on Rock Weathering Along a Glacial Gradient in South Central Alaska, USA

Muñoz,

Jenckes,

Ramos

et al. 2024

JGR Earth Surface

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Rock weathering impacts atmospheric CO2 levels with silicate rock dissolution removing CO2, and carbonate dissolution, pyrite oxidation, and organic rock carbon oxidation producing CO2. Glacierization impacts the hydrology and geomorphology of catchments and glacier retreat due to warming can increase runoff and initiate landscape succession. To investigate the impact of these changes on catchment scale weathering CO2 balances, we report monthly samples of solute chemistry and continuous discharge records for a sequence of glacierized watersheds draining into Kachemak Bay, Alaska. We partition solute and acid sources and estimate inorganic weathering CO2 balances using an inverse geochemical mixing model. Furthermore, we investigated how solutes vary with discharge conditions utilizing a concentration‐runoff framework. We develop an analogous fraction‐runoff framework which allows us to investigate changes in weathering contributions at different flows. Fraction‐runoff relationships suggest kinetic limitations on all reactions in glacierized catchments, and only silicate weathering in less glacierized catchments. Using forest cover as a proxy for landscape age and stability, multiple linear regression shows that faster reactions (pyrite oxidation) contribute less to the solute load with increasing forest cover, whereas silicate weathering (slow reaction kinetics) contributes more. Overall, in glacierized catchments, we find elevated weathering fluxes at high runoff despite significant dilution effects. This makes flux estimates that account for dilution more important in glacierized catchments. Our findings quantify how glaciers modify the inorganic weathering CO2 balance of catchments through hydrologic and geomorphic forcings, and support the previous hypothesis that deglaciation will be accompanied by a shift in inorganic weathering CO2 balances.

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Physical and chemical characterization of remote coastal aquifers and submarine groundwater discharge from a glacierized watershed

Russo,

Jenckes,

Boutt

et al. 2024

Hydrological Processes

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Coastal aquifers play an important role in marine ecosystems by providing high fluxes of nutrients and solutes via submarine groundwater discharge pathways. The physical and chemical characterization of these dynamic systems is foundational to understanding the extent and magnitude of hydrogeologic processes and their subsequent contributions to the marine environment. We describe a km‐scale experimental field site located in a glaciofluvial delta entering Kachemak Bay, Alaska. Our characterization applies geophysical (ERT and HVSR), hydrogeologic (grain size analyses, slug tests and tidal response analyses) and geochemical (major ions and stable water isotopes) methods to describe the complexity of coastal aquifers in proglacial environments currently experiencing rapid transformations. The hydrogeologic and geophysical techniques revealed thick (20–84 m) sediments dominated by sands and gravels and delineated zones of freshwater, brackish water and saltwater at both high and low tides within the subterranean estuary. Estimates of hydraulic conductivities via multiple approaches ranged from 2 to 250 m d−1, with means across the four methods within the same order of magnitude. Tidal response analyses highlighted a coastal aquifer in strong connection with the sea as evidenced by clear spring‐ and neap‐tidal signals within a proximal piezometric hydrograph. Geochemical sampling revealed coastal groundwaters as substantially enriched in solutes compared to proximal river samples with limited variability across seasons. A clear connection between the Wosnesenski River and the adjacent aquifer was also observed, with concentrated recharge from the river corridor during the meltwater season. This combination of approaches provides the basis for a conceptual model for coastal aquifer systems within the Gulf of Alaska and an upscaled mean daily yield of freshwater and solutes from the delta subsurface. Our findings are critical for subsequent numerical simulations of groundwater flow, tidal pumping and chemical reactions and transport in these understudied environments. This approach may be applied for low‐cost, large‐scale hydrogeologic investigations in coastal areas and may be particularly useful for remote sites where access and mobility are challenging.

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Hydroclimate Drives Seasonal Riverine Export Across a Gradient of Glacierized High‐Latitude Coastal Catchments

Abstract: Earth's cold regions are rapidly degrading primarily driven by atmospheric warming. Globally, glaciers are losing mass at an accelerated rate leading to changes in the flux of freshwater, solutes, and sediment (

Cited by 10 publications

References 88 publications

Geochemical Weathering Variability in High Latitude Watersheds of the Gulf of Alaska

Geochemical Weathering Variability in High Latitude Watersheds of the Gulf of Alaska

Hydrologic and Landscape Controls on Rock Weathering Along a Glacial Gradient in South Central Alaska, USA

Physical and chemical characterization of remote coastal aquifers and submarine groundwater discharge from a glacierized watershed

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